Cannabinoid CB1 Receptor Is Downregulated in Clear Cell Renal Cell Carcinoma

7 páginas, 3 figuras, 1 tabla.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 CB1 and CB2, 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 CB1 in tumor tissue and in adjacent non-neoplastic kidney.Conversely, WB and IHC revealed a marked downregulation of CB1 protein in tumor tissue; CB2 was not expressed. The obtained data suggest a possible implication of the endocannabinoid system in renal carcinogenesis. A posttranscriptional downregulation of CB1 and the absence of expression of CB2 characterize CCRCC.This work was supported by grants from the Jesús Gangoiti-Barrera Foundation, Gobierno Vasco (GIC07/84), Ministerio de Educación y Ciencia (CTQ2007-61024/BQU), and SAIOTEK (SA-2008/00046).Peer reviewe