UCHL1 loss alters the cell-cycle in metastatic pancreatic neuroendocrine tumors.

TitleUCHL1 loss alters the cell-cycle in metastatic pancreatic neuroendocrine tumors.
Publication TypeJournal Article
Year of Publication2019
AuthorsFinnerty BM, Moore MD, Verma A, Aronova A, Huang S, Edwards DP, Chen Z, Seandel M, Scognamiglio T, Du Y-CNancy, Elemento O, Zarnegar R, Min IM, Fahey TJ
JournalEndocr Relat Cancer
Date Published2019 04 01
KeywordsAdult, Aged, Aged, 80 and over, Apoptosis, Biomarkers, Tumor, Cell Cycle, Cell Line, Tumor, Cell Proliferation, Female, Humans, Male, Middle Aged, Neuroendocrine Tumors, Pancreatic Neoplasms, Phenotype, Ubiquitin Thiolesterase

Loss of ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) expression by CpG promoter hypermethylation is associated with metastasis in gastroenteropancreatic neuroendocrine tumors; however, the mechanism of how UCHL1 loss contributes to metastatic potential remains unclear. In this study, we first confirmed that loss of UCHL1 expression on immunohistochemistry was significantly associated with metastatic tumors in a translational pancreatic neuroendocrine tumor (PNET) cohort, with a sensitivity and specificity of 78% and 89%, respectively. To study the mechanism driving this aggressive phenotype, BON and QGP-1 metastatic PNET cell lines, which do not produce UCHL1, were stably transfected to re-express UCHL1. In vitro assays, RNA-sequencing, and reverse-phase protein array (RPPA) analyses were performed comparing empty-vector negative controls and UCHL1-expressing cell lines. UCHL1 re-expression is associated with lower anchorage-independent colony growth in BON cells, lower colony formation in QGP cells, and a higher percentage of cells in the G0/G1 cell-cycle phase in BON and QGP cells. On RPPA proteomic analysis, there was an upregulation of cell-cycle regulatory proteins CHK2 (1.2 fold change, p=0.004) and P21 (1.2 fold change, p=0.023) in BON cells expressing UCHL1; western blot confirmed upregulation of phosphorylated CHK2 and P21. There were no transcriptomic differences detected on RNA-Sequencing between empty-vector negative controls and UCHL1-expressing cell lines. In conclusion, UCHL1 loss correlates with metastatic potential in PNETs and its re-expression induces a less aggressive phenotype in vitro, in part by inducing cell-cycle arrest through post-translational regulation of phosphorylated CHK2. UCHL1 re-expression should be considered as a functional biomarker in detecting PNETs capable of metastasis.

Alternate JournalEndocr. Relat. Cancer
PubMed ID30689542