Isolation and characterization of human monoclonal antibodies specific to MMP-1A, MMP-2 and MMP-3

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.

Current Insights into the Formulation and Delivery of Therapeutic and Cosmeceutical Agents for Aging Skin

“Successful aging” counters the traditional idea of aging as a disease and is increasingly equated with minimizing age signs on the skin, face, and body. From this stems the interest in preventative aesthetic dermatology that might help with the healthy aging of skin, help treat or prevent certain cutaneous disorders, such as skin cancer, and help delay skin aging by combining local and systemic methods of therapy, instrumental devices, and invasive procedures. This review will discuss the main mechanisms of skin aging and the potential mechanisms of action for commercial products already on the market, highlighting the issues related to the permeation of the skin from different classes of compounds, the site of action, and the techniques employed to overcome aging. The purpose is to give an overall perspective on the main challenges in formulation development, especially nanoparticle formulations, which aims to defeat or slow down skin aging, and to highlight new market segments, such as matrikines and matrikine-like peptides. In conclusion, by applying enabling technologies such as those delivery systems outlined here, existing agents can be repurposed or fine-tuned, and traditional but unproven treatments can be optimized for efficacious dosing and safety.

Next generation matrix metalloproteinase inhibitors - Novel strategies bring new prospects

Enzymatic proteolysis of cell surface proteins and extracellular matrix (ECM) is critical for tissue homeostasis and cell signaling. These proteolytic activities are mediated predominantly by a family of proteases termed matrix metalloproteinases (MMPs). The growing evidence in recent years that ECM and non-ECM bioactive molecules (e.g., growth factors, cytokines, chemokines, on top of matrikines and matricryptins) have versatile functions redefines our view on the roles matrix remodeling enzymes play in many physiological and pathological processes, and underscores the notion that ECM proteolytic reaction mechanisms represent master switches in the regulation of critical biological processes and govern cell behavior. Accordingly, MMPs are not only responsible for direct degradation of ECM molecules but are also key modulators of cardinal bioactive factors. Many attempts were made to manipulate ECM degradation by targeting MMPs using small peptidic and organic inhibitors. However, due to the high structural homology shared by these enzymes, the majority of the developed compounds are broad-spectrum inhibitors affecting the proteolytic activity of various MMPs and other zinc-related proteases. These inhibitors, in many cases, failed as therapeutic agents, mainly due to the bilateral role of MMPs in pathological conditions such as cancer, in which MMPs have both pro- and anti-tumorigenic effects. Despite the important role of MMPs in many human diseases, none of the broad-range synthetic MMP inhibitors that were designed have successfully passed clinical trials. It appears that, designing highly selective MMP inhibitors that are also effective in vivo, is not trivial. The challenges related to designing selective and effective metalloprotease inhibitors, are associated in part with the aforesaid high structural homology and the dynamic nature of their protein scaffolds. Great progress was achieved in the last decade in understanding the biochemistry and biology of MMPs activity. This knowledge, combined with lessons from the past has drawn new "boundaries" for the development of the next-generation MMP inhibitors. These novel agents are currently designed to be highly specific, capable to discriminate between the homologous MMPs and ideally administered as a short-term topical treatment. In this review we discuss the latest progress in the fields of MMP inhibitors in terms of structure, function and their specific activity. The development of novel highly specific inhibitors targeting MMPs paves the path to study complex biological processes associated with ECM proteolysis in health and disease. This article is part of a Special Issue entitled: Matrix Metalloproteinases edited by Rafael Fridman.

In vivo optical imaging of MMP2 immuno protein antibody: tumor uptake is associated with MMP2 activity

Matrix metalloproteinase-2 (MMP2) is important in tumorigenesis, angiogenesis and tumor invasion. In this study, we investigated if the Cy5-tagged small immuno protein targeting the catalytic domain of human MMP2 (aMMP2-SIP) detects MMP2 in tumors non-invasively. For this purpose, we generated MMP2 expressing (empty vector EV) and knock-down (KD) HT1080, U373 and U87 cells, which were injected subcutaneously in the lateral flank of NMRI-nu mice. Optical imaging (Optix MX2) performed at 0.5, 2, 4, 8, 24 and 48 hour post injection (h.p.i.) of Cy5 tagged aMMP2-SIP, indicated significantly lower tumor to background ratios at both 24 (P = 0.0090) and 48 h.p.i. (P < 0.0001) for the U87 MMP2-KD compared to control tumors. No differences were found for HT1080 and U373 models. U87 MMP2-KD tumors had significantly lower MMP2 activity (P < 0.0001) than EV tumors as determined by gelatin zymography in tumor sections and lysates, while no differences were observed between EV and MMP2-KD in HT1080 and U373. In line with these data, only U87 MMP2-KD tumors had a reduced tumor growth compared to control tumors (P = 0.0053). aMMP2-SIP uptake correlates with MMP2 activity and might therefore be a potential non-invasive imaging biomarker for the evaluation of MMP2 activity in tumors.

Mouse matrix metalloprotease-1a (Mmp1a) gives new insight into MMP function

Matrix metalloprotease-1 (MMP1) has been implicated in many human disease processes, however the lack of a well characterized murine homologue has significantly limited the study of MMP1 and the development of MMP-targeted therapeutics. The discovery of murine Mmp1a in 2001, the functional mouse homologue of MMP1, offers a valuable tool for modeling MMP1-mediated processes in mice. Variation in physiologic expression levels of Mmp1a in mice as compared to MMP1 in humans highlights the importance of understanding the similarities and differences between the homologues. Recent studies have demonstrated tumor growth-, invasion-, and angiogenesis-promoting functions of Mmp1a in lung cancer models, consistent with the analogous functions observed for human MMP1. Biochemical investigations have shown that point mutations in the pro-domain of mouse Mmp1a weaken docking between the pro- and catalytic domains, generating an unstable zymogen primed for activation. The difficulty to effectively maintain Mmp1a in the zymogen form may account for the tight control of Mmp1a expression and reduced expression in normal tissue as compared to inflammatory states or cancer. This discovery raises important questions about the activation mechanisms and regulation of the MMP family in general.

A human monoclonal antibody specific to placental alkaline phosphatase, a marker of ovarian cancer

Placental alkaline phosphatase (PLAP) is a promising ovarian cancer biomarker. Here, we describe the isolation, affinity-maturation and characterization of two fully human monoclonal antibodies (termed B10 and D9) able to bind to human PLAP with a dissociation constant (Kd) of 10 and 30 nM, respectively. The ability of B10 and D9 antibodies to recognize the native antigen was confirmed by Biacore analysis, FACS and immunofluorescence studies using ovarian cancer cell lines and freshly-frozen human tissues. A quantitative biodistribution study in nude mice revealed that the B10 antibody preferentially localizes to A431 tumors, following intravenous administration. Anti-PLAP antibodies may serve as a modular building blocks for the development of targeted therapeutic products, armed with cytotoxic drugs, radionuclides or cytokines as payloads.

Monoclonal antibodies to murine thrombospondin-1 and thrombospondin-2 reveal differential expression patterns in cancer and low antigen expression in normal tissues

There is a considerable interest for the discovery and characterization of tumor-associated antigens, which may facilitate antibody-based pharmacodelivery strategies. Thrombospondin-1 and thrombospondin-2 are homologous secreted proteins, which have previously been reported to be overexpressed during remodeling typical for wound healing and tumor progression and to possibly play a functional role in cell proliferation, migration and apoptosis. To our knowledge, a complete immunohistochemical characterization of thrombospondins levels in normal rodent tissues has not been reported so far. Using antibody phage technology, we have generated and characterized monoclonal antibodies specific to murine thrombospondin-1 and thrombospondin-2, two antigens which share 62% aminoacid identity. An immunofluorescence analysis revealed that both antigens are virtually undetectable in normal mouse tissues, except for a weak staining of heart tissue by antibodies specific to thrombospondin-1. The analysis also showed that thrombospondin-1 was strongly expressed in 5/7 human tumors xenografted in nude mice, while it was only barely detectable in 3/8 murine tumors grafted in immunocompetent mice. By contrast, a high-affinity antibody to thrombospondin-2 revealed a much lower level of expression of this antigen in cancer specimens. Our analysis resolves ambiguities related to conflicting reports on thrombosponding expression in health and disease. Based on our findings, thrombospondin-1 (and not thrombospondin-2) may be considered as a target for antibody-based pharmacodelivery strategies, in consideration of its low expression in normal tissues and its upregulation in cancer.

Noncanonical matrix metalloprotease-1-protease-activated receptor-1 signaling triggers vascular smooth muscle cell dedifferentiation and arterial stenosis

Vascular injury that results in proliferation and dedifferentiation of vascular smooth muscle cells (SMCs) is an important contributor to restenosis following percutaneous coronary interventions or plaque rupture. Protease-activated receptor-1 (PAR1) has been shown to play a role in vascular repair processes; however, little is known regarding its function or the relative roles of the upstream proteases thrombin and matrix metalloprotease-1 (MMP-1) in triggering PAR1-mediated arterial restenosis. The goal of this study was to determine whether noncanonical MMP-1 signaling through PAR1 would contribute to aberrant vascular repair processes in models of arterial injury. A mouse carotid arterial wire injury model was used for studies of neointima hyperplasia and arterial stenosis. The mice were treated post-injury for 21 days with a small molecule inhibitor of MMP-1 or a direct thrombin inhibitor and compared with vehicle control. Intimal and medial hyperplasia was significantly inhibited by 2.8-fold after daily treatment with the small molecule MMP-1 inhibitor, an effect that was lost in PAR1-deficient mice. Conversely, chronic inhibition of thrombin showed no benefit in suppressing the development of arterial stenosis. Thrombin-PAR1 signaling resulted in a supercontractile, differentiated phenotype in SMCs. Noncanonical MMP-1-PAR1 signaling resulted in the opposite effect and led to a dedifferentiated phenotype via a different G protein pathway. MMP-1-PAR1 significantly stimulated hyperplasia and migration of SMCs, and resulted in down-regulation of SMC contractile genes. These studies provide a new mechanism for the development of vascular intimal hyperplasia and suggest a novel therapeutic strategy to suppress restenosis by targeting noncanonical MMP-1-PAR1 signaling in vascular SMCs.

Matrix metalloprotease 1a deficiency suppresses tumor growth and angiogenesis

Matrix metalloprotease-1 (MMP1) is an important mediator of tumorigenesis, inflammation and tissue remodeling through its ability to degrade critical matrix components. Recent studies indicate that stromal-derived MMP1 may exert direct oncogenic activity by signaling through protease-activated receptor-1 (PAR1) in carcinoma cells; however, this has not been established in vivo. We generated an Mmp1a knockout mouse to ascertain whether stromal-derived Mmp1a affects tumor growth. Mmp1a-deficient mice are grossly normal and born in Mendelian ratios; however, deficiency of Mmp1a results in significantly decreased growth and angiogenesis of lung tumors. Coimplantation of lung cancer cells with wild-type Mmp1a(+/+) fibroblasts completely restored tumor growth in Mmp1a-deficient animals, highlighting the critical role of stromal-derived Mmp1a. Silencing of PAR1 expression in the lung carcinoma cells phenocopied stromal Mmp1a-deficiency, thus validating tumor-derived PAR1 as an Mmp1a target. Mmp1a secretion is controlled by the ability of its prodomain to facilitate autocleavage, whereas human MMP1 is efficiently secreted because of stable pro- and catalytic domain interactions. Taken together, these data demonstrate that stromal Mmp1a drives in vivo tumorigenesis and provide proof of concept that targeting the MMP1-PAR1 axis may afford effective treatments of lung cancer.

Matrix metalloprotease-1a promotes tumorigenesis and metastasis

Matrix metalloprotease-1 (MMP1), a collagenase and activator of the G protein-coupled protease activated receptor-1 (PAR1), is an emerging new target implicated in oncogenesis and metastasis in diverse cancers. However, the functional mouse homologue of MMP1 in cancer models has not yet been clearly defined. We report here that Mmp1a is a functional MMP1 homologue that promotes invasion and metastatic progression of mouse lung cancer and melanoma. LLC1 (Lewis lung carcinoma) and primary mouse melanoma cells harboring active BRAF express high levels of endogenous Mmp1a, which is required for invasion through collagen. Silencing of either Mmp1a or PAR1 suppressed invasive stellate growth of lung cancer cells in three-dimensional matrices. Conversely, ectopic expression of Mmp1a conferred an invasive phenotype in epithelial cells that do not express endogenous Mmp1a. Consistent with Mmp1a acting as a PAR1 agonist in an autocrine loop, inhibition or silencing of PAR1 resulted in a loss of the Mmp1a-driven invasive phenotype. Knockdown of Mmp1a on tumor cells resulted in significantly decreased tumorigenesis, invasion, and metastasis in xenograft models. Together, these data demonstrate that cancer cell-derived Mmp1a acts as a robust functional homologue of MMP1 by conferring protumorigenic and metastatic behavior to cells.

Selection and characterization of human antibody fragments specific for psoriasin - a cancer associated protein

S100A7 (psoriasin) is a calcium-binding protein that is upregulated in many types of cancer and often associated with poor prognosis. Its role in carcinogenesis has been associated with the stimulation of VEGF and EGF activity. The recent research showed that psoriasin directly interacts with αvβ6 integrin, a protein related to the invasive phenotype of cancer. Moreover, this interaction promotes the αvβ6-dependent invasive activity. The important function of S100A7 in carcinoma development determines a great need for valuable tools enabling its detection, quantification and also activity inhibition. Here, we show the selection of S100A7 specific antibody fragments from the human scFv phage library ETH-2 Gold. We have selected antibody fragments specific for psoriasin, purified them and analyzed by BIAcore affinity measurements. The best clone was subjected to affinity maturation procedure yielding molecule with a subnanomolar affinity towards human S100A7 protein. Selected clone was expressed in a bivalent format and applied for immunostaining analysis, which confirmed the ability of the antigen recognition in physiological conditions. We therefore propose that obtained antibody, that is the first phage display-derived human antibody against psoriasin, can serve as a useful psoriasin binding platform in research, diagnostics and therapy of cancer.

Development of a novel recombinant biotherapeutic with applications in targeted therapy of human arthritis

OBJECTIVE

To isolate recombinant antibodies with specificity for human arthritic synovium and to develop targeting reagents with joint-specific delivery capacity for therapeutic and/or diagnostic applications.

METHODS

In vivo single-chain Fv (scFv) antibody phage display screening using a human synovial xenograft model was used to isolate antibodies specific to the microvasculature of human arthritic synovium. Single-chain Fv antibody tissue-specific reactivity was assessed by immunostaining of synovial tissues from normal controls and from patients with rheumatoid arthritis and osteoarthritis, normal human tissue arrays, and tissues from other patients with inflammatory diseases displaying neovasculogenesis. In vivo scFv antibody tissue-specific targeting capacity was examined in the human synovial xenograft model using both (125)I-labeled and biotinylated antibody.

RESULTS

We isolated a novel recombinant human antibody, scFv A7, with specificity for the microvasculature of human arthritic synovium. We showed that in vivo, this antibody could efficiently target human synovial microvasculature in SCID mice transplanted with human arthritic synovial xenografts. Our results demonstrated that scFv A7 antibody had no reactivity with the microvasculature or with other cellular components found in a comprehensive range of normal human tissues including normal human synovium. Further, we showed that the reactivity of the scFv A7 antibody was not a common feature of neovasculogenesis associated with chronic inflammatory conditions.

CONCLUSION

Here we report for the first time the identification of an scFv antibody, A7, that specifically recognizes an epitope expressed in the microvasculature of human arthritic synovium and that has the potential to be developed as a joint-specific pharmaceutical.

A novel synthetic naïve human antibody library allows the isolation of antibodies against a new epitope of oncofetal fibronectin

Human monoclonal antibodies (mAbs) can routinely be isolated from phage display libraries against virtually any protein available in sufficient purity and quantity, but library design can influence epitope coverage on the target antigen. Here we describe the construction of a novel synthetic human antibody phage display library that incorporates hydrophilic or charged residues at position 52 of the CDR2 loop of the variable heavy chain domain, instead of the serine residue found in the corresponding germline gene. The novel library was used to isolate human mAbs to various antigens, including the alternatively-spliced EDA domain of fibronectin, a marker of tumor angiogenesis. In particular, the mAb 2H7 was proven to bind to a novel epitope on EDA, which does not overlap with the one recognized by the clinical-stage F8 antibody. F8 and 2H7 were used for the construction of chelating recombinant antibodies (CRAbs), whose tumor-targeting properties were assessed in vivo in biodistribution studies in mice bearing F9 teratocarcinoma, revealing a preferential accumulation at the tumor site.

New opportunities in drug design of metalloproteinase inhibitors: combination between structure-function experimental approaches and systems biology

INTRODUCTION

MMPs (matrix metalloproteinases) and ADAMs (a disintegrin and metalloproteinases) are endopeptidases central to the degradation and remodeling of the extracellular matrix. These proteases also exhibit regulatory activity in cell signaling pathways and thus tissue homeostasis under normal conditions and in many diseases. Consequently, individual members of the MMP and ADAM protein families were identified as important therapeutic targets. However, designing effective inhibitors in vivo for this class of enzymes appears to be extremely challenging. This is attributed to the broad structural similarity of their active sites and to the dynamic functional interconnectivity of MMPs with other proteases, their inhibitors, and substrates (the so-called degradome) in healthy and disease tissues.

AREAS COVERED

The article covers the progress in designing metalloproteinase inhibitors, based on recent advancements in our understanding of enzyme structures and their function as master regulators. It also discusses the potential of utilizing structure-based drug design strategies in conjunction with systems biology experimental approaches for designing potent and therapeutically effective metalloproteinase inhibitors.

EXPERT OPINION

We highlight the use of protein-based drug design strategies, for example, antibodies and protein scaffolds, targeting extracatalytic domains, which are central to proteolytic and non-proteolytic enzyme functions. Such rationally designed function-blocking inhibitors may create new opportunities in disease management and in emerging therapies that require control of dysregulated MMP activity without causing severe side effects. Importantly, the lessons learned from studying these protein-based inhibitors can be implemented to design new and effective small or medium sized synthetic antagonists.

Methods for the identification of vascular markers in health and disease: from the bench to the clinic

Several diseases are characterized by changes in the molecular composition of vascular structures, thus offering the opportunity to use specific ligands (e.g., monoclonal antibodies) for imaging and therapy application. This novel pharmaceutical strategy, often referred to as "vascular targeting", promises to facilitate the discovery and development of selective biopharmaceuticals for the management of angiogenesis-related diseases. This article reviews novel biomedical applications based on vascular targeting strategies, as well as methodologies which have been used for the discovery of vascular markers of pathology.

High-throughput sequencing for the identification of binding molecules from DNA-encoded chemical libraries

DNA-encoded chemical libraries are large collections of small organic molecules, individually coupled to DNA fragments that serve as amplifiable identification bar codes. The isolation of specific binders requires a quantitative analysis of the distribution of DNA fragments in the library before and after capture on an immobilized target protein of interest. Here, we show how Illumina sequencing can be applied to the analysis of DNA-encoded chemical libraries, yielding over 10 million DNA sequence tags per flow-lane. The technology can be used in a multiplex format, allowing the encoding and subsequent sequencing of multiple selections in the same experiment. The sequence distributions in DNA-encoded chemical library selections were found to be similar to the ones obtained using 454 technology, thus reinforcing the concept that DNA sequencing is an appropriate avenue for the decoding of library selections. The large number of sequences obtained with the Illumina method now enables the study of very large DNA-encoded chemical libraries (>500,000 compounds) and reduces decoding costs.

Tumour-targeting properties of antibodies specific to MMP-1A, MMP-2 and MMP-3

PURPOSE

Matrix metalloproteinases (MMPs), a group of more than 20 zinc-containing endopeptidases, are upregulated in many diseases, but several attempts to use radiolabelled MMP inhibitors for imaging tumours have proved unsuccessful in mouse models, possibly due to the limited specificity of these agents or their unfavourable pharmacokinetic profiles. In principle, radiolabelled monoclonal antibodies could be considered for the selective targeting and imaging of individual MMPs.

METHODS

We cloned, produced and characterized high-affinity monoclonal antibodies specific to murine MMP-1A, MMP-2 and MMP-3 in SIP (small immunoprotein) miniantibody format using biochemical and immunochemical methods. We also performed comparative biodistribution analysis of their tumour-targeting properties at three time points (3 h, 24 h, 48 h) in mice bearing subcutaneous F9 tumours using radioiodinated protein preparations. The clinical stage L19 antibody, specific to the alternatively spliced EDB domain of fibronectin, was used as reference tumour-targeting agent for in vivo studies.

RESULTS

All anti-MMP antibodies and SIP(L19) strongly stained sections of F9 tumours when assessed by immunofluorescence methods. In biodistribution experiments, SIP(SP3), specific to MMP-3, selectively accumulated at the tumour site 24 and 48 h after intravenous injection, but was rapidly cleared from other organs. By contrast, SIP(SP1) and SIP(SP2), specific to MMP-1A and MMP-2, showed no preferential accumulation at the tumour site.

CONCLUSION

Antibodies specific to MMP-3 may serve as vehicles for the efficient and selective delivery of imaging agents or therapeutic molecules to sites of disease.