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Drivers of sporadic benign pituitary adenoma growth are largely unknown. Whole-exome sequencing of 159 prospectively resected pituitary adenomas showed that somatic copy number alteration (SCNA) rather than mutation is a hallmark of hormone-secreting adenomas and that SCNAs correlate with adenoma phenotype. Using single-gene SCNA pathway analysis, we observed that both cAMP and Fanconi anemia DNA damage repair pathways were affected by SCNAs in growth hormone-secreting (GH-secreting) somatotroph adenomas. As somatotroph differentiation and GH secretion are dependent on cAMP activation and we previously showed DNA damage, aneuploidy, and senescence in somatotroph adenomas, we studied links between cAMP signaling and DNA damage. Stimulation of cAMP in C57BL/6 mouse primary pituitary cultures using forskolin or a long-acting GH-releasing hormone (GHRH) analog increased GH production and DNA damage measured by H2AX phosphorylation and a comet assay. Octreotide, a somatostatin receptor ligand that targets somatotroph adenoma GH secretion in patients with acromegaly, inhibited cAMP and GH and reversed DNA damage induction. In vivo long- acting GHRH treatment also induced pituitary DNA damage in mice. We conclude that cAMP, which induces somatotroph proliferation and GH secretion, may concomitantly induce DNA damage, potentially linking hormone hypersecretion to SCNA and genome instability. These results elucidating somatotroph adenoma pathophysiology identify pathways for targeted treatment., Introduction Adenomas arising from the anterior pituitary are invariably benign and may either be nonhormone secreting (nonfunctioning) or hormone secreting (functioning) (1, 2). The prevalence of identified pituitary adenomas ranges [...]

Growth hormone (GH) excess in acromegaly is associated with increased precancerous colon polyps and soft tissue adenomas, whereas short-stature humans harboring an inactivating GH receptor mutation do not develop cancer. We show that locally expressed colon GH is abundant in conditions predisposing to colon cancer and in colon adenocarcinoma-associated stromal fibroblasts. Administration of a GH receptor (GHR) blocker in acromegaly patients induced colon p53 and adenomatous polyposis coli (APC), reversing progrowth GH signals. p53 was also induced in skin fibroblasts derived from short-statured humans with mutant GHR. GH-deficient prophet of pituitary-specific positive transcription factor 1 (Prop1)(-/-) mice exhibited induced colon p53 levels, and cross-breeding them with Apc(min+/-) mice that normally develop intestinal and colon tumors resulted in GH-deficient double mutants with markedly decreased tumor number and size. We also demonstrate that GH suppresses p53 and reduces apoptosis in human colon cell lines as well as in induced human pluripotent stem cell-derived intestinal organoids, and confirm in vivo that GH suppresses colon mucosal p53/p21. GH excess leads to decreased colon cell phosphatase and tensin homolog deleted on chromosome 10 (PTEN), increased cell survival with down-regulated APC, nuclear β-catenin accumulation, and increased epithelial-mesenchymal transition factors and colon cell motility. We propose that GH is a molecular component of the "field change" milieu permissive for neoplastic colon growth.

Context: Preclinical studies show seliciclib (R-roscovitine) suppresses neoplastic corticotroph proliferation and pituitary adrenocorticotrophic hormone (ACTH) production. Objective: To evaluate seliciclib as an effective pituitary-targeting treatment for patients with Cushing disease (CD). Methods: Two prospective, open-label, phase 2 trials, conducted at a tertiary referral pituitary center, included adult patients with de novo, persistent, or recurrent CD who received oral seliciclib 400 mg twice daily for 4 consecutive days each week for 4 weeks. The primary endpoint in the proof-of-concept single-center study was normalization of 24-hour urinary free cortisol (UFC; =50 µg/24 hours) at study end; in the pilot multicenter study, primary endpoint was UFC normalization or = 50% reduction in UFC from baseline to study end. Results: Sixteen patients were consented and 9 were treated. Mean UFC decreased by 42%, from 226.4±140.3 µg/24 hours at baseline to 131.3± 114.3 µg/24 hours by study end. Longitudinal model showed significant UFC reductions from baseline to each treatment week. Three patients achieved = 50% UFC reduction (range, 55%-75%), and 2 patients exhibited 48% reduction; none achieved UFC normalization. Plasma ACTH decreased by 19% (P=0.01) in patients who achieved = 48% UFC reduction. Three patients developed grade = 2 elevated liver enzymes, anemia, and/or elevated creatinine, which resolved with dose interruption/reduction. Two patients developed grade 4 liverrelated serious adverse events that resolved within 4 weeks of seliciclib discontinuation. Conclusion: Seliciclib may directly target pituitary corticotrophs in CD and reverse hypercortisolism. Potential liver toxicity of seliciclib resolves with treatment withdrawal. The lowest effective dose requires further determination. [ABSTRACT FROM AUTHOR]

Cushing disease is a condition in which the pituitary gland releases excessive adrenocorticotropic hormone (ACTH) as a result of an adenoma arising from the ACTH-secreting cells in the anterior pituitary. ACTH-secreting pituitary adenomas lead to hypercortisolemia and cause significant morbidity and mortality. Pituitary-directed medications are mostly ineffective, and new treatment options are needed. As these tumors express EGFR, we tested whether EGFR might provide a therapeutic target for Cushing disease. Here, we show that in surgically resected human and canine corticotroph cultured tumors, blocking EGFR suppressed expression of proopiomelanocortin (POMC), the ACTH precursor. In mouse corticotroph EGFR transfectants, ACTH secretion was enhanced, and EGF increased Pomc promoter activity, an effect that was dependent on MAPK. Blocking EGFR activity with gefitinib, an EGFR tyrosine kinase inhibitor, attenuated Pomc expression, inhibited corticotroph tumor cell proliferation, and induced apoptosis. As predominantly nuclear EGFR expression was observed in canine and human corticotroph tumors, we preferentially targeted EGFR to mouse corticotroph cell nuclei, which resulted in higher Pomc expression and ACTH secretion, both of which were inhibited by gefitinib. In athymic nude mice, EGFR overexpression enhanced the growth of explanted ACTH-secreting tumors and further elevated serum corticosterone levels. Gefitinib treatment decreased both tumor size and corticosterone levels; it also reversed signs of hypercortisolemia, including elevated glucose levels and excess omental fat. These results indicate that inhibiting EGFR signaling may be a novel strategy for treating Cushing disease., Introduction Pituitary tumors, accounting for approximately 15% of intracranial tumors, are invariably benign monoclonal adenomas with excessive hormone secretion and/or tumor mass effects compressing vital structures (1). Adrenocorticotropic hormone-secreting (ACTH-secreting) [...]