The MMPs have long been recognized as potential targets for cancer therapy, but drugs developed to target these enzymes have been unsuccessful. A primary reason has been inadequate selectivity, since most MMP inhibitors cannot discriminate among MMPs that drive cancer progression and other MMPs that prevent cancer progression. We have recently developed a new approach, expertise, and methodology for engineering much more highly selective MMP inhibitors based on a human protein, tissue inhibitor of metalloproteinases-2 (TIMP2). In our recently published work, we have created an engineered variant of the TIMP2 N-terminal domain (N-TIMP2) with greatly improved selectivity toward MMP-9, an enzyme critically involved in triple- negative breast cancer (TNBC) progression and metastasis. In preliminary studies, we find that this prototype inhibitor shows enhanced activity for blocking TNBC cellular invasion. We propose to further engineer N- TIMP2 for increased selectivity toward MMP-9 and also for enhanced affinity toward ?3?1 integrin, a second natural target of TIMP2 through which TIMP2 mediates inhibition of tumor growth. We will define the structural basis for selective MMP binding of engineered N-TIMP2 variants to enable yet greater molecular improvements, and we will evaluate the therapeutic potential of these engineered proteins in multiple complementary preclinical models of TNBC.
In Aim 1, we will use a combination of structural insights, computational design and yeast surface display (YSD) technology to engineer N-TIMP2, further optimizing selectivity toward MMP-9 and enhancing beneficial integrin binding activity.
In Aim 2, we will elucidate structures of the engineered proteins with target and anti-target MMPs using X-ray crystallography, to uncover the structural basis for engineered selectivity and to facilitate yet greater refinements of our engineering platform and our selective MMP-9 inhibitors.
In Aim 3, we will use complementary mouse orthotopic, transgenic, and patient-derived xenograft (PDX) models of TNBC to evaluate the utility of engineered N-TIMP2 variants as a therapeutic strategy in TNBC, and identify candidate biomarkers of response with potential for directing this therapeutic approach to patients who will most benefit from it. Our proposal is both conceptually and technically innovative in the combination of approaches toward generating novel protein therapeutics. The proposed research is highly significant because it has substantial potential to develop an entirely new approach for targeted treatment of TNBC by selectively inhibiting MMP-9, a well-validated target with key roles in tumor growth, invasion, metastasis, and angiogenesis.
?Triple negative? breast cancer (TNBC) is a subtype of breast cancer that spreads aggressively and often leads to metastasis and death; it is difficult to treat because it does not respond to current molecularly-targeted drugs. TIMP2 is a natural human protein with two anticancer activities: (1) it inhibits an enzyme involved in TNBC metastasis, and (2) it binds to a cell surface receptor to inhibit TNBC growth. We propose to develop a new cancer drug, based on TIMP2, with improved capability to inhibit both metastasis and tumor growth, providing a new therapy to improve survival for patients with TNBC.
