Curcumin and Quercetin Combined with Cisplatin to Induce Apoptosis in Human Laryngeal Carcinoma Hep-2 Cells through the Mitochondrial Pathway

AIM: Natural chemopreventives and antioxidants may modulate the response to chemotherapy. In this study we have examined the chemoadjuvant potential of cur-cumin and quercetin on cisplatin-mediated cell killing/apoptosis, especially the role of mitochondria in the esophageal cancer cell line Hep-2. METHODS: Apoptosis was detected by flow cytometry. The protein expression of mitochondrion-related apoptotic mediators, i.e. Bcl-2, Bcl-XL, Bax, cytochrome c, and AIF, were studied by Western Blotting. The transcripts of anti-oxidant enzymes were quantitated by RT-PCR. RESULTS: The findings suggest that priming Hep-2 cells with curcumin increased the cisplatin-induced apoptosis by 7.1 % whereas priming with quercetin increased it by 16.3%. Curcumin induced apoptosis in Hep-2 cells, which was mediated by an increase in Bax and nuclear AIF and a decrease in Bcl-XL. Quercetin on the other hand, induced apoptosis through a caspase-3-dependent pathway involving the participation of the proteins Bcl-2, Bcl-XL, Bax and cytochrome c. The anti-oxidant enzymes Mn-superoxide dismutase, Cu-Zn superoxide dismutase, glutathione peroxidase, and catalase did not show any significant increase at the transcriptional level in case of combination of curcumin or quercetin with cisplatin. CONCLUSION: The data suggests that priming with curcumin or quercetin may im-prove the efficacy of chemotherapy for head and neck cancer by inducing apoptosis through the mitochondrial pathway, thus minimizing the side effects associated with combination chemotherapy