Novel MT1-MMP small-molecule inhibitors based on insights into hemopexin domain function in tumor growth

Area of Science:

• Oncology
• Biochemistry
• Drug Discovery

Background:

• Membrane type-1 matrix metalloproteinase (MT1-MMP) is a key target in malignancy due to its role in tumor growth.
• Existing matrix metalloproteinase (MMP) inhibitors lack selectivity, targeting multiple MMPs instead of MT1-MMP alone.
• The hemopexin domain (PEX) of MT1-MMP is structurally distinct and offers a potential target for selective inhibition.

Purpose of the Study:

• To investigate the role of the PEX domain in MT1-MMP-mediated tumor growth.
• To identify and validate novel small molecule inhibitors targeting the PEX domain of MT1-MMP.
• To provide a preclinical rationale for developing selective MT1-MMP inhibitors.

Main Methods:

• Comparison of protumorigenic activity between wild-type MT1-MMP and a PEX-deficient mutant (ΔPEX) in vivo.
• Virtual ligand screening using the X-ray crystal structure of the PEX domain against the NCI/NIH compound library.
• In vivo validation of a novel PEX inhibitor through intratumoral injections in a preclinical cancer model.

Main Results:

• MT1-MMP lacking the PEX domain (ΔPEX) failed to support tumor growth, resulting in fibrotic tumors with increased collagen.
• A novel small molecule inhibitor specifically targeting the PEX domain was identified and validated.
• Intratumoral administration of the PEX inhibitor repressed tumor growth and induced a fibrotic, ΔPEX-like tumor phenotype.

Conclusions:

• The PEX domain of MT1-MMP plays a critical role in promoting tumor growth.
• Selective inhibition of the PEX domain represents a promising therapeutic strategy for targeting MT1-MMP.
• These findings establish a preclinical proof of principle for developing novel, PEX-targeted MT1-MMP inhibitors.