Center for Cancer Research and Therapeutic Development, Clark Atlanta University, Atlanta, GA 30314, USA.
Mol Cancer Res. 2012 Oct;10(10):1380-8. doi: 10.1158/1541-7786.MCR-12-0219. Epub 2012 Aug 30.
Cell- and receptor-specific regulation of cell migration by Gi/oα-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/oα-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 three Giα isoforms were present in PC3 cells, Giα2 was the most abundant isoform that was detected at the protein level. Pertussis toxin (PTx) inhibited the OXT-induced migration of PC3 cells. Ectopic expression of the PTx-resistant Giα2-C352G, but not wild-type Giα2, abolished this effect of PTx on OXT-induced cell migration. The Giα2-targeting siRNA was shown to specifically reduce Giα2 mRNA and protein in prostate cancer cells. The Giα2-targeting siRNA eliminated OXT-induced migration of PC3 cells. These data suggest that Giα2 plays an important role in the effects of OXT on PC3 cell migration. The Giα2-targeting siRNA also inhibited EGF-induced migration of PC3 and DU145 cells. Expression of the siRNA-resistant Giα2, but not wild type Giα2, restored the effects of EGF in PC3 cells transfected with the Giα2-targeting siRNA. In conclusion, Giα2 plays an essential role in OXT and EGF signaling to induce prostate cancer cell migration.
细胞和受体特异性调节前列腺癌细胞中的 Gi/oα 蛋白细胞迁移尚不清楚。在本研究中,在 C81(LNCaP 的雄激素非依赖性亚系)、DU145 和 PC3 前列腺癌细胞的总细胞裂解物中检测到催产素(OXT)受体蛋白,但在永生化正常前列腺腔上皮细胞(RWPE1)和 OXT 诱导的 PC3 细胞迁移中未检测到。OXT 的这种作用已被证明是由 Gi/oα 依赖性信号转导介导的。相应地,OXT 抑制了转染 cAMP 活性荧光素酶报告基因的 PC3 细胞中福斯克林诱导的荧光素酶活性。虽然 PC3 细胞中存在所有三种 Giα 同工型的 mRNA,但在蛋白质水平上检测到 Giα2 是最丰富的同工型。百日咳毒素(PTx)抑制了 OXT 诱导的 PC3 细胞迁移。PTx 抗性 Giα2-C352G 的异位表达,但不是野生型 Giα2,消除了 PTx 对 OXT 诱导的细胞迁移的这种作用。Giα2 靶向 siRNA 特异性地减少了前列腺癌细胞中的 Giα2 mRNA 和蛋白。Giα2 靶向 siRNA 消除了 OXT 诱导的 PC3 细胞迁移。这些数据表明 Giα2 在 OXT 对 PC3 细胞迁移的影响中起重要作用。Giα2 靶向 siRNA 还抑制了 EGF 诱导的 PC3 和 DU145 细胞迁移。在转染了 Giα2 靶向 siRNA 的 PC3 细胞中,表达 siRNA 抗性 Giα2,但不是野生型 Giα2,恢复了 EGF 的作用。总之,Giα2 在 OXT 和 EGF 信号诱导前列腺癌细胞迁移中发挥重要作用。