anandamide and Carcinoma--Squamous-Cell

The endocannabinoids, anandamide (AEA) and 2-arachidonoyl glycerol (2-AG), are considered promising potential anticancer agents. In this study, we examined the anticancer effects of AEA and 2-AG in head and neck squamous cell carcinoma (HNSCC) cell lines.. Our results showed that AEA effectively inhibited proliferation of HNSCC cells whereas 2-AG did not. The anticancer effect of AEA seemed to be mediated by a receptor-independent mechanism. Inhibitors of AEA intracellular transportation and transfection of HNSCC cells with fatty acid amide hydrolase, a key enzyme in AEA metabolism, reversed AEA-dependent inhibition of cell proliferation. We found that cyclooxygenase-2 (COX-2) did not mediate the anticancer effects of AEA; instead we observed an increase in reactive oxygen species (ROS) production after AEA treatment. Moreover, antioxidants partially reversed AEA-dependent inhibition of cell proliferation.. These findings suggest that AEA might have anticancer effects on HNSCC cells by mediating an increase in ROS levels through a receptor-independent mechanism.

Topics: Antineoplastic Agents; Arachidonic Acids; Cannabinoid Receptor Agonists; Carcinoma, Squamous Cell; Cell Line, Tumor; Endocannabinoids; Glycerides; Head and Neck Neoplasms; Humans; Polyunsaturated Alkamides; Reactive Oxygen Species

Nonmelanoma skin cancer is the most prevalent cancer in the United States with approximately 1.25 million new cases diagnosed each year. Cyclooxygenase-2 (COX-2) expression is commonly elevated in these and other epithelial tumors. Cyclooxygenases metabolize arachidonic acid to prostaglandins, which promote growth and survival of tumor cells. COX-2 also metabolizes endocannabinoids forming prostaglandin-ethanolamides (PG-EA); however, the role of these lipid molecules in tumor cell survival is unclear. The goal of this research is to determine if the metabolic products of COX-2 contribute to endocannabinoid-induced cell death. Anandamide [also known as arachidonyl ethanolamide (AEA)] induced cell death in the COX-2 overexpressing squamous carcinoma cell line JWF2. In contrast, AEA did not initiate cell death in HaCaT keratinocytes, which express low basal levels of COX-2. Resistance to AEA-mediated cell death in HaCaT cells was reversed by overexpressing COX-2 in these cells. Next, ELISA assays were carried out to identify prostaglandins involved in AEA-mediated cell death. D-type prostaglandins were predominantly formed in AEA-exposed JWF2 cells although significant increases in E- and F-type prostaglandins were also seen. Cells were then treated with various prostaglandins or PG-EA to determine the contribution of each to AEA-induced cell death. PGD(2) and PGD(2)-EA were found to be cytotoxic to JWF2 keratinocytes and the PGD(2) dehydration products, PGJ(2) and 15-deoxy Delta(12,14) PGJ(2), were also potent inducers of cell death. These results suggest that AEA selectively induces cell death in tumorigenic keratinocytes due to COX-2 overexpression and the resulting metabolism of AEA to cytotoxic prostaglandins.

Topics: Animals; Arachidonic Acids; Blotting, Western; Cannabinoid Receptor Modulators; Carcinoma, Squamous Cell; Cell Death; Cell Proliferation; Cyclooxygenase 2; Endocannabinoids; Keratinocytes; Mice; Polyunsaturated Alkamides; Signal Transduction; Transfection; Tumor Cells, Cultured