MT1-MMP correlates with MMP-2 activation potential seen after epithelial to mesenchymal transition in human breast carcinoma cells |
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Authors: | Helena Pulyaeva Jorge Bueno Myriam Polette Philippe Birembaut Hiroshi Sato Motoharu Seiki Erik W Thompson |
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Institution: | (1) Lombardi Cancer Center, Georgetown University Medical Center, Washington DC, USA;(2) Department of Cell Biology, Georgetown University Medical Center, Washington DC, USA;(3) INSERM U314 and Cell Biology Unit, CHU de Reims, 45, rue Coqnacq-Jay, Reims, France;(4) Department of Molecular Virology and Oncology, Cancer Research Institute, Kanazawa University, Kanazawa Ishikawa, Japan;(5) Department of Orthopedic Surgery, Georgetown University Medical Center, Washington DC, USA |
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Abstract: | We have previously reported that human breast carcinoma (HBC) cell lines expressing the mesenchymal intermediate filament protein vimentin (VIM+) are highly invasive in vitro, and highly metastatic in nude mice when compared to their VIM– counterparts. Since only VIM+ cell lines can be induced to activate matrix metalloproteinase-2 (MMP-2) upon stimulation with Concanavalin A (Con A), we have examined here membrane type 1 MMP (MT1-MMP), a cell surface activator of MMP-2. Northern analysis reveals baseline expression of MT1-MMP in five of the six VIM+ cell lines studied (MDA-MB-231, MDA-MB-435, BT-549, Hs578T, MCF-7ADR), each of which showed variable activation of exogenous MMP-2 after treatment with Con A. In contrast, the four VIM–, poorly invasive HBC cell lines studied (MCF-7, T47D, MDA-MB 468, ZR-75-1) lacked baseline MT1-MMP mRNA expression, and showed no induction of either MT1-MMP expression or MMP-2-activation with Con A. Such differential MT1-MMP expression was confirmed in vivo using in situ hybridization analysis of nude mouse tumor xenografts of representative cell lines. Western analysis of the MDA-MB-231 cells revealed baseline membrane expression of a 60 kDa species, which was strongly induced by Con A treatment along with a weaker band co-migrating with that from MT1-MMP-transfected COS-1 cells (63 kDa), presumably representing latent MT1-MMP. MT1-MMP immunofluorescence strongly decorated Con A-stimulated MDA-MB-231 cells in a manner consistent with membranous staining, but did not decorate the unstimulated MDA-MB-231 cells or MCF-7 cells under either condition. Collectively, the results suggest the constitutive production of active MT1-MMP which is unavailable for either MMP-2 activation or immuno-decoration until Con A treatment. Since VIM expression arises by virtue of the so-called epithelial to mesenchymal transition (EMT) in invasive embryonic epithelia, we propose that this represents a major metastasis mechanism in breast carcinomas. MT1-MMP on the surface of such ÔfibroblastoidÕ carcinoma cells may mediate a paracrine loop for the utilization of stromally produced MMP-2, and contribute to the poorer survival associated with VIM+ breast carcinomas. |
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Keywords: | EMT human breast cancer MMP-2 activation MT1-MMP invasion vimentin |
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