Depletion of c-Myc inhibits human colon cancer colo 320 cells' growth.

Human colon cancer is the leading cause of cancer death in both men and women worldwide. The c-Myc gene is frequently deregulated and overexpressed in this malignancy, and strategies designed to inhibit c-Myc expression in cancer cells may have considerable therapeutic value. We design and use short hairpin RNA (shRNA) to inhibit c-Myc expression in Colo 320 cells and validat its effect on cell proliferation. In this study, four c-Myc-shRNA expression vectors were constructed and introduced into Colo 320 cells, and the cell cycle and apoptotic cells were analyzed by flow cytometry. The effects of c-Myc silencing on tumor-cell growth was assessed by the soft agar assay and by DNA synthesis experiments. Expression of c-Myc was also assessed by real-time reverse transcription polymerase chain reaction and Western blot analysis. Upon transient transfection with plasmid-encoding shRNA, it was found that expression of c-Myc decreased in shRNA-transfected cells, and the downregulation of c-Myc inhibited cell growth and induced apoptosis in Colo 320 cells. c-Myc downregulation also increased cell population in the G0-G1 phase. In conclusion, our findings demonstrate that shRNA can inhibit the DNA replication and induce apoptosis in Colo 320 cells effectively and, therefore, could be used as a new potential anticancer tool for the therapy of human colon cancer.