Regulator of G protein signaling 2 as a suppressor of sphingosine-1-phosphate 2– and 3–mediated signaling in colon cancer cells

Sphingosine-1-phosphate receptor 2 and 3 (S1P₂ and S1P₃) are G protein-coupled receptors that mediate extracellular sphingosine-1-phosphate (S1P) signaling into cells. S1P₂ and S1P₃ are highly expressed in colon cancer cells, but their roles in cancer progression-related cellular phenotypes are not well understood. Recent studies suggest that regulator of G protein signaling 2 (RGS2) interacts with G protein-coupled receptors, either directly or indirectly, to regulate their signaling. However, the precise role of RGS2 in S1P₂ and S1P₃ signaling remains uninvestigated. In this study, we examined the interaction of RGS2 with S1P₂ and S1P₃ using bioluminescence resonance energy transfer analysis and assessed its impact on S1P₂- and S1P₃-mediated signaling in 293T and HCT116 cells. Bioluminescence resonance energy transfer analysis revealed that RGS2 and Gα subunits simultaneously bind to S1P₂ and S1P₃. Furthermore, in the presence of these receptors, RGS2 translocated from the cytoplasm to the cell membrane. These interactions and membrane translocation were not observed with the RGS1 negative control, highlighting the specificity of RGS2 for S1P₂ and S1P₃. RGS2 expression inhibited the activation of Gαi, Gαq, and Gα12, key signaling pathways mediated by S1P₂ and S1P₃. S1P₂ and S1P₃ activation significantly enhanced cell migration and the expression of cancer-associated genes, effects that were effectively suppressed by RGS2 expression. In contrast, RGS1 failed to inhibit S1P₂- and S1P₃-mediated Gα signaling as well as downstream effects, such as enhanced cell migration and cancer-associated gene expression. Our findings show that RGS2 suppresses S1P2- and S1P3-mediated cancer-associated cellular phenotypes by interacting with these receptors and inhibiting Gα-mediated signaling.