4 research outputs found
Inhibition of MT1-MMP proteolytic function and ERK1/2 signalling influences cell migration and invasion through changes in MMP-2 and MMP-9 levels
Membrane type-1 matrix metalloproteinase (MT1-MMP, MMP-14) is a unique protease that cleaves extracellular proteins, activates proMMPs, and initiates intracellular signalling. MCF-7 cells are non-invasive and deficient in MT1-MMP, MMP-2, and MMP-9 expression. We created an MCF-7 cell line (C2) that stably produces active MT1-MMP and demonstrated increased ERK1/2 phosphorylation. MAPK inhibition in this cell line showed an inverse relationship in MMP-2 and MMP-9 transcripts where levels of these genes increased and decreased, respectively. Using invasive MDA-MB 231 cells that endogenously produce MT1-MMP and have naturally high pERK levels, we demonstrated the identical inverse relationship between MMP-2 and -9 transcript and protein levels, suggesting that this novel relationship is conserved amongst MT1-MMP positive breast cancer cells. To further analyze the relationship between MMP-2 and -9 levels, we chemically inhibited activation and catalytic activity of MT1-MMP using a furin and MMP inhibitor, respectively, to show that interference with the functions of MT1-MMP induced changes in MMP-2 and 9 transcript levels that were always inverse of each other, and likely mediated by differential transcriptional activity of the NF-κB transcription factor. Furthermore, we analyzed the functional consequences of these expression changes to show MMP, and in particular ERK, inhibition decreased migration and invasion using 2D culture, and inhibits the formation of an invasive phenotype in Matrigel 3D culture. This study demonstrated a novel inverse transcriptional relationship between MMP-2 and -9 levels and MT1-MMP activity that have functional consequences, and also showed that increases in the levels of MMPs does not necessarily correlate with an invasive phenotype
Less is more: Low expression of MT1-MMP is optimal to promote migration and tumourigenesis of breast cancer cells
Background: Membrane Type-1 Matrix Metalloproteinase (MT1-MMP) is a multifunctional protease implicated in metastatic progression ostensibly due to its ability to degrade extracellular matrix (ECM) components and allow migration of cells through the basement membrane. Despite in vitro studies demonstrating this principle, this knowledge has not translated into the use of MMP inhibitors (MMPi) as effective cancer therapeutics, or been corroborated by evidence of in vivo ECM degradation mediated by MT1-MMP, suggesting that our understanding of the role of MT1-MMP in cancer progression is incomplete. Methods: MCF-7 and MDA-MB 231 breast cancer cell lines were created that stably overexpress different levels of MT1-MMP. Using 2D culture, we analyzed proMMP-2 activation (gelatin zymography), ECM degradation (fluorescent gelatin), ERK signaling (immunoblot), cell migration (transwell/scratch closure/time-lapse imaging), and viability (colorimetric substrate) to assess how different MT1-MMP levels affect these cellular parameters. We also utilized Matrigel 3D cell culture and avian embryos to examine how different levels of MT1-MMP expression affect morphological changes in 3D culture, and tumourigenecity and extravasation efficiency in vivo. Results: In 2D culture, breast cancer cells expressing high levels of MT1-MMP were capable of widespread ECM degradation and TIMP-2-mediated proMMP-2 activation, but were not the most migratory. Instead, cells expressing low levels of MT1-MMP were the most migratory, and demonstrated increased viability and ERK activation. In 3D culture, MCF-7 breast cancer cells expressing low levels of MT1-MMP demonstrated an invasive protrusive phenotype, whereas cells expressing high levels of MT1-MMP demonstrated loss of colony structure and cell fragment release. Similarly, in vivo analysis demonstrated increased tumourigenecity and metastatic capability for cells expressing low levels of MT1-MMP, whereas cells expressing high levels were devoid of these qualities despite the production of functional MT1-MMP protein. Conclusions: This study demonstrates that excessive ECM degradation mediated by high levels of MT1-MMP is not associated with cell migration and tumourigenesis, while low levels of MT1-MMP promote invasion and vascularization in vivo