[Study on the apoptosis and its mechanism of lovo human colorectal cancer cells induced by SFPS].

Human colorectal cancer (lovo) cells were chose to study the anti-tumor effects of SFPS and explore the significance of caspase 3 in the apoptosis of lovo cells induced by SFPS. Inhibition of the cell proliferation was measured by MTT assay. SFPS induced apoptosis of lovo cells was observed by electron microscopy, flow cytometry and DNA electrophoresis. Furthermore, the expressions of caspase 3 mRNA and pro-caspase 3 were tested by RT-PCR and Western blot. SFPS exhibited anti-proliferative activity in the dosage and time-dependent manner. After incubation for 24, 36, 48 and 72 h, the IC50 of SFPS on lovo cells was 375 mg/L, 355 mg/L, 178 mg/L and 60 mg/L, respectively. DNA ladders of lovo cells were showed on agarose gel electrophoresis and the fragments of DNA were integral of 180-200 bp 24 hours after SFPS treatment at the doses of 5 mg/L, 50 mg/L and 300 mg/L. However, mistiness DNA ladder or smear was found in lovo cells treated with 500 mg/L SFPS. When SFPS concentration was 1000 mg/l, DNA ladder disappeared and showed smear entirely. Morphological examination showed chromosomal condensation, karyotheca margination, cell shrinkage and the presence of apoptosis bodies with electron microscopy. With concentration dependent manner, the apoptosis and sub-G1 peaks were observed through flow cytometry, but the cell cycle didn't change obviously. Furthermore, the expression of pro-caspase 3 was decreased and the level of caspase 3 mRNA was increased in the time and dose-dependent manner. It suggests that SFPS may induce the apoptosis of lovo cells in vitro resulting in the inhibition of proliferation. And caspase 3 activation may participate in the processes of the apoptosis of lovo cells induced by SFPS.