Expression of CD44 Isoforms and Its Significance in Renal Cell Carcinoma

ABSTRACT

Background: CD44 is a transmembranous glycoprotein that participates in cell-cell and cell-matrix interactions, and it also contributes to cell migration. In vitro studies have suggested that the expression of CD44 isoforms is associated with tumor metastasis. Since it is not clear whether the CD44 isoforms play a role in the tumorigenesis, differentiation, progression or metastasis of renal cell carcinomas (RCCs). Methods: We performed immunohistochemistry with primary antibodies for the standard CD44 (CD44s) and the CD44 variant exon 6 (CD44v6) on the archival paraffin-embedded tissue microarray (TMA) specimens from 51 RCC patients. Results: In the normal kidney, the expressions of both CD44s and CD44v6 were negligible. The CD44s expression was increased in accordance with the tumor size (p<0.01), but it was not related to the microvessel density (MVD). No CD44v6 expression was observed in all RCC cases. Univariate analysis indicated that stage, tumor size, lymph node metastasis and distant organ metastasis were the statistically significant prognostic factors for disease free survival (DFS) (p<0.01), and the multivariate analysis proved that stage (p<0.01) and tumor size (p<0.05) were the independent prognostic factors for DFS. Conclusions: Our results suggest that CD44s, but not CD44v6, plays a role in tumor progression and it could be a potential prognostic factor for patients with RCCs.