title: Stromal ING1 expression induces a secretory phenotype and correlates with breast cancer patient survival.
abstract: BACKGROUND
  Previous studies have established that levels of the Inhibitor of Growth 1(ING1) tumor suppressor are reduced in a significant proportion of different cancer types. Here we analyzed levels of ING1 in breast cancer patients to determine its prognostic significance as a biomarker for breast cancer prognosis.
  
  
  METHODS
  We used automated quantitative analysis (AQUA) to determine the levels of ING1 in the tumor associated stromal cells of 462 breast cancer samples. To better understand how high ING1 levels affect nearby epithelium, we measured the levels of cytokines and secreted matrix metalloproteases (MMPs), using an ELISA based assay in mammary fibroblasts overexpressing ING1. These cells were also used in a 3-dimensional co-culture with MCF7 cells to determine the effect of released MMPs and other cytokines on growing colonies.
  
  
  RESULTS
  We find that high levels of ING1 in stroma are associated with tumor grade (p = 0.001) and size (p = 0.02), and inversely associated with patient survival (p = 0.0001) in luminal, but not in non-luminal cancers, suggesting that high stromal ING1 promotes cancer development. In this group of patients ING1 could also predict patient survival and act as a biomarker (HR = 2.125). While ING1 increased or decreased the expression of different cytokines, ING1 also increased the levels of MMP1, MMP3 and MMP10 by 5-8 fold, and concomitantly decreased levels of the tissue inhibitors of metalloproteases TIMP2, TIMP3 and TIMP4 by 1.5-3.3 fold, resulting in significant increases in MMP activity as determined by zymography. Co-culturing of MCF7 cells with stromal cells expressing ING1 in 3-dimensional organoid cultures suggested that MCF7 colonies were less well defined, suggesting that secreted MMPs might promote migration.
  
  
  CONCLUSIONS
  These data indicate that stromal ING1 expression can predict the survival of patients with luminal breast cancer. High levels of ING1 in stromal cells can promote the development of breast cancer through increased expression and release of MMPs and down regulation of TIMPs, which may be an underlying mechanism of reduced patient survival.
authors: Department of Biochemistry and Molecular Biology, University of Calgary, 3330 Hospital Drive, Calgary, T2N 4N1, AB, Canada.
authors: Satbir
authors: S
authors: Thakur
authors: Department of Medical Science, University of Calgary, 3330 Hospital Drive, Calgary, T2N 4N1, AB, Canada.
authors: Arash
authors: A
authors: Nabbi
authors: Functional Tissue Imaging Unit, Translational Research Laboratory, Tom Baker Cancer Center, 1331- 29 street NW, Calgary, T2N 4N2, AB, Canada.|Present Address: Boehringer Ingelheim Pharmaceuticals Inc, 900 Ridgebury Road, Ridgefield, CT, 06877, USA.
authors: Alexander
authors: A
authors: Klimowicz
authors: Department of Biochemistry and Molecular Biology, University of Calgary, 3330 Hospital Drive, Calgary, T2N 4N1, AB, Canada. karl@ucalgary.ca.|Department of Oncology, University of Calgary, 311 HMRB, 3330 Hospital Drive, NW, Calgary, T2N 4N1, AB, Canada. karl@ucalgary.ca.
authors: Karl
authors: K
authors: Riabowol
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000096:biosynthesis* / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D018572:Disease-Free Survival; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000076023:Inhibitor of Growth Protein 1; D047908:Intracellular Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000235:genetics; D061986:MCF-7 Cells; D020782:Matrix Metalloproteinases / Q000096:biosynthesis / Q000235:genetics; D008875:Middle Aged; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D011379:Prognosis; D017154:Stromal Cells / Q000378:metabolism / Q000473:pathology; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D014408:Biomarkers, Tumor; C501503:ING1 protein, human; D000076023:Inhibitor of Growth Protein 1; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D025521:Tumor Suppressor Proteins; D020782:Matrix Metalloproteinases