Selective inhibition of matrix metalloproteinase-14 blocks tumor growth, invasion, and angiogenesis

MMPs as potential molecular targets in epithelial-to-mesenchymal transition driven COPD progression

Chronic obstructive pulmonary disease (COPD) is the third leading cause of mortality globally and the risk of developing lung cancer is six times greater in individuals with COPD who smoke compared to those who do not smoke. Matrix metalloproteinases (MMPs) play a crucial role in the pathophysiology of respiratory diseases by promoting inflammation and tissue degradation. Furthermore, MMPs are involved in key processes like epithelial-to-mesenchymal transition (EMT), metastasis, and invasion in lung cancer. While EMT has traditionally been associated with the progression of lung cancer, recent research highlights its active involvement in individuals with COPD. Current evidence underscores its role in orchestrating airway remodeling, fostering airway fibrosis, and contributing to the potential for malignant transformation in the complex pathophysiology of COPD. The precise regulatory roles of diverse MMPs in steering EMT during COPD progression needs to be elucidated. Additionally, the less-understood aspect involves how these MMPs bi-directionally activate or regulate various EMT-associated signaling cascades during COPD progression. This review article explores recent advancements in understanding MMPs' role in EMT during COPD progression and various pharmacological approaches to target MMPs. It also delves into the limitations of current MMP inhibitors and explores novel, advanced strategies for inhibiting MMPs, potentially offering new avenues for treating respiratory diseases.

Restoration of TFPI2 by LSD1 inhibition suppresses tumor progression and potentiates antitumor immunity in breast cancer

Histone lysine-specific demethylase 1 (LSD1) is frequently overexpressed in triple negative breast cancer (TNBC), which is associated with worse clinical outcome in TNBC patients. However, the underlying mechanisms by which LSD1 promotes TNBC progression remain to be identified. We recently established a genetically engineered murine model by crossing mammary gland conditional LSD1 knockout mice with Brca1-deficient mice to explore the role of LSD1 in TNBC pathogenesis. Cre-mediated Brca1 loss led to higher incidence of tumor formation in mouse mammary glands, which was hindered by concurrent depletion of LSD1, indicating a critical role of LSD1 in promoting Brca1-deficient tumors. We also demonstrated that the silencing of a tumor suppressor gene, Tissue Factor Pathway Inhibitor 2 (TFPI2), is functionally associated with LSD1-mediated TNBC progression. Mouse Brca1-deficient tumors exhibited elevated LSD1 expression and decreased TFPI2 level compared to normal mammary tissues. Analysis of TCGA database revealed that TFPI2 expression is significantly lower in aggressive ER-negative or basal-like BC. Restoration of TFPI2 through LSD1 inhibition increased H3K4me2 enrichment at the TFPI2 promoter, suppressed tumor progression, and enhanced antitumor efficacy of chemotherapeutic agent. Induction of TFPI2 by LSD1 ablation downregulates activity of matrix metalloproteinases (MMPs) that in turn increases the level of cytotoxic T lymphocyte attracting chemokines in tumor environment, leading to enhanced tumor infiltration of CD8+ T cells. Moreover, induction of TFPI2 potentiates antitumor effect of LSD1 inhibitor and immune checkpoint blockade in poorly immunogenic TNBC. Together, our study identifies previously unrecognized roles of TFPI2 in LSD1-mediated TNBC progression, therapeutic response, and immunogenic effects.

Vesicle transport of matrix metalloproteinases

Multicellular organisms consist of cells and extracellular matrix (ECM). ECM creates a cellular microenvironment, and cells locally degrade the ECM according to their cellular activity. A major group of enzymes that modify ECM belongs to matrix metalloproteinases (MMPs) and play major roles in various pathophysiological events. ECM degradation by MMPs does not occur in all cellular surroundings but only where it is necessary, and cells achieve this by directionally secreting these proteolytic enzymes. Recent studies have indicated that such enzyme secretion is achieved by targeted vesicle transport along the microtubules, and several kinesin superfamily proteins (KIFs) have been identified as responsible motor proteins involved in the processes. This chapter discusses recent findings of the vesicle transport of MMPs and their roles.

Understanding the matrix: collagen modifications in tumors and their implications for immunotherapy

Tumors are highly complex and heterogenous ecosystems where malignant cells interact with healthy cells and the surrounding extracellular matrix (ECM). Solid tumors contain large ECM deposits that can constitute up to 60% of the tumor mass. This supports the survival and growth of cancerous cells and plays a critical role in the response to immune therapy. There is untapped potential in targeting the ECM and cell-ECM interactions to improve existing immune therapy and explore novel therapeutic strategies. The most abundant proteins in the ECM are the collagen family. There are 28 different collagen subtypes that can undergo several post-translational modifications (PTMs), which alter both their structure and functionality. Here, we review current knowledge on tumor collagen composition and the consequences of collagen PTMs affecting receptor binding, cell migration and tumor stiffness. Furthermore, we discuss how these alterations impact tumor immune responses and how collagen could be targeted to treat cancer.

Combined analysis of secreted proteins and glycosylation identifies prognostic features in cholangiocarcinoma

Secreted proteins are overexpressed in cholangiocarcinoma (CCA) and actively involved in promoting metastatic spread. Many of these proteins possess one or more sites of glycosylation and their various glycoforms have potential utility as prognostic or diagnostic biomarkers. To evaluate the effects of secretome glycosylation on patient outcome, we elucidated the glycosylation patterns of proteins secreted by parental and metastatic CCA cells using liquid chromatography-mass spectrometry. Our analysis showed that the secretome of CCA cells was dominated by fucosylated and fucosialylated glycoforms. Based on the glycan and protein profiles, we evaluated the combined prognostic significance of glycosyltransferases and secretory proteins. Significantly, genes encoding fucosyltransferases and sialyltransferases showed favorable prognostic effects when combined with secretory protein-coding gene expression, particularly thrombospondin-1. Combining these measures may provide improved risk assessment for CCA and be used to indicate stages of disease progression.

Systematic Evaluation of Protein-Small Molecule Hybrids on the Yeast Surface

Protein-small molecule hybrids are structures that have the potential to combine the inhibitory properties of small molecules and the specificities of binding proteins. However, achieving such synergies is a substantial engineering challenge with fundamental principles yet to be elucidated. Recent work has demonstrated the power of the yeast display-based discovery of hybrids using a combination of fibronectin-binding domains and thiol-mediated conjugations to introduce small-molecule warheads. Here, we systematically study the effects of expanding the chemical diversity of these hybrids on the yeast surface by investigating a combinatorial set of fibronectins, noncanonical amino acid (ncAA) substitutions, and small-molecule pharmacophores. Our results show that previously discovered thiol-fibronectin hybrids are generally tolerant of a range of ncAA substitutions and retain binding functions to carbonic anhydrases following click chemistry-mediated assembly of hybrids with diverse linker structures. Most surprisingly, we identified several cases where replacement of a potent acetazolamide warhead with a substantially weaker benzenesulfonamide warhead still resulted in the assembly of multiple functional hybrids. In addition to these unexpected findings, we expanded the throughput of our system by validating a 96-well plate-based format to produce yeast-displayed hybrid conjugates in parallel. These efficient explorations of hybrid chemical diversity demonstrate that there are abundant opportunities to expand the functions of protein-small molecule hybrids and elucidate principles that dictate their efficient discovery and design.

The extracellular matrix as hallmark of cancer and metastasis: From biomechanics to therapeutic targets

The extracellular matrix (ECM) is essential for cell support during homeostasis and plays a critical role in cancer. Although research often concentrates on the tumor's cellular aspect, attention is growing for the importance of the cancer-associated ECM. Biochemical and physical ECM signals affect tumor formation, invasion, metastasis, and therapy resistance. Examining the tumor microenvironment uncovers intricate ECM dysregulation and interactions with cancer and stromal cells. Anticancer therapies targeting ECM sensors and remodelers, including integrins and matrix metalloproteinases, and ECM-remodeling cells, have seen limited success. This review explores the ECM's role in cancer and discusses potential therapeutic strategies for cell-ECM interactions.

MT1-MMP as a Key Regulator of Metastasis

Membrane type1-matrix metalloproteinase (MT1-MMP) is a member of metalloproteinases that is tethered to the transmembrane. Its major function in cancer progression is to directly degrade the extracellular matrix components, which are mainly type I-III collagen or indirectly type IV collagen through the activation of MMP-2 with a cooperative function of the tissue inhibitor of metalloproteinase-2 (TIMP-2). MT1-MMP is expressed as an inactive form (zymogen) within the endoplasmic reticulum (ER) and receives truncation processing via furin for its activation. Upon the appropriate trafficking of MT1-MMP from the ER, the Golgi apparatus to the cell surface membrane, MT1-MMP exhibits proteolytic activities to the surrounding molecules such as extracellular matrix components and cell surface molecules. MT1-MMP also retains a non-proteolytic ability to activate hypoxia-inducible factor 1 alpha (HIF-1A) via factors inhibiting the HIF-1 (FIH-1)-Mint3-HIF-1 axis, resulting in the upregulation of glucose metabolism and oxygen-independent ATP production. Through various functions of MT1-MMP, cancer cells gain motility on migration/invasion, thus causing metastasis. Despite the long-time efforts spent on the development of MT1-MMP interventions, none have been accomplished yet due to the side effects caused by off-target effects. Recently, MT1-MMP-specific small molecule inhibitors or an antibody have been reported and these inhibitors could potentially be novel agents for cancer treatment.

Acquired resistance to anti-PD1 therapy in patients with NSCLC associates with immunosuppressive T cell phenotype

Immune checkpoint inhibitor treatment has the potential to prolong survival in non-small cell lung cancer (NSCLC), however, some of the patients develop resistance following initial response. Here, we analyze the immune phenotype of matching tumor samples from a cohort of NSCLC patients showing good initial response to immune checkpoint inhibitors, followed by acquired resistance at later time points. By using imaging mass cytometry and whole exome and RNA sequencing, we detect two patterns of resistance¨: One group of patients is characterized by reduced numbers of tumor-infiltrating CD8+ T cells and reduced expression of PD-L1 after development of resistance, whereas the other group shows high CD8+ T cell infiltration and high expression of PD-L1 in addition to markedly elevated expression of other immune-inhibitory molecules. In two cases, we detect downregulation of type I and II IFN pathways following progression to resistance, which could lead to an impaired anti-tumor immune response. This study thus captures the development of immune checkpoint inhibitor resistance as it progresses and deepens our mechanistic understanding of immunotherapy response in NSCLC.

Designed Loop Extension Followed by Combinatorial Screening Confers High Specificity to a Broad Matrix MetalloproteinaseInhibitor

Matrix metalloproteinases (MMPs) are key drivers of various diseases, including cancer. Development of probes and drugs capable of selectively inhibiting the individual members of the large MMP family remains a persistent challenge. The inhibitory N-terminal domain of tissue inhibitor of metalloproteinases-2 (N-TIMP2), a natural broad MMP inhibitor, can provide a scaffold for protein engineering to create more selective MMP inhibitors. Here, we pursued a unique approach harnessing both computational design and combinatorial screening to confer high binding specificity toward a target MMP in preference to an anti-target MMP. We designed a loop extension of N-TIMP2 to allow new interactions with the non-conserved MMP surface and generated an efficient focused library for yeast surface display, which was then screened for high binding to the target MMP-14 and low binding to anti-target MMP-3. Deep sequencing analysis identified the most promising variants, which were expressed, purified, and tested for selectivity of inhibition. Our best N-TIMP2 variant exhibited 29 pM binding affinity to MMP-14 and 2.4 µM affinity to MMP-3, revealing 7500-fold greater specificity than WT N-TIMP2. High-confidence structural models were obtained by including NGS data in the AlphaFold multiple sequence alignment. The modeling together with experimental mutagenesis validated our design predictions, demonstrating that the loop extension packs tightly against non-conserved residues on MMP-14 and clashes with MMP-3. This study demonstrates how introduction of loop extensions in a manner guided by target protein conservation data and loop design can offer an attractive strategy to achieve specificity in design of protein ligands.

Substrate derived sequences act as subsite-blocking motifs in protease inhibitory antibodies

Proteases are involved in many physiologic processes, and dysregulated proteolysis is basis of a variety of diseases. Specific inhibition of pathogenetic proteases via monoclonal antibodies therefore holds significant therapeutic promise. Inspired by the competitive mechanism utilized by many naturally occurring and man-made protease inhibitors, we hypothesized that substrate-like peptide sequences can act as protease subsite blocking motifs if they occupy only one side of the reaction center. To test this hypothesis, a degenerate codon library representing MMP-14 substrate profiles at P1-P5' positions was constructed in the context of an anti-MMP-14 Fab by replacing its inhibitory motif in CDR-H3 with MMP-14 substrate repertoires. After selection for MMP-14 active-site binders by phage panning, results indicated that diverse substrate-like sequences conferring antibodies inhibitory potencies were enriched in the isolated clones. Optimal residues at each of P1-P5' positions were then identified, and the corresponding mutation combinations showed improved characteristics as effective inhibitors of MMP-14. Insights on efficient library designs for inhibitory peptide motifs were further discussed. Overall, this study proved the concept that substrate-derived sequences were able to behave as the inhibitory motifs in protease-specific antibodies. With accumulating data available on protease substrate profiles, we expect the approach described here can be broadly applied to facilitate the generation of antibody inhibitors targeting biomedically important proteases.

Identification of small molecule inhibitors against MMP-14 via High-Throughput screening

Matrix metalloproteinases (MMPs) are involved in various cellular events in physiology and pathophysiology through endopeptidases activity. The expression levels and activities of most MMPs remain minimal in the normal conditions, whereas some MMPs are significantly activated in pathological conditions such as cancer and neovascularization. Hence, MMPs are considered as both diagnostic markers and potential targets for therapeutic agents. Twenty-three known human MMPs share a similar active site structure with a zinc-binding motif, resulting in lack of specificity. Therefore, the enhancement of target specificity is a primary goal for the development of specific MMP inhibitors. MMP-14 regulates VEGFA/VEGFR2-system through cleavage of the non-functional VEGFR1 in vascular angiogenesis. In this study, we developed a fluorescence-based enzymatic assay using a specific MMP-14 substrate generated from VEGFR1 cleavage site. This well optimized assay was used as a primary screen method to identify MMP-14 specific inhibitors from 1,200 Prestwick FDA-approved drug library. Of ten initial hits, two compounds showed IC50 values below 30 µM, which were further validated by direct binding analysis using surface plasmon resonance (SPR). Clioquinol and chloroxine, both of which contain a quinoline structure, were identified as MMP-14 inhibitors. Five analogs were tested, four of which were found to be completely devoid of inhibitory activity. Clioquinol exhibited selectivity towards MMP-14, as it showed no inhibitory activity towards four other MMPs.

Interplay of adherens junctions and matrix proteolysis determines the invasive pattern and growth of squamous cell carcinoma

Cancers, such as squamous cell carcinoma, frequently invade as multicellular units. However, these invading units can be organised in a variety of ways, ranging from thin discontinuous strands to thick 'pushing' collectives. Here we employ an integrated experimental and computational approach to identify the factors that determine the mode of collective cancer cell invasion. We find that matrix proteolysis is linked to the formation of wide strands but has little effect on the maximum extent of invasion. Cell-cell junctions also favour wide strands, but our analysis also reveals a requirement for cell-cell junctions for efficient invasion in response to uniform directional cues. Unexpectedly, the ability to generate wide invasive strands is coupled to the ability to grow effectively when surrounded by extracellular matrix in three-dimensional assays. Combinatorial perturbation of both matrix proteolysis and cell-cell adhesion demonstrates that the most aggressive cancer behaviour, both in terms of invasion and growth, is achieved at high levels of cell-cell adhesion and high levels of proteolysis. Contrary to expectation, cells with canonical mesenchymal traits - no cell-cell junctions and high proteolysis - exhibit reduced growth and lymph node metastasis. Thus, we conclude that the ability of squamous cell carcinoma cells to invade effectively is also linked to their ability to generate space for proliferation in confined contexts. These data provide an explanation for the apparent advantage of retaining cell-cell junctions in squamous cell carcinomas.

An MMP-9 exclusive neutralizing antibody attenuates blood-brain barrier breakdown in mice with stroke and reduces stroke patient-derived MMP-9 activity

Rapid upregulation of matrix metalloproteinase 9 (MMP-9) leads to blood-brain barrier (BBB) breakdown following stroke, but no MMP-9 inhibitors have been approved in clinic largely due to their low specificities and side effects. Here, we explored the therapeutic potential of a human IgG monoclonal antibody (mAb), L13, which was recently developed with exclusive neutralizing specificity to MMP-9, nanomolar potency, and biological function, using mouse stroke models and stroke patient samples. We found that L13 treatment at the onset of reperfusion following cerebral ischemia or after intracranial hemorrhage (ICH) significantly reduced brain tissue injury and improved the neurological outcomes of mice. Compared to control IgG, L13 substantially attenuated BBB breakdown in both types of stroke model by inhibiting MMP-9 activity-mediated degradations of basement membrane and endothelial tight junction proteins. Importantly, these BBB-protective and neuroprotective effects of L13 in wild-type mice were comparable to Mmp9 genetic deletion and fully abolished in Mmp9 knockout mice, highlighting the in vivo target specificity of L13. Meanwhile, ex vivo co-incubation with L13 significantly neutralized the enzymatic activities of human MMP-9 in the sera of ischemic and hemorrhagic stroke patients, or in the peri-hematoma brain tissues from hemorrhagic stroke patients. Overall, we demonstrated that MMP-9 exclusive neutralizing mAbs constitute a potential feasible therapeutic approach for both ischemic and hemorrhagic stroke.

Matrix metalloproteinases as therapeutic targets in breast cancer

Matrix metalloproteinases (MMPs) are the most prominent proteinases involved in tumorigenesis. They were initially recognized to promote tumor progression by remodeling the extracellular matrix through their proteolytic activity. However, accumulating evidence has revealed that some MMPs have protective roles in cancer progression, and the same MMP can exert opposing roles depending on the cell type in which it is expressed or the stage of cancer. Moreover, studies have shown that MMPs are involved in cancer progression through their roles in other biological processes such as cell signaling and immune regulation, independent of their catalytic activity. Despite the prognostic significance of tumoral or stromal expression of MMPs in breast cancer, their roles and molecular mechanisms in breast cancer progression remain unclear. As the failures of early clinical trials with broad-spectrum MMP inhibitors were mainly due to a lack of drug specificity, substantial efforts have been made to develop highly selective MMP inhibitors. Some recently developed MMP inhibitory monoclonal antibodies demonstrated promising anti-tumor effects in preclinical models of breast cancer. Importantly, anti-tumor effects of these antibodies were associated with the modulation of tumor immune microenvironment, suggesting that the use of MMP inhibitors in combination with immunotherapy can improve the efficacy of immunotherapy in HER2-positive or triple-negative breast cancer. In this review, the current understanding of the roles of tumoral or stromal MMPs in breast cancer is summarized, and recent advances in the development of highly selective MMP inhibitors are discussed.

Development of anti-membrane type 1-matrix metalloproteinase nanobodies as immunoPET probes for triple negative breast cancer imaging

Triple-negative breast cancer (TNBC) is characterized by aggressiveness and high rates of metastasis. The identification of relevant biomarkers is crucial to improve outcomes for TNBC patients. Membrane type 1-matrix metalloproteinase (MT1-MMP) could be a good candidate because its expression has been reported to correlate with tumor malignancy, progression and metastasis. Moreover, single-domain variable regions (VHHs or Nanobodies) derived from camelid heavy-chain-only antibodies have demonstrated improvements in tissue penetration and blood clearance, important characteristics for cancer imaging. Here, we have developed a nanobody-based PET imaging strategy for TNBC detection that targets MT1-MMP. A llama-derived library was screened against the catalytic domain of MT1-MMP and a panel of specific nanobodies were identified. After a deep characterization, two nanobodies were selected to be labeled with gallium-68 (⁶⁸Ga). ImmunoPET imaging with both ([⁶⁸Ga]Ga-NOTA-3TPA14 and [⁶⁸Ga]Ga-NOTA-3CMP75) in a TNBC mouse model showed precise tumor-targeting capacity in vivo with high signal-to-background ratios. (⁶⁸Ga)Ga-NOTA-3CMP75 exhibited higher tumor uptake compared to (⁶⁸Ga)Ga-NOTA-3TPA14. Furthermore, imaging data correlated perfectly with the immunohistochemistry staining results. In conclusion, we found a promising candidate for nanobody-based PET imaging to be further investigated as a diagnostic tool in TNBC.

Divergent regulation of basement membrane trafficking by human macrophages and cancer cells

Macrophages and cancer cells populations are posited to navigate basement membrane barriers by either mobilizing proteolytic enzymes or deploying mechanical forces. Nevertheless, the relative roles, or identity, of the proteinase -dependent or -independent mechanisms used by macrophages versus cancer cells to transmigrate basement membrane barriers harboring physiologically-relevant covalent crosslinks remains ill-defined. Herein, both macrophages and cancer cells are shown to mobilize membrane-anchored matrix metalloproteinases to proteolytically remodel native basement membranes isolated from murine tissues while infiltrating the underlying interstitial matrix ex vivo. In the absence of proteolytic activity, however, only macrophages deploy actomyosin-generated forces to transmigrate basement membrane pores, thereby providing the cells with proteinase-independent access to the interstitial matrix while simultaneously exerting global effects on the macrophage transcriptome. By contrast, cancer cell invasive activity is reliant on metalloproteinase activity and neither mechanical force nor changes in nuclear rigidity rescue basement membrane transmigration. These studies identify membrane-anchored matrix metalloproteinases as key proteolytic effectors of basement membrane remodeling by macrophages and cancer cells while also defining the divergent invasive strategies used by normal and neoplastic cells to traverse native tissue barriers.

Matrix Metalloproteinases: From Molecular Mechanisms to Physiology, Pathophysiology, and Pharmacology

The first matrix metalloproteinase (MMP) was discovered in 1962 from the tail of a tadpole by its ability to degrade collagen. As their name suggests, matrix metalloproteinases are proteases capable of remodeling the extracellular matrix. More recently, MMPs have been demonstrated to play numerous additional biologic roles in cell signaling, immune regulation, and transcriptional control, all of which are unrelated to the degradation of the extracellular matrix. In this review, we will present milestones and major discoveries of MMP research, including various clinical trials for the use of MMP inhibitors. We will discuss the reasons behind the failures of most MMP inhibitors for the treatment of cancer and inflammatory diseases. There are still misconceptions about the pathophysiological roles of MMPs and the best strategies to inhibit their detrimental functions. This review aims to discuss MMPs in preclinical models and human pathologies. We will discuss new biochemical tools to track their proteolytic activity in vivo and ex vivo, in addition to future pharmacological alternatives to inhibit their detrimental functions in diseases. SIGNIFICANCE STATEMENT: Matrix metalloproteinases (MMPs) have been implicated in most inflammatory, autoimmune, cancers, and pathogen-mediated diseases. Initially overlooked, MMP contributions can be both beneficial and detrimental in disease progression and resolution. Thousands of MMP substrates have been suggested, and a few hundred have been validated. After more than 60 years of MMP research, there remain intriguing enigmas to solve regarding their biological functions in diseases.

First-in-Class Star-Shaped Triazine Dendrimers Endowed with MMP-9 Inhibition and VEGF Suppression Capacity: Design, Synthesis, and Anticancer Evaluation

Off-target side effects are major challenges hindering the clinical success of matrix metalloproteinase (MMP) inhibitors. Various targeting strategies revitalized MMP research to eliminate this drawback. Herein, we developed s-triazine-based dendrimeric architecture not only amenable to tumor targeting but also decorated with pharmacophoric entities to endow MMP-9 inhibition for halting cancer progression. The design rationale utilized hydrazide branching chains as well as carboxylic and hydroxamic acid termini as Zn-binding groups to confer substantial MMP inhibitory potential. The carboxylic acids are tetherable to tumor targeting ligands and other cargo payloads as synergistic drugs via biodegradable linkages. The synthesized series were screened for cytotoxicity against normal fibroblasts (Wi-38) and two selected cancers (MDA-MB 231 and Caco-2) via MTT assay. The most active hexacarboxylic acid dendrimer 8a was more potent and safer than Dox against MDA-MB 231 and Caco-2 cells. It intrinsically inhibited MMP-9 with selectivity over MMP-2. Docking simulations demonstrated that the extended carboxylic acid termini of 8a could possibly chelate the active site Zn of MMP-9 and form hydrogen-bonding interactions with the ligand essential backbone Tyr423. In addition, it suppressed the correlated oncogenic mediators VEGF and cyclin D, upregulated p21 expression, induced apoptosis (>75%), and inhibited the tumor cell migration (∼84%) in the treated cancer cells. Thus, up to our knowledge, it is the first triazine-based MMP-9 inhibitor dendrimer endowed with VEGF suppression potential that can be employed as a bioactive carrier.

Exploiting protease activation for therapy

Proteases have crucial roles in homeostasis and disease; and protease inhibitors and recombinant proteases in enzyme replacement therapy have become key therapeutic applications of protease biology across several indications. This review briefly summarises therapeutic approaches based on protease activation and focuses on how recent insights into the spatial and temporal control of the proteolytic activation of growth factors and interleukins are leading to unique strategies for the discovery of new medicines. In particular, two emerging areas are covered: the first is based on antibody therapies that target the process of proteolytic activation of the pro-form of proteins rather than their mature form; the second covers a potentially new class of biopharmaceuticals using engineered, proteolytically activable and initially inactive pro-forms of antibodies or effector proteins to increase specificity and improve the therapeutic window.

Inverse Molecular Docking Elucidating the Anticarcinogenic Potential of the Hop Natural Product Xanthohumol and Its Metabolites

Natural products from plants exert a promising potential to act as antioxidants, antimicrobials, anti-inflammatory, and anticarcinogenic agents. Xanthohumol, a natural compound from hops, is indeed known for its anticarcinogenic properties. Xanthohumol is converted into three metabolites: isoxanthohumol (non-enzymatically) as well as 8- and 6-prenylnaringenin (enzymatically). An inverse molecular docking approach was applied to xanthohumol and its three metabolites to discern their potential protein targets. The aim of our study was to disclose the potential protein targets of xanthohumol and its metabolites in order to expound on the potential anticarcinogenic mechanisms of xanthohumol based on the found target proteins. The investigated compounds were docked into the predicted binding sites of all human protein structures from the Protein Data Bank, and the best docking poses were examined. Top scoring human protein targets with successfully docked compounds were identified, and their experimental connection with the anticarcinogenic function or cancer was investigated. The obtained results were carefully checked against the existing experimental findings from the scientific literature as well as further validated using retrospective metrics. More than half of the human protein targets of xanthohumol with the highest docking scores have already been connected with the anticarcinogenic function, and four of them (including two important representatives of the matrix metalloproteinase family, MMP-2 and MMP-9) also have a known experimental correlation with xanthohumol. Another important protein target is acyl-protein thioesterase 2, to which xanthohumol, isoxanthohumol, and 6-prenylnaringenin were successfully docked with the lowest docking scores. Moreover, the results for the metabolites show that their most promising protein targets are connected with the anticarcinogenic function as well. We firmly believe that our study can help to elucidate the anticarcinogenic mechanisms of xanthohumol and its metabolites as after consumption, all four compounds can be simultaneously present in the organism.

The Role of Extracellular Matrix Remodeling in Skin Tumor Progression and Therapeutic Resistance

The extracellular matrix remodeling in the skin results from a delicate balance of synthesis and degradation of matrix components, ensuring tissue homeostasis. These processes are altered during tumor invasion and growth, generating a microenvironment that supports growth, invasion, and metastasis. Apart from the cellular component, the tumor microenvironment is rich in extracellular matrix components and bound factors that provide structure and signals to the tumor and stromal cells. The continuous remodeling in the tissue compartment sustains the developing tumor during the various phases providing matrices and proteolytic enzymes. These are produced by cancer cells and stromal fibroblasts. In addition to fostering tumor growth, the expression of specific extracellular matrix proteins and proteinases supports tumor invasion after the initial therapeutic response. Lately, the expression and structural modification of matrices were also associated with therapeutic resistance. This review will focus on the significant alterations in the extracellular matrix components and the function of metalloproteinases that influence skin cancer progression and support the acquisition of therapeutic resistance.

Bioorthogonal PEGylation Prolongs the Elimination Half-Life of N-TIMP2 While Retaining MMP Inhibition

Tissue inhibitors of metalloproteinases (TIMPs) are natural inhibitors of the matrix metalloproteinase (MMP) family of proteins, whose members are key regulators of the proteolysis of extracellular matrix components and hence of multiple biological processes. In particular, imbalanced activity of matrix metalloproteinase-14 (MMP-14) may lead to the development of cancer and cardiovascular and other diseases. This study aimed to engineer TIMP2, one of the four homologous TIMPs, as a potential therapeutic by virtue of its ability to bind to the active-site Zn²⁺ of MMP-14. However, the susceptibility to degradation of TIMP2 and its small size, which results in a short circulation half-life, limit its use as a therapeutic. PEGylation was thus used to improve the pharmacokinetic profile of TIMP2. PEGylation of the MMP-targeting N-terminal domain of TIMP2 (N-TIMP2), via either cysteine or lysine residues, resulted in a significant decrease in N-TIMP2 affinity toward MMP-14 or multisite conjugation and conjugate heterogeneity, respectively. Our strategy designed to address this problem was based on incorporating a noncanonical amino acid (NCAA) into N-TIMP2 to enable site-specific mono-PEGylation. The first step was to incorporate the NCAA propargyl lysine (PrK) at position S31 in N-TIMP2, which does not interfere with the N-TIMP2-MMP-14 binding interface. Thereafter, site-specific PEGylation was achieved via a click chemistry reaction between N-TIMP2-S31PrK and PEG-azide-20K. Inhibition studies showed that PEGylated N-TIMP2-S31PrK did indeed retain its inhibitory activity toward MMP-14. The modified protein also showed improved serum stability vs non-PEGylated N-TIMP2. In vivo pharmacokinetic studies in mice revealed a significant 8-fold increase in the elimination half-life of PEGylated N-TIMP2 vs the non-PEGylated protein. This study shows that site-specific bioorthogonal mono-PEGylation extends the half-life of N-TIMP2 without impairing its biological activity, thereby highlighting the advantage of this strategy for generating potent PEGylated proteins.

Destruction of tumor vasculature by vascular disrupting agents in overcoming the limitation of EPR effect

Nanomedicine greatly improves the efficiency in the delivery of antitumor drugs into the tumor, but insufficient tumoral penetration impairs the therapeutic efficacy of most nanomedicines. Vascular disrupting agent (VDA) nanomedicines are distributed around the tumor vessels due to the low tissue penetration in solid tumors, and the released drugs can selectively destroy immature tumor vessels and block the supply of oxygen and nutrients, leading to the internal necrosis of the tumors. VDAs can also improve the vascular permeability of the tumor, further increasing the extravasation of VDA nanomedicines in the tumor site, markedly reducing the dependence of nanomedicines on the enhanced permeability and retention effect (EPR effect). This review highlights the progress of VDA nanomedicines in recent years and their application in cancer therapy. First, the mechanisms of different VDAs are introduced. Subsequently, different strategies of delivering VDAs are described. Finally, multiple combination strategies with VDA nanomedicines in cancer therapy are described in detail.

Matrix Metalloproteinases in Helicobacter pylori-Associated Gastritis and Gastric Cancer

Gastric cancer is one of the leading causes of the cancer-related mortality worldwide. The etiology of this disease is complex and involves genetic predisposition and environmental factors, including Helicobacter pylori. Infection of the stomach with H. pylori leads to gastritis and gastric atrophy, which can progress stepwise to gastric cancer. Matrix metalloproteinases (MMPs) actively participate in the pathology development. The further progression of gastric cancer seems to be less dependent on bacteria but of intra-tumor cell dynamics. Bioinformatics data confirmed an important role of the extracellular matrix constituents and specific MMPs in stomach carcinoma invasion and metastasis, and revised their potential as predictors of the disease outcome. In this review, we describe, in detail, the impact of MMPs in H. pylori-associated gastritis and gastric cancer.

Coordination of two kinesin superfamily motor proteins, KIF3A and KIF13A, is essential for pericellular matrix degradation by membrane-type 1 matrix metalloproteinase (MT1-MMP) in cancer cells

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MT1-MMP promotes cancer invasion by degrading barrier ECM at the leading edge, and its localization is carried out by direct vesicle transport of MT1-MMP containing vesicles along the microtubule.

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We identified KIF3A, KIF13A, and KIF9 as kinesins involved in MT1-MMP-containing vesicle trafficking in HT1080 cells.

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KIF3A and KIF13A transport MT1-MMP-containing vesicles from the trans-Golgi to the endosomes. KIF13A alone then transports the vesicles from endosomes to the plasma membrane for extracellular matrix degradation.

MT1-MMP plays a crucial role in promoting the cellular invasion of cancer cells by degrading the extracellular matrix to create a path for migration. During this process, its localization at the leading edge of migrating cells is critical, and it is achieved by targeted transport of MT1-MMP-containing vesicles along microtubules by kinesin superfamily motor proteins (KIFs). Here we identified three KIFs involved in MT1-MMP vesicle transport: KIF3A, KIF13A, and KIF9. Knockdown of KIF3A and KIF13A effectively inhibited MT1-MMP-dependent collagen degradation and invasion, while knockdown of KIF9 increased collagen degradation and invasion. Our data suggest that KIF3A/KIF13A dependent MT1-MMP vesicles transport takes over upon KIF9 knockdown. Live-cell imaging analyses have indicated that KIF3A and KIF13A coordinate to transport the same MT1-MMP-containing vesicles from the trans-Golgi to the endosomes, and KIF13A alone transports the vesicle from the endosome to the plasma membrane. Taken together, we have identified a unique interplay between three KIFs to regulate leading edge localization of MT1-MMP and MT1-MMP-dependent cancer cell invasion.

Insights into the Role of Matrix Metalloproteinases in Precancerous Conditions and in Colorectal Cancer

Simple Summary

Colorectal cancer (CRC) is one of the most common cancer worldwide. CRC is derived from polyps and many factors, such as Matrix Metalloproteinases (MMPs) can gain the progression of colorectal carcinogenesis. Many investigations have indicated the role of MMPs in CRC development while there is not enough knowledge about the function of MMPs in precancerous conditions. This review summarizes the current information about the role of MMPs in polyps and CRC progression.

Abstract

Colorectal cancer (CRC) is the third and second cancer for incidence and mortality worldwide, respectively, and is becoming prevalent in developing countries. Most CRCs derive from polyps, especially adenomatous polyps, which can gradually transform into CRC. The family of Matrix Metalloproteinases (MMPs) plays a critical role in the initiation and progression of CRC. Prominent MMPs, including MMP-1, MMP-2, MMP-7, MMP-8, MMP-9, MMP-12, MMP-13, MMP-14, and MMP-21, have been detected in CRC patients, and the expression of most of them correlates with a poor prognosis. Moreover, many studies have explored the inhibition of MMPs and targeted therapy for CRC, but there is not enough information about the role of MMPs in polyp malignancy. In this review, we discuss the role of MMPs in colorectal cancer and its pathogenesis

Antitumoral and Anti-inflammatory Roles of Somatostatin and Its Analogs in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and affects about 8% of cirrhotic patients, with a recurrence rate of over 50%. There are numerous therapies available for the treatment of HCC, depending on cancer staging and condition of the patient. The complexity of the treatment is also justified by the unique pathogenesis of HCC that involves intricate processes such as chronic inflammation, fibrosis, and multiple molecular carcinogenesis events. During the last three decades, multiple in vivo and in vitro experiments have used somatostatin and its analogs (SSAs) to reduce the proliferative and metastatic potential of hepatoma cells by inducing their apoptosis and reducing angiogenesis and the inflammatory component of HCC. Most experiments have proven successful, revealing several different pathways and mechanisms corresponding to the aforementioned functions. Moreover, a correlation between specific effects and expression of somatostatin receptors (SSTRs) was observed in the studied cells. Clinical trials have tested either somatostatin or an analog, alone or in combination with other drugs, to explore the potential effects on HCC patients, in various stages of the disease. While the majority of these clinical trials exhibited minor to moderate success, some other studies were inconclusive or even reported negative outcomes. A complete evaluation of the efficacy of somatostatin and SSAs is still the matter of intense debate, and, if deemed useful, these substances may play a beneficial role in the management of HCC patients.

Single-cell imaging of T cell immunotherapy responses in vivo

T cell immunotherapies have revolutionized treatment for a subset of cancers. Yet, a major hurdle has been the lack of facile and predicative preclinical animal models that permit dynamic visualization of T cell immune responses at single-cell resolution in vivo. Here, optically clear immunocompromised zebrafish were engrafted with fluorescent-labeled human cancers along with chimeric antigen receptor T (CAR T) cells, bispecific T cell engagers (BiTEs), and antibody peptide epitope conjugates (APECs), allowing real-time single-cell visualization of T cell-based immunotherapies in vivo. This work uncovered important differences in the kinetics of T cell infiltration, tumor cell engagement, and killing between these immunotherapies and established early endpoint analysis to predict therapy responses. We also established EGFR-targeted immunotherapies as a powerful approach to kill rhabdomyosarcoma muscle cancers, providing strong preclinical rationale for assessing a wider array of T cell immunotherapies in this disease.

Engineered s-Triazine-Based Dendrimer-Honokiol Conjugates as Targeted MMP-2/9 Inhibitors for Halting Hepatocellular Carcinoma

Despite the advances in developing MMP-2/9 inhibitors, off-target side effects and pharmacokinetics problems remain major challenges hindering their clinical success in cancer therapy. However, recent targeting strategies have clearly revitalized MMP research. Herein, we introduce new s-triazine-based dendrimers endowed with intrinsic MMP-2/9 inhibitory potential and tetherable to hepatocellular carcinoma-specific targeting ligands and anticancer agents via biodegradable linkages for targeted therapy. The designed dendrimeric platform was built with potential zinc-binding branching linkers (hydrazides) and termini (carboxylic acids and hydrazides) to confer potency against MMP-2/9. Preliminary cytotoxicity screening and MMP-2/9 inhibition assay of the free dendrimers revealed promising potency (MMP-9; IC₅₀ =0.35-0.57 μM, MMP-2; IC₅₀ =0.39-0.77 μM) within their safe doses (EC₁₀₀ =94.15-42.75 μM). The hydrazide dendrimer was comparable to NNGH and superior to the carboxylic acid analogue. MTT assay showed that the free dendrimers were superior to the reference anticancer agent honokiol. Their anticancer potency was enhanced by HK conjugation, targeting ligands installation and PEGylation as exemplified by the hydrazide dendrimer conjugate (TPG₃ -NH₂ )-SuHK-FA-SuPEG (Huh-7; IC₅₀ =5.54 μM, HepG-2; IC₅₀ =10.07 μM) being 4 folds more active than HK, followed by the carboxylic acid conjugate (TPG₃ -OH)-HK-LA-PEG (Huh-7; IC₅₀ =14.97, HepG-2; IC₅₀ =21.29 μM). This was consistent with apoptosis studies.

Matrix metalloproteinase contribution in management of cancer proliferation, metastasis and drug targeting

Matrix metalloproteinases (MMPs) or matrixins, are members of a zinc-dependent endopeptidase family. They cause remodeling of the extracellular matrix (ECM) leading to numerous diseases. MMPs subfamilies possess: collagenases, gelatinases, stromelysins and membrane-type MMPs (MT-MMP). They consist of several domains; pro-peptide, catalytic, linker peptide and the hemopexin (Hpx) domains. MMPs are involved in initiation, proliferation and metastasis of cancer through the breakdown of ECM physical barriers. Overexpression of MMPs is associated with poor prognosis of cancer. This review will discuss both types of MMPs and current inhibitors, which target them in different aspects, including, biosynthesis, activation, secretion and catalytic activity. Several synthetic and natural inhibitors of MMPs (MMPIs) that can bind the catalytic domain of MMPs have been designed including; peptidomimetic, non-peptidomimetic, tetracycline derivatives, off-target MMPI, natural products, microRNAs and monoclonal antibodies.

Extracellular Matrices and Cancer-Associated Fibroblasts: Targets for Cancer Diagnosis and Therapy?

Solid cancer progression is dictated by neoplastic cell features and pro-tumoral crosstalks with their microenvironment. Stroma modifications, such as fibroblast activation into cancer-associated fibroblasts (CAFs) and extracellular matrix (ECM) remodeling, are now recognized as critical events for cancer progression and as potential therapeutic or diagnostic targets. The recent appreciation of the key, complex and multiple roles of the ECM in cancer and of the CAF diversity, has revolutionized the field and raised innovative but challenging questions. Here, we rapidly present CAF heterogeneity in link with their specific ECM remodeling features observed in cancer, before developing each of the impacts of such ECM modifications on tumor progression (survival, angiogenesis, pre-metastatic niche, chemoresistance, etc.), and on patient prognosis. Finally, based on preclinical studies and recent results obtained from clinical trials, we highlight key mechanisms or proteins that are, or may be, used as potential therapeutic or diagnostic targets, and we report and discuss benefits, disappointments, or even failures, of recently reported stroma-targeting strategies.

Osteoclast-mediated bone resorption is controlled by a compensatory network of secreted and membrane-tethered metalloproteinases

Osteoclasts actively remodel both the mineral and proteinaceous components of bone during normal growth and development as well as pathologic states ranging from osteoporosis to bone metastasis. The cysteine proteinase cathepsin K confers osteoclasts with potent type I collagenolytic activity; however, cathepsin K-null mice, as well as cathepsin K-mutant humans, continue to remodel bone and degrade collagen by as-yet-undefined effectors. Here, we identify a cathepsin K-independent collagenolytic system in osteoclasts that is composed of a functionally redundant network of the secreted matrix metalloproteinase MMP9 and the membrane-anchored matrix metalloproteinase MMP14. Unexpectedly, whereas deleting either of the proteinases individually leaves bone resorption intact, dual targeting of Mmp9 and Mmp14 inhibited the resorptive activity of mouse osteoclasts in vitro and in vivo and human osteoclasts in vitro. In vivo, Mmp9/Mmp14 conditional double-knockout mice exhibited marked increases in bone density and displayed a highly protected status against either parathyroid hormone- or ovariectomy-induced pathologic bone loss. Together, these studies characterize a collagenolytic system operative in mouse and human osteoclasts and identify the MMP9/MMP14 axis as a potential target for therapeutic interventions for bone-wasting disease states.

Combined Radiochemotherapy: Metalloproteinases Revisited

Besides cytotoxic DNA damage irradiation of tumor cells triggers multiple intra- and intercellular signaling processes, that are part of a multilayered, treatment-induced stress response at the unicellular and tumor pathophysiological level. These processes are intertwined with intrinsic and acquired resistance mechanisms to the toxic effects of ionizing radiation and thereby co-determine the tumor response to radiotherapy. Proteolysis of structural elements and bioactive signaling moieties represents a major class of posttranslational modifications regulating intra- and intercellular communication. Plasma membrane-located and secreted metalloproteinases comprise a family of metal-, usually zinc-, dependent endopeptidases and sheddases with a broad variety of substrates including components of the extracellular matrix, cyto- and chemokines, growth and pro-angiogenic factors. Thereby, metalloproteinases play an important role in matrix remodeling and auto- and paracrine intercellular communication regulating tumor growth, angiogenesis, immune cell infiltration, tumor cell dissemination, and subsequently the response to cancer treatment. While metalloproteinases have long been identified as promising target structures for anti-cancer agents, previous pharmaceutical approaches mostly failed due to unwanted side effects related to the structural similarities among the multiple family members. Nevertheless, targeting of metalloproteinases still represents an interesting rationale alone and in combination with other treatment modalities. Here, we will give an overview on the role of metalloproteinases in the irradiated tumor microenvironment and discuss the therapeutic potential of using more specific metalloproteinase inhibitors in combination with radiotherapy.

Extracellular Matrix: Emerging Roles and Potential Therapeutic Targets for Breast Cancer

Increasing evidence shows that the extracellular matrix (ECM) is an important regulator of breast cancer (BC). The ECM comprises of highly variable and dynamic components. Compared with normal breast tissue under homeostasis, the ECM undergoes many changes in composition and organization during BC progression. Induced ECM proteins, including fibrinogen, fibronectin, hyaluronic acid, and matricellular proteins, have been identified as important components of BC metastatic cells in recent years. These proteins play major roles in BC progression, invasion, and metastasis. Importantly, several specific ECM molecules, receptors, and remodeling enzymes are involved in promoting resistance to therapeutic intervention. Additional analysis of these ECM proteins and their downstream signaling pathways may reveal promising therapeutic targets against BC. These potential drug targets may be combined with new nanoparticle technologies. This review summarizes recent advances in functional nanoparticles that target the ECM to treat BC. Accurate nanomaterials may offer a new approach to BC treatment.

Metalloproteinases in Ovarian Cancer

Proteases play a crucial role in the progression and metastasis of ovarian cancer. Pericellular protein degradation and fragmentation along with remodeling of the extracellular matrix (ECM) is accomplished by numerous proteases that are present in the ovarian tumor microenvironment. Several proteolytic processes have been linked to cancer progression, particularly those facilitated by the matrix metalloproteinase (MMP) family. These proteases have been linked to enhanced migratory ability, extracellular matrix breakdown, and development of support systems for tumors. Several studies have reported the direct involvement of MMPs with ovarian cancer, as well as their mechanisms of action in the tumor microenvironment. MMPs play a key role in upregulating transcription factors, as well as the breakdown of structural proteins like collagen. Proteolytic mechanisms have been shown to enhance the ability of ovarian cancer cells to migrate and adhere to secondary sites allowing for efficient metastasis. Furthermore, angiogenesis for tumor growth and development of metastatic implants is influenced by upregulation of certain proteases, including MMPs. While proteases are produced normally in vivo, they can be upregulated by cancer-associated mutations, tumor-microenvironment interaction, stress-induced catecholamine production, and age-related pathologies. This review outlines the important role of proteases throughout ovarian cancer progression and metastasis.

Assay of extracellular matrix degradation and transmigration of chicken peripheral blood mononuclear cells after infection with genotype VII Newcastle disease virus in vitro

Previous studies showed that, compared to genotype IV Newcastle disease virus (NDV), genotype VII NDV induced extensive extracellular matrix (ECM) degradation by up-regulating the protein expression of matrix metalloproteinase (MMP)-14 in chicken spleens. To investigate potential relationship between MMP-14 function and the ECM degradation, an in vitro peripheral blood mononuclear cells (PBMCs) infection model was established to study the effect of genotype VII NDV (JS5/05) infection on MMP-14 expression, ECM degradation and cell transmigration. The gene and protein expression levels of MMP-14 in NDV-infected chicken PBMCs were measured by quantitative real-time PCR (qRT-PCR) and Western blot, and the subcellular location of MMP-14 was analyzed using immunofluorescence microscopy. A fluorescence-based collagen degradation assay was optimized to measure ECM degradation in PBMCs. Additionally, parameters of a transwell-based transmigration assay were also optimized to determine chemotaxis and transmigration of virus-infected PBMCs. The results showed that JS5/05 up-regulated significantly the expression of MMP-14 in PBMCs at the mRNA and protein levels compared to genotype IV NDV (Herts/33). MMP-14 was transported towards the membrane and accumulated on the cell surface of the JS5/05-infected cells, whereas it remained mainly in the cytoplasm of the Herts/33-infected cells. Collagen degradation assay showed that JS5/05-infected cells exhibited significant collagen degradation compared to the Herts/33-infected cells, and the areas of collagen degradation co-localized with cell surface MMP-14 in the JS5/05-infected cells. The transwell-based transmigration system showed that the transmigration of the JS5/05-infected PBMCs was enhanced significantly compared to the Herts/33-infected cells. These results demonstrated that genotype VII NDV induced up-regulation and surface accumulation of MMP-14 in PBMCs, leading to enhanced ECM degradation and cell migration, and the assays optimized for this study were useful for investigating the regulation of cell behaviour by NDV.

Overcoming Obstacles to Targeting Muscarinic Receptor Signaling in Colorectal Cancer

Despite great advances in our understanding of the pathobiology of colorectal cancer and the genetic and environmental factors that mitigate its onset and progression, a paucity of effective treatments persists. The five-year survival for advanced, stage IV disease remains substantially less than 20%. This review examines a relatively untapped reservoir of potential therapies to target muscarinic receptor expression, activation, and signaling in colorectal cancer. Most colorectal cancers overexpress M₃ muscarinic receptors (M₃R), and both in vitro and in vivo studies have shown that activating these receptors stimulates cellular programs that result in colon cancer growth, survival, and spread. In vivo studies using mouse models of intestinal neoplasia have shown that using either genetic or pharmacological approaches to block M₃R expression and activation, respectively, attenuates the development and progression of colon cancer. Moreover, both in vitro and in vivo studies have shown that blocking the activity of matrix metalloproteinases (MMPs) that are induced selectively by M₃R activation, i.e., MMP1 and MMP7, also impedes colon cancer growth and progression. Nonetheless, the widespread expression of muscarinic receptors and MMPs and their importance for many cellular functions raises important concerns about off-target effects and the safety of employing similar strategies in humans. As we highlight in this review, highly selective approaches can overcome these obstacles and permit clinicians to exploit the reliance of colon cancer cells on muscarinic receptors and their downstream signal transduction pathways for therapeutic purposes.

The Pharmacological TAILS of Matrix Metalloproteinases and Their Inhibitors

Matrix metalloproteinases (MMPs) have been demonstrated to have both detrimental and protective functions in inflammatory diseases. Several MMP inhibitors, with the exception of Periostat^®, have failed in Phase III clinical trials. As an alternative strategy, recent efforts have been focussed on the development of more selective inhibitors or targeting other domains than their active sites through specific small molecule inhibitors or monoclonal antibodies. Here, we present some examples that aim to better understand the mechanisms of conformational changes/allosteric control of MMPs functions. In addition to MMP inhibitors, we discuss unbiased global approaches, such as proteomics and N-terminomics, to identify new MMP substrates. We present some examples of new MMP substrates and their implications in regulating biological functions. By characterizing the roles and substrates of individual MMP, MMP inhibitors could be utilized more effectively in the optimal disease context or in diseases never tested before where MMP activity is elevated and contributing to disease progression.

Hold on or Cut? Integrin- and MMP-Mediated Cell-Matrix Interactions in the Tumor Microenvironment

The tumor microenvironment (TME) has become the focus of interest in cancer research and treatment. It includes the extracellular matrix (ECM) and ECM-modifying enzymes that are secreted by cancer and neighboring cells. The ECM serves both to anchor the tumor cells embedded in it and as a means of communication between the various cellular and non-cellular components of the TME. The cells of the TME modify their surrounding cancer-characteristic ECM. This in turn provides feedback to them via cellular receptors, thereby regulating, together with cytokines and exosomes, differentiation processes as well as tumor progression and spread. Matrix remodeling is accomplished by altering the repertoire of ECM components and by biophysical changes in stiffness and tension caused by ECM-crosslinking and ECM-degrading enzymes, in particular matrix metalloproteinases (MMPs). These can degrade ECM barriers or, by partial proteolysis, release soluble ECM fragments called matrikines, which influence cells inside and outside the TME. This review examines the changes in the ECM of the TME and the interaction between cells and the ECM, with a particular focus on MMPs.

Tumor cell MT1-MMP is dispensable for osteosarcoma tumor growth, bone degradation and lung metastasis

The membrane-anchored matrix metalloprotease MT1-MMP is a potent collagenolytic enzyme with a well-established role in extracellular matrix turnover and cellular invasion into collagen-rich tissues. MT1-MMP is highly expressed in various types of cancer and has been demonstrated to be directly involved in several stages of tumor progression, including primary tumor growth, angiogenesis, invasion and metastasis. Osteosarcoma is the most common type of primary bone cancer. This disease is characterized by invasive tumor growth, leading to extensive bone destruction, and metastasis to the lungs. The tumor cells in human osteosarcoma display a strong expression of MT1-MMP, but the role of MT1-MMP in osteosarcoma progression is currently unknown. In this study, we investigated the role of MT1-MMP during various stages of osteosarcoma development. We utilized an optimized orthotopic murine osteosarcoma model and human osteosarcoma cells in which the MT1-MMP gene was knocked out using CRISPR/Cas9. We observed a strong expression of MT1-MMP in wildtype cells of both primary tumors and lung metastases, but, surprisingly, MT1-MMP deficiency did not affect primary tumor growth, bone degradation or the formation and growth of lung metastases. We therefore propose that, unlike findings reported in other cancers, tumor-expressed MT1-MMP is dispensable for all stages of osteosarcoma progression.

Protease Inhibition Mechanism of Camelid-like Synthetic Human Antibodies

Macromolecular protease inhibitors and camelid single-domain antibodies achieve their enzymic inhibition functions often through protruded structures that directly interact with catalytic centers of targeted proteases. Inspired by this phenomenon, we constructed synthetic human antibody libraries encoding long CDR-H3s, from which highly selective monoclonal antibodies (mAbs) that inhibit multiple proteases were discovered. To elucidate their molecular mechanisms, we performed in-depth biochemical characterizations on a panel of matrix metalloproteinase (MMP)-14 inhibitory mAbs. Assays included affinity and potency measurements, enzymatic kinetics, a competitive enzyme-linked immunosorbent assay, proteolytic stability, and epitope mapping followed by quantitative analysis of binding energy changes. The results collectively indicated that these mAbs of convex paratopes were competitive inhibitors recognizing the vicinity of the active cleft, with their significant epitopes scattered across the north and south rims of the cleft. Remarkably, identified epitopes were the surface loops that were highly diverse among MMPs and predominately located at the prime side of the proteolytic site, shedding light on the mechanisms of target selectivity and proteolytic resistance. Substrate sequence profiling and paratope mutagenesis further suggested that mAb 3A2 bound to the active-site cleft in a canonical (substrate-like) manner, by direct interactions between 100hNLVATP100m of its CDR-H3 and subsites S1-S5' of MMP-14. Overall, synthetic mAbs carrying convex paratopes can achieve efficient inhibition and thus hold great therapeutic promise for effectively and safely targeting biomedically important proteases.

Challenges with matrix metalloproteinase inhibition and future drug discovery avenues

INTRODUCTION

Matrix metalloproteinases have been in the scope of pharmaceutical drug discovery for decades as promising targets for drug development. Until present, no modulator of the enzyme class survived clinical trials, all failing for various reasons. Nevertheless, the target family did not lose its attractiveness and there is ever more evidence that MMP modulators are likely to overcome the hurdles and result in successful clinical therapies.

AREAS COVERED

This review provides an overview of past efforts that were taken in the development of MMP inhibitors and insight into promising strategies that might enable drug discovery in the field in the future. Small molecule inhibitors as well as biomolecules are reviewed.

EXPERT OPINION

Despite the lack of successful clinical trials in the past, there is ongoing research in the field of MMP modulation, proving the target class has not lost its appeal to pharmaceutical research. With ever-growing insights from different scientific fields that shed light on previously unknown correlations, it is now time to use synergies deriving from biological knowledge, chemical structure generation, and clinical application to reach the ultimate goal of bringing MMP derived drugs on a broad front for the benefit of patients into therapeutic use.

Generation of highly selective monoclonal antibodies inhibiting a recalcitrant protease using decoy designs

Matrix metalloproteinase-12 (MMP-12), also known as macrophage elastase, is a potent inflammatory mediator and therefore an important pharmacological target. Clinical trial failures of broad-spectrum compound MMP inhibitors suggested that specificity is the key for a successful therapy. To provide the required selectivity, monoclonal antibody (mAb)-based inhibitors are on the rise. However, poor production of active recombinant human MMP-12 catalytic domain (cdMMP-12) presented a technical hurdle for its inhibitory mAb development. We hypothesized that this problem could be solved by designing an expression-optimized cdMMP-12 mutant without structural disruptions at its reaction cleft and surrounding area, and thus isolated active-site inhibitory mAbs could maintain their binding and inhibition functions toward wild-type MMP-12. We combined three advances in the field-PROSS algorithm for cdMMP-12 mutant design, convex paratope antibody library construction, and functional selection for inhibitory mAbs. As a result, isolated Fab inhibitors showed nanomolar affinity and potency toward cdMMP-12 with high selectivity and high proteolytic stability. Particularly, Fab LH11 targeted the reaction cleft of wild-type cdMMP-12 with 75 nM binding K_D and 23 nM inhibition IC₅₀ . We expect that our methods can promote the development of mAbs inhibiting important proteases, many of which are recalcitrant to functional production.

Inhibiting Matrix Metalloproteinase-2 Activation by Perturbing Protein-Protein Interactions Using a Cyclic Peptide

We report on a cyclic peptide that inhibits matrix metalloproteinase-2 (MMP2) activation with a low-nM-level potency. This inhibitor specifically binds to the D₅₇₀-A₅₈₃ epitope on proMMP2 and interferes with the protein-protein interaction (PPI) between proMMP2 and tissue inhibitor of metalloproteinases-2 (TIMP2), thereby preventing the TIMP2-assisted proMMP2 activation process. We developed this cyclic peptide inhibitor through an epitope-targeted library screening process and validated its binding to proMMP2. Using a human melanoma cell line, we demonstrated the cyclic peptide's ability to modulate cellular MMP2 activities and inhibit cell migration. These results provide the first successful example of targeting the PPI between proMMP2 and TIMP2, confirming the feasibility of an MMP2 inhibition strategy that has been sought after for 2 decades.

Molecular and functional extracellular vesicle analysis using nanopatterned microchips monitors tumor progression and metastasis

Longitudinal cancer monitoring is crucial to clinical implementation of precision medicine. There is growing evidence indicating important functions of extracellular vesicles (EVs) in tumor progression and metastasis, including matrix remodeling via transporting matrix metalloproteases (MMPs). However, the clinical relevance of EVs remains largely undetermined, partially owing to challenges in EV analysis. Distinct from existing technologies mostly focused on characterizing molecular constituents of EVs, here we report a nanoengineered lab-on-a-chip system that enables integrative functional and molecular phenotyping of tumor-associated EVs. A generalized, high-resolution colloidal inkjet printing method was developed to allow robust and scalable manufacturing of three-dimensional (3D) nanopatterned devices. With this nanochip platform, we demonstrated integrative analysis of the expression and proteolytic activity of MMP14 on EVs to detect in vitro cell invasiveness and monitor in vivo tumor metastasis, using cancer cell lines and mouse models. Analysis of clinical plasma specimen showed that our technology could be used for cancer detection including accurate classification of age-matched controls and patients with ductal carcinoma in situ, invasive ductal carcinoma, or locally metastatic breast cancer in a training cohort (n = 30, 96.7% accuracy) and an independent validation cohort (n = 70, 92.9% accuracy). With clinical validation, our technology could provide a useful liquid biopsy tool to improve cancer diagnostics and real-time surveillance of tumor evolution in patients to inform personalized therapy.

Matrix Metalloproteinases as New Targets in Alzheimer's Disease: Opportunities and Challenges

Although matrix metalloproteinases (MMPs) are implicated in the regulation of numerous physiological processes, evidence of their pathological roles have also been obtained in the last decades, making MMPs attractive therapeutic targets for several diseases. Recent discoveries of their involvement in central nervous system (CNS) disorders, and in particular in Alzheimer's disease (AD), have paved the way to consider MMP modulators as promising therapeutic strategies. Over the past few decades, diverse approaches have been undertaken in the design of therapeutic agents targeting MMPs for various purposes, leading, more recently, to encouraging developments. In this article, we will present recent examples of inhibitors ranging from small molecules and peptidomimetics to biologics. We will also discuss the scientific knowledge that has led to the development of emerging tools and techniques to overcome the challenges of selective MMP inhibition.

Metalloproteinases and Their Inhibitors: Potential for the Development of New Therapeutics

The metalloproteinase (MP) family of zinc-dependent proteases, including matrix metalloproteinases (MMPs), a disintegrin and metalloproteases (ADAMs), and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs) plays a crucial role in the extracellular matrix (ECM) remodeling and degradation activities. A wide range of substrates of the MP family includes ECM components, chemokines, cell receptors, and growth factors. Metalloproteinases activities are tightly regulated by proteolytic activation and inhibition via their natural inhibitors, tissue inhibitors of metalloproteinases (TIMPs), and the imbalance of the activation and inhibition is responsible in progression or inhibition of several diseases, e.g., cancer, neurological disorders, and cardiovascular diseases. We provide an overview of the structure, function, and the multifaceted role of MMPs, ADAMs, and TIMPs in several diseases via their cellular functions such as proteolysis of other cell signaling factors, degradation and remodeling of the ECM, and other essential protease-independent interactions in the ECM. The significance of MP inhibitors targeting specific MMP or ADAMs with high selectivity is also discussed. Recent advances and techniques used in developing novel MP inhibitors and MP responsive drug delivery tools are also reviewed.