Institute of Biomedical Sciences, National Chung Hsing University, Taichung 40227, Taiwan, ROC.
Mol Cancer Res. 2012 Oct;10(10):1319-31. doi: 10.1158/1541-7786.MCR-12-0189. Epub 2012 Aug 21.
YWHAZ, also known as 14-3-3zeta, has been reportedly elevated in many human tumors, including non-small cell lung carcinoma (NSCLC) but little is known about its specific contribution to lung cancer malignancy. Through a combined array-based comparative genomic hybridization and expression microarray analysis, we identified YWHAZ as a potential metastasis enhancer in lung cancer. Ectopic expression of YWHAZ on low invasive cancer cells showed enhanced cell invasion, migration in vitro, and both the tumorigenic and metastatic potentials in vivo. Gene array analysis has indicated these changes associated with an elevation of pathways relevant to epithelial-mesenchymal transition (EMT), with an increase of cell protrusions and branchings. Conversely, knockdown of YWHAZ levels with siRNA or short hairpin RNA (shRNA) in invasive cancer cells led to a reversal of EMT. We observed that high levels of YWHAZ protein are capable of activating β-catenin-mediated transcription by facilitating the accumulation of β-catenin in cytosol and nucleus. Coimmunoprecipitation assays showed a decrease of ubiquitinated β-catenin in presence of the interaction between YWHAZ and β-catenin. This interaction resulted in disassociating β-catenin from the binding of β-TrCP leading to increase β-catenin stability. Using enforced expression of dominant-negative and -positive β-catenin mutants, we confirmed that S552 phosphorylation of β-catenin increases the β-catenin/YWHAZ complex formation, which is important in promoting cell invasiveness and the suppression of ubiquitnated β-catenin. This is the first demonstration showing YWHAZ through its complex with β-catenin in mediating lung cancer malignancy and β-catenin protein stability.
YWHAZ，也被称为 14-3-3zeta，据报道在许多人类肿瘤中升高，包括非小细胞肺癌（NSCLC），但对其在肺癌恶性肿瘤中的具体作用知之甚少。通过结合基于阵列的比较基因组杂交和表达微阵列分析，我们确定 YWHAZ 是肺癌中潜在的转移增强子。在低侵袭性癌细胞中外源表达 YWHAZ 显示出增强的细胞侵袭、体外迁移，以及体内的致瘤和转移潜能。基因阵列分析表明，这些变化与上皮-间充质转化（EMT）相关途径的升高有关，细胞突起和分支增加。相反，用 siRNA 或短发夹 RNA（shRNA）在侵袭性癌细胞中敲低 YWHAZ 水平导致 EMT 的逆转。我们观察到高水平的 YWHAZ 蛋白能够通过促进β-catenin 在细胞质和核中的积累来激活β-catenin 介导的转录。免疫共沉淀实验表明，在 YWHAZ 与β-catenin 相互作用的情况下，泛素化的β-catenin 减少。这种相互作用导致β-catenin 从β-TrCP 的结合中解离出来，从而增加β-catenin 的稳定性。通过强制表达显性负和正β-catenin 突变体，我们证实 S552 磷酸化的β-catenin 增加了β-catenin/YWHAZ 复合物的形成，这对促进细胞侵袭性和抑制泛素化的β-catenin 很重要。这是首次表明 YWHAZ 通过其与β-catenin 的复合物在介导肺癌恶性肿瘤和β-catenin 蛋白稳定性方面的作用。
