MULTIDRUG-RESISTANCE OF TESTIS CANCERS - THE STUDY OF CLINICAL RELEVANCE OF P-GLYCOPROTEIN EXPRESSION

Germ cell testicular tumors (GCTTs) are very sensitive to anticancer t reatment. However some patients ultimately die of their disease due to tumor resistance. Multidrug resistance is mediated by the mdr1 gene p roduct P-glycoprotein (P-gp) which is one important mechanism of drug resistance. This study attempted to examine the con-elation between P- gp and tumor progression and to evaluate the clinical relevance of P-g p immunoreactivity in patients with GCTT. Expression of the P-glycopro tein was screened in 48 primary human GCTTs, that have not been treate d with chemotherapy, using monoclonal antibody (C219) and immunoenzyme staining. Of the samples from 14 seminomatous germ cell testicular tu mors (SGCT) 2 seminomas (14 %), and of 34 non-seminomatous tumors (NSG CT) 18 (53 %) showed high expression of P-glycoprotein. This differenc e proved to be significant (P=0,006). The expression of P-gp showed a statistically significant positive correlation with cancers of advance d stages (P=0,003) and cancers that showed resistance to chemotherapy (P=0,0052). Detection of P-gp expression in patients with GCTTs before the application of anti-cancer treatment cart be used as a useful pro gnostic marker to isolate patient subgroups with worse prognosis and l ess susceptibility to chemotherapy.