Abstract
Pancreatic cancer is a highly malignant cancer of the pancreas with a very poor prognosis. Methylation of histone lysine residues is essential for regulating cancer physiology and pathophysiology, mediated by a set of methyltransferases (KMTs) and demethylases (KDMs). This study surveyed the expression of methylation regulators functioning at lysine 9 of histone 3 (H3K9) in pancreatic lesions and explored the underlying mechanisms. We analyzed KDM1A and KDM3A expression in clinical samples by immunohistochemical staining and searching the TCGA PAAD program and GEO datasets. Next, we identified the variation in tumor growth in vitro and in vivo after knockdown of KDM1A or KDM3A and explored the downstream regulators of KDM1A and KDM3A via RNA-seq, and gain- and loss-of-function assays. Eleven H3K9 methylation regulators were highly expressed in pancreatic cancer, and only KDM1A and KDM3A expression positively correlated with the clinicopathological characteristics in pancreatic cancer. High expression of KDM1A or KDM3A positively correlated with pathological grade, lymphatic metastasis, invasion, and clinical stage. Kaplan-Meier analysis indicated that a higher level of KDM1A or KDM3A led to a shorter survival period. Knockdown of KDM1A or KDM3A led to markedly impaired tumor growth in vitro and in vivo. Mechanistically, CCNA2, a cell cycle-associated gene was partially responsible for KDM1A knockdown-mediated effect and CDK6, also a cell cycle-associated gene was partially responsible for KDM3A knockdown-mediated effect on pancreatic cancer cells. Our study demonstrates that KDM1A and KDM3A are highly expressed in pancreatic cancer and are intimately correlated with clinicopathological factors and prognosis. The mechanism of action of KDM1A or KDM3A was both linked to the regulation of cell cycle-associated genes, such as CCNA2 or CDK6, respectively, by an H3K9-dependent pathway.