TY - JOUR T1 - Induction of Apoptosis by Cannabinoids in Prostate and Colon Cancer Cells Is Phosphatase Dependent JF - Anticancer Research JO - Anticancer Res SP - 3799 LP - 3807 VL - 31 IS - 11 AU - SANDEEP SREEVALSAN AU - SONIA JOSEPH AU - INDIRA JUTOORU AU - GAYATHRI CHADALAPAKA AU - STEPHEN H. SAFE Y1 - 2011/11/01 UR - http://ar.iiarjournals.org/content/31/11/3799.abstract N2 - Aim: We hypothesized that the anticancer activity of cannabinoids was linked to induction of phosphatases. Materials and Methods: The effects of cannabidiol (CBD) and the synthetic cannabinoid WIN-55,212 (WIN) on LNCaP (prostate) and SW480 (colon) cancer cell proliferation were determined by cell counting; apoptosis was determined by cleavage of poly(ADP)ribose polymerase (PARP) and caspase-3 (Western blots); and phosphatase mRNAs were determined by real-time PCR. The role of phosphatases and cannabinoid receptors in mediating CBD- and WIN-induced apoptosis was determined by inhibition and receptor knockdown. Results: CBD and WIN inhibited LNCaP and SW480 cell growth and induced mRNA expression of several phosphatases, and the phosphatase inhibitor sodium orthovanadate significantly inhibited cannabinoid-induced PARP cleavage in both cell lines, whereas only CBD-induced apoptosis was CB1 and CB2 receptor-dependent. Conclusion: Cannabinoid receptor agonists induce phosphatases and phosphatase-dependent apoptosis in cancer cell lines; however, the role of the CB receptor in mediating this response is ligand-dependent. ER -