Abstract 4596: Synthesis and biological evaluation of small molecules inhibitors targeting heterotrimeric Gαi2 protein

Abstract

Abstract Heterotrimeric G-proteins are ubiquitously expressed in cells, and they transduce signals from activated G-protein coupled receptors. It is well known that these proteins are differentially expressed in cancer, thereby activating signals that lead to different biological functions such as proliferation and cell motility. Previously, we have shown that Gαi2 protein is essential for cell migration and invasion in prostate cancer cell lines, and its action is downstream of PI3-kinase/Rac1 activation. We have also shown that in PC3 prostate cancer cells, pre-treated with Pertussis toxin (PTX), a well know inhibitor of Gαi/0, resulted in the attenuation of TGFβ1- and oxytocin-induced migration and PI3-kinase activation, without affecting EGF-induced PI3-kinase activation and cell migration. Here, we synthesized new small molecules inhibitors, GDIs, capable of preventing nucleotide exchange and subunit activation. Compounds #29 and #46 are analogs of the lead compound, lacking the thiophene OH-group and with a thiol- to N-methyl amino-group substitution, respectively. Compound #35, a methyl ether derivative of #46, is designed to test the effect of the modification to the phenolic group on Gαi2 inhibition activity. We pretreated PC3 cells with the small molecules and then stimulated with EGF and oxytocin to activate Gαi2 subunit. Immunoprecipitation of the active Gαi and western blot for Gαi2 showed a decrease in the amount of active Gαi2 that was pulled down compared with the controls. Using cell migration assay, we observed that #29 and #46, both at 10 μM, caused inhibition of migration in different prostate cancer cell lines in response to EGF treatments. In contrast, #35 is inactive in this assay at the same concentration. To determine if the effects of Gαi2 are the same in other cancer cells, we first knockdown Gαi2 protein expression in breast and ovarian cancer cells and performed migration assays. The knock-down of endogenous Gαi2 attenuated cell migration, compared to the control cells. We also performed migration assays in the same cells using compound #29 at 10 μM and observed significant inhibition of migratory behavior in response to EGF- and FBS stimuli compared to the controls. We conclude that the small molecules we used in this study may be considered as potential therapeutic tools, inhibiting the migratory capability of metastatic cells. Citation Format: Silvia Caggia, Autumn S. Garrett, Aditi Kumar, Subhasish Tapadar, Adegboyega K. Oyelere, Smrruthi Vaidegi Venugopal, Shafiq A. Khan. Synthesis and biological evaluation of small molecules inhibitors targeting heterotrimeric Gαi2 protein [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4596.