Cadherin-6 gene expression in conventional renal cell carcinoma: a useful marker to detect circulating tumor cells.

Dissemination of cancer cells into the circulation is an essential step in the development of a metastasis. Detection of circulating cancer cells may improve the monitoring methods for cancer patients. However, the detection of circulating renal cancer cells is mainly hampered by the lack of markers available for renal cell carcinoma (RCC). In this study, we evaluated cadherin-6 mRNA as a new molecular marker for the detection of circulating renal cancer cells.Forty-six blood samples of conventional RCCs were included. A standard protocol of RT-PCR, assisted by computer densitometric analysis to establish a cut-off, was performed to examine cadherin-6 mRNA expression by using specific primers. A renal cancer cell line, SKRC-59 and forty tumor biopsies from conventional RCCs were used as positive controls. Twenty-five blood samples from non-RCC patients were also analyzed.Cadherin-6 mRNA could be detected in 38140 (95%) conventional RCC specimens. Cadherin-6 mRNA was positive in 21/46 (45.7%) blood samples of RCC patients, while no positivity was found in non-RCC blood samples. Among the localized RCCs, 14/35 (40.0%) blood samples were positive while 7/11 (63.6%) were positive among the blood samples from metastatic RCCs.Our data indicate that cadherin-6 gene is frequently expressed in conventional RCCs. Cadherin-6 is a useful molecular marker to detect the circulating cancer cells disseminated from conventional RCC.