Journal
LUNG CANCER
Volume 87, Issue 3, Pages 249-257Publisher
ELSEVIER IRELAND LTD
DOI: 10.1016/j.lungcan.2014.12.015
Keywords
NSCLC; CDH2; TGF-beta; SMAD; Transcription regulation; EMT
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Funding
- National Natural Science Foundation of China [81372277, 81171894, 31270940]
- Jiangsu Province's Key Provincial Talents Program [RC2011106]
- Jiangsu Province's Outstanding Medical Academic Leader Program [LJ201138]
- Science and Technology Committee of Jiangsu Province [BK2012606]
- 333 Project of Jiangsu Province Government, Graduate Innovation Project of Jiangsu Province [CXZZ13_0830]
- Soochow Scholar Project of Soochow University, Suzhou Key Laboratory for Molecular Cancer Genetics [SZS201209]
- Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
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Objectives: Epithelial-mesenchymal transition (EMT) is a key process in early stage of cancer metastasis. TGF-beta-mediated EMT is characterized by repression of E-cadherin and induction of N-cadherin (CDH2) in various cancers. Although many investigations have focused on the regulation of E-cadherin expression, the transcription-mediated events that directly induce N-cadherin expression in TGF-beta-induced EMT are not fully clear. Here, we mainly focus on non-small cell lung cancer (NSCLC) cells, in which expression of CDH2 can be activated upon TGF-beta stimulation, to investigate the underlying mechanisms of CDH2 expression regulation. Materials and methods: Western blot analysis, real-time quantitative reverse transcriptase PCR, luciferase reporter gene assays, RNA interference and in vivo chromatin immunoprecipitation (ChIP) assay were performed on human NSCLC cell lines A549 and SPC-A1. Twenty-six paired NSCLC tissues and adjacent noncancerous lung tissues were collected. Results: Luciferase reporter assay revealed that a functional TGF-beta-response element was located at position -1078 to -891 in the CDH2 promoter region. Furthermore, in vivo ChIP experiment indicated that TGF-beta-activated SMAD3/4 complex was directly recruited to CDH2 promoter region (-1078 to -891). Upon TGF-beta 1 stimulation, knockdown of SMAD3 or/and SMAD4 led to a significant reduction in CDH2 promoter activity, and silencing of SMAD3 or SMAD4 significantly inhibited CDH2 mRNA and protein expression in A549 and SPC-A1 cells. In human NSCLC tissues, SMAD3 or SMAD4 mRNA level was positively correlated with CDH2 mRNA level, respectively. Conclusions: We found that TGF-beta-activated SMAD3/4 complex may upregulate CDH2 expression by directly interacting with a specific SMAD-binding element in CDH2 promoter. Our findings provide insights into mechanisms underlying the transcriptional regulation of CDH2 expression in TGF-beta-induced EMT and SMADs-based therapeutic strategies for NSCLCs. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
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