G protein inhibitory α subunit 2 is a molecular oncotarget of human glioma

Identification of novel therapeutic oncotargets for human glioma is extremely important. Here we tested expression, potential functions and underlying mechanisms of G protein inhibitory α subunit 2 (Gαi2) in glioma. Bioinformatics analyses revealed that Gαi2 expression is significantly elevated in human glioma, correlating with poor patients' survival, higher tumor grade and wild-type IDH status. Moreover, increased Gαi2 expression was also in local glioma tissues and different glioma cells. In primary and immortalized (A172) glioma cells, Gαi2 shRNA or knockout (KO, by Cas9-sgRNA) potently suppressed viability, proliferation, and mobility, and induced apoptosis. Ectopic Gαi2 overexpression, using a lentiviral construct, further augmented malignant behaviors in glioma cells. p65 phosphorylation, NFκB activity and expression of NFκB pathway genes were decreased in Gαi2-depleted primary glioma cells, but increased following Gαi2 overexpression. There was an increased binding between Gαi2 promoter and Sp1 (specificity protein 1) transcription factor in glioma tissues and different glioma cells. In primary glioma cells Gαi2 expression was significantly reduced following Sp1 silencing, KO or inhibition. In vivo studies revealed that Gαi2 shRNA-expressing AAV intratumoral injection hindered growth of subcutaneous glioma xenografts in nude mice. Moreover, Gαi2 KO inhibited intracranial glioma xenograft in nude mice. Gαi2 depletion, NFκB inhibition and apoptosis induction were observed in subcutaneous and intracranial glioma xenografts with Gαi2 depletion. Together, overexpressed Gαi2 is important for glioma cell growth possibly by promoting NFκB cascade activation.