Study On The Mechanism Of Green Tea Polyphenol EGCG In Chemotherapy And Combined Therapy Of Non - Small Cell Lung Cancer

Objective: The effect of the combination of low concentration of EGCG and curcumin on NSCLC cells was investigated, meanwhile, the potential mechanism was also analyzed.Methods: MTT assay was used to evaluate the anti-proliferation effect of EGCG and curcumin either administrated alone or in combination. Flow cytometry analysis showed the distribution of cell cycle. Ed U fluorescence staining was performed to observe the replication of DNA in NSCLC cells. The expression of cell cycle related proteins was detected by Western Blot. An in vivo experiment was also performed.Results: At low concentrations, the combination of the two agents exhibited a synergistic effect of anti-proliferation, with a CI value of 0.57713 and 0.67703 in A549 and NCI-H460 cells respectively. The two compounds strongly enhanced cell cycle arrest. The cells were arrested at G1 and S/G2 phase. Two main cell cycle related proteins cyclin D1 and cyclin B1 were significantly inhibited at the present of EGCG and curcumin. Ed U fluorescence staining showed that the DNA replication was significantly blocked. A clonal growth assay also confirmed a marked repression of cell growth. In a lung cancer xenograft node mice model, the combination ofEGCG and curcumin had protective effect against the weight loss due to tumor burden. Tumor growth was strongly repressed by EGCG and curcumin, without causing any serious side-effects.Conclusion: At a low and physically achievable concentration, EGCG in combination with curcumin exhibited a synergistic anti-tumor effect, and could be a candidate for chemoprevention agent of NSCLC.Objective: The enhanced efficacy of cisplatin caused by EGCG in NSCLC cells was investigated, and the potential mechanism was also analyzed.Methods: The survival fraction of NSCLC cells was measured by MTT assay. Tumor volumn was recorded to evaluate the effect of EGCG combined with cisplatin in a lung cancer xenograft node mice model. mi RNAs which differentially expressed with or without EGCG treatment were screened by a mi RNA microarray. The expression of these mi RNAs were detected by q PCR. Bioinformatics analysis was performed to predict the possible target genes and related pathways of the mi RNAs. The m RNAs of the potential target genes were detected by agarose gel electrophoresis after the NSCLC cells were transfected with specific mi RNA mimic or inhibitor.Results: The efficacy of cisplatin was strengthened by EGCG in A549 cells in vitro and in vivo. But in NCI-H460 cells, which was another NSCLC cell, the efficacy of cisplatin was antagonized by EGCG. Besides, the proliferation of NCI-H460 cells was strongly promoted by low dose of EGCG. mi RNA microarray showed that hsa-mi R-98-5p and hsa-mi R-125a-3p were differentially expressed after EGCG treatment in A549 and NCI-H460 cells. By transfecting hsa-mi R-98-5p inhibitor into NCI-H460 cells, the cells’ survival fraction was significantly decreased after cisplatintreatment. Meanwhile, the expression of p53 m RNA was elevated. Bioinformatics analysis showed that hsa-mi R-125a-3p might inhibit the classical MAPK pathway, which could be the reason why EGCG could promote the proliferation of NCI-H460 cells.Conclusion:. As p53 might be a potential target of hsa-mi R-98-5p, we suspected that the EGCG treatment inhibited the expression of hsa-mi R-98-5p, followed by an increase of p53, thus, the efficacy of cisplatin was enhanced. Hsa-mi R-98-5p might be a potential target in clinical cisplatin treatment of NSCLC. Hsa-mi R-125a-3p might inhibit the classical MAPK pathway, which could be the reason why EGCG could promote the proliferation of NCI-H460 cells.