Small-Molecule Anticancer Compounds Selectively Target the Hemopexin Domain of Matrix Metalloproteinase-9

Abstract

Lack of target specificity by existing matrix metalloproteinase (MMP) inhibitors has hindered anti-metastatic cancer drug discovery. Inhibitors that bind to non-catalytic sites of MMPs and disrupt protease signaling function have the potential to be more specific and selective. In this work, compounds that target the hemopexin (PEX) domain of MMP-9 were identified using an in silico docking approach and evaluated using biochemical and biological approaches. Two of the selected compounds interfere with MMP-9-mediated cancer cell migration and proliferation in cells expressing exogenous or endogenous MMP-9. Furthermore, these inhibitors do not modulate MMP-9 catalytic activity. The lead compound, N-[4-(difluoromethoxy)phenyl]-2-[(4-oxo-6-propyl-1H-pyrimidin-2-yl)sulfanyl]-acetamide, specifically binds to the PEX domain of MMP-9, but not other MMPs. This interaction between the compound and the PEX domain results in the abrogation of MMP-9 homodimerization and leads to blockage of a downstream signaling pathway required for MMP-9-mediated cell migration. In a tumor xenografic model, this pyrimidinone retarded MDA-MB-435 tumor growth and inhibited lung metastasis. Thus, we have demonstrated for the first time that a novel small molecule interacts specifically with the PEX domain of MMP-9 and inhibits tumor growth and metastasis by reducing cell migration and proliferation.

A 17-residue Sequence from the Matrix Metalloproteinase-9 (MMP-9) Hemopexin Domain Binds α4β1 Integrin and Inhibits MMP-9-induced Functions in Chronic Lymphocytic Leukemia B Cells

“…Targeting the PEX9 domain is becoming an important focus for drug development, and a recent study (17) has identified a small-molecule compound that binds to PEX9 and inhibits carcinoma cell migration, proliferation, and metastasis. Using an in silico docking approach, these authors mapped the binding site of this compound to the central cavity of PEX9, in fact in close proximity to the VPLDTHDVFQ sequence identified in our study.…”

“…Two synthetic peptides (SRPQGPFL and NQVDQVGY) mimicking sequences in blade 1 and blade 4 of PEX9, respectively, were shown to affect MMP-9-CD44 interaction, MMP-9 dimerization, and migration of fibrosarcoma and carcinoma cells (16). A recent in silico approach has identified two small-molecule compounds that bind to PEX9 and inhibit tumor growth and metastasis (17). The isolated murine PEX9 on the other hand was shown to inhibit MMP-9 activity and invasion of melanoma cells (18), adhesion and migration of colorectal cancer cells (19), and angiogenesis and tumor growth in a glioblastoma model (20).…”

Matrix metalloproteinases in head and neck cancer: current perspectives

“…In both in vitro and in vivo systems, designed small molecules and peptides exert their inhibitory effects by preventing dimerization, thereby reducing tumor size, MMP-induced migration, and angiogenesis. [158][159][160] Promising studies have shown that these selective compounds could bind on specific sites for each MMP inside their hemopexin domain and prevent dimer-induced functions of several MMPs, including MMP14 and -9. [158][159][160][161][162] A more sophisticated approach proposed a bifunctional fusion protein able to bind and inactivate both the catalytic and hemopexin domains of MMP2.…”

Identification of genes potentially involved in bone metastasis by genome-wide gene expression profile analysis of non-small cell lung cancer in mice

“…44). A latest report shows that small-molecule compounds that selectively target the hemopexin domain of MMP-9 can control tumor growth and inhibit lung metastasis in breast cancer xenograft model in mice (45). Moreover, VTN, an extracellular protein that interacts with many integrins, is also expressed highly in the liver, and was previously reported to be upregulated in primary hepatocellular carcinoma (46), or liver metastases from colorectal cancer (46,47) and neuroblastoma (48).…”