Breast cancer research : BCR

1465-542X1912017Mar23Breast cancer research : BCRBreast Cancer ResLoss of MMP-8 in ductal carcinoma in situ (DCIS)-associated myoepithelial cells contributes to tumour promotion through altered adhesive and proteolytic function.33333310.1186/s13058-017-0822-9Normal myoepithelial cells (MECs) play an important tumour-suppressor role in the breast but display an altered phenotype in ductal carcinoma in situ (DCIS), gaining tumour-promoter functions. Matrix metalloproteinase-8 (MMP-8) is expressed by normal MECs but is lost in DCIS. This study investigated the function of MMP-8 in MECs and the impact of its loss in DCIS.Primary normal and DCIS-associated MECs, and normal (N-1089) and DCIS-modified myoepithelial (β6-1089) cell lines, were used to assess MMP-8 expression and function. β6-1089 lacking MMP-8 were transfected with MMP-8 WT and catalytically inactive MMP-8 EA, and MMP-8 in N-1089 MEC was knocked down with siRNA. The effect on adhesion and migration to extracellular matrix (ECM), localisation of α6β4 integrin to hemidesmosomes (HD), TGF-β signalling and gelatinase activity was measured. The effect of altering MEC MMP-8 expression on tumour cell invasion was investigated in 2D and 3D organotypic models.Assessment of primary cells and MEC lines confirmed expression of MMP-8 in normal MEC and its loss in DCIS-MEC. Over-expression of MMP-8 WT but not MMP-8 EA in β6-1089 cells increased adhesion to ECM proteins and reduced migration. Conversely, knock-down of MMP-8 in N-1089 reduced adhesion and increased migration. Expression of MMP-8 WT in β6-1089 led to greater localisation of α6β4 to HD and reduced retraction fibre formation, this being reversed by MMP-8 knock-down in N-1089. Over-expression of MMP-8 WT reduced TGF-β signalling and gelatinolytic activity. MMP-8 knock-down enhanced TGF-β signalling and gelatinolytic activity, which was reversed by blocking MMP-9 by knock-down or an inhibitor. MMP-8 WT but not MMP-8 EA over-expression in β6-1089 reduced breast cancer cell invasion in 2D and 3D invasion assays, while MMP-8 knock-down in N-1089 enhanced cancer cell invasion. Staining of breast cancer cases for MMP-8 revealed a statistically significant loss of MMP-8 expression in DCIS with invasion versus pure DCIS (p = 0.001).These data indicate MMP-8 is a vital component of the myoepithelial tumour-suppressor function. It restores MEC interaction with the matrix, opposes TGF-β signalling and MMP-9 proteolysis, which contributes to inhibition of tumour cell invasion. Assessment of MMP-8 expression may help to determine risk of DCIS progression.SarperMugeMTranslational Cancer Discovery Team, CRUK Cancer Therapeutics Unit, Institute of Cancer Research, 15 Cotswold Road, Sutton, Surrey, SM2 5NG, UK.AllenMichael DMD0000-0003-2121-8087Centre for Tumour Biology, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK. m.allen@qmul.ac.uk.GommJennyJCentre for Tumour Biology, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.HaywoodLindaLCentre for Tumour Biology, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.DecockJulieJCancer Research Centre, Qatar Biomedical Research Institute, Qatar Foundation, Doha, Qatar.ThirkettleSallySCentre for Tumour Biology, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.UstaogluAhsenACentre for Tumour Biology, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.SarkerShah-JalalSJCentre for Experimental Cancer Medicine, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.MarshallJohnJCentre for Tumour Biology, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.EdwardsDylan RDRSchool of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.JonesJ LouiseJLCentre for Tumour Biology, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK. l.j.jones@qmul.ac.uk.engJournal ArticleResearch Support, Non-U.S. Gov't20170323