Hochu-ekki-to (Bu-zhong-yi-qi-tang), a herbal medicine, enhances cisplatin-induced apoptosis in HeLa cells

摘要

Hochu-ekki-to (HET), a Kampo herbal medicine composed of ten medicinal plants, is traditionally used to improve the general state of patients with malignant diseases such as cancer. Recent studies showed that HET had an anti-cancer effect against several cancer cell lines in vitro by inducing apoptosis. However, high doses of HET may have cytotoxic effects attributed to saponins or detergent-like compounds. Therefore, the present study used low doses of HET (50 mu g/ml, which did not affect cell viability, to evaluate its synergistic anti-cancer effects with cisplatin. HeLa cells were cultured for 24 h with 50 mu g/ml HET, followed by cisplatin treatment for 24 h at various concentrations. Subsequently, the sensitivity of the cells to cisplatin was assessed using a colony survival and a crystal violet cell viability assay. Furthermore, cisplatin-induced apoptosis was analyzed by flow cytometry. Proteins associated with cell viability and apoptosis, including phosphorylated (p-) Akt, p53, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax) and active caspase-3 were analyzed by immunoblotting. The present study revealed that cell survival was decreased and apoptosis was increased in HeLa cells pre-treated with HET prior to cisplatin treatment compared with HET-untreated cells. Furthermore, protein expression of p53 and active caspase-3 was increased, while the expression of p-Akt as well as the Bcl-2/Bax ratio, an index of survival activity in cells, were decreased in the HET-pre-treated cells compared with those in HET-untreated cells following incubation with cisplatin. In conclusion, the present study indicated that HET enhanced cisplatin-induced apoptosis of HeLa cells and that the administration of HET may therefore be clinically beneficial alongside apoptosis-inducing chemotherapy.