title: Higher levels of TIMP-1 expression are associated with a poor prognosis in triple-negative breast cancer.
abstract: Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a multifunctional protein that can directly regulate apoptosis and metastasis. In this study, we investigated the functional and molecular mechanisms by which TIMP-1 influences triple-negative breast cancer (TNBC).
  
  
  
  The expression level of TIMP-1 in breast cancer tissues was analyzed using the ONCOMINE microarray database. The overall survival of patients with distinct molecular subtypes of breast cancer stratified by TIMP-1 expression levels was evaluated using Kaplan-Meier analysis. Bisulfate sequencing PCR (BSP) was used to analyze the methylation status of the TIMP-1 promoter. Real-time-PCR (RT-PCR), Western blot and ELISA assays were used to evaluate gene and protein expression in cell lines and human tissue specimens. In addition, TIMP-1 function was analyzed using a series of in vitro and in vivo assays with cells in which TIMP-1 was inhibited using RNAi or neutralizing antibodies.
  
  
  
  We found that serum TIMP-1 levels were strongly enhanced in patients with TNBC and that elevated TIMP-1 levels were associated with a poor prognosis in TNBC. However, TIMP-1 levels were not significantly associated with overall survival in other subtypes of breast cancer or in the overall population of breast cancer patients. We also report the first evidence that the TIMP-1 promoter is hypomethylated in TNBC cell lines compared with non-TNBC cell lines, suggesting that aberrant TIMP-1 expression in TNBC results from reduced DNA methylation. RNAi-mediated silencing of TIMP-1 in TNBC cells induced cell cycle arrest at the G1 phase and reduced cyclin D1 expression. In addition, mechanistic analyses revealed that the p-Akt and p-NF-κB signaling pathways, but not the GSK-3β and MAPK1/2 pathways, are associated with TIMP-1 overexpression in TNBC cells. Moreover, neutralizing antibodies against TIMP-1 significantly decreased the rate of tumor growth in vivo.
  
  
  
  Our findings suggest that TIMP-1 is a biomarker indicative of a poor prognosis in TNBC patients and that targeting TIMP-1 may provide an attractive therapeutic intervention specifically for triple-negative breast cancer patients.
authors.affiliation: Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China.
authors.forename: Guangcun
authors.initials: G
authors.lastname: Cheng
authors.affiliation: Department of Biochemistry and Molecular Cell Biology, Shanghai key Laboratory of Tumor Microenvironment and Inflammation, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Fan
authors.affiliation: Department of Biochemistry and Molecular Cell Biology, Shanghai key Laboratory of Tumor Microenvironment and Inflammation, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
authors.forename: Mingang
authors.initials: M
authors.lastname: Hao
authors.affiliation: Department of Biochemistry and Molecular Cell Biology, Shanghai key Laboratory of Tumor Microenvironment and Inflammation, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
authors.forename: Jinglong
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Biochemistry and Molecular Cell Biology, Shanghai key Laboratory of Tumor Microenvironment and Inflammation, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Biochemistry and Molecular Cell Biology, Shanghai key Laboratory of Tumor Microenvironment and Inflammation, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China. sunxueqing@msn.com.
authors.forename: Xueqing
authors.initials: X
authors.lastname: Sun
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D059447:Cell Cycle Checkpoints / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019295:Computational Biology / Q000379:methods; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D030541:Databases, Genetic; D004195:Disease Models, Animal; D005260:Female; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D053208:Kaplan-Meier Estimate; D051379:Mice; D011379:Prognosis; D011401:Promoter Regions, Genetic; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D064726:Triple Negative Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000401:mortality* / Q000473:pathology; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D019715:Tissue Inhibitor of Metalloproteinase-1; D019938:Cyclin D1; D051057:Proto-Oncogene Proteins c-akt
keywords: G1 phase; Poor prognosis; TIMP-1; Triple-negative breast cancer