Differential role of CD133 and CXCR4 in renal cell carcinoma

The chemokine receptor CXCR4 and CD133, putative stem cell markers, were previously described in renal cancer (RCC). To evaluate the biological and prognostic role of CD133 and CXCR4 in RCC the expression was evaluated through qPCR and immunoblotting in human renal cancer cell lines (786-O, A498, ACHN, CAKI-1, SN12C, TK10, UO31) and patients biopsies. Renal cancer cells and surgical biopsies expressed functional CXCR4 while CD133 was not detectable. CXCR4 and CD133 expression was then evaluated in 240 renal cancer patients through immunohistochemistry. CXCR4 and CD133 were low in 19.1% and 59.6%; intermediate in 20% and 17.9%; high in 60.8% and 22.5% of the cases, respectively. CXCR4 was overexpressed in tumors (p = 0.02), while CD133 was overexpressed in healthy tissues (p = 0.04). Disease free survival Kaplan Meier plots suggest that prognosis is unfavorable for patients whose primary tumors express CXCR4 (p = 0.0199) but nor CD133 (p = 0.151) neither the concomitant CXCR4-CD133 (p = 0.848) high expression affected prognosis. Analysis of prognostic factors suggests that age, clinical presentation, AJCC stage and CXCR4 had a significant prognostic value at the univariate analysis. The CXCR4 predictive ability was confirmed at the multivariate analysis while no prognostic role was identified for CD133. Thus, concomitant CD133 and CXCR4 evaluation is not worth in RCC patient while the CXCR4 prognostic role encourage CXCR4 antagonists as promising therapeutic option.