Safety and Efficacy of Virus-Specific Cytotoxic T-Lymphocytes Manufactured By the IFN-γ Cytokine Capture System for the Treatment of Refractory Adenovirus, Cytomegalovirus, Epstein Barr Virus, and BK Virus Infections in Children, Adolescents and Young Adults after Allogeneic Hematopoietic Stem Cell Transplantation, Solid Organ Transplantation, or with Primary Immunodeficiency (IND# 17449)

(R,R′)-4′-Methoxy-1-naphthylfenoterol (MNF) promotes growth inhibition and apoptosis of human HepG2 hepatocarcinoma cells via cannabinoid receptor (CBR) activation. The synthetic CB1R inverse agonist, AM251, has been shown to block the anti-mitogenic effect of MNF in these cells; however, AM251 is also an agonist of the recently deorphanized, lipid-sensing receptor, GPR55, whose upregulation contributes to carcinogenesis. Here, we investigated the role of MNF in GPR55 signaling in human HepG2 and PANC-1 cancer cell lines in culture by focusing first on internalization of the fluorescent ligand Tocrifluor 1117 (T1117). Initial results indicated that cell pretreatment with GPR55 agonists, including the atypical cannabinoid O-1602 and l-α-lysophosphatidylinositol, dose-dependently reduced the rate of cellular T1117 uptake, a process that was sensitive to MNF inhibition. GPR55 internalization and signaling mediated by O-1602 was blocked by MNF in GPR55-expressing HEK293 cells. Pretreatment of HepG2 and PANC-1 cells with MNF significantly abrogated the induction of ERK1/2 phosphorylation in response to AM251 and O-1602. Moreover, MNF exerted a coordinated negative regulation of AM251 and O-1602 inducible processes, including changes in cellular morphology and cell migration using scratch wound healing assay. This study shows for the first time that MNF impairs GPR55-mediated signaling and, therefore, may have therapeutic potential in the management of cancer.