EXPRESSION PATTERNS OF CD44 ADHESION MOLECULE IN TESTICULAR GERM-CELLTUMORS AND NORMAL TESTES

Despite recent extensive immunohistochemical studies, the expression p atterns of CD44 in testicular germ cell tumors are still controversial . In the present study, we investigated the CD44 gene expression in 40 specimens including 18 seminomas, 16 nonseminomatous germ cell tumors (NSGCT), and 6 normal testes by reverse transcriptase-polymerase chai n reaction and Western blotting, Reverse transcriptase-polymerase chai n reaction analysis revealed that the standard CD44 isoform (CD44s) wa s expressed in all of the specimens, whereas the variant CD44 isoforms were highly expressed in NSGCTs but barely detectable in seminomas an d normal testes. In addition, we confirmed by direct DNA sequence anal ysis that the predominantly expressed variant isoform in NSGCTs was CD 44v8-10. In germ cell tumors, these results were paralleled in Western blot analysis; that is, CD44s protein was expressed in all of the tum or specimens, whereas high molecular weight variant isoforms were expr essed only in NSGCTs. However, at the protein level, no detectable CD4 4 was ex-pressed in normal testes. These findings show that the combin ed assessment of CD44 expression patterns at both the RNA and protein levels enables us to distinguish among seminoma, NSGCT, and normal tes tis specimens; hence, it could serve as a useful practical adjunct to conventional diagnostic methods for testicular germ cell tumors.