| 1.Investigation on Relationship Between Topo II and Multidrug Resistance in BladderCarcinoma Cells in Vitro2.Reversal Effects of Carvedilol on Multidrug Resistance in Bladder CellsAbstractMultidrug resistance (MDR) is a phenomenon in which cancer cells display chemoresi stance to a broad spectrum of structurally and mechanically unrelated cytotoxic agents after exposure to a single or a few natural drugs,and it is the main reason why the clinical chemotherapy fails.Nowadays the study on the mechanisom of MDR has gone a step further.These mechanisoms include:the overexpression of the mdr-l gene and p-gp encoded by the mdr-1 gene; the alteration of glotathione-SH and its related enzyme;the alteration of topoisomerase II (Topo II );the agents and genes corellactive with apoptosis(P53 for exemple) et al.The relationship between Topo II and multidrug resistance in bladder carcinoma cells and reversal effects of carvedilol on multidrug resistance in bladder cells were studied on this research.The first part of the research: the expression of Topo II in drug-resistance cells was detected on two levels: mRNA and protein.The result of immunobistochemistry indicated that the content of Topo II in cell lines BIU87/ADM was decreased;the result of in situ hybridization and reverse transcriptase polymerase chain reaction(RT-PCR) indicated that the transcription of the Topo II gene in cell lines BIU-87/ADM was decreased.It needed further study whether the activity of Topo II was also decreased inmechemnisms of MDR in bladder carcinoma cells.The second part of the research: the degree of drug-resistance was detected by MIT method,and it was found that the cell lines BIU-87/ADM were 7.4 times more resistant to ADM than the cell lines BIU-87.It was found that pretreatment of BIU-87/ADM cells with carvedilol or verapamil increased its sensitivity to low dose of Adriamycin(ADM) ,and the effect of carvedilol was more evident than that of verapamil,but similar treatment did not change the sensitivity of BIU-87 cells.The concentration of ADM in cells was detected ,and the result indicated that the concentration of ADM in BIU-87/ADM cells was much lower than that in BIU-87 cells.Pretreatment by 10 ii. mol/L carvedilol or verapamil increased the concentration of ADM in BIU-87/ADM cells,and the concentration was much higher than that in those cells treated only by ADM,and the effect of carvedilol was more evident than that of verapamil.The result of immunohistochemistry of P-gp indicated that the expression of P-gp was strongly positive in BIU-87/ADM cells;and the expression was decreased after treatment by carvedilol;whereas the expression of P-gp was poorly positive in BIU-87 eells.In addition,the expression of P53 in bladder carcinoma cells was detected through immunohistochemistry method.The result indicated that mutational P53 was positively expressed in drug-resistant BIU-87/ADM cells,but the expression of mutational P53 was poorly positive in BIU-87 cells.The expression of Topo II in BIU-87 and BIU-87/ADM cells treated by carvedilol was detected through inimunohistochemistry method in order to investigate the relationship between carvedilol and Topo II in bladder carcinoma cells,and the result indicated that carvedilol did not influence the expression of Topo II. |
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