The development of drug resistance is a major obstacle in effective cancer chemotherapy. Multidrug resistance(MDR) is a widely studied henomenon of interest to both clinicians and research workers because many different cancer chemotherapeutic
agents
are involved and the genetic basis of MDR is understood to a large extent. Several studies show that the P-glycoprotein (P-gp), multidrug resistance-associated protein(MRP), glutathione-s-transferase-π(GST-π), and DNA topoisomerase II(topo II)
have a
complex role for the malignant phenotypes and MDR. Clearly, there is a need to investigate links between the diverse characteristics of tumors and the emergence of drug resistance. We have therefore used reverse transcription-polymerase chain
reaction(RT-PCR) assay to analyze expressions of MER-related genes including the mdr1, MRP, topo II and GST-πgene in normal testis and testis tumors. The results are as follows: 1. The expression levels of topo II and GST-πgenes in tesstis
tumors,
especially in the nonseminomatous germ cell tumor(NSGCT), were significantly higher than in normal testis(p=0.015 and 0.025, respectively). 2. The MDR-related gene expressions in testis tumors did not appear to be correlated with stage(p>0.05 in
each
case) and chemotherapy status(p<0.05 in each case). 3. MRP expression levels in primary tumors were much higher than in metastatic tumors. 4. In NSGCT, the conexpressions of the topo II and GST-πor MRP genes were singnificantly correlated but,
seminoma
showed no correlation between MDR-related genes in the same sample. Although the mechanism of these connection are not known, the results suggest that these expression patterns and higher GST-πexpression in NSGCT compared to seminoma confer
diverse
characteristics including difference in the presentation of tumor markers and the responsiveness of chemotherapy on NSGCT and seminoma.
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