Reduced expression of Slit2 in renal cell carcinoma.

Slit2, initially identified as an important axon guidance molecule in the nervous system, was suggested to be involved in multiple cellular processes. Recently, Slit2 was reported to function as a potential tumor suppressor in diverse tumors. In this study, we systematically analyzed the expression level of Slit2 in renal cell carcinoma. Compared to paired adjacent non-malignant tissues, both Slit2 mRNA and protein expression were significantly down-regulated in renal cell carcinoma (RCC). Methylation-specific PCR showed that Slit2 promoter was methylated in two renal carcinoma cell lines. Pharmacologic demethylation dramatically induced Slit2 expression in cancer cell lines with weak expression of Slit2. Besides, bisulfite genomic sequencing confirmed that dense methylation existed in Slit2 promoter. Furthermore, in paired RCC samples, Slit2 methylation was observed in 8 out of 38 patients (21.1 %), which was well correlated with the down-regulation of Slit2 in RCC. Therefore, Slit2 may also be a potential tumor suppressor in RCC, which is down-regulated in RCC partially due to promoter methylation.