Downregulation of human choline kinase α gene expression by miR-876-5p.

Choline kinase (CK) is the first enzyme in the CDP-choline pathway for the synthesis of phosphatidylcholine, the most abundant phospholipid in the mammalian cell membrane. This enzyme exists as three isozymes (alpha 1, alpha 2 and beta) and the CK isozyme has been implicated in cancer pathogenesis. Inhibition of CK activity has been proposed for cancer therapies. MicroRNAs (miRNAs/miRs) are non-coding RNAs that serve important roles in diverse biological pathways and human diseases, including cancer. However, the regulation of CK gene expression by miRNAs has never been investigated, to the best of the authors' knowledge. In the present study, two miRNA mimics, miR-876-5p and miR-646, were transfected into the HepG2 cell line and the effect of these miRNAs on the levels of CK alpha mRNA were determined by reverse transcription-quantitative polymerase chain reaction. Cells transfected with 25 nM miR-876-5p for 48 h exhibited significantly lower levels of CK mRNA. Following optimization, miR-876-5p caused four times lower levels of CK mRNA compared to the negative control. Effects of the miRNAs on HepG2 cell viability and cellular morphology were additionally analyzed using an MTT cell viability assay and scanning electron microscopy, respectively. HepG2 cells that were transfected with the optimum concentration of miR-876-5p for the optimum duration exhibited 25% lower viability than negative control and signs of apoptosis in electron micrographs. The results suggested miR-876-5p as a potential miRNA modulator of CK alpha expression in the cells, and may be relevant for the design of more effective anticancer strategy targeting CK.