Abstract 340: MT1-MMP triggers an epithelial to mesenchymal transition program via activation of a TGF-β signaling pathway leading to Wnt5a induction

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Metastases account for the vast majority of cancer-related deaths and is thought to involve a process known as epithelial-to-mesenchymal transition (EMT). EMT alters cells from a connected, stationary epithelial state to a more motile, invasive mesenchymal state. Expression of the Membrane-type 1 matrix metalloproteinase (MT1-MMP), one of the key mediators of tumor invasion and metastasis, has been reported to trigger prostate cancer cells to undergo EMT. We have found that MT1-MMP overexpression in LNCaP prostate cancer (LNCaP/MT1-MMP-GFP) and MCF-7 breast cancer (MCF-7/MT1-MMP) cells resulted in increased Wnt5a mRNA and protein. Conversely, MT1-MMP shRNA knockdown, in DU145 cells (DU145/MT1 shRNA) that express high endogenous MT1-MMP, decreased Wnt5a. Increased Wnt5a was required for MT1-MMP-mediated EMT; Wnt5a shRNA expression in MT1-MMP overexpressing cells reversed EMT, resulting in increased E-cadherin and a more epithelial morphology. Increased Wnt5a expression occured via MT1-MMP-mediated activation of a TGF-β signaling pathway. LNCaP/ MT1-MMP-GFP cells had enhanced levels of activated TGF-β, and DU145/MT1 shRNA cells displayed reduced levels of activated TGF-β relative to their respective control cells. Inhibition of TGF-β activity with a neutralizing antibody in LNCaP/MT1-MMP-GFP resulted in decreased Wnt5a expression relative to control cells. MT1-MMP-mediated TGF-β activation was inhibited with the MMP inhibitor BB3103, and LNCaP cells overexpressing the catalytically inactive MT1-MMP (LNCaP/MT1/E240-A) had almost undetectable levels of activated TGF-β. Both LNCaP/MT1-MMP-GFP treated with BB3101 and LNCaP/MT1/E-240-A failed to induce increased Wnt5a. These results support MT1-MMP catalytic activity as a requirement for activating TGF-β and for MT1-MMP mediated upregulation of Wnt5a. The CUTL1 transcription factor has been reported to be regulated by TGF-β signaling. LNCaP/MT1-MMP-GFP and MCF-7/MT1-MMP cells showed enhanced CUTL1 expression, and DU145/MT1 shRNA cells had decreased CUTL1 relative to control DU145/GFP shRNA. shRNA targeting of CUTL1, in LNCaP/MT1-MMP-GFP cells, resulted in decreased Wnt5a expression and reversal of the EMT phenotype. Upregulation of Wnt5a promoted anchorage-independent growth; Wnt5a shRNA knockdown in either LNCaP/MT1-MMP-GFP or in DU145 cells each resulted in markedly decreased growth in soft agar. Wnt5a shRNA expression in LNCaP/MT1-MMP-GFP also significantly decreased the growth of mouse tumors derived from these cells relative to tumors from LNCaP/MT1-MMP-GFP. These results demonstrate the significance of Wnt5a expression in MT1-MMP-mediated tumor progression. Collectively, these results highlight a novel link between MT1-MMP and the Wnt pathway, mediated by TGF-β signaling, that illuminate the relationship between these factors and their roles in EMT and metastasis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 340. doi:1538-7445.AM2012-340