Li Chien-Feng, Wu Wen-Jeng, Wu Wen-Ren, Liao Yu-Jing, Chen Lih-Ren, Huang Chun-Nung, Li Ching-Chia, Li Wei-Ming, Huang Hsuan-Ying, Chen Yi-Ling, Liang Shih-Shin, Chow Nan-Haw, Shiue Yow-Ling
Department of Pathology, Chi Mei Medical Center, Tainan, Taiwan.
National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan.
Oncotarget. 2015 Apr 20;6(11):9220-39. doi: 10.18632/oncotarget.3312.
In this study, we report that EMP2 plays a tumor suppressor role by inducing G2/M cell cycle arrest, suppressing cell viability, proliferation, colony formation/anchorage-independent cell growth via regulation of G2/M checkpoints in distinct urinary bladder urothelial carcinoma (UBUC)-derived cell lines. Genistein treatment or exogenous expression of the cAMP responsive element binding protein 1 (CREB1) gene in different UBUC-derived cell lines induced EMP2 transcription and subsequent translation. Mutagenesis on either or both cAMP-responsive element(s) dramatically decreased the EMP2 promoter activity with, without genistein treatment or exogenous CREB1 expression, respectively. Significantly correlation between the EMP2 immunointensity and primary tumor, nodal status, histological grade, vascular invasion and mitotic activity was identified. Multivariate analysis further demonstrated that low EMP2 immunoexpression is an independent prognostic factor for poor disease-specific survival. Genistein treatments, knockdown of EMP2 gene and double knockdown of CREB1 and EMP2 genes significantly inhibited tumor growth and notably downregulated CREB1 and EMP2 protein levels in the mice xenograft models. Therefore, genistein induced CREB1 transcription, translation and upregulated pCREB1(S133) protein level. Afterward, pCREB1(S133) transactivated the tumor suppressor gene, EMP2, in vitro and in vivo. Our study identified a novel transcriptional target, which plays a tumor suppressor role, of CREB1.
在本研究中，我们报告称，在不同的膀胱尿路上皮癌（UBUC）衍生细胞系中，EMP2通过调控G2/M检查点诱导G2/M期细胞周期阻滞，抑制细胞活力、增殖、集落形成/非锚定依赖性细胞生长，从而发挥肿瘤抑制作用。在不同的UBUC衍生细胞系中，染料木黄酮处理或cAMP反应元件结合蛋白1（CREB1）基因的外源性表达可诱导EMP2转录及随后的翻译。对一个或两个cAMP反应元件进行诱变，分别在未进行染料木黄酮处理或外源性CREB1表达的情况下，显著降低了EMP2启动子活性。我们确定了EMP2免疫强度与原发性肿瘤、淋巴结状态、组织学分级、血管侵犯和有丝分裂活性之间存在显著相关性。多变量分析进一步表明，低EMP2免疫表达是疾病特异性生存率低的一个独立预后因素。在小鼠异种移植模型中，染料木黄酮处理、EMP2基因敲低以及CREB1和EMP2基因双重敲低均显著抑制肿瘤生长，并显著下调CREB1和EMP2蛋白水平。因此，染料木黄酮诱导CREB1转录、翻译并上调pCREB1（S133）蛋白水平。随后，pCREB1（S133）在体外和体内反式激活肿瘤抑制基因EMP2。我们的研究确定了CREB1的一个新的转录靶点，该靶点发挥肿瘤抑制作用。
