Johnson Thomas R, Khandrika Lakshmipathi, Kumar Binod, Venezia Sarah, Koul Sweaty, Chandhoke Ryan, Maroni Paul, Donohue Robert, Meacham Randall B, Koul Hari K
Program in Urosciences, Division of Urology-Department of Surgery, University of Colorado Denver School of Medicine, Denver, Colorado, USA.
Mol Cancer Res. 2008 Oct;6(10):1639-48. doi: 10.1158/1541-7786.MCR-08-0052.
Overexpression of focal adhesion kinase (FAK) has been well correlated with tumor development and/or the maintenance of tumor phenotype. In addition, inappropriate activation of the extracellular regulated kinase (ERK) signaling pathway is common to many human cancers. In the present study, we investigated the interplay between FAK and ERK in androgen-independent prostate cancer cells (PC3 and DU145 cells). We observed that suppression of FAK expression using small interfering RNA-mediated knockdown decreased the clonogenic activity, whereas overexpression of FAK increased it. We also observed that detachment of PC3 and DU145 cells from their substrate induced tyrosine phosphorylation of FAK. ERK knockdown diminished FAK protein levels and tyrosine phosphorylation of FAK as well as FAK promoter-reporter activity. We also tested the effect of MEK inhibitors and small interfering RNA-mediated knockdown of ERK1 and/or ERK2 on cell proliferation, invasiveness, and growth in soft agar of PC3 and DU145 cells. Inhibition of ERK signaling grossly impaired clonogenicity as well as invasion through Matrigel. However, inhibition of ERK signaling resulted in only a modest inhibition of 3H-thymidine incorporation and no effect on overall viability of the cells or increased sensitivity to anoikis. Taken together, these data show, for the first time, a requirement for FAK in aggressive phenotype of prostate cancer cells; reveal interdependence of FAK and ERK1/2 for clonogenic and invasive activity of androgen-independent prostate cancer cells; suggest a role for ERK regulation of FAK in substrate-dependent survival; and show for the first time, in any cell type, the regulation of FAK expression by ERK signaling pathway.
粘着斑激酶（FAK）的过表达与肿瘤发展和/或肿瘤表型的维持密切相关。此外，细胞外调节激酶（ERK）信号通路的不适当激活在许多人类癌症中很常见。在本研究中，我们调查了雄激素非依赖性前列腺癌细胞（PC3和DU145细胞）中FAK与ERK之间的相互作用。我们观察到，使用小干扰RNA介导的敲低抑制FAK表达会降低克隆形成活性，而FAK的过表达则会增加克隆形成活性。我们还观察到，PC3和DU145细胞从其底物上脱离会诱导FAK的酪氨酸磷酸化。ERK敲低会降低FAK蛋白水平、FAK的酪氨酸磷酸化以及FAK启动子报告基因活性。我们还测试了MEK抑制剂以及ERK1和/或ERK2的小干扰RNA介导的敲低对PC3和DU145细胞增殖、侵袭和软琼脂中生长的影响。抑制ERK信号通路严重损害了克隆形成能力以及通过基质胶的侵袭能力。然而，抑制ERK信号通路仅适度抑制了3H-胸苷掺入，对细胞的总体活力没有影响，也没有增加对失巢凋亡的敏感性。综上所述，这些数据首次表明FAK在前列腺癌细胞侵袭性表型中的必要性；揭示了FAK与ERK1/2在雄激素非依赖性前列腺癌细胞克隆形成和侵袭活性方面的相互依赖性；提示ERK对FAK的调节在底物依赖性存活中的作用；并首次在任何细胞类型中表明ERK信号通路对FAK表达的调节作用。
