Effective Of Topo Ⅱ α On Chemotherapy Resistance To Cisplatin And Adriamycin In Human Lung Cancer Cell Lines

Objective:To investigate the relationship between the expression of TopoⅡαat mRNA and protein levels in SPCA-1, NCI-H460, NCI-H446 three different histological subtype cell lines of lung cancer with the inhibitor of Topo II a etoposide and resistance to chemotherapeutic agents (cisplatin and adriamycin).Methods:The expression of TopoⅡαat mRNA and protein level etoposide were analized by RT-PCR, Western blotting and Immunofluo-rescence, respectively for the three cell lines pretreated with or without etoposide at 0,2.5,5,7.5,10μmol/L.Cell viability was detected by the colorimetric MTT assay after being exposed to chemotherapeutic agents (cisplatin and adriamycin). Data was analyzed for statistical significance using the SPSS 16.0 soft.Results:1.The expression of TopoⅡαmRNA in NCI-H460 and NCI-H446 cell lines was lower in the etoposide pretreated-group compared to the control group(p<0.05), while there was no significant difference between the etoposide pretreated-group and the control group in the SPCA-1 cell line. (p>0.05) 2.Western blotting indicated that there was significant difference between the etoposide pretreated-group and the control group in the SPCA-1, NCI-H460 and NCI-H446 cell lines(p<0.05). There was no significant difference in the control group of the three cell lines. (p>0.05) 3.The expression of TopoⅡαat protein level detected by immunofluorescence decreased in SPCA-1,NCI-H460 and NCI-H446 cell lines inhibited by etoposide with a manner of dose-dependent on etoposide to a great degree assayed. The fluorescence intensity for the cells pretreated with etoposide was weaker than that for the control cell obviously.4. Cell viability was examined by MTT assay and the IC50 values for cisplatin and adriamycin were calculated. The IC50 value of etoposide-pretreated cells for cisplatin was lower than that of the control cells in SPCA-1 and NCI-H460 cell lines, and the difference was significant (P< 0.05), except NCI-H446 cell line, while there was no significant difference in the three types cell lines treated with adriamycin.Conclusion:Our findings indicated that etoposide can inhibit the expression of TopoⅡαat protein level in SPCA-1,NCI-H460 and NCI-H446 cell lines, and subsequent increase the sensitivity of cisplatin to SPCA-1 and NCI-H-460 cell lines. This study indicated that down-regul-ation of lung multidrug resistance proteins maybe a novel approach to overcome drug resistance in lung cancer and need to be studied further.