Luteolin induces apoptosis in oral squamous cancer cells.

Oral squamous cell carcinoma is the most common malignancy of the oral cavity, and treatment approaches are inadequate. Luteolin, a natural flavonoid compound, has been shown to have anti-tumorigenic properties on various types of tumors. Therefore, we hypothesized that luteolin has anti-tumorigenic properties for oral squamous cell carcinoma, and may provide effective chemotherapy. Results revealed that luteolin reduced the viability of SCC-4 cells and induced apoptosis by decreasing the expression of cyclin-dependent kinase (CDKs), cyclins, and phosphor- retinoblastoma (p-Rb) anti-apoptotic protein, but increased the expression of pro-apoptotic proteins and activated caspase 9 and 3, with a concomitant increase in the levels of cleaved poly-ADP-ribose polymerase (PARP). Combination treatment of luteolin with paclitaxel enhanced the cytotoxic effect of paclitaxel in SCC-4 cells, and continuous administration of luteolin suppressed the growth of xenograft tumors in nude mice. These results suggest that luteolin could be an effective chemotherapeutic agent for the treatment of oral squamous cell carcinoma.