EXPRESSION OF CD44 VARIANT PROTEINS IN HUMAN COLORECTAL-CANCER IS RELATED TO TUMOR PROGRESSION

Specific CD44 variant glycoproteins are overexpressed at particular st ages of colorectal tumor progression. Some variants of the CD44 glycop rotein without exon v6 sequences appear at the earliest stage of tumor igenesis, i.e., in early adenomas. Expression of variants containing e xon v6 sequences is largely restricted to the advanced stages of tumor development and in addition is more prevalent and intense in metastat ic (Dukes C/D) than in nonmetastatic (Dukes A/B) carcinomas. The obser vation that CD44 variants containing a protein domain of CD44 that con fers full metastatic potential to rat carcinoma and sarcoma cell lines is increasingly expressed during colorectal tumor progression indicat es that this domain may have an important role in tumor progression an d metastasis in humans. Information on v6 expression, which can be obt ained by routine immunohistochemistry, may prove of important prognost ic value, particularly in carcinomas (Dukes A and B) that have not yet given rise to detectable metastases.