Effect of Inhibitor UNC0642 on Expression of G9a and Its Proliferative and Apoptotic Markers in Breast Cancer Cell Line MCF-7

Abstract

G9a is a lysine methyltransferase that has been reported to downregulate the expression of tumor suppressor genes in a variety of cancerous cells. The present study explores the anti-cancer activity of UNC0642, a novel potent inhibitor of G9a in MCF-7 breast cancer cell line. Analysis of growth and proliferation parameters by various cell-based assays such as neutral red assay and BrdU cell proliferation assay showed that higher concentrations were lethal for the cancerous cells. IC 50 was found to be 12.6 µM. Further contextualization of the therapeutic potential of G9a inhibition was provided by expression analysis of the G9a gene and genes associated with cell proliferation, tumor suppression, and apoptosis. The gene expression of fibroblast growth factor 1 (FGF1), enolase 2 (ENO2), cyclin D1 (CCND1), catalytic subunit of AMP-activated protein kinase (AMPKα2), RNA polymerase II transcription elongation factor (ELL2), and pro-apoptotic Bcl-2 homology 3-only protein (BIM) in MCF-7 breast cancer and normal human embryonic kidney HEK-293 cell lines were studied in response to treatment with different concentrations of UNC0642. Inhibition of G9a expression was observed in a dose-dependent manner in both cell lines with increasing UNC0642 concentrations. A dose-dependent downregulation of gene expression of proliferation marker genes (FGF-1, CCND1, and ENO2) was observed in both cell lines, whereas upregulation of tumor suppressor genes (AMPKα2 and ELL2) and apoptotic marker gene (BIM) was observed in a dose-dependent manner. Taken together, the results indicated the potential of G9a inhibition in the reduction of cancerous cell proliferation and inducing apoptosis in cancerous cells. Further elucidation of the signaling pathways associated with G9a, in-vitro and in-vivo safety analyses is required to fully establish G9a as a therapeutic target for cancer progression and UNC0642 as an anticancerous therapeutic agent for the treatment of breast cancer.