Abstract:
Objective To evaluate the mechanism of combined effects of recombinant adenovirus-mediated retinoblastoma gene 94(Ad-Rb94)with γ-ray radiation on inhibiting the growth of human colorectal cancer cells in vitro.
Methods HT29 cells were transfected by Ad-Rb94 and irradiated by 4 Gy 137Cs γ-ray 12 h after transfection. The cohorts were divided into five groups:blank control, Ad-LacZ, Ad-Rb94, radiation and Ad-Rb94 combined with radiation. The cells growth curve of HT29 cells was detected by MTT assay. Changes of cell cycle and cell apoptosis in HT29 cells were detected by flow cytometry.
Results The growth of cells treated with Ad-Rb94 or radiation alone was all inhibited when Ad-Rb94 was transfected effectively into HT29 cells. The growth of HT29 cells treated with radiation or combination of Ad-Rb94 and radiation was slower than that of blank control and Ad-lacZ at 4 d after transfection. The growth of HT29 cells treated with combination of Ad-Rb94 and radiation resulted in greater inhibition compared with that of Ad-Rb94 or radiation alone(t=15.02 and 17.30, P < 0.01). Cell cycle data showed that HT29 cells treated with radiation were arrested at G2 phase, and there were significant differences compared with that of blank control, Ad-lacZ and Ad-Rb94(t=18.65, 15.23 and 16.38, P < 0.01). Cells treated with combination of Ad-Rb94 and radiation arrested at G2 phases increasingly, reached 40%, significantly higher than that of radiation alone(t=7.78, P < 0.05). Cells apoptosis data showed that the apoptosis ratio of HT29 cells treated with Ad-Rb94 or radiation was markedly increased compared with that of blank control(t=16.19 and 10.72, P < 0.01). Cells apoptosis ratio of HT29 cells treated with combination of Ad-Rb94 and radiation was the highest, reached 21%, and there were significant differences compared with that of Ad-Rb94 or radiation alone(t=6.17 and 9.25, P < 0.05).
Conclusion The recombinant Ad-Rb94 transfection combined with radiation shows synergism for the suppression of colorectal cancer cells growth. Retard the cell in G2 phase and promote cells apoptosis is may be the main mechanism.