Abstract
Several studies in cell cultures and in animal models have demonstrated that cannabinoids have important antitumoral properties. Because many of these effects are mediated through cannabinoid (CB) receptors CB&sub1; and CB&sub2;, the study of their expression in human neoplasms has become of great interest in recent years. Fresh and formalin-fixed tissue samples of 20 consecutive clear cell renal cell carcinomas (CCRCCs) were collected prospectively and analyzed for the expression of both CB receptors by using RT-PCR, Western blot (WB), and immunohistochemical techniques. RT-PCR assays demonstrated the expression of mRNA encoding the CB&sub1; in tumor tissue and in adjacent non-neoplastic kidney. Conversely, WB and IHC revealed a marked downregulation of CB&sub1; protein in tumor tissue; CB&sub2; was not expressed. The obtained data suggest a possible implication of the endocannabinoid system in renal carcinogenesis. A posttranscriptional downregulation of CB&sub1; and the absence of expression of CB&sub2; characterize CCRCC.