Increase in Glucose Uptake by Cushing’s Disease-associated Tumors Could Improve Early Detection

An increase in glucose uptake by Cushing’s disease-associated pituitary tumors could improve their detection, new research shows.

The study, “Corticotropin releasing hormone can selectively stimulate glucose uptake in corticotropinoma via glucose transporter 1,” appeared in the journal Molecular and Cellular Endocrinology.

The study’s senior author was Dr. Prashant Chittiboina, MD, from the Department of Neurosurgery, Wexner Medical Center, The Ohio State University, in Columbus, Ohio.

Microadenomas – tumors in the pituitary gland measuring less than 10 mm in diameter – that release corticotropin, or corticotropinomas, can lead to Cushing’s disease. The presurgical detection of these microadenomas could improve surgical outcomes in patients with Cushing’s.

But current tumor visualization methodologies – magnetic resonance imaging (MRI) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) – failed to detect a significant percentage of pituitary microadenomas.

Stimulation with corticotropin-releasing hormone (CRH), which increases glucose uptake, has been suggested as a method of increasing the detection of adenomas with 18F-FDG PET, by augmenting the uptake of 18F-FDG – a glucose analog.

However, previous studies aiming to validate this idea have failed, leading the research team to hypothesize that it may be due to a delayed elevation in glucose uptake in corticotropinomas.

The scientists used clinical data to determine the effectiveness of CRH in improving the detection of corticotropinomas with 18F-FDG PET in Cushing’s disease.

They found that CRH increased glucose uptake in human and mouse tumor cells, but not in healthy mouse or human pituitary cells that produce the adrenocorticotropic hormone (ACTH). Exposure to CRH increased glucose uptake in mouse tumor cells, with a maximal effect at four hours after stimulation.

Similarly, the glucose transporter GLUT1, which is located at the cell membrane, was increased two hours after stimulation, as was GLUT1-mediated glucose transport.

These findings indicate a potential mechanism linking CRH exposure to augmented glucose uptake through GLUT1. Expectedly, the inhibition of glucose transport with fasentin suppressed glucose uptake.

The researchers consistently observed exaggerated evidence of GLUT1 in human corticotropinomas. In addition, human corticotroph tumor cells showed an increased breakdown of glucose, which indicates that, unlike healthy cells, pituitary adenomas use glucose as their primary source of energy.

Overall, the study shows that corticotropin-releasing hormone (CRH) leads to a specific and delayed increase in glucose uptake in tumor corticotrophs.

“Taken together, these novel findings support the potential use of delayed 18F-FDG PET imaging following CRH stimulation to improve microadenoma detection in [Cushing’s disease],” researchers wrote. The scientists are now conducting a clinical trial to further explore this promising finding.

From https://cushingsdiseasenews.com/2017/10/12/glucose-uptake-in-cushings-disease-could-improve-presurgical-tumor-detection/

Basal Cortisol Elevated in Patients with ACTH-Staining Pituitary Macroadenoma

Preoperative identification of patients with silent adrenocorticotrophic hormone-secreting tumors could potentially change the approach to management. A new study aimed to determine whether a preoperative adrenocorticotrophic hormone stimulation test for evaluation of nonfunctional pituitary macroadenoma could aid in identifying adrenocorticotrophic hormone-staining pathology yielded large variability and did not allow clinical utility.

Thus, researchers concluded that larger, multicenter research is needed to determine whether this test can be useful.

“As ACTH stimulation tests are performed routinely when evaluating macroadenoma when there is no suspicion for a state of endogenous hypercortisolism, we sought to determine if the test could reliably identify these pathologies during the preoperative evaluation. We hypothesized that patients with subclinical Cushing’s disease or silent ACTH-secreting tumors would have a higher delta cortisol on the ACTH stimulation tests vs. other types of macroadenoma pathologies,” Kevin Pantalone, DO, ECNU, FACE, staff endocrinologist and director of clinical research in the department of endocrinology at Cleveland Clinic, told Endocrine Today.

Pantalone and colleagues performed a retrospective chart review of 148 patients with pituitary macroadenoma who underwent preoperative ACTH stimulation tests, with the goal of determining whether the test can aid in the identification of ACTH-staining pathology.

Overall, 9.5% of patients showed diffuse staining, 50.6% showed other-staining (diffuse staining for anterior pituitary hormones other than ACTH) and 39.9% showed no staining (no staining for any anterior pituitary hormones).

The researchers calculated delta total cortisol at 30 and 60 minutes from baseline and reviewed preoperative ACTH stimulation tests. Additionally, Pantalone and colleagues compared the basal and maximal delta cortisol between the ACTH-staining pituitary macroadenoma and the non-ACTH staining (n = 134), other staining (n = 75) and non-staining (n = 59) tumors.

According to data reported at the American Association of Clinical Endocrinologists Annual Scientific and Clinical Congress, the ACTH-staining group had higher mean basal cortisol levels compared with the non-ACTH-staining (P = .012), other staining (P = .018) and the non-staining (P = .012) tumors. The researchers found no significant differences in maximal delta cortisol between the groups.

“While we found basal cortisol levels were higher in patients with ACTH-staining pituitary microadenoma vs. non-ACTH-staining macroadenoma, the large variability in cortisol values did not allow for clinical utility,” Pantalone told Endocrine Today.

“Unfortunately, in the end, our study was limited by the number of cases with ACTH-staining pathology. Thus, we were unable to determine if the ACTH stimulation test could reliably assist clinicians in potentially identifying ACTH-staining pathology in the preoperative setting,” he said. “A multicenter study, affording a large number of ACTH-staining tumors, is needed. This may allow for us to determine if the ACTH-stimulation test can really be clinically useful in preoperatively identifying ACTH-staining pathology.” – by Amber Cox

Science Teacher Receives Support After Cushing’s Disease Diagnosis

I find it amazing that it’s newsworthy in this day and age for anyone receiving support after a diagnosis.  Of course, a diagnosed person should be getting support as a matter of course.  If she had cancer, everyone would be all over this.

For Kara Murrow, the most rewarding moments as a teacher come when students learn about animals in the classroom. So it’s difficult for the Bonham Elementary fifth-grade science and social studies teacher to be away from school while she prepares for surgery.

“I enjoy it, and I know my kids enjoy the class and enjoy science because of it,” Murrow said. “With the science club I do after school once a week, the kids get upset when it gets canceled because of meetings. Not having it now is upsetting, too.”

Murrow was diagnosed this month with Cushing’s disease, a condition that develops when a tumor on the pituitary gland causes it to secrete too much adrenocorticotropic hormone. Murrow, who moved to West Texas from Arizona three years ago, said she has received support from Midland ISD employees and others in the local community.

Murrow’s mother, Louise Gonzalez, also appreciates Midlanders’ concerns for her daughter.

“People in Midland have been wonderful, considering how new we are to the area,” Gonzalez said. “The school district sent out the GoFundMe page and there’s been an outpouring of support for that. People at my church always ask me.”

Murrow’s family is collecting donations from the website GoFundMe to cover the costs of medical and travel expenses. Murrow and her husband, Kai, recently spent money on hospital stays connected to their 4-year-old son’s food sensitivities.

“They’ve been paying off those bills and doing OK until this came,” Gonzalez said. “Plus, she’s been going to the doctor about this. Because Cushing’s is so rare, doctors don’t recognize it.”

Murrow was diagnosed with the disease after medical professionals discovered a tumor on her pituitary gland. For six years, she experienced symptoms — including weight gain, dizziness and headaches — but said doctors couldn’t determine the cause. Murrow was thankful when she received an answer.

“It was a huge relief to finally have a diagnosis and know that I wasn’t crazy or making things up,” Murrow said. “It’s weird to be excited about a brain tumor. It’s a relief to know what was happening and that I have a solution.”

Murrow traveled this week to Barrow Neurological Institute in Phoenix, where she’s scheduled to undergo surgery to remove the tumor. Though Murrow said recovery lasts several months, she hopes to return to the classroom next school year.

Jaime White, fourth-grade language arts and social studies teacher at Bonham, said both staff and students miss her presence. She said Murrow expresses concern for her students during her time away.

“She’s worried about how kids will do on the STAAR [State of Texas Assessments of Academic Readiness],” White said. “She doesn’t want them to think she abandoned them. The disease has to take center stage.”

At school, White said she noticed her colleague’s dedication toward helping her students understand science.

“She’s hands-on,” White said. “When it comes to science, she’s always making sure the kids are doing some sort of experiment. She wants to make sure the kids grasp it.”

Murrow teaches students about animals through dissections and presentations. Before she became a teacher nine years ago, she coordinated outreach programs at an Arizona zoo.

When she came to MISD, Murrow saw an opportunity to generate enthusiasm about science. She launched an invite-only science club for fifth-graders who show interest in the subject.

“I started it because there wasn’t really anything,” Murrow said. “They have tutorials for reading and math. There’s not a lot kids can do with science after school. They get science in the younger grades, but the focus is on reading and math. Science is something kids really enjoy.”

Though Murrow is disappointed about not being able to facilitate the club, she recognizes the importance of her upcoming surgery. She’s happy her mother, husband and two children will be in Phoenix for support.

“I hope that it will bring about a sense of relief to all the symptoms I’ve been dealing with and provide a chance for myself and my family to continue along with a full life,” Murrow said.

From http://www.mrt.com/news/local/article/Science-teacher-receives-support-after-11026581.php

Postoperative ACTH, cortisol levels may predict Cushing’s disease remission rate

Early and midterm nonremission after transsphenoidal surgery in people with Cushing’s disease may be predicted by normalized early postoperative values for adrenocorticotropic hormone and cortisol, study data show.

Prashant Chittiboina, MD, MPH, assistant clinical investigator in the neurosurgery unit for pituitary and inheritable diseases at the National Institute of Neurological Diseases and Stroke at the NIH, and colleagues evaluated 250 patients with Cushing’s disease who received 291 transsphenoidal surgery procedures during the study period to determine remission after the procedure. Patients were treated between December 2003 and July 2016. Early remission was assessed at 10 days and medium-term remission was assessed at 11 months.

Early nonremission was predicted by normalized early postoperative values for cortisol (P = .016) and by normalized early postoperative values for adrenocorticotropic hormone (ACTH; P = .048). Early nonremission was further predicted with 100% sensitivity, 39% specificity, 100% negative predictive value and 18% positive predictive value for a cutoff of –12 µg/mL in normalized early postoperative values for cortisol and with 88% sensitivity, 41% specificity, 96% negative predictive value and 16% positive predictive value for a cutoff of –40 pg/mL in normalized early postoperative values for ACTH.

Medium-term nonremission was also predicted by normalized early postoperative values for cortisol (P = .023) and ACTH (P = .025).

“We evaluated the utility of early postoperative cortisol and ACTH levels for predicting nonremission after transsphenoidal adenomectomy for Cushing’s disease,” the researchers wrote. “Postoperative operative day 1 values at 6 a.m. performed best at predicting early nonremission, albeit with a lower [area under the receiver operating characteristic curve]. Normalizing early cortisol and ACTH values to post-[corticotropin-releasing hormone] values improved their prognostic value. Further prospective studies will explore the utility of normalized very early postoperative day 0 cortisol and ACTH levels in identifying patients at risk for nonremission following [transsphenoidal surgery] in patients with [Cushing’s disease].” – by Amber Cox

Disclosure: The researchers report no relevant financial disclosures.

From http://www.healio.com/endocrinology/adrenal/news/in-the-journals/%7B7de200ed-c667-4b48-ab19-256d90a7bbc5%7D/postoperative-acth-cortisol-levels-may-predict-cushings-disease-remission-rate

The Cables1 Gene in Glucocorticoid Regulation of Pituitary Corticotrope Growth and Cushing Disease

Abstract :
Context: Cushing disease (CD) is due to pituitary corticotrope adenomas that produce unrestrained ACTH secretion and have lost the negative feedback exerted by glucocorticoids (GCs). GCs also restrain corticotrope proliferation, and the mechanisms of this inhibition are poorly understood.
Objective: The aim of the study was to identify cell cycle regulatory genes that are regulated by GCs and the glucocorticoid receptor and to assess regulatory genes that have a rate-limiting action on corticotrope proliferation and may be disregulated in CD.
Design: The mouse corticotrope tumor cells AtT-20 were used to identify GC-regulated genes that contribute to control of cell cycle progression. Surgery sections from patients with CD were used to assess expression of CABLES1 in corticotrope adenomas.
Methods: Gene expression profiling, small interfering RNA knockdowns, cell cycle analyses, and genetic manipulations were performed in AtT-20 cells. Sequencing of chromatin immunoprecipitation for pituitary-restricted transcription factors and RNA polymerase II were used to identify regulatory elements and genes that bind GR and are direct transcriptional targets. A panel of previously well-characterized corticotrope adenomas was used to correlate expression of CABLES1 with that of other markers. Results: GCs altered expression of 3 positive and 3 negative regulators of cell cycle progression. Two Myc genes (L-Myc and N-Myc) and E2F2 are repressed by GCs, whereas genes for the negative regulators of the cell cycle, Gadd45, Gadd45, and Cables1 are activated by GCs. Cables1 small interfering RNA knockdown strongly stimulates AtT-20 cell proliferation and antagonizes the growth inhibition produced by GCs. The Gadd45 and Cables1 genes have the hallmarks of direct GC targets. CABLES1 is expressed in normal human pituitary cells, but expression is lost in 55% of corticotrope adenomas, and this is strongly correlated with the loss of p27 Kip1 expression.
Conclusions: CABLES1 is a critical regulator of corticotrope proliferation that defines a pathway often inactivated in CD and links proliferation to GC resistance. (J Clin Endocrinol Metab

Document type :

Journal articles
Journal of Clinical Endocrinology and Metabolism, Endocrine Society, 2016, 101 (2), pp.513-522. <10.1210/jc.2015-3324>
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