title: Up-regulation of long noncoding RNA MALAT1 contributes to proliferation and metastasis in esophageal squamous cell carcinoma.
abstract: BACKGROUND
  Metastasis Associated Lung Adenocarcinoma Transcript 1 (MALAT1) has been demonstrated to be an important player in various human malignancies; it is thought to promote tumor growth by cell cycle regulating. However, the roles of MALAT1 in esophageal squamous cell carcinoma(ESCC), and the mechanisms involved in cell cycle regulation remain poorly understood. Moreover, the factors contributing to its up-regulation in tumor tissues are still largely unclear.
  
  
  METHODS
  Expression of MALAT1 was determined from cell lines and clinical samples by qRT-PCR. The effects of MALAT1 knockdown on cell proliferation, cell cycle, apoptosis, migration, and invasion were evaluated by in vitro and in vivo assays. The potential protein expression changes were investigated by Western-blotting. The methylation status of the CpG island in the MALAT1 promoter was explored by bisulfite sequencing, while the copy numbers in tumor tissues and blood samples were detected by a well-established AccuCopy(TM) method.
  
  
  RESULTS
  MALAT1 was over-expressed in 46.3% of ESCC tissues, mostly in the high-stage tumor samples. Enhanced MALAT1 expression levels were positively correlated with clinical stages, primary tumor size, and lymph node metastasis. Inhibition of MALAT1 suppressed tumor proliferation in vitro and in vivo, as well as the migratory and invasive capacity. MALAT1 depletion also induced G2/M phase arrest and increased the percentage of apoptotic cells. Western-blotting results implicated that the ATM-CHK2 pathway which is associated with G2/M arrest was phosphorylated by MALAT1 knockdown. No effects of CpG island methylation status on MALAT1 expression were found, whereas amplification of MALAT1 was found in 22.2% of tumor tissues, which correlated significantly with its over-expression. However, neither association between tissue copy number amplification and germline copy number variation, nor correlation between germline copy number variation and ESCC risk were identified in the case-control study.
  
  
  CONCLUSIONS
  Our data suggest that MALAT1 serves as an oncogene in ESCC, and it regulates ESCC growth by modifying the ATM-CHK2 pathway. Moreover, amplification of MALAT1 in tumor tissues may play an important role for its up-regulation, and it seems that the gene amplification in tumor tissues emerges during ESCC progression, but is not derived from germline origins.
authors.affiliation: Department of Cardiothoracic Surgery, Southwest Hospital, Third Military Medical University, Gaotanyan St., Shapingba District, Chongqing, People's Republic of China. lw_hoo@163.com.
authors.forename: Liwen
authors.initials: L
authors.lastname: Hu
authors.affiliation: Department of Medical Genetics, College of Basic Medical Science, Third Military Medical University, Gaotanyan St., Shapingba District, Chongqing, People's Republic of China. 82468097@qq.com.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Cardiothoracic Surgery, Southwest Hospital, Third Military Medical University, Gaotanyan St., Shapingba District, Chongqing, People's Republic of China. tdli1029@163.com.
authors.forename: Deli
authors.initials: D
authors.lastname: Tan
authors.affiliation: Department of Medical Genetics, College of Basic Medical Science, Third Military Medical University, Gaotanyan St., Shapingba District, Chongqing, People's Republic of China. menghui0926@gmail.com.
authors.forename: Hui
authors.initials: H
authors.lastname: Meng
authors.affiliation: Department of Medical Genetics, College of Basic Medical Science, Third Military Medical University, Gaotanyan St., Shapingba District, Chongqing, People's Republic of China. wangk008@gmail.com.
authors.forename: Kai
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Medical Genetics, College of Basic Medical Science, Third Military Medical University, Gaotanyan St., Shapingba District, Chongqing, People's Republic of China. yunbai@tmmu.edu.cn.
authors.forename: Yun
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Department of Cardiothoracic Surgery, Southwest Hospital, Third Military Medical University, Gaotanyan St., Shapingba District, Chongqing, People's Republic of China. yangkangxwk@163.com.
authors.forename: Kang
authors.initials: K
authors.lastname: Yang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D016022:Case-Control Studies; D059447:Cell Cycle Checkpoints / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D064447:Checkpoint Kinase 2 / Q000378:metabolism; D018899:CpG Islands; D056915:DNA Copy Number Variations; D019175:DNA Methylation; D004195:Disease Models, Animal; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D000077277:Esophageal Squamous Cell Carcinoma; D005260:Female; D005784:Gene Amplification; D018628:Gene Dosage; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D005854:Germ Cells / Q000378:metabolism; D064593:Heterografts; D006801:Humans; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D062085:RNA, Long Noncoding / Q000235:genetics*; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: C557041:MALAT1 long non-coding RNA, human; D062085:RNA, Long Noncoding; D064447:Checkpoint Kinase 2; D064007:Ataxia Telangiectasia Mutated Proteins