Przemysław Witek, Grzegorz Zieliński, Katarzyna Szamotulska, Maria Maksymowicz and Grzegorz Kamiński
Corticotroph macroadenomas are a rare cause of Cushing's disease (CD), but their properties are not well-recognised. The aim of this study was to evaluate the clinical and pathological aspects of corticotroph macroadenomas with particular emphasis on proliferation markers and their associations with the efficacy of surgical treatment.
A prospective cohort study was conducted in a tertiary referral centre in Poland.
In total, 59 patients with CD (20 macroadenomas and 39 microadenomas) were included in this study. Hormonal and imaging parameters, histopathological and ultrastructural features of the corticotroph tumours and the early surgical outcomes were evaluated.
ACTH and ACTH/cortisol ratios were higher in macroadenomas (P<0.001 and P=0.002 respectively). Greater tumour volumes were associated with higher Ki-67 and p53 expression (P
trend=0.009 and P
trend=0.024 respectively) and the rates of sparsely granulated adenomas (P
trend=0.036). Immediate postoperative remission and early biochemical remission rates were lower in macroadenomas compared to microadenomas (P<0.001). A logistic regression model showed that the immediate postoperative remission or early biochemical remission depended on tumour volume (P=0.005 and P=0.006 respectively) and invasiveness based on Knosp grades 3 and 4 for macroadenomas and a lack of surgical pseudocapsule for microadenomas (P=0.004 and P=0.007 respectively).
Corticotroph macroadenomas differ from the more common microadenomas not only in terms of hormonal and imaging characteristics but also in terms of immunohistochemical and ultrastructural features and proliferation markers. The early effectiveness of surgery depends primarily on tumour volume and invasiveness.
Mateusz Bujko, Paulina Kober, Joanna Boresowicz, Natalia Rusetska, Agnieszka Paziewska, Michalina Dąbrowska, Agata Piaścik, Monika Pękul, Grzegorz Zieliński, Jacek Kunicki, Wiesław Bonicki, Jerzy Ostrowski, Janusz A Siedlecki and Maria Maksymowicz
Pituitary corticotroph adenomas commonly cause Cushing’s disease (CD) but part of these tumours are hormonally inactive (silent corticotroph adenomas, SCA). USP8 mutations are well-known driver mutations in corticotrophinomas. Differences in transcriptomic profiles between functioning and silent tumours or tumours with different USP8 status have not been investigated.
Design and methods
Forty-eight patients (28 CD, 20 SCA) were screened for USP8 mutations with Sanger sequencing. Twenty-four patients were included in transcriptomic profiling with Ampliseq Transcriptome Human Gene Expression Core Panel. The entire patients group was included in qRT-PCR analysis of selected genes expression. Immunohistochemistry was used for visualization of selected protein.
We found USP8 mutation in 15 patients with CD and 4 SCAs. USP8 mutations determine molecular profile of the tumours as showed by hierarchical clustering and identification of 1648 genes differentially expressed in USP8-mutated and USP8-wild-type tumours. Mutations affect many molecular pathways as observed in Gene Set Enrichment analysis. USP8-mutated adenomas showed higher level of POMC, CDC25A, MAPK4 but lower level of CCND2, CDK6, CDKN1B than USP8-wt tumours. Eighty-seven genes differentially expressed between CD-related adenomas and SCAs were found, including those involved in cell signalling (GLI2, DLC1, TBX2, RASSF6), cell adhesion (GJA1, CDH6), ion transport (KCNN4, KCNJ5) and GABA signalling (GABBR2, GABRD).
USP8 mutations occur in functioning and silent corticotrophinomas. They have pleiotropic effect, not limited to EGFR signalling, and affect expression levels of many genes involved in different pathways. Expression of GABA-related genes GABBR2, GNAL, GABARD and KCNJ5 correspond to functional status of the tumours.