Pien Tze Huang induces apoptosis in multidrug-resistant U2OS/ADM cells via downregulation of Bcl-2, survivin and P-gp and upregulation of Bax

Pien Tze Huang (PZH) is a well-known traditional Chinese formula that was first prescribed by a royal physician in the Ming Dynasty. PZH has been used to treat various types of cancers including osteosarcoma. Previous studies have shown that PZH may effectively inhibit osteosarcoma cell growth in vivo and in vitro via induction of apoptosis and inhibition of migratory and invasive abilities. However, little is known regarding the effects of PZH on osteosarcomas that are resistant to chemotherapy, which has emerged as a major clinical problem. In the present study, the cellular effects of PZH on multidrug-resistant U2OS/ADM human osteosarcoma cells were investigated. Our results showed that PZH reduced cell viability in a dose- and time-dependent manner and arrested cells in the G(2)/M phase of the cell cycle, suggesting that PZH inhibits the proliferation of U2OS/ADM cells. Hoechst 33258 staining and Annexin V/propidium iodide double staining revealed typical nuclear features of apoptosis, and treatment with PZH increased the proportion of apoptotic Annexin V-positive cells in a dose-dependent manner. Further experiments demonstrated that apoptosis induction by PZH was accompanied by downregulation of Bcl-2 and survivin and upregulation of Bax. In addition, following treatment with PZH, intracellular Rhodamine 123 accumulation was increased and the expression of P-gp was significantly suppressed. Taken together, these results provide a possible molecular mechanism for the anticancer effect of PZH on U2OS/ADM cells and suggest that PZH may be a potent therapeutic agent for drug-resistant osteosarcoma.