Ceballos María Paula, Parody Juan Pablo, Quiroga Ariel Darío, Casella María Laura, Francés Daniel Eleazar, Larocca María Cecilia, Carnovale Cristina Ester, Alvarez María de Luján, Carrillo María Cristina
Instituto de Fisiología Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario , Rosario, Argentina .
J Interferon Cytokine Res. 2014 Nov;34(11):858-69. doi: 10.1089/jir.2013.0124. Epub 2014 Jun 20.
Interferon-α2b (IFN-α2b) reduces proliferation and increases apoptosis in hepatocellular carcinoma cells by decreasing β-catenin/TCF4/Smads interaction. Forkhead box O-class 3a (FoxO3a) participates in proliferation and apoptosis and interacts with β-catenin and Smads. FoxO3a is inhibited by Akt, IκB kinase β (IKKβ), and extracellular-signal-regulated kinase (Erk), which promote FoxO3a sequestration in the cytosol, and accumulates in the nucleus upon phosphorylation by c-Jun N-terminal kinase (JNK) and p38 mitogen-activated kinase (p38 MAPK). We analyzed FoxO3a subcellular localization, the participating kinases, FoxO3a/β-catenin/Smads association, and FoxO3a target gene expression in IFN-α2b-stimulated HepG2/C3A and Huh7 cells. Total FoxO3a and Akt-phosphorylated FoxO3a levels decreased in the cytosol, whereas total FoxO3a levels increased in the nucleus upon IFN-α2b stimulus. IFN-α2b reduced Akt, IKKβ, and Erk activation, and increased JNK and p38 MAPK activation. p38 MAPK inhibition blocked IFN-α2b-induced FoxO3a nuclear localization. IFN-α2b enhanced FoxO3a association with β-catenin and Smad2/3/7. Two-step coimmunoprecipitation experiments suggest that these proteins coexist in the same complex. The expression of several FoxO3a target genes increased with IFN-α2b. FoxO3a knockdown prevented the induction of these genes, suggesting that FoxO3a acts as mediator of IFN-α2b action. Results suggest a β-catenin/Smads switch from TCF4 to FoxO3a. Such events would contribute to the IFN-α2b-mediated effects on cellular proliferation and apoptosis. These results demonstrate new mechanisms for IFN-α action, showing the importance of its application in antitumorigenic therapies.
干扰素-α2b（IFN-α2b）通过减少β-连环蛋白/TCF4/ Smads相互作用来降低肝癌细胞的增殖并增加其凋亡。叉头框O类3a（FoxO3a）参与增殖和凋亡，并与β-连环蛋白和Smads相互作用。FoxO3a受到Akt、IκB激酶β（IKKβ）和细胞外信号调节激酶（Erk）的抑制，这些激酶促进FoxO3a在细胞质中的隔离，并在被c-Jun氨基末端激酶（JNK）和p38丝裂原活化蛋白激酶（p38 MAPK）磷酸化后在细胞核中积累。我们分析了在IFN-α2b刺激的HepG2/C3A和Huh7细胞中FoxO3a的亚细胞定位、参与的激酶、FoxO3a/β-连环蛋白/ Smads的关联以及FoxO3a靶基因的表达。细胞质中总FoxO3a和Akt磷酸化的FoxO3a水平降低，而在IFN-α2b刺激后细胞核中总FoxO3a水平升高。IFN-α2b降低了Akt、IKKβ和Erk的活化，并增加了JNK和p38 MAPK的活化。p38 MAPK抑制阻断了IFN-α2b诱导的FoxO3a核定位。IFN-α2b增强了FoxO3a与β-连环蛋白和Smad2/3/7的关联。两步免疫共沉淀实验表明这些蛋白存在于同一复合物中。几种FoxO3a靶基因的表达随IFN-α2b而增加。敲低FoxO3a可阻止这些基因的诱导，表明FoxO3a作为IFN-α2b作用的介质。结果表明存在从TCF4到FoxO3a的β-连环蛋白/ Smads转换。这些事件将有助于IFN-α2b对细胞增殖和凋亡的介导作用。这些结果证明了IFN-α作用的新机制，显示了其在抗肿瘤治疗中应用的重要性。
