Alteration Of Expression And Activity Of Glutathione S-transferases π Associates With Drug-resistance In Human Lung Cancer Cell Lines

Objective: To investigate the relationship between the expression and activity of glutathione S-transferasesπ(GST-π) treated with ethacrynic acid (EA ) and resistance to anti-cancer drug cisplatin, adriamycin and VP-16 in vitro in lung adenocarcinoma SPCA-1, lung large cell carcinoma NCI-H- 460 and small cell lung caner NCI-H-446 cell lines.Methods: Immunofluorescence was used to detect the expression of GST-πof three cell lines treated by EA(concentrations were 60,80,100,160μmol/L respectively, for 24h)and the control cells. GST-πenzymatic activity was detected by the ultraviolet spectrophotometry. Cell viability was detected by the colorimetric MTT assay after being exposed to chemotherapeutic agents. Data was analyzed for statistical significance using the SPSS 11.5 software.Results: 1. The expression of GST-πat protein level decreased obvio- usly in SPCA-1 and NCI-H-446 cell lines inhibited by EA with a manner of dose-dependent on EA to a great degree assayed by immunofluorescence. The fluorescence intensity for the cells treated by EA was weaker than that for the control cell obviously. Whereas there was no difference between the EA-treated group and the control group in NCI-H-460 cell line. 2. Inhibiton ratios of GST-πactivity by treated EA in SPCA1, NCI-H-460 and NCIH446 cell lines were 23.96%, 30.80% and 24.12% respectively, showing no significant difference among the three types of cell lines. 3. The cell viability detected by MTT for the cells being treated by cisplatin or adriamycin showed that the viability of EA-treated cells was lower than that significant (P < 0.05), while there was no significant difference of the viability for the cells of the other two types of SPCA-1 and NCI-H-460.Conclusions: EA is effective in the inhibition of GST-πenzymatic activity in the three human lung cancer cell lines, which can decrease the expression of GST-πin SPCA-1 and NCI-H-446 cell lines, and subsequent increase the sensitivity of cisplatin and adriamycin to the NCI-H-446 cell line. Based on the trend of the change of cell viability and the level of GST-πin different disposed cells, we conclude that the reduction of expression and enzymatic activity of GST-πby EA could increase the sensitivity to cisplatin or adriamycin in the NCI-H-446 cell line. All these suggest that to decrease the expression and activity of GST-πby chemicals such as EA may be a new therapeutic approach to lung cancer.