Abstract: AIM: To inhibit c-Myc gene expression in human rectal cancer cell line Colo320 by small interfering RNA ( siRNA) , and to provide a new method to study the role of c-Myc in Colo320 cell.METHODS: The c-Myc gene specific siRNA was designed according to its sequence and made by in vitro transcription.The c-Myc siRNA was transfected into Colo320 cell, and the cell was cultured for 48 to 96 hours before harvesting.c-Myc mRNA and protein level were monitored by using fluorescence real time reverse transcription polymerase chain reaction.Cellular proliferation activities were assayed by tetrazolium bromide (MTT) colorimetry and clone test.RESULTS: Compared with control group, there was a significant decrease in the c-Myc mRNA.Colo320 cells transfected with c-Myc siRNA had lower cellular proliferation than no-transfected Colo320 cells.CONCLUSION: Our results suggest that there exist RNA interference mechanism in Colo320 cell line, and the c-Myc siRNA can specifically inhibit the expression of c-Myc gene in Colo320 cells.RNA interference method provides a new way to study the role of c-Myc in cancer cell.

Key words: small interfering RNA, human rectal cancer, c-Myc gene