[Expression of CD44 variant isoforms in human primary colon carcinomas and metastasis]

The CD44 is a cell adhesion molecule that is present as numerous isoforms created by mRNA alternative splicing. A variety of human carcinomas display the overexpression of CD44 variant isoforms. To identify the relationship between the expression of CD44 variant isoforms and the metastatic potential of colon carcinomas, we performed a polymerase chain reaction analysis following reverse transcriptase treatment for CD44 expression in fresh surgical specimens obtained from 25 colon carcinomas and corresponding normal colonic mucosa. The CD44H, a common type of the CD44 isoform, was amplified from all carcinomas and normal tissues, whereas a splice variant form corresponding to CD44E was expressed in 19 out of 23 colon carcinomas (83%) and 7 out of 19 normal mucosa specimens (37%), suggesting that the CD44E expression was predominantly observed in colon carcinomas compared to normal tissues (p < 0.05). The multivariant form of CD44 was identified in 10 out of 23 carcinomas (44%) and 5 out of 19 normal samples (26%). The CD44E/CD44H (E/H) ratio was significantly higher in colon carcinomas than in normal mucosa (p < 0.01). However, neither the E/H ratio nor CD44 multivariant expression correlated with the clinicopathological features. These results suggest that CD44E expression and high E/H ratio are commonly observed in colon carcinomas and that the expression of the CD44 multivariants is not associated with clinicopathological parameters.