OBJECTIVETo investigate the biological behavioral effects of specific siRNA expression plasmids targeted against c-Myc and vascular endothelial growth factor (VEGF) on human colorectal cancer cell line Volo.

METHODSThe expression plasmids with small interfering RNA (siRNA) aiming at c-Myc and VEGF were designed and constructed respectively, then transfected into Volo cells by eukaryocyte transfection technique. The protein expressions of c-Myc and VEGF were detected by Western blotting. Cellular proliferation, apoptosis, cycle distribution and invasion character were analyzed by tetrazolium bromide colorimetry (MTT), flow cytometry (FCM), TUNEL assay and matrigel invasion assay respectively.

RESULTSEnzymatic digestion and DNA sequencing confirmed that the c-Myc and VEGF specific siRNA expression plasmids were constructed successfully. After plasmids were transfected into cells, the protein expressions of c-Myc and VEGF were significantly down-regulated respectively as compared with control group (P<0.01). The cellular proliferation inhibitory rates in c-Myc siRNA group, VEGF siRNA group and c-Myc+VEGF group were (59.20+/-5.05)%, (32.31+/-3.48)% and (75.81+/-7.89)% respectively, which were higher than that in control group [(6.80+/-1.45)%] (all P<0.05). The cell apoptosis rate in above 3 groups were (40.50+/-4.37)%, (21.30+/-2.98)% and (62.59+/-9.66)% respectively, which were higher than that in control group [(2.90+/-0.36)%] (all P<0.05). The cell invasion rates in VEGF siRNA group and c-Myc+VEGF siRNA group were (7.34+/-3.65)% and (2.80+/-1.02)%, which were lower than that in control group [(18.57+/-7.46)%] (P<0.05). The effect of c-Myc+VEGF siRNA group was greater.

CONCLUSIONSThe specific siRNA efficiently silences the expression of c-Myc and VEGF, subsequently, suppresses the cell proliferation, triggers the cell apoptosis and inhibits the cell invasiveness in these transfected colorectal cancer Volo cells. In addition, the synergism of siRNA-c-Myc and siRNA-VEGF in transfected cells can be found.