Non-small cell lung cancer (NSCLC) is a leading form of cancer with limited treatment regimens and is a major cause of cancer related mortality in the United States. The endocannabinoid system composed of two cannabinoid receptors- CB1 and CB2, their endogenous ligands and the enzymes for their metabolism has been implicated in several pathophysiological conditions. They have been extensively studied in various cancers as inhibitors of tumor cell growth by modulating key cell survival pathways. Anandamide (AEA), a well characterized neurotransmitter is an endogenous cannabinoid and agonist for the cannabinoid receptor CB1. One way to enhance the effect of endocannabinoid signaling is to inhibit the enzyme fatty acid amide hydrolase (FAAH), which metabolizes AEA by using the selective FAAH inhibitor URB597. To understand the physiological role of the endocannabinoid system, the NSCLC cell lines A549 and H460 were treated with either Met-F-AEA, URB597 or in combination and subjected to further analysis. Cells which were incubated in combination with Met-F-AEA and URB597 showed reduced proliferative and chemotactic activities in vitro when compared to AEA alone, which were confirmed by reduced MMP2 secretion and stress fiber formation. Also, we have shown that the combination treatment modulates activation of epidermal growth factor receptor (EGFR) and its downstream targets. In response to EGFR pathway activation, cells treated with Met-F-AEA in combination with URB597 underwent GO/G1 cell cycle arrest, ultimately leading to apoptosis via activation of caspase-9 and PARP. Furthermore, these results were validated in vivo in a xenograft nude mouse model system. Mouse xenografts treated with both Met-F-AEA and URB597 underwent reduction in tumor growth when compared to Met-F-AEA or URB597 alone. In summary, our results presented here show that Met-F-AEA in combination with URB597 inhibits the EGFR pathway, resulting in cell cycle arrest and apoptosis. Our findings suggest a novel perspective for the antitumorigenic activity of the endocannabinoid Met-F-AEA when used in combination with URB597 in NSCLC.

Citation Format: Janani Ravi, Amita Sneh, Konstantin Shilo, Mohd Nasser, Ramesh Ganju. The endocannabinoid system inhibits non-small cell lung cancer tumorigenesis by modulating the EGF/EGFR pathway. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3324. doi:10.1158/1538-7445.AM2014-3324