Green tea polyphenol induces significant cell death in human lung cancer cells

Purpose: To investigate the dose–response relationship of green tea polyphenol in an animal model of lung cancer. Methods: The effects of epigallocatechin-3-gallate (EGCG) on the inhibition of xenograft tumor growth, the accumulation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), and apoptosis based on 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay were evaluated in non-small cell lung cancer (NSCLC) cell lines, namely, H1155, H661, and A427 (a human lung carcinoma-derived cell line). The dose-dependent effects of EGCG on H1155 xenograft tumor growth, as well as the levels of EGCG in plasma and tissue, were also determined in male nude mice. Results: EGCG inhibited the growth of NSCLC-derived cell lines (H1155) over a 45-day period. There was a significant reduction (57 %) in tumor weight in EGCG-fed (0.5 %) animals compared with the control group (p < 0.05). Linear regression analysis revealed a dose-dependent reduction in tumor size. MTT assay results revealed inhibition of H1155 cell growth (25 %, p < 0.05) after 24 h treatment with EGCG. The addition of superoxide dismutase (5 U/mL) and catalase (30 U/mL) reduced the inhibitory effect of EGCG. Mice administered 30 mg/kg EGCG via intraperitoneal injection exhibited the least amount of oxidative stress. Conclusion: The results demonstrate the concentration-dependent inhibitory effects of EGCG on lung cancer cells, including H1155 cells, both in vitro and in vivo . The induction of reactive oxygen species, oxidative DNA damage, and apoptosis were evident following EGCG treatment. Keywords: Green tea, Lung cancer, Catechins, Epigallocatechin-3-gallate, Oxidative stress, Oxidative DNA damage