Metabolic reprogramming contributes to
oncogenesis,
tumor growth, and treatment resistance in pancreatic ductal
adenocarcinoma (PDAC). Here we report the effects of (R,S')-4'-methoxy-1-naphthylfenoterol (MNF), a GPR55 antagonist and biased β2-adrenergic receptor (β2-AR) agonist on cellular signaling implicated in proliferation and metabolism in PDAC cells. The relative contribution of GPR55 and β2-AR in (R,S')-MNF signaling was explored further in PANC-1 cells. Moreover, the effect of (R,S')-MNF on
tumor growth was determined in a PANC-1 mouse xenograft model. PANC-1 cells treated with (R,S')-MNF showed marked attenuation in GPR55 signal transduction and function combined with increased β2-AR/Gαs/
adenylyl cyclase/PKA signaling, both of which contributing to lower
MEK/ERK, PI3K/AKT and YAP/TAZ signaling. (R,S')-MNF administration significantly reduced PANC-1
tumor growth and circulating L-
lactate concentrations. Global metabolic profiling of (R,S')-MNF-treated
tumor tissues revealed decreased glycolytic metabolism, with a shift towards normoxic processes, attenuated
glutamate metabolism, and increased levels of
ophthalmic acid and its precursor,
2-aminobutyric acid, indicative of elevated oxidative stress. Transcriptomics and immunoblot analyses indicated the downregulation of gene and
protein expression of HIF-1α and c-Myc, key initiators of metabolic reprogramming in PDAC. (R,S')-MNF treatment decreased HIF-1α and c-Myc expression, attenuated glycolysis, shifted
fatty acid metabolism towards β-oxidation, and suppressed de novo
pyrimidine biosynthesis in PANC-1
tumors. The results indicate a potential benefit of combined GPR55 antagonism and biased β2-AR agonism in PDAC
therapy associated with the deprogramming of altered cellular metabolism.