EXPRESSION OF CD44 ISOFORMS AND BETA-1,6-BRANCHED OLIGOSACCHARIDES INHUMAN-MALIGNANT MELANOMA IS CORRELATED WITH TUMOR PROGRESSION BUT NOTWITH METASTATIC POTENTIAL

CD44, a family of closely related glycoproteins generated by alternati ve splicing, as well as the increased beta 1,6-branching of Asn-linked oligosaccharides (beta 1,6-branches), have been implicated in tumor p rogression and metastasis. We have investigated the expression of CD44 standard (CD44s), various CD44 splice variants (CD44v3, -v4, -v5, -v6 and -v9), and of beta 1,6-branches in a total of 37 paraffin-embedded human primary melanomas and metastases. Out of the 28 studied primary melanomas, 27 were positive for CD44s, 21 for CD44v5 (cytoplasmic sta ining) and 26 for beta 1,6 branches. Furthermore, superficial spreadin g melanomas showed a significant (p=0.004) stronger staining for CD44s than the thick (> 1.5 mm) nodular melanomas, whereas no significant d ifference was found with regard to staining for CD44v5 and beta 1,6-br anches. Eight of the 9 studied melanoma metastases were positive for C D44s, 6 for CD44v5 (cytoplasmic staining) and 7 for beta 1,6-branches. No CD44v3, -v4, -v6 and -v9 could be detected in any of the tumors. O n average, metastases as compared to primary tumors, exhibited a signi ficant (p=0.002) weaker staining for CD44s. However, metastasizing mel anomas could not be distinguished from non-metastasizing ones based on CD44 immunostaining.