Activation of dimerized BRS3-EP3 suppresses melanoma cell migration through coupling Gαs protein

The mechanism underlying the crosstalk between Gα_q-coupled bombesin receptor subtype-3 (BRS3) and Gα_i-coupled E-prostanoid 3 receptor (EP3) remains unknown. Here, we report that BRS3 and EP3 form dimers in the membrane of living HEK-293T cells. BRS3-EP3 dimers switched to couple Gα_s protein upon PGE2 stimulation, which provoked cAMP accumulation and enhanced P38 phosphorylation. Quantitative proteomics analysis revealed that the activation of BRS3-EP3 dimers was associated with cell migration. B16 melanoma cell line, which endogenously expresses BRS3 and EP3, was selected to investigate the function of BRS3-EP3 dimers. The results demonstrated that the presence of BRS3 inhibited the migration of B16 melanoma cells upon PGE2 stimulation. Utilizing inhibitors of Gα_s and P38, we found that BRS3 interacted with EP3 and switched to couple Gα_s protein, causing P38 phosphorylation to inhibit F-actin rearrangement and ultimately suppressed cell migration. Our study reveals the crosstalk between the orphan receptor BRS3 and EP3, and provides a potential novel target for disease treatment.