The proteolytic activity of MT4‐MMP is required for its pro‐angiogenic and pro‐metastatic promoting effects

Abstract

Membrane-type 4 matrix metalloprotease (MT4-MMP) expression in breast adenocarcinoma stimulates tumor growth and metastatic spreading to the lung. However, whether these pro-tumorigenic and pro-metastatic effects of MT4-MMP are related to a proteolytic action is not yet known. Through site directed mutagenesis MT4-MMP has been inactivated in cancer cells through Glutamic acid 249 substitution by Alanine in the active site. Active MT4-MMP triggered an angiogenic switch at day 7 after tumor implantation and drastically accelerated subcutaneous tumor growth as well as lung colonization in recombination activating gene-1-deficient mice. All these effects were abrogated upon MT4-MMP inactivation. In sharp contrast to most MMPs being primarily of stromal origin, we provide evidence that tumor-derived MT4-MMP, but not host-derived MT4-MMP contributes to angiogenesis. A genetic approach using MT4-MMP-deficient mice revealed that the status of MT4-MMP produced by host cells did not affect the angiogenic response. Despite of this tumor intrinsic feature, to exert its tumor promoting effect, MT4-MMP requires a permissive microenvironment. Indeed, tumor-derived MT4-MMP failed to circumvent the lack of an host angio-promoting factor such as plasminogen activator inhibitor-1. Overall, our study demonstrates the key contribution of MT4-MMP catalytic activity in the tumor compartment, at the interface with host cells. It identifies MT4-MMP as a key intrinsic tumor cell determinant that contributes to the elaboration of a permissive microenvironment for metastatic dissemination.

EGFR Activation and Signaling in Cancer Cells Are Enhanced by the Membrane-Bound Metalloprotease MT4-MMP

“…MDA-MB-231 cells overexpressing MT4-MMP or control cells were subcutaneously injected into RAG1 À/À mice as previously described (27,29). In accordance with our previous reports, MT4-MMP expression resulted in increased tumor growth as indicated by the higher volumes of MT4-MMPexpressing tumors (MT4 tumors) than those of control tumors (CTR tumors; Fig.…”

“…The implication of the GPI-anchored MT4-MMP in breast cancer progression is supported by clinical data (27,34,35) and experimental observations (27)(28)(29). Until now, MT4-MMP functions have been ascribed to its capacity to regulate tumor vascularization.…”

“…These data point to unprecedented noncatalytic function of MT4-MMP on cell proliferation. This differs from its angiogenic effect requiring its proteolytic activity (29). Indeed, we previously demonstrated that the inactive MT4-MMP E249A form failed to induce an early angiogenic switch, leading to tumor growth.…”

“…The failure of MT4-MMP to induce proliferation when cells are mixed in 3D collagen matrix might be ascribed to its inability to cleave type I collagen in contrast with MT1-MMP (26). Alternatively, these observations combined with the absence of a mitogenic effect of MT4-MMP in 2D cultures (27,29) suggest that MT4-MMP proliferating phenotype is dependent on matrix-induced cell aggregation, which could affect TK-mediated signal transduction. In addition, it is worth mentioning that 3D culture conditions can affect the homodimerization or heterodimerization of EGFR family member and downstream signaling pathway (46).…”

“…Although, most MMPs are produced by stromal cells, MT4-MMP (MMP17) is produced by tumor cells in human breast cancer samples (27). MT4-MMP emerged recently as a key intrinsic feature of breast cancer cells that stimulates tumor growth and metastasis into the lung (27)(28)(29). This impact on metastatic dissemination is related to changes in blood vasculature characterized by pericyte detachment, vessel enlargement, and destabilization (28).…”