Aim: In this study, we investigated the inhibitive effects of Oplopanax horridus extract (OhE) and its fractions (OhF1, OhF2, OhF3, OhF4 and OhF5) on the growth of human colorectal cancer cells and the possible mechanisms involved were investigated.
Materials and methods: The antiproliferative effects were evaluated by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) cell proliferation assay. Apoptotic effects and cell cycle distribution were analyzed by flow cytometry after staining with Annexin V/PI or PI/RNase.
Results: After treatment for 48 h, OhE, OhF4 and OhF5 (10-100 microg/ml) inhibited proliferation of HCT-116, SW-480 and HT-29 cell lines, and cell growth decreased most with the treatment of OhF4. On the other hand, OhF1, OhF2 and OhF3 were not observed to have obvious suppressive effects on these cell lines at concentrations of 10-100 microg/ml. OhE, OhF4 and OhF5 (1-10 microg/ml) noticeably induced apoptosis time- and concentration-dependently compared to the control at the same time point. Treatment with OhE, OhF4 or OhF5 (1-10 microg/ml) for 24 h distinctly induced a G(2)/M-phase arrest of the cell cycle in a dose-dependent manner. The trend of increasing cyclin A and cyclin B1 were similar to the increase of G(2)/M phase cells in all treated groups.
Conclusion: These results showed that OhE had potential antiproliferative effects on human colorectal cancer cells, and the active components are enriched in the OhF4 and OhF5 fractions. The anticancer mechanism of OhE, OhF4 and OhF5 might be attributed to the induction of apoptosis and the regulation of cell cycle transition.