VASE MINI-EXON USAGE BY NCAM IS NOT RESTRICTED TO TUMORS OF NEUROECTODERMAL ORIGIN

The neural cell adhesion molecule (NCAM) plays an important role in no rmal development. Many variants of NCAM are generated through post-tra nscriptional and post-translational modifications. These variants are tissue-specific and their expression is developmentally regulated. NCA M is also re-expressed in a number of human tumours, including neurobl astoma, rhabdomyosarcoma, Wilms' tumour and Ewing's sarcoma. We have c haracterized the NCAM variants associated with rhabdomyosarcoma. Polys ialylated NCAMs are present in this tumour and, after neuraminidase tr eatment, they resolve into 2 bands of 140 and 120 kDa. These data were corroborated by Northern-blot analysis where mRNA species of 6.7 and 5.5 kb are detected. These mRNA code for the 140- and 120-kDa NCAM pro teins respectively. PCR analysis shows that the previously described V ASE mini-exon is also present in NCAM found in rhabdomyosarcoma. The V ASE mini-exon, spliced at exon 7-8 junctions, has previously been dete cted in neural and heart NCAM, as well as in NCAMs found in human smal l-cell lung carcinoma (SCLC). DNA sequencing confirmed that the VASE m ini-exon in rhabdomyosarcoma is identical to that found in neuroblasto ma and SCLC. (C) 1993 Wiley-Liss, Inc.