The Physiology Of Hypercortisolism

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Cushing's syndrome (CS) is associated with a hypercoagulable state resulting in an increased risk on venous thromboembolism (VTE). In patients with untreated active CS VTE incidence is up to 18-fold higher compared to the general population, whereas after pituitary and adrenal surgery a postoperative VTE risk between 2.6 and 5.6% has been reported. Interestingly, after surgery the VTE risk is not only increased in the first week but also during several months postoperatively. The hypercoagulable state in CS is thought to be caused, at least in part, by an imbalance between activity of pro- and anticoagulant pathways. However, changes in activated partial thromboplastin time and plasma concentrations of pro-and anticoagulant factors are not observed in every CS patient. Only retrospective studies have shown that thromboprophylaxis lowers VTE risk in CS. Future prospective studies should asses the optimal timing, duration and type of thromboprophylaxis in CS to improve VTE-related morbidity and mortality. Using single-cell RNA sequencing (RNA-seq) analysis of 27594 cells, we identified CD adenoma transcriptomic signatures compared with adjacent normal cells, with validation by bulk RNA-seq, DNA methylation, qRT-PCR, and immunohistochemistry in 25 corticotrope adenomas. CD adenoma cells include a subpopulation of proliferating, terminally differentiated corticotrophs. We found 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.