Over-Expression of MicroRNA-122 Inhibits Proliferation and Induces Apoptosis in Colon Cancer Cells

Background: MicroRNA, a non-coding RNA molecule plays a vital role in post transcriptional gene expression. MicroRNA-122, a liver specific microRNA was found to be downregulated in liver cancer and is associated with hepatocarcinogenesis. Being confirmed as tumor suppressor microRNA in liver carcinogenesis, we aimed to study the expression of microRNA-122 in colon cancer cell lines and the role of microRNA-122 in cell proliferation, invasion and migration of colon cancer cells. Methods: The expression of microRNA-122 is quantified using qRT-PCR by TaqMan universal primers. Colon cancer cell lines (SW480, SW620, HCT116) were transfected with microRNA-122 mimic and further studied for determining cell proliferation using CCK-8 kit, migration using Scratch assay, invasion using Transwell assay, apoptosis using Annexin-V FITC kit, and also gene expression. Results: Gene expression results displayed decreased expression of microRNA-122 in colon cancer cell lines. Transfection with microRNA-122 mimics impaired the cell proliferation and migration compared with control. FACS analysis confirmed that the percentage of microRNA-122 mimic transfected cells undergoing early apoptosis was increased. Gene expression of AEG-1, PI3K, CDK6, and PCNA were found to be downregulated in microRNA-122 overexpressed cells. Migratory and invasion potential of transfected cells was lessened in mimic transfected cells compared to control. Conclusion: The overexpression of microRNA-122 inhibited the cellular proliferation, migration, invasion and increased percentage of cells undergoing early apoptosis, suggesting its anti-cancer potential. Studying the role of microRNA-122 and its interactions with oncogenes might pave the way to understand the underlying mechanism in colon cancer.