Silibinin Triggers the Mitochondrial Pathway of Apoptosis in Human Oral Squamous Carcinoma Cells

BACKGROUND: Silibinin, a natural polyphenolic flavonoid present in seed extracts of milk thistle (Silybum marianum). It has been shown to interact with various cancer-related cell signalling pathways in preclinical models, demonstrating promising anticancer effects in vitro and in vivo. MATERIALS AND METHODS: The cytotoxic effect of silibinin was evaluated in human oral squamous carcinoma (SCC-25) cells by MTT assay. The apoptosis-related morphological changes were investigated by AO/EB dual staining. The cytochrome c, caspases-3, and -9, B-cell lymphoma-2 (Bcl-2), and B-cell associated X protein (Bax) gene expressions were analysed by PCR. RESULTS: We have shown that silibinin treatment for 24 h in SCC-25 cells induced cytotoxicity in a concentration-dependent manner. The cytotoxic potential was due to the induction of apoptosis via the release of mitochondrial cytochrome c into the cytosol and subsequent activation of caspases-3 and -9. Dual staining assay was further confirmed the induction of early apoptosis upon silibinin treatment. CONCLUSION: The results from this study show that silibinin can be considered as a promising drug candidate for the treatment of oral squamous cell carcinoma.