Enhancement of cisplatin induced apoptosis by suberoylanilide hydroxamic acid in human oral squamous cell carcinoma cell lines

Both the resistance of tumor cells to cisplatin and dose-related toxicity remain two of the most important problems in the chemotherapy of clinical oral squamous cell carcinoma (OSCC). Researchers have been seeking a combinative treatment regimen to improve the effect of chemotherapy. As potent new anti-cancer drugs, histone deacetylase inhibitors (HDACIS) have been reported to be associated with chromatin modification and display synergistic activities with some traditional chemotherapeutic agents. In this study, we evaluated the potential combinative effect of low dose cisplatin and suberoylanilide hydroxamic acid (SAHA, one of the most potent HDACIS) in OSCC cell lines. Cell viability and apoptotic assay were examined. Compared with either cisplatin (4 μg/ml) or SAHA (2 μM) treated alone, co-administration of both drugs synergistically induces cytotoxicity and apoptosis in both Tca8113 and KB cell lines. Furthermore, diverse apoptosis-associated proteins, including p53, BID, cytochrome C and caspase-3 were involved in the induction of apoptosis. Our results suggest that concurrent treatment with SAHA enhances tumor cell sensitivity to subtoxic doses of cisplatin. This may be regarded as a novel strategy for treatment of OSCC.