Faivre S, Régnauld K, Bruyneel E, Nguyen Q D, Mareel M, Emami S, Gespach C
Institut National de la Santé et de la Recherche Médicale U482, Hôpital Saint-Antoine, Paris, France.
Mol Pharmacol. 2001 Aug;60(2):363-72. doi: 10.1124/mol.60.2.363.
It was shown previously that platelet-activating factor receptors (PAF-Rs) inhibit invasiveness of colonic and kidney epithelial cells induced by the src and Met oncogenes via a pertussis toxin-sensitive mechanism. Therefore, Madin-Darby canine kidney (MDCKts.src) cells were stably transfected with constitutively activated forms of Galphao, Galphai1, Galphai2, Galphai3 (AGalphao/i), two Gbetagamma sequestering proteins [C-terminal end of beta-adrenergic receptor kinase (ct-betaARK) and the Galphat subunit of retinal G-protein transducin], and Gbeta1-Ggamma2 subunits alone or in combination. Cellular invasion induced by src, Met, and leptin was abrogated by the AGalphao/i, ct-betaARK, and Galphat-positive clones, but was induced by coexpression of Gbeta1gamma2. In contrast, invasion stimulated by the trefoil factors (TFFs) pS2 and intestinal trefoil factor in MDCKts.src cells or human colonic epithelial cells PCmsrc and HCT8/S11 was insensitive to PAF, AGalphao, AGalphai1, and AGalphai2, but was abolished by AGalphai3 and the protease-activated receptor-1 (PAR-1) agonist thrombin receptor-activating peptide. Depletion of free Gbetagamma heterodimers by ct-betaARK resulted in a remarkable decrease of cellular adhesion and spreading on collagen matrix. Our data demonstrate the following: 1) PAF-Rs impair cellular invasion induced by src, Met, and leptin via the activation of Galphao and Galphai1 to -3; 2) invasion induced by TFFs is selectively inhibited by PAR-1 receptors and Galphai3 activation; and 3) Gbetagamma dimers are required as positive effectors of invasion pathways induced by oncogenes and epigenetic factors. Thus, redistribution of Galphao/Galphai and Gbeta/gamma heterotrimeric G-proteins by PAF-R and PAR-1 exert differential functions on positive and negative signaling pathways involved in cellular invasion and may serve as potential targets for anticancer therapy.
先前的研究表明,血小板活化因子受体(PAF-Rs)通过百日咳毒素敏感机制抑制src和Met致癌基因诱导的结肠和肾上皮细胞的侵袭性。因此,用组成型激活形式的Gαo、Gαi1、Gαi2、Gαi3(AGαo/i)、两种Gβγ隔离蛋白[β-肾上腺素能受体激酶的C末端(ct-βARK)和视网膜G蛋白转导素的Gαt亚基]以及单独或组合的Gβ1-Gγ2亚基对Madin-Darby犬肾(MDCKts.src)细胞进行稳定转染。AGαo/i、ct-βARK和Gαt阳性克隆消除了src、Met和瘦素诱导的细胞侵袭,但Gβ1γ2的共表达诱导了细胞侵袭。相反,三叶因子(TFFs)pS2和肠三叶因子在MDCKts.src细胞或人结肠上皮细胞PCmsrc和HCT8/S11中刺激的侵袭对PAF、AGαo、AGαi1和AGαi2不敏感,但被AGαi3和蛋白酶激活受体-1(PAR-1)激动剂凝血酶受体激活肽消除。ct-βARK对游离Gβγ异二聚体的消耗导致细胞在胶原基质上的黏附和铺展显著减少。我们的数据表明:1)PAF-Rs通过激活Gαo和Gαi1至-3损害src、Met和瘦素诱导的细胞侵袭;2)TFFs诱导的侵袭被PAR-1受体和Gαi3激活选择性抑制;3)Gβγ二聚体是致癌基因和表观遗传因子诱导的侵袭途径的正效应器。因此,PAF-R和PAR-1对Gαo/Gαi和Gβ/γ异三聚体G蛋白的重新分布在参与细胞侵袭的正负信号通路中发挥不同功能,并可能作为抗癌治疗的潜在靶点。