The expression levels of CD44v6 are correlated with the invasiveness of hepatocellular carcinoma in vitro, but do not appear to be clinically significant.

The finding that the expression of a variant isoform of CD44 induced a metastatic phenotype in locally growing tumor cells has attracted considerable attention. A number of studies have analyzed the expression of CD44v6 in human tumors of different origins. However, the findings of these studies have been controversial. Therefore, in the present study, we assessed the association between CD44v6 expression and the invasive capacity of hepatocellular carcinoma (HCC) cell lines and also investigated the clinical significance of CD44v6 in 150 HCC patients by immunohistochemical analysis. The HCC cell lines with a high CD44v6 expression, including HLF, HLE and SK HEP-1, showed high invasive potential, whereas those with a low CD44v6 expression, including PLC/PRF/5 and HuH1, showed low invasiveness. Despite these observations, we did not find any significant correlation between CD44v6 expression and clinicopathological factors in patients. By contrast, there was a weak correlation between a low CD44v6 expression and vascular invasion in HCC patients (P=0.080). Kaplan-Meier curves revealed that a high CD44v6 expression was not significantly associated with disease-free survival (P=0.736) or overall survival (P=0.736). Our study suggests that the expression levels of CD44v6 are correlated with the invasiveness of HCC in vitro, but do not appear to be clinically significant. Future experiments should investigate the role of the various CD44 isoforms, including the CD44 standard isoform, in HCC cell lines and in patients with HCC.