Expression And Significance Of Breast Cancer Resistance Protein And Topoisomerase Ⅱ In Nude Mice Transplanted Tumor Model Of A549/CDDP Multidrug Resistance Cell

Objective The aim of this study is to firstly establish a nude mice transplanted tumor model of human lung adenocarcinoma multidrug resistance cell(A549/CDDP), and then detect the expression of Breast Cancer Resistance Protein (BCRP) and Topoisomerase II(TOPOⅡ) gene and protein and significance in transplanted tumor cells.Methods: With (CDDP) cisplatin for induction, by using the method of high-dose intermittent and gradually increasing dosage, establish multidrug resistance A549 / CDDP cell lines, A549 and A549/CDDP cells were subcutaneously transplanted into the nude mice's left neck. Tumor growth characteristics were observed, and multidrug resistance index of transplanted tumor cell was detected by MTT assay. RT-PCR and Western-Blot assays were employed to analyze the expression of mRNA and protein of BCRP and TOPOⅡ. Results:①Prior to the nude mice were sacrificed, none in both groups was dead. The growth rate in A549 group increased significantly faster than in A549/CDDP group. There were no significantly different tumor weight between A549 group (2.23±0.34g) and A549/CDDP group (2.15±0.27 g) (P>0.05).②Tumor cells in both groups grew to the side of petri culture dish. Tumor cells in A549 group was spindle, whereas in A549/CDDP group was smaller and irregular. The IC50 of transplanted tumor cells in A549/DDP group was 17.3 fold compared to the A549 group, and the degree of resistance to anti-tumor agents in A549/DDP group was higher than in A549 group. The resistance index to Etoposide, doxorubicin, vinorelbine,5-FU.was 5.1,5.4,2.7,16.5, respectively.④According to RT-PCR assays , the gene expressions of BCRP and TOPOⅡwere not identical, the expression of BCRP was higher in A549/CDDP group (P?), whereas the expression of TOPOⅡwas higher in A549 group(P<0.001).⑤According to Western-blot assays, the expressions of BCRP and TOPOⅡprotein in A549 / CDDP group and A549 group were in varying degrees. The expression of BCRP protein in A549 / CDDP group was significantly higher , whereas the expression of TOPOⅡprotein in A549 group was significantly higher.Conclusion: Transplanted tumor model of A549/CDDP drug resistance cell in nude mice was successfully established. A549/CDDP drug resistance cell had developed resistance to many anti-cancer agents, in which the high expression of BCRP but low expression of TOPOII is probably related to multidrug resistance .