β-catenin is constitutively active and increases STAT3 expression/activation in anaplastic lymphoma kinase-positive anaplastic large cell lymphoma
β-catenin is constitutively active and increases STAT3 expression/activation in anaplastic lymphoma kinase-positive anaplastic large cell lymphoma
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DOI：
10.3324/haematol.2010.027086
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发表时间：
2011-02-01
期刊：
影响因子：
--
通讯作者：
Gelebart, Pascal
中科院分区：
文献类型：
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作者：
Anand, Mona;Lai, Raymond;Gelebart, Pascal
背景β-连环蛋白在癌症中的作用在上皮细胞来源的肿瘤中得到了最多的研究。该蛋白在间变性淋巴瘤激酶 (ALK) 阳性间变性大细胞淋巴瘤中的功能状态和生物学意义尚不清楚。设计和方法检查 ALK 阳性间变性大细胞淋巴瘤细胞系和患者肿瘤样本的 β-连环蛋白表达和信号传导状态。使用免疫组织化学、亚细胞分级分离和共聚焦显微镜评估 β-连环蛋白的亚细胞定位，同时使用 TOPFlash/FOPFlash 荧光素酶报告基因测定研究其转录活性。为了检查 β-连环蛋白的生物学意义，使用短干扰 RNA 来降低其表达；使用台盼蓝排除法和 MTS 测定法研究由此产生的生物效应，并使用定量实时聚合酶链反应和蛋白质印迹评估对其各种下游靶标的影响。结果 β-连环蛋白在三个 ALK 阳性间变性大细胞淋巴瘤细胞系中的三个中具有转录活性，这一发现与这些细胞中 β-连环蛋白的核定位以及大多数患者肿瘤样本中鉴定的肿瘤细胞相关。 β-连环蛋白在 ALK 阳性间变性大细胞淋巴瘤中具有生物学意义，因为 β-连环蛋白的下调会导致细胞生长显着减少。 β-连环蛋白的下调导致总蛋白水平和 STAT3 的激活/磷酸化形式显着降低，STAT3 是另一种信号蛋白，之前显示在 ALK 阳性间变性大细胞淋巴瘤的发病机制中很重要。与一些致癌酪氨酸激酶相反，核磷蛋白-间变性淋巴瘤激酶表达的调节不会导致β-连环蛋白的蛋白质水平、核定位或酪氨酸磷酸化发生任何可检测到的变化；然而，抑制核磷蛋白-间变性淋巴瘤激酶表达会显着下调 β-连环蛋白的转录活性。结论 β-连环蛋白信号传导在 ALK 阳性间变性大细胞淋巴瘤中持续活跃，代表了一种先前未知的机制，通过该机制，这些肿瘤中 STAT3 的高水平表达和激活得以持续。我们的结果表明，致癌酪氨酸激酶和各种细胞信号蛋白之间的相互作用可能比以前认为的更复杂。
BackgroundThe role of beta-catenin in cancer has been most studied in tumors of epithelial cell origin. The functional status and biological significance of this protein in anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma is unknown.Design and MethodsALK-positive anaplastic large cell lymphoma cell lines and patients' tumor samples were examined for status of beta-catenin expression and signaling. The subcellular localization of beta-catenin was assessed using immunohistochemistry, sub-cellular fractionation and confocal microscopy, while its transcriptional activity was studied using the TOPFlash/FOPFlash luciferase reporter assay. To examine the biological significance of beta-catenin, short interfering RNA was used to knock-down its expression; the resulting biological effects were studied using trypan-blue exclusion and MTS assay, and the impact on its various downstream targets was assessed using quantitative real-time polymerase chain reaction and western blots.Resultsbeta-catenin was transcriptionally active in three of three ALK-positive anaplastic large cell lymphoma cell lines, and this finding correlates with the nuclear localization of beta-catenin in these cells and the neoplastic cells identified in most of the patients' tumor samples. beta-catenin is biologically significant in ALK-positive anaplastic large cell lymphoma, since down-regulation of beta-catenin resulted in a significant reduction in their cell growth. Down-regulation of beta-catenin led to a marked reduction in both the total protein level and the activated/phosphorylated form of STAT3, another signaling protein previously shown to be important in the pathogenesis of ALK-positive anaplastic large cell lymphoma. In contrast to some of the oncogenic tyrosine kinases, modulation of nucleophosmin-anaplastic lymphoma kinase expression did not result in any detectable change in the protein level, nuclear localization or tyrosine phosphorylation of beta-catenin; however, inhibition of nucleophosmin-anaplastic lymphoma kinase expression significantly down-regulated the transcriptional activity of beta-catenin.Conclusionsbeta-catenin signaling is constitutively active in ALK-positive anaplastic large cell lymphoma and represents a previously unknown mechanism by which the high levels of STAT3 expression and activation in these tumors are sustained. Our results suggest that the interaction between oncogenic tyrosine kinases and various cell signaling proteins may be more complex than previously believed.