Cannabinoid Receptors, CB1 and CB2, as Novel Targets for Inhibition of Non-Small Cell Lung Cancer Growth and Metastasis

Non-small cell lung cancer (NSCLC) is the leading cause of cancer deaths worldwide; however, only limited therapeutic treatments are available. Hence, we investigated the role of cannabinoid receptors, CB1 and CB2, as novel therapeutic targets against NSCLC. We observed expression of CB1 (24%) and CB2 (55%) in NSCLC patients. Furthermore, we have shown that the treatment of NSCLC cell lines (A549 and SW-1573) with CB1/CB2 and CB2-specific agonists Win55,212-2 and JWH-015, respectively, significantly attenuated random as well as growth factor-directed in vitro chemotaxis and chemoinvasion in these cells. We also observed significant reduction in focal adhesion complex, which plays an important role in migration, upon treatment with both JWH-015 and Win55,212-2. In addition, pre-treatment with CB1/CB2 selective antagonists AM251 and AM630, prior to JWH-015 and Win55,212-2 treatments, attenuated the agonist-mediated inhibition of in vitro chemotaxis and chemoinvasion. Additionally, both CB1 and CB2 agonists Win55,212-2 and JWH-133, respectively, significantly inhibited in vivo tumor growth and lung metastasis (~50%). These effects were receptor-mediated as pre-treatment with CB1/CB2 antagonists abrogated CB1/CB2 agonist-mediated effects on tumor growth and metastasis. Reduced proliferation and vascularization along with increased apoptosis was observed in tumors obtained from animals treated with JWH-133 and Win55,212-2. Upon further elucidation into the molecular mechanism, we observed that both CB1 and CB2 agonists inhibited phosphorylation of AKT, a key signaling molecule controlling cell survival, migration and apoptosis, and reduced MMP-9 expression and activity. These results suggest that CB1 and CB2 could be used as novel therapeutic targets against NSCLC.