Differential binding activities of lectins and neoglycoproteins in human testicular tumors

Testicular germ-cell tumors, a morphologically and clinically diverse group of malignancies provide an ideal model for investigating the biology of glycoconjugates because the biosynthesis of oligosaccharide chains of glycoproteins monitored by plant/invertebrate lectins often changes during tumorigenesis, tumor progression, and metastasis. To investigate such changes in germ-cell tumors, we analyzed 67 surgical specimens from 31 seminomas, 32 embryonic carcinomas, and four choriocarcinomas using glyco- and immunohistochemistry that involved five plant/invertebrate lectins, 16 neoglycoproteins, and galectin-1 antibody. The results showed that some of these markers, such as melibiose-, lactose-, and beta-N-acetylgalactosamine-BSA-biotin were clearly differentially expressed amongst these tumors and between primary and metastatic embryonic carcinomas. The differences in staining for positivity, intensity, and heterogeneity indicate that the differential display of glycoconjugates in tumor cells may be important in tumor growth, metastasis, or prognosis because subtypes of these tumors behave quite differently from one another. Furthermore, we also found identical staining for positivity between most neoglycoproteins and their corresponding lectins, though the staining intensity of neoglycoproteins was weaker. This suggests that neoglycoproteins may be useful markers to replace their plant lectins.