Johnson Rarnice, Caggia Silvia, Khan Shafiq A
Center for Cancer Research and Therapeutic Development and Department of Biological Sciences, Clark Atlanta University, 223 James P. Brawley Dr, Atlanta, GA 30314, USA.
Department of Microbiology and Immunology, Miller School of Medicine, University of Miami, Coral Gables, FL 33101, USA.
Int J Mol Sci. 2025 Mar 15;26(6):2663. doi: 10.3390/ijms26062663.
Metastatic prostate cancer occurs when the tumor spreads from the prostate gland to other parts of the body. Previous studies have shown that Gα2, a subunit of the heterotrimeric G protein complex, plays a critical role in inducing cell migration and invasion in prostate cancer cells in response to diverse stimuli. Rac1 is a small rho-GTPase, which is activated by the phosphoinositide 3-kinase (PI3K)/AKT pathway and plays an essential role during cell migration. Previous studies have shown that the knockdown of Gα2 attenuates cell migration without causing any reduction in basal Rac1 activity in both PC3 and DU145 cells, and has only marginal effects on the epidermal growth facotor (EGF)-induced increase in Rac1 activity. Therefore, Gα2 may be involved in the regulation of cell motility and invasion independently or downstream of Rac1 activation. In this study, we investigated the possible mechanism of Gα2 at the level of the Rac1-dependent activation of Wiskott-Aldrich Syndrome Protein)-family verprolin homologous protein2 (Wave2) and actin related protein 2/3 (Arp 2/3) proteins, downstream effectors of activated Rac1. PC3 cells with a stable overexpression of constitutively active Rac1 were transfected with control siRNA or Gα2 siRNA to knockdown endogenous Gα2 expression. Western blot analysis showed that the Rac1-dependent activation of Wave2 was impaired in the absence of Gα2. The overexpression of constitutively active Gα2 (Gα2-Q205L) in PC3 cells significantly increased cell migration compared to cells transfected with control plasmids. In the parallel experiments, a specific Gα2 inhibitor blocked Gα2-Q205L-induced cell migration in PC3 cells. Furthermore, the Rac1 inhibitor did not block increased cell migration in PC3 cells overexpressing constitutively active Gα2. We conclude that activated Gα2 plays a crucial role in cell migration in prostate cancer cells independent of Rac1 activation.
转移性前列腺癌是指肿瘤从前列腺扩散至身体其他部位时发生的情况。先前的研究表明，异源三聚体G蛋白复合物的一个亚基Gα2，在响应多种刺激时，对诱导前列腺癌细胞的细胞迁移和侵袭起着关键作用。Rac1是一种小的rho-GTP酶，由磷酸肌醇3-激酶（PI3K）/AKT途径激活，在细胞迁移过程中起重要作用。先前的研究表明，在PC3和DU145细胞中，敲低Gα2可减弱细胞迁移，而不会导致基础Rac1活性降低，并且对表皮生长因子（EGF）诱导的Rac1活性增加只有轻微影响。因此，Gα2可能独立或在Rac1激活的下游参与细胞运动和侵袭的调节。在本研究中，我们在活化Rac1的下游效应分子威斯科特-奥尔德里奇综合征蛋白家族维普洛林同源蛋白2（Wave2）和肌动蛋白相关蛋白2/3（Arp 2/3）蛋白的Rac1依赖性激活水平上，研究了Gα2的可能机制。将组成型活性Rac1稳定过表达的PC3细胞用对照siRNA或Gα2 siRNA转染，以敲低内源性Gα2表达。蛋白质印迹分析表明，在没有Gα2的情况下，Wave2的Rac1依赖性激活受损。与用对照质粒转染的细胞相比，PC3细胞中组成型活性Gα2（Gα2-Q205L）的过表达显著增加了细胞迁移。在平行实验中，一种特异性Gα2抑制剂阻断了Gα2-Q205L诱导的PC3细胞迁移。此外，Rac1抑制剂并未阻断组成型活性Gα2过表达的PC3细胞中增加的细胞迁移。我们得出结论，活化的Gα2在前列腺癌细胞的细胞迁移中起着关键作用，且独立于Rac1激活。
