PT - JOURNAL ARTICLE AU - McKallip, Robert J. AU - Jia, Wentao AU - Schlomer, Jerome AU - Warren, James W. AU - Nagarkatti, Prakash S. AU - Nagarkatti, Mitzi TI - Cannabidiol-Induced Apoptosis in Human Leukemia Cells: A Novel Role of Cannabidiol in the Regulation of p22<em><sup>phox</sup></em> and Nox4 Expression AID - 10.1124/mol.106.023937 DP - 2006 Sep 01 TA - Molecular Pharmacology PG - 897--908 VI - 70 IP - 3 4099 - http://molpharm.aspetjournals.org/content/70/3/897.short 4100 - http://molpharm.aspetjournals.org/content/70/3/897.full SO - Mol Pharmacol2006 Sep 01; 70 AB - In the current study, we examined the effects of the nonpsychoactive cannabinoid, cannabidiol, on the induction of apoptosis in leukemia cells. Exposure of leukemia cells to cannabidiol led to cannabinoid receptor 2 (CB2)-mediated reduction in cell viability and induction in apoptosis. Furthermore, cannabidiol treatment led to a significant decrease in tumor burden and an increase in apoptotic tumors in vivo. From a mechanistic standpoint, cannabidiol exposure resulted in activation of caspase-8, caspase-9, and caspase-3, cleavage of poly(ADP-ribose) polymerase, and a decrease in full-length Bid, suggesting possible cross-talk between the intrinsic and extrinsic apoptotic pathways. The role of the mitochondria was further suggested as exposure to cannabidiol led to loss of mitochondrial membrane potential and release of cytochrome c. It is noteworthy that cannabidiol exposure led to an increase in reactive oxygen species (ROS) production as well as an increase in the expression of the NAD(P)H oxidases Nox4 and p22phox. Furthermore, cannabidiol-induced apoptosis and reactive oxygen species (ROS) levels could be blocked by treatment with the ROS scavengers or the NAD(P)H oxidase inhibitors. Finally, cannabidiol exposure led to a decrease in the levels of p-p38 mitogen-activated protein kinase, which could be blocked by treatment with a CB2-selective antagonist or ROS scavenger. Together, the results from this study reveal that cannabidiol, acting through CB2 and regulation of Nox4 and p22phox expression, may be a novel and highly selective treatment for leukemia. The American Society for Pharmacology and Experimental Therapeutics