A., Sesta M.F., Cassarino M., Terreni A.G., Ambrogio L., Libera D., Bardelli G., Lasio M., Losa F., PecoriGiraldi Supplementary Material for: <b><i>Ubiquitin-Specific Protease 8</i></b> Mutant Corticotrope Adenomas Present Unique Secretory and Molecular Features and Shed Light on the Role of Ubiquitylation on ACTH Processing <b><i>Background:</i></b> Somatic mutations in the ubiquitin-specific protease 8 (USP8) gene have recently been shown to occur in ACTH-secreting pituitary adenomas, thus calling attention to the ubiquitin system in corticotrope adenomas. <b><i>Objectives:</i></b> Assess the consequences of <i>USP8</i> mutations and establish the role of ubiquitin on ACTH turnover in human ACTH-secreting pituitary adenomas. <b><i>Methods:</i></b> <i>USP8</i> mutation status was established in 126 ACTH-secreting adenomas. Differences in ACTH secretion and <i>POMC</i> expression from adenoma primary cultures and in microarray gene expression profiles from archival specimens were sought according to <i>USP8</i> sequence. Ubiquitin/ACTH coimmunoprecipitation and incubation with MG132, a proteasome inhibitor, were performed in order to establish whether ubiquitin plays a role in POMC/ACTH degradation in corticotrope adenomas. <b><i>Results:</i></b> <i>USP8</i> mutations were identified in 29 adenomas (23%). Adenomas presenting <i>USP8</i> mutations secreted greater amounts of ACTH and expressed <i>POMC</i> at higher levels compared to <i>USP</i> wild-type specimens. <i>USP8</i> mutant adenomas were also more sensitive to modulation by CRH and dexamethasone in vitro. At microarray analysis, genes associated with endosomal protein degradation and membrane components were downregulated in <i>USP8</i> mutant adenomas as were <i>AVPR1B</i>, <i>IL11RA</i>, and<i> PITX2</i>. Inhibition of the ubiquitin-proteasome pathway increased ACTH secretion and POMC itself proved a target of ubiquitylation, independently of <i>USP8</i> sequence status. <b><i>Conclusions:</i></b> Our study has shown that <i>USP8</i> mutant ACTH-secreting adenomas present a more “typical” corticotrope phenotype and reduced expression of several genes associated with protein degradation. Further, ubiquitylation is directly involved in intracellular ACTH turnover, suggesting that the ubiquitin-proteasome system may represent a target for treatment of human ACTH-secreting adenomas. Ubiquitylation;Cushing’s disease;Gene expression profiling;POMC;ACTH-secreting adenomas;Ubiquitin-specific protease 8 2019-10-16
    https://karger.figshare.com/articles/dataset/Supplementary_Material_for_b_i_Ubiquitin-Specific_Protease_8_i_b_Mutant_Corticotrope_Adenomas_Present_Unique_Secretory_and_Molecular_Features_and_Shed_Light_on_the_Role_of_Ubiquitylation_on_ACTH_Processing/9988820
10.6084/m9.figshare.9988820.v1