Description
Although renal cell carcinoma (RCC) is the sixth-leading cause of cancer death, the molecular events leading to disease onset and progression are not well understood. Genomic profiling of clear cell RCC (cRCC) patients indicated that loss of a negative regulator of the Wnt pathway, secreted frizzled-related protein 1 (sFRP1), occurred in the majority of more than 100 patients tested. To our knowledge, this is the first report of loss of sFRP1 expression in patients diagnosed with cRCC; this loss occurs in early stage cRCC, suggesting that it may be an important early event in renal carcinogenesis. Genomic profiling of patient matched normal and cRCC tissues identified Wnt regulated genes to be aberrantly increased in cRCC tissues suggesting sFRP1 suppresses Wnt signaling in cRCC. In order to test the hypothesis that sFRP1 acts as a tumor suppressor in cRCC, we have stably expressed sFRP1 in cRCC cells. sFRP1 expression in cRCC cells resulted in decreased growth in cell culture, inhibition of anchorage-independent growth, and decreased tumor volume in a nude mouse model. Together these data suggest an important role for sFRP1 as a tumor suppressor in cRCC.