Inhibitory effect of resveratrol on the growth of human colon cancer ls174t cells and its subcutaneously transplanted tumor in nude mice and the mechanism of action

Objective To explore the effect and mechanism of resveratrol against human colon cancer ls174t cells in vitro and the growth of colon cancer in tumor-bearing nude mice. Methods MTT method was used to test the inhibiting effect of resveratrol on the growth and proliferation of ls174t cells. Transmission electron microscopy was used to observe the morphological changes of cell apoptosis, and FCM assay was performed to measure the changes of cell apoptosis rate and cell cycle. RT-PCR method was used to detect the expression of bcl-2 and hax mRNA, and Western blot was used to detect the expression of bcl- 2 and bax protein. Results MTT test revealed that resveratrol showed significant inhibiting effect on lsl74t cells in a concentration-and time-dependent manner. In the concentration range of 25, 50, 100, 200 and 400μmol/L, the inhibition rate after resveratrol treatment for 24 hours was respectively 1.0% , 9.1% , 17.4% , 27.8% and 66.5% , while the inhibition rate after treatment for 48 hours was respectively 3.6% , 13.7% , 30.2% , 58.4% and 86. I% , and the inhibition rate after treatment for 72 hours was 18.1% , 33.0%, 48.6%, 61.2% and 89.4%, respectively, showing a very significant difference （ P 〈 0.01 ）. Typical ultrastructural apoptotic changes were observed in resveratrol-treated ls174t ceils. It was found through FCM assay that resveratrol caused apoptosis in ls174 cells and blocked the cell cycle at S phase. RT- PCR and Western blot test showed that after the treatment of colon cancer cells with resveratrol at different concentrations （25, 50, 100 and 200μmol/L）, the expression level of bcl-2 was decreased, while expression level of bax was increased. The highest inhibition rate was 47.9%. In 200 mg/kg and 800 mg/kg resveratrol treatment groups, the weight of subcutaneously transplanted tumors in nude mice was 4.10±0.18 g and 3.05±0.35 g, respectively, the difference was significant compared with that of the control group （P 〈0.01）. Conclusion Resveratrol can inhibit the growth of ls174t cells through apoptosis induction. The mechanism is probably related to inhibition of anti-apoptotic factor bcl-2 and enhancement of expression of apoptotic factor bax. Key words: Resveratrol;  Colonic neoplasms ;  Apoptosis ;  Nude mice