Characterization of Adrenal miRNA-Based Dysregulations in Cushing’s Syndrome

Abstract

MiRNAs are important epigenetic players with tissue- and disease-specific effects. In this study, our aim was to investigate the putative differential expression of miRNAs in adrenal tissues from different forms of Cushing’s syndrome (CS). For this, miRNA-based next-generation sequencing was performed in adrenal tissues taken from patients with ACTH-independent cortisol-producing adrenocortical adenomas (CPA), from patients with ACTH-dependent pituitary Cushing’s disease (CD) after bilateral adrenalectomy, and from control subjects. A confirmatory QPCR was also performed in adrenals from patients with other CS subtypes, such as primary bilateral macronodular hyperplasia and ectopic CS. Sequencing revealed significant differences in the miRNA profiles of CD and CPA. QPCR revealed the upregulated expression of miR-1247-5p in CPA and PBMAH (log2 fold change > 2.5, p < 0.05). MiR-379-5p was found to be upregulated in PBMAH and CD (log2 fold change > 1.8, p < 0.05). Analyses of miR-1247-5p and miR-379-5p expression in the adrenals of mice which had been exposed to short-term ACTH stimulation showed no influence on the adrenal miRNA expression profiles. For miRNA-specific target prediction, RNA-seq data from the adrenals of CPA, PBMAH, and control samples were analyzed with different bioinformatic platforms. The analyses revealed that both miR-1247-5p and miR-379-5p target specific genes in the WNT signaling pathway. In conclusion, this study identified distinct adrenal miRNAs as being associated with CS subtypes.

1. Introduction

Cushing’s syndrome (CS) results from the excessive secretion of cortisol, leading to visceral obesity, resistance to insulin, osteoporosis, and altered lipid and glucose metabolism [1,2]. Excessive production of cortisol by the adrenal glands can be either ACTH-dependent or -independent. In the majority of patients, hypercortisolism is due to ACTH secretion by corticotroph adenomas of the pituitary gland (Cushing’s disease, CD) or by ectopic tumors [3]. Approximately 20% of cases are ACTH-independent, where cortisol is secreted autonomously by the adrenal cortex. The pathology of ACTH-independent cases is diverse; they are most often caused by unilateral cortisol-producing adrenocortical adenomas (CPA). Rare causes are cortisol-secreting adrenocortical carcinomas (ACC), primary bilateral macronodular adrenocortical hyperplasia (PBMAH), bilateral CPAs, and primary pigmented nodular adrenal disease (PPNAD) [4,5]. Irrespective of the subtype, prolonged exposure to cortisol in CS is associated with increased mortality and cardiovascular morbidity in its patients [6]. Treatment is based on the underlying cause of hypercortisolism, with pituitary surgery or adrenalectomy being the preferred choice. Medical therapy options in CS are few and consist of pituitary-directed drugs, steroid synthesis inhibitors, and glucocorticoid receptor antagonists [7]. For the timely diagnosis and targeted management of CS and its subtypes, a comprehensive understanding of cortisol secretion, in terms of canonical signaling pathways as well as upstream epigenetic factors, is needed.
MiRNA molecules have emerged as key epigenetic players in the transcriptional regulation of cortisol production. Briefly, the deletion of Dicer in adrenals, a key miRNA processing enzyme, revealed diverse expression changes in miRNAs along with related changes in steroidogenic enzymes such as Cyp11b1 [8]. Furthermore, key enzymes in the cortisol biosynthesis pathway, namely Cyp11a1, Cyp21a1, Cyp17a1, Cyp11b1, and Cyp11b2, were also found to be regulated by various miRNAs (miRNA-24, miRNA-125a-5p, miRNA-125b-5p, and miRNA-320a-3p) in in vitro studies [9]. Consequently, various studies have also characterized miRNA expression profiles in CS subtypes. Importantly, miRNA expression in the corticotropinomas of CD patients was found to vary according to USP8 mutation status [10]. Other studies have also identified specific miRNA candidates and associated target genes in the adrenals of patients with PPNAD [11], PBMAH [12,13], and massive macronodular adrenocortical disease [14]. Interestingly, no common miRNA candidates were found among these studies, indicating the specificity of miRNAs to the different underlying pathologies in CS.
There are limited studies directly comparing miRNA expression profiles of ACTH-dependent and ACTH-independent CS patients. Consequently, in our previous study, we found differences in expression profiles when comparing circulating miRNAs in CD and CPA patients [15]. We hypothesized that the presence of ACTH possibly influences the miRNA profile in serum due to the upstream differential expression in the origin tissues. In this study, we aim to further explore this hypothesis by comparing the miRNA expression profile of adrenal tissues in ACTH-dependent and ACTH-independent CS. In brief, miRNA specific sequencing was performed in two prevalent subtypes of CS: in CD, the most prevalent ACTH-dependent form; and in CPA, the most prevalent ACTH-independent form. Specific miRNA candidates related to each subtype were further validated in other forms of CS. To further investigate our hypothesis, the response of miRNA candidates following ACTH stimulation was assessed in mice, and the expression of miRNAs in murine adrenals was subsequently investigated. Finally, an extensive targeted gene analysis was performed based on in silico predictions, RNA-seq data, and luciferase assays.

2. Results

2.1. Differentially Expressed miRNAs

NGS revealed differentially expressed miRNAs between the different groups analyzed (Figure 1). CD and CPA taken together as CS showed a differentially expressed profile (42 significant miRNAs) in comparison to controls. Moreover, individually, CPA and CD were found to show a significantly different expression profile in comparison to controls (n = 38 and n = 17 miRNAs, respectively). Interestingly, there were no significantly upregulated genes in the adrenals of patients with CD in comparison to the control adrenals. A comparative analysis of the top significant miRNAs (log2 fold change (log2 FC) > 1.25 & p < 0.005) between the two groups was performed and the representative Venn diagrams are given in Figure 2. Briefly, miR-1247-5p, miR-139-3p, and miR-503-5p were significantly upregulated in CPA, in comparison to both CD and controls. Furthermore, miR-150-5p was specifically upregulated in CPA as compared to CD. Several miRNAs (miR-486-5p, miR-551b-3p, miR-144-5p, miR-144-3p, and miR-363-3p) were found to be significantly downregulated in the groups of CPA and CD in comparison to controls. MiR-19a-3p and miR-873-5p were found to be commonly downregulated in CPA in comparison to both CD and controls. Principal component analyses based on miRNA sequencing did not identify any major clusters among the samples. Furthermore, the miRNA profile was not different among the CPA samples based on the mutation status of PRKACA (Supplementary Materials Figure S1).
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Figure 1. Differentially expressed miRNAs from sequencing. Volcano plot showing the relationship between fold change (log2 fold change) and statistical significance (−log10 p value). The red points in the plot represent significantly upregulated miRNAs, while blue points represent significantly downregulated miRNAs. CPA, cortisol producing adenoma; CD, Cushing’s disease; Cushing’s syndrome represents CPA and CD, taken together.
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Figure 2. Venn analyses of the common significant miRNAs from each group. The significantly expressed miRNAs from each sequencing analysis were shortlisted and compared between the groups. CPA, cortisol producing adenoma; CD, Cushing’s disease.

2.2. Validation and Selection of Candidate miRNAs

For validation by QPCR, the most significant differentially expressed miRNAs (log2 FC > 1.25 & p < 0.005) among the groups were chosen (Table S1). According to the current knowledge, upregulated miRNAs are known to contribute more to pathology than downregulated miRNAs [16]. Since the total number of significantly upregulated miRNAs was six, all these miRNAs were chosen for validation. Contrarily, 25 miRNAs were significantly downregulated among the groups. In particular, miR-486-5p, miR-551b-3p, miR-144-5p, miR-144-3p, and miR-363-3p were found to be commonly downregulated in the CS group in comparison to controls; therefore, these miRNAs were chosen for validation.
Among the upregulated miRNA candidates, miR-1247-5p QPCR expression confirmed the NGS data (Figure 3A, Table S1). Moreover, miR-150-5p and miR-139-3p were upregulated in CPA specifically in comparison to CD, and miR-379-5p was upregulated in CD in comparison to controls by QPCR. In the case of downregulated genes, none of the selected miRNAs could be confirmed by QPCR (Figure 3B). Thus, analysis of the six upregulated and five downregulated miRNAs from NGS yielded two significantly upregulated miRNA candidates, miR-1247-5p in CPA and miR-379-5p in CD, when compared to controls. These miRNA candidates were taken up for further QPCR validation in an independent cohort of other subtypes of CS (Figure 4), namely ACTH-dependent ectopic CS (n = 3) and ACTH-independent PBMAH (n = 10). The QPCR analysis in the other subtypes revealed miR-1247-5p to be consistently upregulated in ACTH-independent CS (PBMAH and CPA) in comparison to ACTH-dependent CS (CD and ectopic CS) and controls. On the other hand, miR-379-5p was upregulated in CD and PBMAH in comparison to controls.
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Figure 3. QPCR analyses of significant miRNAs from sequencing analyses. Data are represented as mean ± standard deviation (SD) of −dCT values: (A) Expression analysis of significantly upregulated miRNAs; (B) Expression analysis of common significantly downregulated miRNAs. Housekeeping gene: miR-16-5p. Statistics: ANOVA test with Bonferroni correction to detect significant differences between patient groups with at least a significance of p-value < 0.05 (*).
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Figure 4. QPCR analyses of significantly upregulated miRNAs from validation QPCR. Data are represented as mean ± standard deviation (SD) of −dCT values. Housekeeping gene: miR-16-5p. Statistics: ANOVA test with Bonferroni correction to detect significant differences between patient groups with at least a significance of p-value < 0.05 (*).

2.3. In Vivo Assessment of ACTH-Independent miR-1247-5p

To analyze the influence of ACTH on miRNA expression, the expression of miR-1247-5p and miR-379-5p were assessed in the adrenal tissues of ACTH stimulated mice at different time points. For this analysis, miR-96-5p was taken as a positive control, as it has previously been reported to be differentially expressed in ACTH stimulated mice [17]. The analyses revealed that the expression of miR-1247-5p and miR-379-5p did not change at different timepoints of the ACTH stimulation (Figure 5). Meanwhile, the positive control of mir-96-5p showed a dynamic expression pattern with upregulation after 10 min, followed by downregulation at the subsequent 30 and 60 min time points, in concordance with previously reported findings [18].
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Figure 5. Analysis of miRNA expression in ACTH stimulated mice tissue. QPCR analyses of positive controls, miR-96-5p, and candidates miR-379-5p and miR-1247-5p. Mice were injected with ACTH, and adrenals were collected at different timepoints to assess the impact of ACTH on miRNA expression. Data are represented as mean ± standard deviation (SD) of −dCT values. Housekeeping gene: miR-26a-5p. Statistics: ANOVA test with Bonferroni correction to detect significant differences between patient groups with at least a significance of p-value < 0.05 (*).

2.4. In Silico Analyses of miRNA Targets

Two diverse approaches were employed for a comprehensive in silico analysis of the miRNA targets. First, the predicted targets of miR-1247-5p and miR-379-5p were taken from the TargetScan database, which identified miRNA–mRNA target pairs based on sequence analyses [19]. The expression status of these targets was then checked in the RNA sequencing data from CPA vs. controls (miR-1247-5p) and PBMAH vs. controls (miR-379-5p). Targets that showed significant expression changes in the sequencing data were shortlisted (Figure 6A). Among the 1061 predicted miR-1247-5p targets, 28 genes were found to show significant expression changes in CPA (20 upregulated, 8 downregulated). On the other hand, for 124 predicted miR-379-5p targets, 23 genes were found to show significant expression changes in PBMAH (20 upregulated, 3 downregulated). Interestingly, the selected targets were found to be unique for each miRNA, except for FICD (FIC domain protein adenylyltransferase) (Figure 6B).
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Figure 6. (A) Differentially expressed target genes of miRNAs from sequencing. Data are represented as log2 fold change in comparison to the controls. Statistics: ANOVA test with Bonferroni correction to detect significant differences between patient groups with at least a significance of p-value < 0.05. (B) Venn analyses of common significant miRNA target genes and related pathways. The significantly expressed targets from each sequencing analysis were shortlisted and compared between the groups. Predicted pathways of the targets from the Panther database were shortlisted and compared between the groups.

2.5. In Vitro Analyses of miR-1247-5p Targets

For in vitro analyses, we focused on downregulated targets, as we expect our upregulated miRNA candidates to cause a downregulation of the target mRNAs. For our downregulated mRNAs, only targets of miR-1247-5p were found to have published links to CS, namely Cyb5a, Gabbr2, and Gnaq (Table 1). Therefore, these three targets were then verified by QPCR in the groups of CPA, CD, PBMAH, ectopic CS, and controls (Figure 6). Only Cyb5A was found to be significantly downregulated in ACTH-dependent forms (ectopic CS and CD) as well as in ACTH-independent CS (PBMAH and CPA) in comparison to controls. Consequently, to assess whether Cyb5a is indeed regulated by miR-1247-5p, a dual luciferase assay was performed. To prove our hypothesis, treatment of Cyb5a-WT cells with miR-1247-5p mimic was expected to lead to a reduced luminescence, whereas no effects were expected in cells treated with the miR-1247-5p inhibitor or the Cyb5a-mutant (with a mutation in the miR-1247-5p binding site). As shown in Figure 7, transfection of miR-1247-5p significantly reduced luminescence from Cyb5a-WT in comparison to cells transfected with Cyb5a-WT and miR-1247-5p inhibitors. However, these predicted binding results were not found to be specific, as there were no significant differences when compared to wells transfected with Cyb5a-WT alone (Figure 8). Consecutively, when the mutated Cyb5a-Mut were transfected along with the mimics and inhibitors, no significant differences in luminescence were observed in the transfected population. Thus, direct interaction between miR-1247-5p and its predicted target gene Cyb5A could not be conclusively proven using this luciferase assay.
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Figure 7. QPCR analyses of the top predicted targets of miR-1247-5p. Data are represented as mean ± standard deviation (SD) of −dCT values. Housekeeping gene: PPIA. Statistics: ANOVA test with Bonferroni correction to detect significant differences between patient groups with at least a significance of p-value < 0.05 (*).
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Figure 8. Results of dual luminescence assay on cells transfected with miR-1247-5p mimics and related controls. Cells were transfected with plasmids containing either the WT or Mut miRNA binding sequence in Cyb5a. Either miR-1247-5p mimics or miR-1247-5p inhibitors were transfected together with the respective plasmids. Data are represented as mean ± standard error of mean (SEM) of relative luminescence unit values. Statistics: ANOVA test with Bonferroni correction to detect significant differences between patient groups with at least a significance of p value < 0.05 (*).
Table 1. Analysis of the predicted targets of miR-1247-5p and their expression levels in comparison to controls (log2 fold change). Published literature on target genes in reference to CS is highlighted in bold.
Table

2.6. Pathway Analyses of miRNA Targets

For the pathway analysis (Reactome) we used the 28 predicted miRNA-1247-5p targets and the 23 predicted miRNA-379-5p targets from TargetScan, which were significantly differently expressed in the RNA-seq (Figure 6). Concurrently, the pathways commonly enriched by both miRNAs included the WNT signaling pathway and N-acetyl-glucosamine synthesis (Figure 9A). As a complementary approach, in silico analyses were also performed based on the targets from miRTarBase. In this database, targets are shortlisted based on published experimental results. In this analysis, miR-1247-5p (n = 21) and miR-379-5p targets (n = 85) were unique. While the validated targets of miR-379-5p were found to show significant changes in expression in the RNA-seq data from PBMAH (n = 12), none of the validated miR-1247-5p targets were found to show significant expression changes in the RNA-seq data from CPA. Therefore, all the validated targets of the miRNAs were subjected to pathway analyses (Panther). Interestingly, the WNT signaling pathway was also found to be commonly regulated by both miRNAs using this approach (Figure 9B). Finally, the expression status of target genes related to WNT signaling pathways were checked in our RNA-seq data (Figure S2). Given the upregulated status of the miRNAs, a downregulated expression of its target genes was expected. However, a significantly upregulated expression was observed for DVL1 in CPA in comparison to controls and for ROR1 in PBMAH in comparison to controls.
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Figure 9. Pathway analyses of miRNA target genes. (A) The predicted targets were matched with the RNA-seq expression data. For miR-1247-5p, CPA vs. controls expression data; and for miR-379-5p, PBMAH vs. controls expression data. The significantly expressed target genes were then subjected to pathway analyses by Reactome. The significantly enriched pathway networks (p < 0.05) and their related genes are given. (B) The experimentally validated target genes from miRTarBase were analyzed for their role in pathways by the Panther database. The target genes and their related pathways are given. The commonly represented pathways are marked in bold.

3. Discussion

MiRNAs are fine regulators of both physiology and pathology and have diverse roles as diagnostic biomarkers as well as therapeutic targets. While circulating miRNAs have been investigated as potential biomarkers for hypercortisolism in CS subtypes (36), comprehensive analyses of their pathological role in CS subtypes have not yet been performed. This study hoped to uncover the pathological role of miRNAs in different CS subtypes as well as identify unique epigenetic targets contributing to hypercortisolism in these subtypes. As such, miRNA sequencing was performed in the ACTH-independent CPA and ACTH-dependent CD, with additional QPCR validation in PBMAH and ectopic CS. As expected, miRNA expression profiles in CD and CPA were very different.

3.1. ACTH-Independent Upregulated miRNAs in CS

Among the analyzed miRNAs, only miR-1247-5p and miR-379-5p showed the most prominent changes in expression levels. Briefly, miR-1247-5p was significantly upregulated in ACTH-independent forms of CS, CPA, and PBMAH (Figure 1 and Figure 3) while miR-379-5p was found to be upregulated in CD and PBMAH, in comparison to controls. Even though CD and PBMAH represent CS subtypes with different ACTH dependence, albeit both with hyperplastic tissue, it is interesting to find a shared miRNA expression status. Concurrently, miRNAs have been identified as dynamic players in regulating the acute effect of ACTH on adrenal steroidogenesis in in vivo murine studies [20,21]. Further diverse miRNAs have been characterized to regulate steroidogenesis in ACTH and dexamethasone treated rats [22] (suppressed ACTH) as well as in in vitro studies [20]. It is possible that miR-379-5p contributes to the adrenal hyperplasia present in both PBMAH and CD by targeting specific genes related to hyperplasia, and miR-1247-5p by contributing to cortisol production independent of ACTH regulation in CPA and PBMAH.
Interestingly, the miRNA candidates (mir-1247-5p and miR-379-5p) in our study have not been previously characterized in any of these studies. Furthermore, the expression of mir-1247-5p and miR-379-5p were found to be independent of ACTH stimulation, underlying their role in CS independently of the HPA axis control and postulating specific regulatory processes.

3.2. Target Genes of miRNAs in CS

Initially, we focused on the selection of known CS specific target genes that could be directly repressed by miRNAs, thereby contributing to pathology. The predicted target genes of miR-1247-5p and miR-379-5p were assessed for their downregulated expression status in the RNA-seq data. Among the selected target genes, only Cyb5a was found to be significantly downregulated in all forms of CS (Figure 6). Cytochrome b5 (CYB5A) is a marker of the zona reticularis and is an important regulator of androstenedione production [23,24]. Based on its role in adrenal steroidogenesis, it is possible that Cyb5a is downregulated by miR1247-5p. To prove our hypothesis, a dual luciferase assay was performed in HELA cell line to identify a direct interaction between Cyb5a and miR-1247-5p (Figure 7). Unfortunately, a direct interaction could not be proven, indicating that miR-1247-5p perhaps regulates its target genes in different ways.

3.3. Pathway Analyses of miRNA Targets

To identify miRNA specific regulatory processes, comprehensive target and pathway analyses were performed. Independent pathway analyses of the respective targets with two different databases of Reactome and Panther showed the WNT signaling pathway as a common targeted pathway of both mir-1247-5p and miR-379-5p (Figure 8). The WNT signaling pathway represents a crucial regulator in diverse developmental as well as pathological processes with tissue-specific effects [25,26]. Consequently, the WNT pathway has been largely characterized as one of the dysregulated pathophysiological mechanisms in CPA. Mutations in PRKACA, one of the WNT signaling proteins, are present in approximately 40% of CPA [27]. In the case of CD, dysregulated WNT signaling has been characterized as promoting proliferation in ACTH-secreting pituitary adenomas [28]. Moreover, activating mutations in beta catenin, one of the WNT signaling pathways, has been characterized as driving adrenal hyperplasia through both proliferation-dependent and -independent mechanisms [29]. Thus, it could be hypothesized that by targeting specific genes in the pathway, miRNAs drive specific pathophysiological processes in diverse CS subtypes.

3.4. MiRNA Target Genes in WNT Signaling

DVL1 (TargetScan) and DVL3 (miRTar) are the shortlisted target genes of miR-1247-5p in the WNT signaling pathway. These genes are members of canonical WNT pathways and, importantly, activation of the cytoplasmic effector Dishevelled (Dvl) is a critical step in WNT/β-catenin signaling initiation [30,31]. Interestingly, no difference in DVL1 and DVL3 gene expression was found in the analyses of ACTH-secreting pituitary adenomas [32]. Therefore, it could be possible that DVL1 and DVL3 are only targeted by miR-1247-5p specifically in the adrenal of CPA and PBMAH patients, leading to its characterized tumor progression. EDN1, TGFBR1 (TargetScan), and ROR1 (miRTar) were the target genes of miR-379-5p related to the WNT pathway. In epithelial ovarian cancer, Endothelin-1 (EDN-1) was found to regulate the epithelial–mesenchymal transition (EMT) and a chemoresistant phenotype [33]. In the case of receptor tyrosine kinase-like orphan receptor 1 (ROR1), higher expression of the gene was associated with a poor prognosis in ovarian cancer [34]. Concurrently, suppression of TGFBR1-mediated signaling by conditional knockout in mice was found to drive the pathogenesis of endometrial hyperplasia, independent of the influence of ovarian hormones [35]. Therefore, it could be hypothesized that the dysregulated expression of these factors in adrenals could trigger similar hyperplastic effects mediated by these factors, as in ovarian tissues.

3.5. Bottlenecks and Future Outlook

Interestingly, among these genes, only DVL1 and ROR1 were found to be significantly upregulated in the RNA-seq data (Figure S2). The major regulatory role of miRNAs in gene expression come from their ability to repress gene expression at the level of transcription and translation. There are also reports of miRNA-mediated gene upregulation; however, the physiological evidence of the role is still unresolved [36]. Therefore, it is interesting to see the selected targets of miR-1247-5p and miR-379-5p upregulated. Moreover, it should be noted that most of the experimentally validated miRNA targets were identified by CLIP methods [37]. Crosslinking immunoprecipitation (CLIP) are binding assays that provide genome-wide maps of potential miRNA-target gene interactions based on sequencing. Moreover, these assays do not make functional predictions on the outcome of miRNA binding, and neither do upregulation or downregulation [38,39]. Therefore, in our current experimental setting, we could only identify potential miRNA target genes and speculate on their pathological role based on the published literature and in silico analyses. Furthermore, extensive mechanistic analyses based on these potential targets could help in elaborating the specific epigenetic pathways that fine-tune CS pathology in different subtypes.

4. Materials and Methods

4.1. Sample Collection and Ethics Approval

All patients were registered in the German Cushing’s Registry, the ENS@T or/and NeoExNET databases (project number protocol code 379-10 and 152-10). The study was approved by the Ethics Committee of the University of Munich. All experiments were performed according to relevant guidelines and protocols, and written informed consent was obtained from all patients involved. The adrenal samples used in the sequencing (miRNA and RNA) belong to the same patient.
For miRNA-specific next-generation sequencing (NGS), a total of 19 adrenocortical tissue samples were used. The cohort consisted of the following patient groups: ACTH-independent CPA, n = 7; ACTH-dependent hypertrophic adrenals of CD patients after bilateral adrenalectomy, n = 8; normal adjacent adrenal tissue from patients with pheochromocytoma as controls, n = 8. For QPCR validation, the patient groups included adrenal tissue from ACTH-independent PBMAH, n = 10, and ACTH-dependent ectopic CS, n = 3.
In the case of mRNA sequencing, a total of 23 adrenocortical tissue samples were used. This includes the following patient groups: CPA, n = 7; PBMAH, n = 8; normal adjacent adrenal tissue from patients with pheochromocytoma as controls, n = 8.
The clinical characteristics of the patients are given in Table 2. Furthermore, of the eight CPA samples in the study, three of them carried known somatic driver mutations in the PRKACA gene and in the ten PBMAH samples, two carried germline mutations in the ARMC5 gene.
Table 2. Clinical characteristics of the patient groups. Data are given as median with 25th and 75th percentiles in brackets. CPA, cortisol producing adenoma; CD, Cushing’s disease.
Table
The adrenal tissues were stored at −80 °C. Total RNA isolation was carried out from all adrenal cortex samples by an RNeasy Tissue Kit (Qiagen, Hilden, Germany). The isolated RNA was kept frozen at −80 °C until further use.

4.2. MiRNA and RNA Sequencing

RNA integrity and the absence of contaminating DNA were confirmed by Bioanalyzer RNA Nano (Agilent Technologies, Santa Clara, CA, USA) and by Qubit DNA High sensitivity kits, respectively. Sequencing libraries were prepared using the Illumina TruSeq Small RNA Library Preparation Kit. NGS was performed on 2 lanes of an Illumina HiSeq2500 (Illumina, CA, USA) multiplexing all samples (paired end read, 50 bp). The quality of sequencing reads was verified using FastQC0.11.5 (http://www.bioinformatics.babraham.ac.uk/projects/fastqc, date last accessed: 13 March 2020) before and after trimming. Adapters were trimmed using cutadapt [40]. Reads with <15 bp and >40 bp insert sequences were discarded. An alignment of reads was performed using miRBase V21 [41,42] with sRNAbench [43]. EdgeR and DeSeq in R were used for further analyses [44,45]. MiRNAs with at least 5 raw counts per library were included. RNA-seq was performed by Qiagen, Hilden, Germany. For mRNA, sequencing was performed on Illumina NextSeq (single end read, 75 bp). Adapter and quality trimming were performed by the “Trim Reads” tool from CLC Genomics Workbench. Furthermore, reads were trimmed based on quality scores. The QC reports were generated by the “QC for Sequencing Reads” tool from CLC Genomics Workbench. Read mapping and gene quantification were performed by the “RNA-seq Analysis” tool from CLC Genomics Workbench [46]. The miRNA-seq data generated in this study have been submitted to the NCBI (PRJNA847385).

4.3. Validation of Individual miRNAs

MiRNAs and genes significantly differentially expressed by NGS were validated by QPCR. Reverse transcription of miRNA-specific cDNA was performed by using the TaqMan MicroRNA Reverse Transcription Kit (Thermo Fisher Scientific, Munich, Germany), and the reverse transcription of RNA genes was done by using the Superscript VILO cDNA synthesis Kit (Thermo Fisher Scientific, Munich, Germany). 50 ng of RNA was used for each of the reverse transcription reactions. Quantitative real-time PCR was performed using the TaqMan Fast Universal PCR Master Mix (2×) (Thermo Fisher Scientific, Munich, Germany) on a Quantstudio 7 Flex Real-Time PCR System (Thermo Fisher Scientific, Munich, Germany) in accordance with the manufacturer’s protocol. All QPCR reactions were performed in a final reaction volume of 20 μL and with 1 μL of 1:5 diluted cDNA. Negative control reactions contained no cDNA templates. Gene expression was quantified using the relative quantification method by normalization with reference gene [47]. Statistical analysis using the bestkeeper tool was used to compare and select the best reference gene with stable expression across the human adrenal samples [48]. Reference genes with significantly different Ct values (p-value < 0.01) between the samples were excluded. Furthermore, primer efficiency and the associated correlation coefficient R2 of the selected reference gene were determined by the standard curve method in serially diluted cDNA samples [49]. In the case of miRNA reference genes, miR-16-5p [48,50,51] and RNU6B [52] previously used in similar studies were compared. MiR-16-5p was found to show the most stable expression levels across the samples with a p-value of 0.452 in comparison to RNU6B which had a p-value of 0.001. In the case of RNA reference genes, PPIA [53] and GAPDH [54] were compared. Here, PPIA was found to show the most stable expression levels across the samples with a p-value of 0.019 in comparison to GAPDH which had a p-value of 0.003. Therefore, these genes were used for the normalization of miRNA and RNA expression in human adrenal samples.

4.4. Target Screening

In silico prediction of the possible miRNA targets was performed using the miRNA target database, TargetScan, and miRTarBase [19,37]. The top predicted targets were further screened based on their expression status in the RNA-seq data from the adrenocortical tissues of CPA, PBMAH, and controls (unpublished data). Pathway analyses of the targets were performed using Reactome [55] and Panther [56] online platforms. The selected downregulated targets were analyzed by QPCR in the adrenocortical samples to confirm their expression status. The successfully validated candidates were then analyzed for regulation by the miRNA using a dual luciferase assay [57].

4.5. Dual Luciferase Assay

The interaction between the predicted 3′-UTR region of Cyb5a and miR-1247-5p was detected using a luciferase activity assay. The 3′UTR sequences of Cyb5a (129 bp) containing the predicted miR-1247-5p binding sites (psiCHECK-2 Cyb5a 3′UTR WT) were cloned into the psiCHECK-2 vector (Promega, Fitchburg, WI, USA). A QuikChange Site-Directed Mutagenesis kit (Agilent Technologies, CA, USA) was used to mutate the miR-1247-5p binding site (psiCHECK-2 Cyb5a 3′UTR mutant) according to the manufacturer’s protocol. All the sequences were verified by Sanger sequencing. Then, 200 ng of the plasmid was used for each transfection. Synthetic miR-1247-5p mimics and specific oligonucleotides that inhibit endogenous miR-1247-5p (miR-1247-5p inhibitors) were purchased from Promega and 100 nmol of the molecules were used for each transfection according to the manufacturer’s protocol. For the assay, HeLa cells were seeded in 96-well plates and incubated for 24 h. The following day, cells were transfected using the following different conditions: (1) psiCHECK-2 Cyb5a 3′UTR WT + miR-1247-5p mimic; (2) psiCHECK-2 Cyb5a 3′UTR WT + miR-1247-5p inhibitor; (3) psiCHECK-2 Cyb5a 3′UTR WT + water; (4) psiCHECK-2 Cyb5a 3′UTR mutant + miR-1247-5p mimic; (5) psiCHECK-2 Cyb5a 3′UTR mutant + miR-1247-5p inhibitor; (6) psiCHECK-2 Cyb5a 3′UTR mutant + water. Forty-eight hours later, luciferase activity in the cells was measured using the dual luciferase assay system (Promega, Fitchburg, WI, USA) in accordance with the manufacturer’s instructions. Renilla luciferase activity was normalized to firefly luciferase activity. Each treatment was performed in triplicate. Any interaction between the cloned gene, Cyb5a (WT and mutant), and miR-1247-5p mimic is accompanied by a decrease in luminescence. This decrease in luminescence would not be observed when the plasmids are transfected with the miR-1247-5p inhibitor, indicating that observed luminescence differences are caused by specific interactions between the plasmid and the miR-1247-5p mimic. Transfection of the plasmid with water corrects any background interactions between the cloned gene and endogenous miRNAs in the culture.

4.6. In Vivo ACTH Stimulation

Experiments were performed on 13-week-old C57BL/6 J female mice (Janvier, Le Genest-Saint-Isle, France). Mice were intraperitoneally injected with 1 mg/kg of ACTH (Sigma Aldrich, Munich, Germany) and adrenals were collected after 10, 30, and 60 min of injections. In addition, control adrenals were collected from mice at baseline conditions (0 min). Mice were killed by cervical dislocation and adrenals were isolated, snap-frozen in liquid nitrogen, and stored at −80 °C for later RNA extraction. MiR-26a was taken as a housekeeping gene in the QPCR [58]. All mice were maintained in accordance with facility guidelines on animal welfare and approved by Landesdirektion Sachsen, Chemnitz, Germany.

4.7. Statistical Analysis and Software

R version 3.6.1 was used for the statistical analyses. To identify RNAs differentially expressed, a generalized linear model (GLM, a flexible generalization of ordinary linear regression that allows for variables that have distribution patterns other than a normal distribution) in the software package edgeR (Empirical Analysis of DGE in R) was employed to calculate p-values [45,59]. p-values were adjusted using the Benjamin–Hochberg false discovery rate (FDR) procedure [60]. Disease groups were compared using the unpaired Mann–Whitney test, and to decrease the false discovery rate a corrected p-value was calculated using the Benjamin–Hochberg method. p adjusted < 0.05 and log2 fold change >1.25 was applied as the cut-off for significance for NGS data. GraphPad Prism Version 8 was used for the statistical analysis of QPCR. To calculate differential gene expression, the dCt method (delta Ct (cycle threshold) value equals target miRNA’s Ct minus housekeeping miRNA’s Ct) was used (Microsoft Excel 2016, Microsoft, Redmond, WA, USA). For QPCR, an ANOVA test with Bonferroni correction was used [61] to assess significance; p-values < 0.05 were considered significant.

5. Conclusions

In conclusion, while comprehensive information regarding the role of miRNAs in acute and chronic phases of steroidogenesis is available, there is little known about the pathological independent role of miRNAs in the pathology of CS. In our study, we have described ACTH-independent miR-1247-5p and miR-379-5p expression in CS for the first time. Thus, by regulating different genes in the WNT signaling pathway, the miRNAs may individually contribute to the Cushing’s pathology in specific subtypes.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/ijms23147676/s1.

Author Contributions

Conceptualization, S.V., A.C. and A.R.; methodology, S.V., R.Z. and M.E.; software, S.V. and M.E.; validation, R.Z., A.O., D.W. and B.W.; formal analysis, S.V.; investigation, S.V., R.Z., M.E., A.O. and D.W.; resources, A.C., B.W., M.R. and A.R.; data curation, S.V. and R.Z.; writing—original draft preparation, S.V., R.Z. and A.R.; writing—review and editing, S.S., M.R. and A.R.; visualization, S.V.; supervision, A.R.; project administration, A.R.; funding acquisition, A.C., S.S., M.R. and A.R. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by a grant from the Deutsche Forschungsgemeinschaft (DFG) (within the CRC/Transregio 205/1 “The Adrenal: Central Relay in Health and Disease”) to A.C., B.W., S.S., M.R. and A.R., and individual grant SB 52/1-1 to S.S. This work is part of the German Cushing’s Registry CUSTODES and has been supported by a grant from the Else Kröner-Fresenius Stiftung to MR (2012_A103 and 2015_A228). A.R. was supported by the FöFoLe Program of the Ludwig Maximilian University, Munich. We thank I. Shapiro, A. Parl, C. Kühne, and S. Zopp for their technical support.

Institutional Review Board Statement

The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Ethics Committee of the Ludwig Maximilian University, Munich (protocol code 379-10, 152-10 and 20 July2021).

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Data Availability Statement

The miRNA-seq data generated in this study have been submitted to the NCBI (PRJNA847385).

Conflicts of Interest

The authors declare no conflict of interest.

References

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Association of Chronic Central Serous Chorioretinopathy with Subclinical Cushing’s Syndrome

https://doi.org/10.1016/j.ajoc.2022.101455

Abstract

Purpose

To report the clinical course of a patient with central serous chorioretinopathy (CSCR) secondary to subclinical hypercortisolism before and after adrenalectomy.

Observations

A 50-year-old female patient with multifocal, chronic CSCR was found to have an adrenal incidentaloma and was diagnosed with subclinical hypercortisolism. Patient elected to undergo minimally-invasive adrenalectomy and presented at 3 months after surgery without subretinal fluid.

Conclusions and Importance

Subclinical Cushing’s Syndrome (SCS) may present an underrecognized risk factor for developing chronic CSCR. Further investigation is needed to determine the threshold of visual comorbidity that may influence surgical management.

Keywords

Central serous chorioretinopathy
Subclinical Cushing’s syndrome
Hypercortisolism
Adrenalectomy
Retina
Surgical intervention

1. Introduction

Central serous chorioretinopathy (CSCR) is characterized by accumulation of fluid in the subretinal or sub-RPE space, often with consequential visual impairment. Chronic CSCR has been reported as a manifestation of hypercortisolism due to Cushing’s syndrome and subclinical hypercortisolism.1,2 However, the latter is often underrecognized owing to its inherently subtle nature and the optimal threshold for intervention based on associated comorbidities remains unclear. Herein we report the clinical course of a patient with CSCR secondary to subclinical hypercortisolism before and after adrenalectomy.

2. Case report

A 50-year-old female presented with blurred, discolored spots in the right eye for several months. Her past medical history included mild hypertension treated with amlodipine. Past ocular and family history were noncontributory.

On exam, Snellen visual acuity was 20/50 OD, 20/25 OS. Her pupils, intraocular pressure, and anterior segment exam were within normal limits. Dilated fundus exam revealed bilateral, multifocal areas of subretinal fluid and mottled pigmentary changes (Fig. 1A). Optical coherence tomography confirmed areas of subretinal fluid and other areas of outer retinal atrophy (Fig. 1B). Fundus autofluorescence revealed areas of hyperautofluorescence that highlighted the fundoscopic findings (Fig. 1C). Fluorescein angiography showed multifocal areas of expansile dot leakage (Fig. 1D). Altogether these findings were consistent with multifocal, chronic CSCR.

Fig. 1

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Fig. 1. Multimodal imaging of bilateral multifocal central serous chorioretinopathy. Fundus photographs reveal multifocal subretinal fluid and pigmentary changes (Fig. 1A). Optical coherence tomography demonstrates subretinal fluid and outer retinal atrophy (Fig. 1B). Areas of hyperautofluorescence highlight the fundoscopic findings of subretinal fluid (Fig. 1C). Fluorescein angiography showing multiple areas of expansile dot leakage (Fig. 1D).

On further clinical follow-up, an adrenal incidentaloma (AI) was detected when the patient underwent imaging for back pain. Subsequently she saw an endocrinologist; she had a normal serum cortisol, but low ACTH and an abnormal dexamethasone suppression test. This led to a diagnosis of subclinical hypercortisolism and provided a reason for her hypertension and chronic CSCR.

Since the blur and relative scotomata interfered with her daily activities, she elected to try eplerenone, which yielded a moderate but suboptimal therapeutic response at 50 mg daily. While contemplating photodynamic therapy, in discussion with her endocrinologist, the patient opted to undergo minimally-invasive adrenalectomy. At last follow-up 3 months after surgery and 6 years after her initial presentation, she has been off eplerenone and without subretinal fluid (Fig. 2).

Fig. 2

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Fig. 2. Optical coherence tomography imaging at presentation and at last follow-up 3 months after adrenalectomy. There is a significant improvement in subretinal fluid in both eyes, though outer retinal irregularity remains.

3. Discussion

CSCR has previously been associated with many risk factors including exposure to excess steroid. A recent study analyzing a nationally representative dataset of 35,000 patients found that patients with CSCR had a higher odds of Cushing’s syndrome (OR 2.19, 95% CI 1.33 to 3.59, p = 0.002) than exposure to exogenous steroids (OR 1.14, 95% CI 1.09 to 1.19, p < 0.001)1 Our case highlights the importance of thorough medication reconciliation and careful consideration of comorbid conditions in patients with chronic CSCR.

In recent years, subtle endogenous hypercortisolism, termed subclinical Cushing’s syndrome (SCS), has been of particular interest in the endocrinology literature because it can be a challenging diagnosis and the most appropriate management remains controversial.3 In general, SCS is comprised of: 1) the presence of an adrenal incidentaloma or mass, 2) biochemical confirmation of cortisol excess, and 3) no classic phenotypic manifestations of Cushing’s syndrome.4 Since adrenal incidentaloma has an estimated prevalence of 1–8% of the population,5 it is quite possible that SCS is an underrecognized risk factor for CSCR.

SCS may potentiate metabolic syndrome and osteoporosis; studies have found that surgical resection of adrenal incidentalomas improve weight, blood pressure, and glucose control. Consequently, some authors recommend those with SCS-associated comorbidities be considered for resection.6 An important consideration in these patients is how visual comorbidity factors into intervention. In our patient’s case, the recurrent CSCR, hypertension, and increased risk of metabolic syndrome were sufficient reasons to elect to have surgery.

4. Conclusion

In summary, SCS is a condition of subtle cortisol dysregulation that may represent an underrecognized risk factor for chronic CSCR. Further investigation is needed to determine the threshold of visual comorbidity that may influence surgical management.

Patient consent

Consent to publish the case report was not obtained. This report does not contain any personal information that could lead to the identification of the patient.

Acknowledgments and Disclosures

Grant support was from the J. Arch McNamara Retina Research Fund. The following authors have no financial disclosures: RRS, AS, AC All authors attest that they meet the current ICMJE criteria for Authorship. No other contributions to acknowledge.

References

© 2022 The Authors. Published by Elsevier Inc.

Adrenalectomy in ectopic Cushing’s syndrome: A retrospective cohort study from a tertiary care centre

First published: 13 August 2021

Abstract

Neuroendocrine neoplasms (NENs) causing ectopic Cushing’s syndrome (ECS) are rare and challenging to treat. In this retrospective cohort study, we aimed to evaluate different approaches for bilateral adrenalectomy (BA) as a treatment option in ECS. Fifty-three patients with ECS caused by a NEN (35 females/18 men; mean ± SD age: 53 ± 15 years) were identified from medical records. Epidemiological and clinical parameters, survival, indications for surgery and timing, as well as duration of surgery, complications and surgical techniques, were collected and further analysed. The primary tumour location was thorax (n = 30), pancreas (n = 14) or unknown (n = 9). BA was performed in 37 patients. Median time from diagnosis of ECS to BA was 2 months (range 1–10 months). Thirty-two patients received different steroidogenesis inhibitors before BA to control hypercortisolaemia. ECS resolved completely after surgery in 33 patients and severe peri- or postoperative complications were detected in 12 patients. There were fewer severe complications in the endoscopic group compared to open surgery (p = .030). Posterior retroperitoneoscopic BA performed simultaneously by a two surgeon approach had the shortest operating time (p = .001). Despite the frequent use of adrenolytic treatment, BA was necessary in a majority of patients to gain control over ECS. Complication rate was high, probably as a result of the combination of metastatic disease and metabolic disorders caused by high cortisol levels. The two surgeon approach BA may be considered as the method of choice in ECS compared to other BA approaches as a result of fewer complications and a shorter operating time.

1 INTRODUCTION

Endogenous Cushing’s syndrome (CS) has an estimated incidence of 0.2–5.0 per million people per year.1 In 5–10% of these, it is caused by ectopic secretion of adrenocorticotrophic hormone (ACTH) or, in extremely rare cases, corticotrophin-releasing hormone, from a non-pituitary tumour.12

The treatment of neuroendocrine neoplasms (NENs) with ectopic secretion of ACTH is challenging. Because of the rarity and heterogeneity of this condition, there is no established evidence-based recommendation.3 Most patients with ectopic Cushing’s syndrome (ECS) have severe hypercortisolaemia leading to disrupted electrolyte and glucose levels, metabolic alkalosis, thrombosis and life-threatening infections, amongst many other manifestations. Initiation of oncological treatment is often delayed as a result of the consequences of high cortisol levels. A reduction of the cortisol level is crucial for survival and hypercortisolaemia and hypokalaemia are negative prognostic factors.45 If radical surgery of the tumour is not possible because of metastatic disease, normo-cortisolaemia can be achieved either by medical treatment with steroidogenesis inhibitors (SI) or bilateral adrenalectomy (BA),6 and BA has also been considered a treatment option for patients with occult or cyclic ECS. In patients with metastatic neuroendocrine carcinomas, platinum-based chemotherapy may be applied as first-line action, combined by SI and/or followed by BA. Computed tomography-guided percutaneous adrenal ablation has been reported in several case reports as a possible therapeutic alternative for patients in whom medical treatment has failed and BA is not feasible,710 althhough more data is needed to recommend this method in daily practice.

In the 1930s, transabdominal open access BA was introduced as a treatment option for uncontrolled cortisol secretion.11 Sixty years later, in the 1990s, laparoscopic methods were established1213 and are now considered as the gold standard for BA (except for adrenal carcinomas) because they result in less postoperative pain, a shorter hospitalisation time and faster recovery.14 Laparoscopic transperitoneal adrenalectomy (LTA) is the most frequently applied surgical method. However, posterior retroperitoneoscopic adrenalectomy (PRA), introduced in 1995 by Walz et al,15 is gaining popularity.16 Using PRA compared to LTA offers a more direct approach to the adrenal glands, a shorter operating time (no need for reposition of the patient), less blood loss and faster recovery, and it aso has advantages for patients with obesity or a history of previous abdominal surgery.16 There are centres where PRA is performed by a two surgeon approach; thus, a simultaneous bilateral approach offers the possibility of decreasing the surgical time by up to 50% and reducing operative stress.1719

The present study aimed to evaluate BA as a treatment option for ECS, as well as the effects of different approaches on morbidity and mortality. We hypothesised that endoscopic surgery methods could be superior regarding complication rate, operating and hospitalisation time compared to open access surgery and also influence overall survival.

2 MATERIALS AND METHODS

2.1 Patients and data

A cohort of 59 patients with ECS was identified retrospectively from medical records of 894 patients with NENs, referred to the Department of Endocrine Oncology, Uppsala University Hospital between 1984 and 2019. None of the patients had a small-cell lung cancer (SCLC) because these tumours are not treated at our centre and possibly have a different mechanism behind ACTH production compared to that of NENs. Furthermore, SCLCs have a much more severe course of disease compared to well differentiated NENs and including them in the present study could mask any results important for NEN clinical management. Six patients were from outside Sweden and were excluded from further analysis because of a lack of follow-up data; thus, in total, 53 patients were available for analysis. Diagnosis of ECS was confirmed by histopathological examination of tumour specimen (n = 48) together with the clinical and biochemical picture of ACTH-dependent Cushing’s syndrome (elevated serum and urinary cortisol, high ACTH and pathological functional tests). In five patients where neither primary tumor, nor metastatic disease was found despite several PET examinations, including 68 Ga- DOTATOC-PET, 11C-5HTP-PET and 18FDG-PET in four of the five patients, ECS was confirmed on the basis of the clinical/biochemical picture and exclusion of pituitary origin by magnetic resonance imaging, as well as inferior sinus petrosus sampling.

Epidemiological data, data on clinical parameters, survival, indication and duration of surgery, complications and surgical technique were extracted and further analysed.

2.2 Surgery

BA was performed either by an open access approach, LTA or PRA. PRA was performed either by one surgeon (PRA-1S) or by two surgeons operating on both sides simultaneously (PRA-2S). Some patients were operated twice (one adrenal at the time) and, for those patients, operating time was pooled from both surgeries, if both sessions were performed within 1 week. Cases where conversion from an endoscopic to an open access approach was made peroperatively were grouped as open access surgery in further analysis. Patients who died during the postoperative stage (within 30 days) were excluded from calculation of hospitalisation time.

Postoperative complications were graded using the Clavien–Dindo classification where complications of Grade 1 are defined as “any deviation from the normal postoperative course without the need for pharmacological treatment or surgical, endoscopic and radiological interventions. Allowed therapeutic regimens are drugs as antiemetics, antipyretics, analgesics, diuretics and electrolytes and physiotherapy”.20 Because almost all patients had mild, Grade 1 postoperative complications (metabolic disturbances caused by hypercortisolaemia), this variable is not described. We defined complications up to Grade 2 as mild and Grade 3–5 as severe.

2.3 Statistical analysis

All parameters were analysed by descriptive statistics: normally distributed data as the mean ± SD, and data with skewed distribution and/or outliers were described as medians, accompanied by the 25th to 75th percentile ranges (Q1-Q3) or minimum-maximum (min-max). The defined event was death from any cause. Overall survival (OS) was defined as time from diagnosis of ECS or time of BA until date of death or, if the event was not found, censored at date of last observation, 31 December 2019. Kaplan-Meier plots were used for survival analysis and the log-rank test was used for comparison. Chi-squared was used for testing relationships between categorical variables. p < .05 was considered statistically significant. All statistical analyses were performed using IBM, version 27 (IBM Corp., Armonk, USA).

3 RESULTS

3.1 Studied patients

ECS represented six% (n = 59) of NENs in our cohort. Six patients were excluded from further analysis, resulting in 53 ECS patients who were analysed; there were 35 females and 18 males with a mean ± SD age of 53 ± 15 years. The localisation of the primary NEN was thorax (n = 30), pancreas (n = 14) or unknown (n = 9). Histopathological staining for Ki-67 was available in 38 patients and Ki-67 was < 2% in five patients, 3–20% in 22 patients and > 20% in 11 patients. Patient characteristics are shown in Tables 1 and 2. Twenty-two patients (41.5%) in this cohort had concomitant hypersecretion of hormones other than ACTH from their tumour (5-HIAA, n = 10; calcitonin, n = 3; 5-HIAA + calcitonin, n = 2; glucagon, n = 3, gastrin, n = 2; growth hormone, n = 1; insulin + gastrin + vasointestinal peptide, n = 1).

3.2 Surgery

Adrenalectomy was performed in 37 patients (70%); 24 patients were operated at Uppsala University Hospital, nine at Karolinska University Hospital in Stockholm and four at Umeå University Hospital. Median time from diagnosis of ECS to BA was 2 months (range 1–10 months). Median Ki-67 in patients who were operated within 2 months after ECS diagnosis was higher (Ki-67 18.5%) compared to those with BA performed later in the course of disease (Ki-67 9.5%), although the difference was not statistically significant (p = .085).

Thirty-two (86%) patients received different SI prior to BA to control hypercortisolaemia. Eight of those were treated with chemotherapy as well in an attempt to reduce cortisol levels. The majority of patients was treated with ketoconazole, often in combination with other drugs (Table 3). Indications for BA in our cohort included (1) persistent hypercortisolaemia despite use of SI (n = 30); (2) BA as first choice of treatment to reduce cortisol levels (n = 5); and (3) no effect combined with severe side effects from SI including liver toxicity and severe leukopenia (n = 2). In 16 patients, BA was not performed as a result of (1) good control of ECS with SI (n = 4); (2) radical surgery of the primary tumour (n = 3); (3) good control of ECS with SI followed by radical surgery of the primary tumour (n = 5) and (4) the bad condition of the patient (n = 4).

3.3 Survival analysis

There was no operative mortality in this cohort. Four patients died within 1 month after adrenalectomy (on day 5, 16, 22 and 30, respectively) as a result of multiple organ dysfunction syndrome and progression of NEN. At the end of the follow-up period, 14 patients were still alive and 39 had died.

Median survival after BA was 24 months (95% confidence interval [CI] = 7–41, min-max: 0–428) with a 5-year survival of 22%. Median follow-up time for all patients from time of ECS diagnosis was 26 (range 6–62) months and after BA was 19 (range 3–50) months. OS was longer in patients where ECS was treated by radical surgery of the primary tumour or where good biochemical control was achieved by SI compared to patients who underwent BA, 96 months (95% CI 0–206) vs 29 months (95% CI 7–51), respectively. However, this difference was not statistically significant (p = .086), most likely as a result of the small sample size. Multiple hormone secretion correlated with shorter OS after BA (p = .009; hazard ratio = 2.9; 95% CI= 1.3–6.7). There was no significant difference in OS after BA depending on localisation of primary tumour (thoracic NENs 24 months [95% CI = 8–40, min-max: 0–428], pancreatic NENs 19 months [95% CI = 0–43, min-max: 0–60], p = .319) or surgical approach (open access approach 24 months [95% CI = 1–47], endoscopic approach 19 months [95% CI = 1–37], p = .720).

Median time from ECS diagnosis to BA was 2 months (range 1–10). Patients who underwent BA within 2 months after ECS diagnosis had shorter OS compared to those who were operated at a later stage: 6 months (95% CI = 0–18) and 45 months (95% CI = 3–86) respectively (p = .007). The former group had a slightly higher median Ki-67 level (18% vs 9%), lower potassium (2.7 mmol L-1 vs 3.0 mmol L-1) and higher hormone levels (ACTH 217 vs 120 ng mL-1, morning cortisol 1448 vs 1181 nmol L-1 and UFC 5716 vs 4234 nmol per 24 h) at diagnosis compared to those who were operated later in the course of disease.

4 DISCUSSION

The present study highlights new aspects of the advantages of an endoscopic approach of BA compared to open access surgery, regarding the incidence of severe complications graded using the Clavien-Dindo classification, as well as operation- and hospitalisation time. Our results indicate that PRA performed by two surgeons simultaneously is the method of choice for patients with ECS. However, despite these advantages, the endoscopic approach did not appear to improve overall survival.

Recent Endocrine Society guidelines recommend SI as primary treatment for ECS in patients with occult or metastatic ECS followed by BA.6 Although the toxicity of SI in our cohort was low (n = 2; 6%), 32 patients (73%) had persistent hypercortisolaemia despite medical treatment and proceeded to BA. BA, especially with an endoscopic approach, with a short operating time and low complication risk, appears to play a major role in the appropriate management of hypercortisolaemia in ECS, where rapid reduction of cortisol levels is very important.

Prolonged exposure to high cortisol levels, in combination with high risk for hepatotoxic and nephrotoxic SI side effects, increases morbidity and risk for severe complications, and often delays the start of oncological treatment. However, the trauma caused by surgery can also postpone initiation of chemotherapy.21 Therefore, a fast and minimally invasive surgical procedure appears to be a crucial factor for the better survival in ECS. The endoscopic approach is now considered as the gold standard for BA. Our study presents fewer severe complications, as well as shorter operating and hospitalisation times, when the endoscopic approach is compared with open surgery. In line with previous studies,1922 we observed a significantly shorter operating time when applying PRA compared to LTA because there is no need for repositioning of the patient during PRA. PRA-2S had the shortest operating time and should be considered as the best choice of surgical approach in ECS. This result ties well with previous studies reporting the median operating time to be between 43 and 157 min in PRA-2S, which is significantly shorter compared to LTA and PRA-1S.1719

The median time from diagnosis to BA was 2 months, which is consistent with a previous study.23 However, OS was significantly shorter in patients who were operated within 2 months after diagnosis of ECS in our cohort compared to those operated at a later stage. These early operated patients probably had a more aggressive clinical course of disease, as indicated by slightly higher median Ki-67, lower potassium and higher hormone levels at diagnosis, and they were operated as a result of more acute indications (without time to proper pre-treatment with SI) than the other group.

In our previous report on patients with ACTH-producing NENs, multiple hormone secretion was identified as the strongest indicator of a worse prognosis.4 A similar pattern of results was observed in this cohort, showing that patients with NENs, with concomitant hypersecretion of other hormones than ACTH from their tumour, had a shorter OS after BA compared to those with ACTH hypersecretion only.

As a result of the extremely high preoperative cortisol levels in ECS, the substitution therapy needed after successful BA may be challenging.21 Over-replacement of glucocorticoids may lead to higher morbidity24 and mortality, especially in patients with metastatic NENs, who often have impaired immune function because of oncological treatment. Many patients suffer from glucocorticoid withdrawal syndrome, despite adequate replacement therapy, and it can take ≥ 1 year to gain control over these symptoms.6 This frequently leads to high dosage of glucocorticoids. The Endocrine Society guidelines recommend glucocorticoid replacement with hydrocortisone, 10–12 mg m-2 day-1 in divided doses.6 If we assume that most of our patients have body surface area around 2 m2 or less, the daily hydrocortisone dose should not exceed 25 mg. However, 1 year after BA, only one patient received 25 mg of hydrocortisone daily, with the majority receiving 30 mg or more. One-third of the patients had residual arterial hypertension and diabetes 3 months after BA, probably partially depending on too high a dose of glucocorticoids.

There was a higher complication rate in our cohort compared to other studies192526 and five patients needed conversion from an endoscopic approach to open surgery. In particular, the outcome of BA in ECS has not previously been systematically evaluated27 because most of the reports include patients with various aetiologies of CS.1922232829 In a systematic review of the literature published between 1980 and 2012 on BA in CS, Reincke et al23 identified 37 studies and ECS was present in 13% of the patients. There are only few papers focused on BA in ECS solely2125263031 and only one has a cohort with > 50 patients (n = 54).26 Patients with ECS have almost always a more aggressive course and more severe metabolic disturbance than patients with other types of Cushing’s syndrome, which probably leads to higher risk for postoperative complications. Furthermore, multiple liver metastases, fibrotic processes in the abdomen as a result of previous surgery or large primary tumour in pancreas could be some of the factors influencing surgical outcome in ECS.

The present study has several limitations. First, all data were collected retrospectively from patient records and not all the preferred parameters were available for all patients. Second, even if our cohort is one of the largest regarding studies on BA in ECS, the number of patients is too low for reliable statistical analysis. Finally, our study covered more than three decades, BAs were performed at different clinics and by different surgeons. Therefore, the data should be interpreted carefully.

In conclusion, the present study is one of few reports focusing on BA in specifically NEN patients with ECS and includes one of the largest patient cohorts analysed in the field. PRA-2S can be considered as method of choice in ECS compared to other BA approaches. The aim is to avoid administrating too high a hydrocortisone replacement dosage postoperatively because this can worsen the metabolic disturbance. As a result of the rarity of the condition, multicentre studies are needed with large, prospective cohorts and standardised inclusion criteria, aiming to further improve our knowledge about the management of ECS.

ACKNOWLEDGEMENTS

This study was funded by the Swedish Cancer Society (grant number CAN 18 0576), the Lions Foundation for Cancer Research at Uppsala University Hospital, Selanders Foundation and Söderbergs foundation at Uppsala University.

CONFLICT OF INTERESTS

The authors declare that they have no conflicts of interest.

AUTHOR CONTRIBUTIONS

Ieva Lase: Conceptualisation; Data curation; Formal analysis; Investigation; Methodology; Visualisation; Writing – original draft; Writing – review & editing. Malin Grönberg: Formal analysis; Supervision; Visualisation; Writing – review & editing. Olov Norlén: Conceptualisation; Writing – review & editing. Peter Stålberg: Conceptualisation; Writing – review & editing. Staffan Welin: Conceptualisation; Supervision; Writing – review & editing. Eva Tiensuu Janson: Conceptualisation; Funding acquisition; Methodology; Supervision; Writing – review & editing.

ETHICAL APPROVAL

The need for informed consent was waived by the local ethics committee. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The study was approved by the local ethics committee, Regionala etikprövningsnämnden (EPN), in Uppsala, Sweden.

PEER REVIEW

The peer review history for this article is available at https://publons.com/publon/10.1111/jne.13030.

The entire article, PDF, supporting tables and more can be found at https://onlinelibrary.wiley.com/doi/full/10.1111/jne.13030

Even in Remission, Cushing’s Patients Have Excess Mortality

Cushing’s disease patients in Sweden have a higher risk of death than the general Swedish population, particularly of cardiovascular complications, and that increased risk persists even in patients in remission, a large nationwide study shows.

The study, “Overall and disease-specific mortality in patients with Cushing’s disease: a Swedish nationwide study,” was published in the Journal of Clinical Endocrinology and Metabolism.

The outcomes of Cushing’s disease patients have improved with the introduction of several therapeutic approaches, such as minimally invasive surgery and cortisol-lowering therapies. However, mortality is still high, especially among those who do not achieve remission.

While currently patients in remission are thought to have a better prognosis, it is still unclear whether these patients still have a higher mortality than the general population. Understanding whether these patients are more likely to die and what risk factors are associated with increased mortality is critical to reduce death rates among Cushing’s patients.

A team of Swedish researchers thus performed a retrospective study that included patients diagnosed with Cushing’s disease who were part of the Swedish National Patient Registry between 1987 and 2013.

A total of 502 patients with Cushing’s disease were included in the study, 419 of whom were confirmed to be in remission. Most patients (77%) were women; the mean age at diagnosis was 43 years, and the median follow-up time was 13 years.

During the follow-up, 133 Cushing’s patients died, compared to 54 expected deaths in the general population — a mortality rate 2.5 times higher, researchers said.

The most common causes of death among Cushing’s patients were cardiovascular diseases, particularly ischemic heart disease and cerebral infarctions. However, infectious and respiratory diseases (including pneumonia), as well as diseases of the digestive system, also contributed to the increased mortality among Cushing’s patients.

Of those in remission, 21% died, compared to 55% among those not in remission. While these patients had a lower risk of death, their mortality rate was still 90% higher than that of the general population. For patients who did not achieve remission, the mortality rate was 6.9 times higher.

The mortality associated with cardiovascular diseases was increased for both patients in remission and not in remission. Also, older age at the start of the study and time in remission were associated with mortality risk.

“A more aggressive treatment of hypertension, dyslipidemia [abnormal amount of fat in the blood], and other cardiovascular risk factors might be warranted in patients with CS in remission,” researchers said.

Of the 419 patients in remission, 315 had undergone pituitary surgery, 102 had had their adrenal glands removed, and 116 had received radiation therapy.

Surgical removal of the adrenal glands and chronic glucocorticoid replacement therapy were associated with a worse prognosis. In fact, glucocorticoid replacement therapy more than twice increased the mortality risk. Growth hormone replacement was linked with better outcomes.

In remission patients, a diagnosis of diabetes mellitus or high blood pressure had no impact on mortality risk.

Overall, “this large nationwide study shows that patients with [Cushing’s disease] continue to have excess mortality even after remission,” researchers stated. The highest mortality rates, however, were seen in “patients with persistent disease, those who were treated with bilateral adrenalectomy and those who required glucocorticoid replacement.”

“Further studies need to focus on identifying best approaches to obtaining remission, active surveillance, adequate hormone replacement and long-term management of cardiovascular and mental health in these patients,” the study concluded.

From https://cushingsdiseasenews.com/2019/02/28/even-in-remission-cushings-patients-have-excess-mortality-swedish-study-says/

Cushing’s Syndrome Patients at More Risk of Blood-clotting Problems After Adrenal Surgery

Cushing’s syndrome patients who undergo adrenal surgery are more likely to have venous thromboembolism — blood clots that originate in the veins — than patients who have the same procedure for other conditions, a study suggests.

Physicians should consider preventive treatment for this complication in Cushing’s syndrome patients who are having adrenal surgery and maintain it for four weeks after surgery due to late VTE onset.

The study, “Is VTE Prophylaxis Necessary on Discharge for Patients Undergoing Adrenalectomy for Cushing Syndrome?” was published in the Journal of Endocrine Society.

Cushing’s syndrome is a condition characterized by too much cortisol in circulation. In many cases, it is caused by a tumor in the pituitary gland, which produces greater amounts of the cortisol-controlling adrenocorticotropic hormone (ACTH). In other cases, patients have tumors in the adrenal glands that directly increase cortisol production.

When the source of the problem is the pituitary gland, the condition is known as Cushing’s disease.

The imbalance in cortisol levels generates metabolic complications that include obesity, high blood pressure, diabetes, and cardiovascular complications. Among the latter, the formation of blood clots in the deep veins of the leg, groin or arm — a condition called venous thromboembolism (VTE) — is higher in both Cushing’s disease and Cushing’s syndrome patients.

VTE is believed to be a result of excess coagulation factors that promote blood clot formation, and is thought to particularly affect Cushing’s disease patients who have pituitary gland surgery.

Whether Cushing’s syndrome patients who have an adrenalectomy — surgical removal of one or both adrenal glands — are at a higher risk for VTE is largely unknown. This is important for post-operative management, to decide whether they should have preventive treatment for blood clot formation.

Researchers at the National Cancer Institute in Maryland did a retrospective analysis of a large group of patients in the American College of Surgeons National Quality Improvement Program database.

A total of 8,082 patients underwent adrenal gland surgery between 2005 and 2016. Data on these patients included preoperative risk factors, as well as 30-day post-surgery mortality and morbidity outcomes. Patients with malignant disease and without specified adrenal pathology were excluded from the study.

The final analysis included 4,217 patients, 61.8% of whom were females. In total, 310 patients had Cushing’s syndrome or Cushing’s disease that required an adrenalectomy. The remaining 3,907 had an adrenal disease other than Cushing’s and were used as controls.

The incidence of VTE after surgery — defined as pulmonary embolism (a blockage of an artery in the lungs) or deep-vein thrombosis — was 1% in the overall population. However, more Cushing’s patients experienced this complication (2.6%) than controls (0.9%).

Those diagnosed with Cushing’s syndrome were generally younger, had a higher body mass index, and were more likely to have diabetes than controls. Their surgery also lasted longer — 191.2 minutes versus 142 minutes — as did their hospital stay – 2.4 versus two days.

Although without statistical significance, the researchers observed a tendency for longer surgery time for patients with Cushing’s syndrome than controls with VTE. They saw no difference in the time for blood coagulation between Cushing’s and non-Cushing’s patients, or postoperative events other than pulmonary embolism or deep-vein thrombosis.

In addition, no differences were detected for VTE incidence between Cushing’s and non-Cushing’s patients according to the type of surgical approach — laparoscopic versus open surgery.

These results suggest that individuals with Cushing syndrome are at a higher risk for developing VTE.

“Because the incidence of VTE events in the CS group was almost threefold higher than that in the non-CS group and VTE events occurred up to 23 days after surgery in patients with CS undergoing adrenalectomy, our data support postdischarge thromboprophylaxis for 28 days in these patients,” the researchers concluded.

From https://cushingsdiseasenews.com/2019/02/14/cushings-syndrome-patients-blood-clots-adrenal-surgery/

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