Reduced Expression of Histone Methyltransferases KMT2C and KMT2D Correlates with Improved Outcome in Pancreatic Ductal Adenocarcinoma

Genes encoding the histone H3 lysine 4 methyltransferases KMT2C and KMT2D are subject to deletion and mutation in pancreatic ductal adenocarcinoma (PDAC), where these lesions identify a group of patients with a more favorable prognosis. In this study, we demonstrate that low KMT2C and KMT2D expression in biopsies also defines better outcome groups, with median survivals of 15.9 versus 9.2 months (P = 0.029) and 19.9 versus 11.8 months (P = 0.001), respectively. Experiments with eight human pancreatic cell lines showed attenuated cell proliferation when these methyltransferases were depleted, suggesting that this improved outcome may reflect a cell-cycle block with diminished progression from G(0)-G(1). RNA-seq analysis of PDAC cell lines following KMT2C or KMT2D knockdown identified 31 and 124 differentially expressed genes, respectively, with 19 genes in common. Gene-set enrichment analysis revealed significant downregulation of genes related to cell-cycle and growth. These data were corroborated independently by examining KMT2C/D signatures extracted from the International Cancer Genome Consortium and The Cancer Genome Atlas datasets. Furthermore, these experiments highlighted a potential role for NCAPD3, a condensin II complex subunit, as an outcome predictor in PDAC using existing gene expression series. Kmt2d depletion in KC/KPC cell lines also led to an increased response to the nucleoside analogue 5-fluorouracil, suggesting that lower levels of this methyltransferase may mediate the sensitivity of PDAC to particular treatments. Therefore, it may also be therapeutically beneficial to target these methyltransferases in PDAC, especially in those patients demonstrating higher KTM2C/D expression. (C) 2016 AACR.