EXPRESSION PATTERNS OF MULTIDRUG-RESISTANCE (MDRl), GLUTATHIONE-S-TRANSFERASE-T (GST-T) AND DNA TOPOISOMERASE MULTIDRUG RESISTANCE-ASSOCIATED PROTEIN (MRP), I1 (TOP0 11) GENES IN RENAL CELL CARCINOMAS AND NORMAL KIDNEY

Purpose: Expression levels of the multidrug-resistance (mdrl), multidrug resistance-associated protein (MRP), glutathione-S-transferase-.rr (GST-.rr) and DNA topoisomerase I1 (Topo 11) genes in normal kidney and renal cell carcinomas were analyzed to study the complexity of the roles of these genes. Materials and Methods: The reverse transcription-polymerase chain reaction (RT-PCR) assay was used with p2 microglobulin (p2 m) as the internal control. Results: In normal kidneys, the expression levels of the 4 genes in individual normal kidney samples correlated significantly with one another. Comparisons of the expression levels between normal kidneys and renal cell carcinomas showed that only the mean MRP gene expression level was higher in renal cell carcinomas than in normal kidneys (p = 0.018). The expression patterns of the 4 genes in renal cell carcinomas differed markedly for nonpapillary and papillary tumors. The mean MRPIP, m ratio for the papillary type was significantly lower than that for the nonpapillary alveolar type carcinoma (p = 0.004). The 4 genes showed moderate positive correlations with one another in alveolar type renal carcinoma similar to the correlations observed in normal kidneys. In contrast, in papillary type, MRP expression was inversely correlated with mdrl and Top0 I1 expression. Conclusion: Differences in cytogenetic changes, origins and natural histories between papillary and nonpapillary carcinoma may be associated with these distinct expression patterns of the resistance-related genes. Further study is required to clarify whether the differences in the expression patterns between these 2 structural types of carcinoma affect their chemosensitivities and clinical outcomes.