Green tea polyphenol enhances the anticancer activity of chemotherapeutic drug, cisplatin in CaSki cell line and a murine cervical cancer model

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Objective: Green tea polyphenol (GTP) has been known to possess anti-cancer properties. In the present study, we assessed the utility of GTP along with cisplatin for enhances the antitumor activity against papillomavirus (HPV)-16 associated tumor cells, and TC-1 using an animal model. Methods: Human papillomavirus (HPV) 16-infected human cervical cancer cell line, CaSki was used. Cells were incubated with and without GTP (100ug/ml) and at different concentration of ciaplatin (0-12.5uM). Cell viability was determined using MTT assay after 2days. Animals were divided into three treatments and control group, with C57BL/6 mice (n=40) and inoculated with TC-1 cells. In the control group, mice received saline solution. In treatment Group I, mice were injected i.p. with 10mgkg^-1 body weight of cisplatin. One day before the same dosage of cisplatin administration, 100mgkg^-1 body weight of GTP was given to mice in group II. Mice in treatment Group III received GTP only. Mice were injected at four times for every week and monitored twice per week for tumor growth. Results: The viability of CaSki cells was decreased to 82.6, 73.6 and 64.83% at 3.125, 6.25 and 12.5uM concentration of cisplatin. However, in the co-culture with GTP (100ug/ml), the cell viability was more decreased to 52.9, 42.4 and 40.78%, respectively. In TC-1 tumor-bearing mice, the rates of tumor inhibition following treatment with GTP alone, cisplatin alone and combination of GTP and cisplatin were 93.88%, 71.72% and 62.94 %; 84.27%, 49.83% and 39.35 %; 88.38%, 44.58% and 34.14 % and 98.18%, 46.78% and 41.28% by tumor mean diameters in comparison to control mice on day 7, 14, 21 and 28, respectively. When combined with GTP, a significant reduction in growth of subcutaneous transplanted tumors more was observed without an increase in the cisplatin dosage. Conclusions: In vitro experiments showed the GTP has potentiating effect on cisplatin cytotoxicity. And the combination of GTP with cisplatin significantly reduced tumor growth in a murine cervical cancer model. These data promise the positive effects of the combination of GTP and cisplatin chemotherapy for cervical cancer.