Pituitary adenomas evade apoptosis via noxa deregulation in Cushing’s disease
David T. Asuzu, Reinier Alvarez, Patrick A. Fletcher, Debjani Mandal, Kory Johnson, Weiwei Wu, Abdel Elkahloun, Paúl E. Clavijo, Clint Allen, Dragan Maric, Abhik Ray‐Chaudhury, Sharika Rajan, Zied Abdullaev, Diana Nwokoye, Kenneth Aldape, Lynnette K. Nieman, Constantine A. Stratakis, Stanko S. Stojilković, Prashant Chittiboina
Abstract
Sporadic pituitary adenomas occur in over 10% of the population. Hormone-secreting adenomas, including those causing Cushing's disease (CD), cause severe morbidity and early mortality. Mechanistic studies of CD are hindered by a lack of in vitro models and control normal human pituitary glands. Here, we surgically annotate adenomas and adjacent normal glands in 25 of 34 patients. Using single-cell RNA sequencing (RNA-seq) analysis of 27594 cells, we identify CD adenoma transcriptomic signatures compared with adjacent normal cells, with validation by bulk RNA-seq, DNA methylation, qRT-PCR, and immunohistochemistry. CD adenoma cells include a subpopulation of proliferating, terminally differentiated corticotrophs. In CD adenomas, we find recurrent promoter hypomethylation and transcriptional upregulation of PMAIP1 (encoding pro-apoptotic BH3-only bcl-2 protein noxa) but paradoxical noxa downregulation. Using primary CD adenoma cell cultures and a corticotroph-enriched mouse cell line, we find that selective proteasomal inhibition with bortezomib stabilizes noxa and induces apoptosis, indicating its utility as an anti-tumor agent.