Piper betle leaf extract enhances the cytotoxicity effect of 5-fluorouracil in inhibiting the growth of HT29 and HCT116 colon cancer cells

Objective： The combination effect of Piperbetle （PB） and 5-fluorouracil （5-FU） in enhancing the cytotoxic potential of 5-FU in inhibiting the growth of colon cancer cells was investigated. Methods： HT29 and HCT116 cells were subjected to 5-FU or PB treatment. 5-FU and PB were then combined and their effects on both cell lines were observed after 24 h of treatment. PB-5-FU interaction was elucidated by isobologram analysis. Apoptosis features of the treated cells were revealed by annexin V/PI stain. High-performance liquid chromatography （HPLC） was performed to exclude any possible chemical interaction between the compounds. Results： In the presence of PB extract, the cytotoxicity of 5-FU was observed at a lower dose （IC^0 12.5 pmol/L） and a shorter time （24 h） in both cell lines. Both cell lines treated with 5-FU or PB alone induced a greater apoptosis effect compared with the combination treatment. Isobologram analysis indicated that PB and 5-FU interacted synergistically and antagonistically in inhibiting the growth of HT29 and HCT116 cells, respectively. Conclusions： In the presence of PB, a lower dosage of 5-FU is required to achieve the maximum drug effect in inhibiting the growth of HT29 cells. However, PB did not significantly reduce 5-FU dosage in HCT116 cells. Our result showed that this interaction may not solely contribute to the apoptosis pathway.

Chlorella vulgaris triggers apoptosis in hepatocarcinogenesis-induced rats

Chlorella vulgaris （CV） has been reported to have antioxidant and anticancer properties. We evaluated the effect of CV on apoptotic regulator protein expression in liver cancer-induced rats. Male Wistar rats （200-250 g） were divided into eight groups： control group （normal diet）, CDE group （choline deficient diet supplemented with ethionine in drinking water to induce hepatocarcinogenesis）, CV groups with three different doses of CV （50, 150, and 300 mg/kg body weight）, and CDE groups treated with different doses of CV （50, 150, and 300 mg/kg body weight）. Rats were sacrificed at various weeks and liver tissues were embedded in paraffin blocks for immunohistochemistry studies. CV, at increasing doses, decreased the expression of anti-apoptotic protein, Bcl-2, but increased the expression of pro-apoptotic protein, caspase 8, in CDE rats, which was correlated with decreased hepatoctyes proliferation and increased apoptosis as determined by bromodeoxy-uridine （BrdU） labeling and terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling （TUNEL） assay, respectively. Our study shows that CV has definite chemopreventive effect by inducing apoptosis via decreasing the expression of Bcl-2 and increasing the expression of caspase 8 in hepatocarcinogenesis-induced rats.