Down-modulation of heat shock protein 70 and up-modulation of Caspase-3 during schisandrin B-induced apoptosis in human hepatoma SMMC-7721 cells

AIM: To investigate the effect of schisandrin B (Sch B) on proliferation and apoptosis of human hepatoma SMMC-7721 cells in vitro and regulation of Hsp70 and Caspases-3, 7, 9 expression by Sch B. METHODS: Human hepatoma cell line SMMC-7721 was cultured and treated with Sch B at various concentrations. Growth suppression was detected with MTT colorimetric assay. Cell apoptosis was confirmed by DNA ladder detection and flow cytometric analysis. The expression of Hsp70, Caspases-3, 7, 9 were analyzed by Western blot analysis. RESULTS: Sch B inhibited the growth of hepatoma SMMC-7721 cells in a dose-dependent manner, leading to a 50% decrease in cell number (LC50) value of 23.50 mg/L. Treatment with Sch B resulted in degradation of chromosomal DNA into small internucleosomal fragments, evidenced by the formation of a 180-200 bp DNA ladder on agarose gels. FCM analysis showed the peak areas of subdiploid at the increased concentration of Sch B. The results of Western bolt analysis showed that Hsp70 was down-regulated and Caspase-3 was up-regulated, while the activity of Caspases-7,-9 had no significant change. CONCLUSION: Sch B is able to inhibit the proliferation ofhuman hepatoma SMMC-7721 cells and induce apoptosis, which goes through Caspase-3-dependent and Caspase-9-independent pathway accompanied with the down-regulation of Hsp70 protein expression at an early event.

Honokiol:A potent chemotherapy candidate for human colorectal carcinoma

AIM: To investigate the anticancer activity of Honokiol on RKO,a human colorectal carcinoma cell line in vitro and in vivo,and to evaluate its possible use in clinic.METHODS: In vitro anticancer activity of honokiol was demonstrated by its induction of apoptosis in tumor cells.We analyzed cell proliferation with MTT assay, cell cycle with flow cytosmeter, DNA fragment with electrophoresis on agarose gels. To test the mechanism of honokiol-induced apoptosis, Westem blotting was used to investigate the factors involved in this process. The pharmacokinetics study of honokiol was tested by high phase liquid chromatography.In in vivo study, Balb/c nude mice were incubated with RKO cells. Honokiol was injected intraperitoneally every other day into tumor bearing Balb/c nude mice.RESULTS: Our results showed that honokiol induced apoptosis of RKO cells in a time- and dose-dependent manner. At 5-10 ug/mL for 48 h, honokiol induced apoptosis through activating Caspase cascades. Pharmacokinetics study demonstrated that, honokiol could be absorbed quickly by intraperitoneal injection, and maintained in plasma for more than 10 h. In nude mice bearing RKO-incubated tumor, honokiol displayed anticancer activity by inhibiting tumor growth and prolonging the lifespan of tumor bearing mice.CONCLUSION: With its few toxicity to normal cells and potent anticancer activity in vitroand in vivo, honokiol might be a potential chemotherapy candidate in treating human colorectal carcinoma.