The present study aimed to investigate the molecular mechanisms and effect of Beclin-1 on autophagy, proliferation and apoptosis in the colorectal cancer (CRC) HCT116 and SW620 cells. Beclin-1 was silenced by RNA interference (RNAi) in HTC116 and SW620 cells. Reverse transcription-polymerase chain reaction and western blot were used to measure the expression of Beclin-1. The percentage of apoptotic cells was analyzed by cell counting kit-8 (CCK-8) and flow cytometry (FCM). Cell cycle and cell proliferation were analyzed by FCM and the MTT assay. The present study created 3 groups in the two cell lines, consisting of the targeting siRNA (TS) group, in which Beclin-1 was partially silenced, non-specific siRNA (NS) group and control group (CG; without transfection). By siRNA transfection, the mRNA and protein level of Beclin-1 in the TS group were significantly inhibited compared with the NS group and CG (P<0.05). After 0, 24, 48 and 72 h, the survival rate of the cells in the TS group was significantly decreased compared with the survival rate of the cells in the NS group and CG, as detected by CCK-8 methods (P<0.05). FCM and MTT results showed the apoptotic rate of the cells in the TS group was significantly decreased compared with the rate in the NS group and CG (P<0.05), and the proliferation of the cells in the NS group was evidently increased compared with the CG. In conclusion, Beclin-1 played an important role in regulating autophagy, proliferation and apoptosis in HCT116 and SW620 cells. The inhibition of Beclin-1 by RNAi suppressed the autophagic activity and proliferation, but promoted apoptosis in CRC cells. Beclin-1 was the new target of gene therapy for CRC.
Keywords: Beclin-1; HCT116 cells; apoptosis; autophagy; colorectal cancer; proliferation; small interfering RNA.