Small Molecule Inhibitors Targeting Gα(i)2 Protein Attenuate Migration of Cancer Cells

Heterotrimeric G-proteins are ubiquitously expressed in several cancers, and they transduce signals from activated G-protein coupled receptors. These proteins have numerous biological functions, and they are becoming interesting target molecules in cancer therapy. Previously, we have shown that heterotrimeric G-protein subunit alphai2 (Gα(i)2) has an essential role in the migration and invasion of prostate cancer cells. Using a structure-based approach, we have synthesized optimized small molecule inhibitors that are able to prevent specifically the activation of the Gα(i)2 subunit, keeping the protein in its inactive GDP-bound state. We observed that two of the compounds (13 and 14) at 10 μΜ significantly inhibited the migratory behavior of the PC3 and DU145 prostate cancer cell lines. Additionally, compound 14 at 10 μΜ blocked the activation of Gα(i)2 in oxytocin-stimulated prostate cancer PC3 cells, and inhibited the migratory capability of DU145 cells overexpressing the constitutively active form of Gα(i)2, under basal and EGF-stimulated conditions. We also observed that the knockdown or inhibition of Gα(i)2 negatively regulated migration of renal and ovarian cancer cell lines. Our results suggest that small molecule inhibitors of Gα(i)2 have potential as leads for discovering novel anti-metastatic agents for attenuating the capability of cancer cells to spread and invade to distant sites.