Signaling and Regulation The Essential Role of Gia2 in Prostate Cancer Cell Migration

Celland receptor-specific regulation of cell migration by Gi/oa-proteins remains unknown in prostate cancer cells. In the present study, oxytocin (OXT) receptor was detected at the protein level in total cell lysates from C81 (an androgen-independent subline of LNCaP), DU145 and PC3 prostate cancer cells, but not in immortalized normal prostate luminal epithelial cells (RWPE1), and OXT-induced migration of PC3 cells. This effect of OXT has been shown to be mediated by Gi/oa-dependent signaling. Accordingly, OXT inhibited forskolin-induced luciferase activity in PC3 cells that were transfected with a luciferase reporter for cyclic AMP activity. Although mRNAs for all threeGia isoformswere present in PC3 cells, Gia2was themost abundant isoform thatwas detected at the protein level. Pertussis toxin (PTx) inhibited the OXT-inducedmigration of PC3 cells. Ectopic expression of the PTx-resistant Gia2-C352G, but not wild-type Gia2, abolished this effect of PTx on OXT-induced cell migration. TheGia2-targeting siRNAwas shown to specifically reduceGia2mRNAand protein in prostate cancer cells. The Gia2-targeting siRNA eliminated OXT-induced migration of PC3 cells. These data suggest that Gia2 plays an important role in the effects of OXT on PC3 cell migration. The Gia2-targeting siRNA also inhibited EGF-induced migration of PC3 and DU145 cells. Expression of the siRNA-resistant Gia2, but not wild type Gia2, restored the effects of EGF in PC3 cells transfected with the Gia2-targeting siRNA. In conclusion, Gia2 plays an essential role in OXT and EGF signaling to induce prostate cancer cell migration.Mol Cancer Res; 10(10);