Researches On The Inhibition Of Lung Cancer Proliferation And Mechanism In Repair Of Cigarette-smoke-extracts-damaged Cells By EGCG, ECG And TFDG

Smoking and passive smoking induced lung injury and lung cancer. Tea contains rich polyphenols and others flavonoids compounds, and it plays an important role in prevention and treatment of lung cancer and other malignant tumors. This experiment has discovered the tea polyphenols can be used for cells damaged repair agent by cigarette smoke extracts. This paper mainly studied the effects of lung cancer cells treated by epigallocatechin-3-gallate (EGCG), epigallocatechin gallate (ECG) and theaflavin-3,3’-digallate (TFDG); normal cells damaged by cigarette smoke water extracts (CSE) and repaired by EGCG, ECG and TFDG. Using MTT assay to screen the sensitive lung tumor cell lines and normal cell lines with suitable concentrations of EGCG, ECG, TFDG and cigarette smoke extracts. The cell cycle and apoptotic rates were measured by flow cytometry, and the protein expression varieties of Bax, Bcl-2, JAK2and STAT3were detected by western blotting method.We have found that:(1) EGCG showed anti-cancer effects on different lung cancer cell lines (H1299, HTB-182, A549and95C) in a dose-dependent manner. H1299cell line was the most sensitive to EGCG than other lung cancer cell lines, but95cell lines was the least sensitive to EGCG;(2) Cell survival rates of HI299cells treated by EGCG, ECG and TFDG were decreased with the increase of concentrations, in a dose-dependent manner. But HI299cells treated by EGCG, ECG, TFDG present different intensity inhibitory effect, the strongest inhibition capacity was EGCG (IC50value was about33μ M), the secondary inhibition capacity was TFDG (IC50value was about94μ M), the leastest inhibition capacity was ECG (IC50value was greater than256μ M);(3) HEK293cells treatmed by CSE, the cell survival rate with the increase of concentration decreased, in a dose-dependent manner.(4) Using0.5%,1%CSE treated HEK293cells with24h can lead to cell damage increasing, cell survival rate decreasing, downregulation the expression of STAT3and Bax, upregulation of the expression of Bcl-2, downregulation the Bax:Bcl-2. Using0.5%CSE treatment of HEK293cells with24h to establish cigarette smoke extract damage model and using this suitable concentration to research the damage and repair mechanism induced by TFDG and EGCG, ECG;(5) The survival rates of0.5%CSE-damaged HEK293cells treated by16μM EGCG,32μM ECG and32μM TFDG with24h, the HEK293cells survival rate were increased;(6) The0.5%CSE-damaged HEK293 cells treated by16μM EGCG,32μM ECG and32μM TFDG with24h, the HEK293cells were repaired, upregulated the expression of STAT3, Bax, Bcl-2and Bax∶ Bcl-2.In conclusion, we have found that EGCG, ECG and TFDG had anti-cancer effects on lung cancers and reversal repair effects on CSE-damaged HEK293cells. It still needs further studies in animal experiments and clinical researches.