n-arachidonoylalanine and Squamous-Cell-Carcinoma-of-Head-and-Neck

Endocannabinoids have recently drawn attention as promising anti-cancer agents. We previously observed that anandamide (AEA), one of the representative endocannabinoids, effectively inhibited the proliferation of head and neck squamous cell carcinoma (HNSCC) cell lines in a receptor-independent manner. In this study, using HNSCC cell lines, we examined the anti-cancer effects and the mechanisms of action of docosahexaenoyl ethanolamide (DHEA) and N-arachidonoyl-L-alanine (NALA), which are polyunsaturated fatty acid (PUFA)-based ethanolamides like AEA.. DHEA and NALA were found to effectively inhibit HNSCC cell proliferation. These anti-proliferative effects seemed to be mediated in a cannabinoid receptor-independent manner, since the antagonist of cannabinoid receptor-1 (CB1) and vanilloid receptor-1 (VR1), two endocannabinoid receptors, did not reverse the ability of DHEA and NALA to induce cell death. Instead, we observed an increase in reactive oxygen species (ROS) production and a decrease of phosphorylated Akt as a result of DHEA and NALA treatment. Antioxidants efficiently reversed the inhibition of cell proliferation and the decrease of phosphorylated Akt induced by DHEA and NALA; inhibition of 5-lipoxygenase (5-LO), which is expected to be involved in DHEA- and NALA-degradation pathway, also partially blocked the ability of DHEA and NALA to inhibit cell proliferation and phosphorylated Akt. Interestingly, ROS production as a result of DHEA and NALA treatment was decreased by inhibition of 5-LO.. From these findings, we suggest that ROS production induced by the 5-LO pathway mediates the anti-cancer effects of DHEA and NALA on HNSCC cells. Finally, our findings suggest the possibility of a new cancer-specific therapeutic strategy, which utilizes 5-LO activity rather than inhibiting it.

Topics: Alanine; Antineoplastic Agents; Apoptosis; Arachidonate 5-Lipoxygenase; Arachidonic Acids; Azoles; Benzoquinones; Carcinogenesis; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Proliferation; Endocannabinoids; Head and Neck Neoplasms; Humans; Hydroxyurea; Isoindoles; Lipoxygenase Inhibitors; Organoselenium Compounds; Phosphorylation; Piperidines; Proto-Oncogene Proteins c-akt; Pyrazoles; Reactive Oxygen Species; Receptor, Cannabinoid, CB1; Signal Transduction; Squamous Cell Carcinoma of Head and Neck; TRPV Cation Channels