Matrix metalloproteinase inhibitors: a critical appraisal of design principles and proposed therapeutic utility

The behavior of matrix metalloproteinases and their inhibitors in colorectal cancer

Matrix metalloproteinases (MMPs) play an important role in the degradation of extracellular matrix components crucial for tumor growth, invasion and metastasis. MMPs are controlled by natural inhibitors called tissue inhibitors of metalloproteinases (TIMPs). We and others have demonstrated that MMPs and TIMPs are especially important in the process of tumor invasion, progression and the metastasis of colorectal cancer (CRC). It has been proposed that MMPs and TIMPs might play a part not only in tumor invasion and initiation of metastasis but also in carcinogenesis from colorectal adenomas. Several recent studies demonstrated that high preoperative serum or plasma MMP-2, MMP-9 and TIMP-1 antigen levels are strong predictive factors for poor prognosis in patients with CRC and their determination might be useful for identification of patients with higher risk for cancer recurrence. MMP-9 and TIMP-1 have significant potential tumor marker impact in CRC. Their diagnostic sensitivity is consistently higher than those of conventional biomarkers. The pharmacological targeting of CRC by the development of a new generation of selective inhibitors of MMPs, that is highly specific for certain MMPs, is a promising and challenging area for the future.

Cell-cell and cell-matrix dynamics in intraperitoneal cancer metastasis

The peritoneal metastatic route of cancer dissemination is shared by cancers of the ovary and gastrointestinal tract. Once initiated, peritoneal metastasis typically proceeds rapidly in a feed-forward manner. Several factors contribute to this efficient progression. In peritoneal metastasis, cancer cells exfoliate into the peritoneal fluid and spread locally, transported by peritoneal fluid. Inflammatory cytokines released by tumor and immune cells compromise the protective, anti-adhesive mesothelial cell layer that lines the peritoneal cavity, exposing the underlying extracellular matrix to which cancer cells readily attach. The peritoneum is further rendered receptive to metastatic implantation and growth by myofibroblastic cell behaviors also stimulated by inflammatory cytokines. Individual cancer cells suspended in peritoneal fluid can aggregate to form multicellular spheroids. This cellular arrangement imparts resistance to anoikis, apoptosis, and chemotherapeutics. Emerging evidence indicates that compact spheroid formation is preferentially accomplished by cancer cells with high invasive capacity and contractile behaviors. This review focuses on the pathological alterations to the peritoneum and the properties of cancer cells that in combination drive peritoneal metastasis.

The history of matrix metalloproteinases: milestones, myths, and misperceptions

Since the discovery of tadpole collagenase in 1962, the matrix metalloproteinase (MMP) family has emerged as a significant proteinase group with recognized effects on the cardiovascular system. Over the last 40 years, many milestones have been achieved, from the identification of the first MMP, to the generation of the first MMP cDNA clone and null mouse, to the clinical approval of the first MMP inhibitor. Over the years, a few myths and misunderstandings have interwoven into the truths. In this review, we will discuss the major milestones of MMP research, as well as review the misinterpretations and misperceptions that have evolved. Clarifying the confusions and dispelling the myths will both provide a better understanding of MMP properties and functions and focus the cardiovascular field on the outstanding research questions that need to be addressed.

Structure of human ADAM-8 catalytic domain complexed with batimastat

The role of ADAM-8 in cancer and inflammatory diseases such as allergy, arthritis and asthma makes it an attractive target for drug development. Therefore, the catalytic domain of human ADAM-8 was expressed, purified and crystallized in complex with a hydroxamic acid inhibitor, batimastat. The crystal structure of the enzyme-inhibitor complex was refined to 2.1 Å resolution. ADAM-8 has an overall fold similar to those of other ADAM members, including a central five-stranded β-sheet and a catalytic Zn(2+) ion. However, unique differences within the S1' binding loop of ADAM-8 are observed which might be exploited to confer specificity and selectivity to ADAM-8 competitive inhibitors for the treatment of diseases involving this enzyme.

Pro- and anti-angiogenic agents

The vascular endothelium has been characterized in every organ system, and is described as a selective permeable barrier and as a dynamic and disseminated organ with endocrine function. These activities have been shown to result from the interactions of ligands with membrane-bound receptors as well as through specific junctional proteins and receptors that govern cell-cell interactions. The endothelial cells' movement (e.g., angiogenesis) has been hypothesized to occur following the release of stimuli that could promote the formation of new blood vessels. Angiogenesis has also been reported to be the continued expansion of the vascular tree in avascular regions, as a result of the sprouting of endothelial cells from existing vessels. Most commonly, angiogenesis has been characterized during wound healing and tumour growth. Herein we summarize and discuss the latest results from fundamental laboratory research aimed at proving a link between the proliferation of cancer and angiogenesis, as well as the new rationale around novel pro- and anti-angiogenic molecules.

Total glucosides of Danggui Buxue Tang attenuates bleomycin-induced pulmonary fibrosis via inhibition of extracellular matrix remodelling

OBJECTIVES

This study was designed to investigate the antifibrosis effects and possible mechanism of action of total glucosides of Danggui Buxue Tang (DBTG) on bleomycin-induced pulmonary fibrosis in rats.

METHODS

DBTG was extracted from Radix Astragali and Radix Angelicae Sinensis. Pulmonary fibrosis was induced by intratracheal instillation of bleomycin (5 mg/kg) in Wistar rats. Subsequently, the rats received daily intragastric administration of DBTG (16, 32 or 64 mg/kg per day) or cortisone (3 mg/kg) 1 day after bleomycin instillation for 4 weeks. Histological changes in the lung were evaluated by hematoxylin and eosin and Masson's trichrome staining. Markers of fibrosis in serum were determined by radioimmunoassay. The mRNA expression of metalloproteinases 1 and 9 (MMP-1, MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) in lung tissue were detected by reverse transcription PCR.

KEY FINDINGS

DBTG administration attenuated the degree of alveolitis and lung fibrosis, and markedly reduced the elevated levels of hyaluronic acid, laminin, type III procollagen and type IV collagen in serum. DBTG decreased the mRNA levels of MMP-9 and TIMP-1. MMP-1 expression was only moderately decreased by DBTG.

CONCLUSIONS

DBTG had an inhibitory effect on bleomycin-induced pulmonary fibrosis and its effect may be associated with the ability of DBTG to inhibit the synthesis of extracellular matrix and balance the MMP/TIMP-1 system.

Tissue inhibitor of metalloproteinases in oral squamous cell carcinomas - a therapeutic target?

Matrix metalloproteinases (MMPs) are proteases responsible for remodeling the extracellular matrix (ECM) and enabling spreading and metastasis of tumor cells, a common phenomenon in oral squamous cell carcinomas (OSCC). They are strongly blocked by several inhibitors, among which we must highlight, for their specificity and potency, the endogenous tissue inhibitors of metalloproteinases (TIMP-1, -2, -3 and -4). The goal of this paper is to describe the expression of TIMPs in OSCC, determining their relation with clinical, histological and prognostic factors, delving into OSCC regulation mechanisms and discussing the use of exogenous TIMPs to treat this type of tumors. Expression of TIMPs in OSCC is higher in tumors than in normal tissue, which correlates with an increase of metastatic risk and regional lymph node affectation. Although some metalloproteinases inhibitors (MMIs) have shown promising results in the treatment of these tumors, their use in OSCC has not been widely tested; and although some indirect MMIs, like COX-2 inhibitors, flavonoids and endostatin seem to have beneficial effects on the invasive capacity of OSCC through regulation of MMPs and TIMP levels, routine clinical use has not been accepted yet.

Imbalanced matrix metalloproteinases in cardiovascular complications of end-stage kidney disease: a potential pharmacological target

End-stage kidney disease (ESKD) is a major health problem associated with very high morbidity and mortality secondary to cardiovascular complications, especially in ESKD patients on dialysis. Therefore, exploring key mechanisms underlying cardiovascular alterations associated with ESKD may offer reasonable pharmacological targets that may benefit these patients. Imbalanced matrix metalloproteinases (MMP) activities have been implicated in many cardiovascular diseases, and growing evidence now indicates that excessive MMP activities contribute to cardiovascular complications in ESKD patients. However, there is no study on the effects of MMP inhibitors (MMPIs) in such patients. MMPIs may prevent against the vascular and cardiac changes associated with ESKD. In this MiniReview, we aimed at reviewing current evidence supporting the idea that pharmacological inhibition of imbalanced MMP activities in ESKD may decrease the morbidity and mortality associated with cardiovascular complications in ESKD patients. However, MMPs have variable effects during different phases of kidney disease, and therefore optimal timing for MMP inhibition during a disease process may vary significantly and is largely undetermined. While current research shows that MMPs play a role in the pathogenesis of the cardiovascular alterations found in ESKD patients, clinical studies are required to validate the idea of using MMPIs in ESKD.

Matrix metalloproteinase inhibition therapy for vascular diseases

The matrix metalloproteinases (MMPs) are 23 secreted or cell surface proteases that act together and with other protease classes to turn over the extracellular matrix, cleave cell surface proteins and alter the function of many secreted bioactive molecules. In the vasculature MMPs influence the migration proliferation and apoptosis of vascular smooth muscle, endothelial cells and inflammatory cells, thereby affecting intima formation, atherosclerosis and aneurysms, as substantiated in clinical and mouse knockout and transgenic studies. Prominent counterbalancing roles for MMPs in tissue destruction and repair emerge from these experiments. Naturally occurring tissue inhibitors of MMPs (TIMPs), pleiotropic mediators such as tetracyclines, chemically-synthesised small molecular weight MMP inhibitors (MMPis) and inhibitory antibodies have all shown effects in animal models of vascular disease but only doxycycline has been evaluated extensively in patients. A limitation of broad specificity MMPis is that they prevent both matrix degradation and tissue repair functions of different MMPs. Hence MMPis with more restricted specificity have been developed and recent studies in models of atherosclerosis accurately replicate the phenotypes of the corresponding gene knockouts. This review documents the established actions of MMPs and their inhibitors in vascular pathologies and considers the prospects for translating these findings into new treatments.

The selected genetic polymorphisms of metalloproteinases MMP2, 7, 9 and MMP inhibitor TIMP2 in sarcoidosis

BACKGROUND

Increased activity of metalloproteinases may play a role in the initiation and propagation of inflammation in sarcoidosis, and may also be one of the factors responsible for the development of lung fibrosis. The aim of this study was to verify whether polymorphisms of MMP2 C-735T, MMP7 A-181G, MMP9 T-1702A and tissue inhibitor of metalloproteinase (TIMP)2 G-418C predispose to sarcoidosis.

MATERIAL/METHODS

The study included 139 patients with sarcoidosis and 100 healthy subjects. MMPs and TIMP2 mRNA were measured in peripheral blood lysate using real-time RT-PCR. DNA for genetic polymorphism was extracted from peripheral blood by GTC method. Protein concentrations in peripheral blood lysates were measured by ELISA, and MMP2 and 9 activities in BAL fluid were estimated by gel zymography.

RESULTS

TT genotype in MMP9 T-1702A was more frequent in sarcoidosis (p<0.0001, OR = 13.71, 95% CI 7.02-26.80) and resulted in higher expression of MMP9 mRNA (p<0.0001). No differences were found between TT and AT/AA patients in terms of radiological stage, lung function test parameters, activity markers and the presence/absence of Löfgren syndrome. There were no differences in the distribution of MMP2, MMP7 and TIMP2 polymorphisms. Messenger RNAs, as well as protein concentrations of MMP2, 7, 9, and TIMP2 were elevated in patients with sarcoidosis (p<0.0001 for each).

CONCLUSIONS

The TT homozygotes of MMP9 T-1702A genotype may be predisposed to sarcoidosis. Elevated MMP2, 7, 9, and TIMP2 mRNAs suggest their inducibility.

Quantitative analysis of gradient sensing: towards building predictive models of chemotaxis in cancer

Chemotaxis of tumor cells in response to a gradient of extracellular ligand is an important step in cancer metastasis. The heterogeneity of chemotactic responses in cancer has not been widely addressed by experimental or mathematical modeling techniques. However, recent advancements in chemoattractant presentation, fluorescent-based signaling probes, and phenotypic analysis paradigms provide rich sources for building data-driven relational models that describe tumor cell chemotaxis in response to a wide variety of stimuli. Here we present gradient sensing, and the resulting chemotactic behavior, in a 'cue-signal-response' framework and suggest methods for utilizing recently reported experimental methods in data-driven modeling ventures.

Targeting the Fas/FasL signaling pathway in cancer therapy

INTRODUCTION

The Fas/FasL system plays a significant role in tumorigenesis. Research has shown that its impairment in cancer cells may lead to apoptosis resistance and contribute to tumor progression. Thus, the development of effective therapies targeting the Fas/FasL system may play an important role in the fight against cancer.

AREAS COVERED

In this review the recent literature on targeting the Fas/FasL system for therapeutic exploitation at different levels is reviewed. Promising pre-clinical approaches and various exceptions are highlighted. The potential of combined therapies is also explored, whereby tumor sensitivity to Fas-mediated apoptosis is restored, before an effective targeted therapy is employed.

EXPERT OPINION

The success of the Fas/FasL system targeting for therapeutics will require a better understanding of the alterations conferring resistance, in order to use the most appropriate sensitizing chemotherapeutic or radiotherapeutic agents in combination with effective targeted therapies.

Discovery and evaluation of a non-Zn chelating, selective matrix metalloproteinase 13 (MMP-13) inhibitor for potential intra-articular treatment of osteoarthritis

Osteoarthritis (OA) is a nonsystemic disease for which no oral or parenteral disease-modifying osteoarthritic drug (DMOAD) is currently available. Matrix metalloproteinase 13 (MMP-13) has attracted attention as a target with disease-modifying potential because of its major role in tissue destruction associated with OA. Being localized to one or a few joints, OA is amenable to intra-articular (IA) therapy, which has distinct advantages over oral therapies in terms of increasing therapeutic index, by maximizing drug delivery to cartilage and minimizing systemic exposure. Here we report on the synthesis and biological evaluation of a non-zinc binding MMP-13 selective inhibitor, 4-methyl-1-(S)-({5-[(3-oxo-3,4-dihydro-2H-benzo[1,4]oxazin-6-ylmethyl)carbamoyl]pyrazolo[1,5-a]pyrimidine-7-carbonyl}amino)indan-5-carboxylic acid (1), that is uniquely suited as a potential IA-DMOAD: it has long durability in the joint, penetrates cartilage effectively, exhibits nearly no detectable systemic exposure, and has remarkable efficacy.

Nuclear localization of matrix metalloproteinases

Matrix metalloproteinases (MMPs) were originally identified as matrixin proteases that act in the extracellular matrix. Recent works have uncovered nontraditional roles for MMPs in the extracellular space as well as in the cytosol and nucleus. There is strong evidence that subspecialized and compartmentalized matrixins participate in many physiological and pathological cellular processes, in which they can act as both degradative and regulatory proteases. In this review, we discuss the transcriptional and translational control of matrixin expression, their regulation of intracellular sorting, and the structural basis of activation and inhibition. In particular, we highlight the emerging roles of various matrixin forms in diseases. The activity of matrix metalloproteinases is regulated at several levels, including enzyme activation, inhibition, complex formation and compartmentalization. Most MMPs are secreted and have their function in the extracellular environment. MMPs are also found inside cells, both in the nucleus, cytosol and organelles. The role of intracellular located MMPs is still poorly understood, although recent studies have unraveled some of their functions. The localization, activation and activity of MMPs are regulated by their interactions with other proteins, proteoglycan core proteins and / or their glycosaminoglycan chains, as well as other molecules. Complexes formed between MMPs and various molecules may also include interactions with noncatalytic sites. Such exosites are regions involved in substrate processing, localized outside the active site, and are potential binding sites of specific MMP inhibitors. Knowledge about regulation of MMP activity is essential for understanding various physiological processes and pathogenesis of diseases, as well as for the development of new MMP targeting drugs.

Microbial and fungal protease inhibitors--current and potential applications

Proteolytic enzymes play essential metabolic and regulatory functions in many biological processes and also offer a wide range of biotechnological applications. Because of their essential roles, their proteolytic activity needs to be tightly regulated. Therefore, small molecules and proteins that inhibit proteases can be versatile tools in the fields of medicine, agriculture and biotechnology. In medicine, protease inhibitors can be used as diagnostic or therapeutic agents for viral, bacterial, fungal and parasitic diseases as well as for treating cancer and immunological, neurodegenerative and cardiovascular diseases. They can be involved in crop protection against plant pathogens and herbivorous pests as well as against abiotic stress such as drought. Furthermore, protease inhibitors are indispensable in protein purification procedures to prevent undesired proteolysis during heterologous expression or protein extraction. They are also valuable tools for simple and effective purification of proteases, using affinity chromatography. Because there are such a large number and diversity of proteases in prokaryotes, yeasts, filamentous fungi and mushrooms, we can expect them to be a rich source of protease inhibitors as well.

Novel effects of macrolide antibiotics on cardiovascular diseases

Macrolide antibiotics are broadly used for the treatment of various microbial infections. However, they are also known to have multiple biologic effects, such as alteration of inflammatory factors and matrix metalloproteinases (MMPs). Because of controversial results in clinical trials, the effects of macrolides on cardiovascular diseases are still to be elucidated. It has been reported that MMP activity is upregulated in various cardiovascular diseases, such as myocarditis, cardiac transplant rejection and myocardial infarction. However, little is known about the effects of macrolides on cardiovascular diseases. We have reported that clarithromycin suppressed the development of myocarditis, cardiac rejection and myocardial ischemia using animal models. In this article, we reviewed the roles of MMPs in cardiovascular diseases and the effects of macrolides on the prevention of adverse tissue remodeling.

Hypoxia differentially affects IL-1β-stimulated MMP-1 and MMP-13 expression of fibroblast-like synoviocytes in an HIF-1α-dependent manner

OBJECTIVES

To further understand the expression regulation of MMP-1 and MMP-13 under physiological and pathological conditions, we investigated the combined effects of hypoxia and pro-inflammatory stimuli on the expression of MMP-1 and MMP-13 in rheumatoid synovial fibroblasts.

METHODS

Synovial fibroblasts were cultured under either hypoxic or normoxic conditions in the presence of IL-1β stimulation. The culture supernatant was analysed for secreted levels of VEGF, MMP-1 and MMP-13. Their gene expression was quantified with real-time and semi-quantitative PCR. Another group of cells was transfected with small-interfering RNA (siRNA) specific for hypoxia-inducible factor-1 α (HIF-1α). The protein levels of HIF-1α were detected by western blot analysis.

RESULTS

In response to 10 ng/ml of IL-1β under normoxia, the levels of MMP-1 and MMP-13 increased compared with the levels observed under hypoxia. IL-1β stimulation under hypoxia induced a 2-fold increase in the level of MMP-1 and a 2-fold decrease in the level of MMP-13 compared with cells cultured under normoxia. A similar pattern of differential expression for MMP-1 and MMP-13 was observed with 1 and 5 ng/ml IL-1β, but not at 0.1 ng/ml. The differential expression of MMPs under the combined effect of IL-1β and hypoxia was significantly attenuated by silencing HIF-1α with siRNA.

CONCLUSIONS

Hypoxia in arthritic joints may differentially affect the IL-1β-stimulated expression of MMP-1 and MMP-13 in rheumatoid synovial fibroblasts. This effect is dependent on HIF-1α expression. This hypoxia-mediated differential effect should be taken into consideration when testing the efficiency of therapies that target HIF-1α.

Novel 1-hydroxypiperazine-2,6-diones as new leads in the inhibition of metalloproteinases

New compounds containing a novel zinc-binding group (1-hydroxypiperazine-2,6-dione, HPD) have been identified as effective inhibitors of matrix metalloproteinases (MMPs), with activities in the nanomolar concentration range. That moiety seemed to bind the catalytic zinc ion of MMPs, revealing itself as a new potential substitute for the hydroxamate group in the next generation of metalloproteinase inhibitors. The X-ray crystal structure of 1b elucidated its 3D conformation and supramolecular packing in solid state. Theoretical procedures were used to investigate the binding mode of this class of compounds, within the active site of MMP13. A computational method involving docking and hybrid quantum mechanical and molecular mechanical (QM/MM) dynamic simulations was developed and applied. This study suggested that the HPD moiety binds bidentately to the catalytic zinc through its oxygen atoms. The final structure obtained will allow straightforward drug design approaches in view of further optimization and development of new MMP inhibitors bearing the HPD moiety.

Targeting the tumor microenvironment by immunotherapy: part 2

Cancer therapy was traditionally centered on the neoplastic cells. This included mainly surgery, radiation, and chemotherapy, in some cases hormone therapy and to a lesser extent immunotherapy – all traditionally targeted to the highly proliferating mutated tumor cells. In view of our present understanding of the powerfull influence of the tumor microenvironment (TME) on cancer behavior and response – and lack of response – to treatment, this previously ignored constituent of cancer now has to be considered as an important, even indispensable target for therapy. The TME may be targeted both to its immune and to its nonimmune components. The various immune evasion elements of the TME should be targeted as well.

Role of polyethylene particles in peri-prosthetic osteolysis: A review

There is convincing evidence that particles produced by the wear of joint prostheses are causal in the peri-prosthetic loss of bone, or osteolysis, which, if it progresses, leads to the phenomenon of aseptic loosening. It is important to fully understand the biology of this bone loss because it threatens prosthesis survival, and loosened implants can result in peri-prosthetic fracture, which is disastrous for the patient and presents a difficult surgical scenario. The focus of this review is the bioactivity of polyethylene (PE) particles, since there is evidence that these are major players in the development and progression of osteolysis around prostheses which use PE as the bearing surface. The review describes the biological consequences of interaction of PE particles with macrophages, osteoclasts and cells of the osteoblast lineage, including osteocytes. It explores the possible cellular mechanisms of action of PE and seeks to use the findings to date to propose potential non-surgical treatments for osteolysis. In particular, a non-surgical approach is likely to be applicable to implants containing newer, highly cross-linked PEs (HXLPEs), for which osteolysis seems to occur with much reduced PE wear compared with conventional PEs. The caveat here is that we know little as yet about the bioactivity of HXLPE particles and addressing this constitutes our next challenge.

New facets of matrix metalloproteinases MMP-2 and MMP-9 as cell surface transducers: outside-in signaling and relationship to tumor progression

This review focuses on matrix metalloproteinases (MMPs)-2 (gelatinase A) and -9 (gelatinase B), both of which are cancer-associated, secreted, zinc-dependent endopeptidases. Gelatinases cleave many different targets (extracellular matrix, cytokines, growth factors, chemokines and cytokine/growth factor receptors) that in turn regulate key signaling pathways in cell growth, migration, invasion, inflammation and angiogenesis. Interactions with cell surface integral membrane proteins (CD44, αVβ/αβ1/αβ2 integrins and Ku protein) can occur through the gelatinases' active site or hemopexin-like C-terminal domain. This review evaluates the recent literature on the non-enzymatic, signal transduction roles of surface-bound gelatinases and their subsequent effects on cell survival, migration and angiogenesis. Gelatinases have long been drug targets. The current status of gelatinase inhibitors as anticancer agents and their failure in the clinic is discussed in light of these new data on the gelatinases' roles as cell surface transducers - data that may lead to the design and development of novel, gelatinase-targeting inhibitors.

Matrix metalloproteinases as drug targets in ischemia/reperfusion injury

Deficient blood supply (ischemia) is a common consequence of some surgical procedures and certain pathologies. Once blood circulation is re-established (reperfusion), a complex series of events results in recruitment of inflammatory cells, rearrangement of the extracellular matrix and induction of cell death, which lead to organ dysfunction. Although ischemia/reperfusion (I/R) injury is an important cause of death, there is no effective therapy targeting the molecular mechanism of disease progression. Matrix metalloproteinases (MMPs), which are important regulators of many cellular activities, have a central role in disease progression after I/R injury, as suggested by numerous studies using MMP inhibitors or MMP-deficient mice. Here, we review the involvement of MMP activity in the various processes following I/R injury and the therapeutic potential of MMP inhibition.

Molecular discrimination of cutaneous squamous cell carcinoma from actinic keratosis and normal skin

Actinic keratosis is widely believed to be a neoplastic lesion and a precursor to invasive squamous cell carcinoma. However, there has been some debate as to whether actinic keratosis is in fact actually squamous cell carcinoma and should be treated as such. As the clinical management and prognosis of patients is widely held to be different for each of these lesions, our goal was to identify unique gene signatures using DNA microarrays to discriminate among normal skin, actinic keratosis, and squamous cell carcinoma, and examine the molecular pathways of carcinogenesis involved in the progression from normal skin to squamous cell carcinoma. Formalin-fixed and paraffin-embedded blocks of skin: five normal skins (pooled), six actinic keratoses, and six squamous cell carcinomas were retrieved. The RNA was extracted and amplified. The labeled targets were hybridized to the Affymetrix human U133plus2.0 array and the acquisition and initial quantification of array images were performed using the GCOS (Affymetrix). The subsequent data analyses were performed using DNA-Chip Analyzer and Partek Genomic Suite 6.4. Significant differential gene expression (>2 fold change, P<0.05) was seen with 382 differentially expressed genes between squamous cell carcinoma and normal skin, 423 differentially expressed genes between actinic keratosis and normal skin, and 9 differentially expressed genes between actinic keratosis and squamous cell carcinoma. The differentially expressed genes offer the possibility of using DNA microarrays as a molecular diagnostic tool to distinguish between normal skin, actinic keratosis, and squamous cell carcinoma. In addition, the differentially expressed genes and their molecular pathways could be potentially used as prognostic markers or targets for future therapeutic innovations.

Pleomorphic liposarcoma: clinical observations and molecular variables

BACKGROUND

Pleomorphic liposarcoma (PLS) is a rare high-grade sarcoma that has lipoblastic differentiation. In this study, the authors evaluated PLS natural history, patient outcomes, and commonly deregulated protein biomarkers.

METHODS

Medical records from patients (n = 155) who had PLS from 1993 to 2010 were reviewed. Univariate and multivariate analyses were conducted to identify independent prognosticators. A PLS tissue microarray (TMA) (n = 56 patient specimens) was constructed for immunohistochemical analysis of molecular markers, and p53 gene sequencing (exons 5-9) was conducted.

RESULTS

The average patient age was 57 years, and the patients presented with primary disease (n = 102), recurrent disease (n = 16), and metastatic disease (n = 37). Lower extremity was the most common disease site (40%), and the average tumor size was 11 cm. Complete follow-up data were available for 83 patients, and their median follow-up was 22.6 months. The 5-year disease-specific survival rate was 53%; and recurrent disease, unresectability, and microscopic positive margins were identified as predictors of a poor prognosis. Systemic relapse (the strongest poor prognostic determinant) developed in 35% of patients with localized PLS. Immunohistochemical analysis revealed increased expression of peroxisome proliferator-activated receptor gamma (an adipogenic marker), B-cell leukemia 2 and survivin (survival factors), vascular endothelial growth factor (an angiogenic factor), matrix metalloproteinase 2, and other biomarkers. Frequent loss of retinoblastoma protein expression and high p53 mutation rates (approximately 60%) were observed.

CONCLUSIONS

PLS is an aggressive, metastasizing sarcoma. Identifying ubiquitous molecular events underlying PLS progression is crucial for progress in patient management and outcomes.

Matrix metalloproteinases and their clinical relevance in urinary bladder cancer

Matrix metalloproteinases (MMPs) have important roles in several cancer-supporting cellular processes, such as extracellular matrix (ECM) remodeling, angiogenesis, apoptosis, epithelial-to-mesenchymal transition and cell proliferation. This broad range of activity has led to considerable interest in the use of MMPs in the clinical setting as diagnostic or prognostic biomarkers and as therapeutic targets. Levels of the different MMPs can be measured in several sample types, including paraffin-embedded or fresh frozen tissue, serum, plasma and urine, and by various analytical methodologies, such as immunohistochemistry, real-time PCR, western and northern blot analyses, enzyme-linked immunosorbent assay and zymography. Several MMPs have been identified as having potential diagnostic or prognostic utility, whether alone or in combination with currently available diagnostic tests or imaging modalities. Although the early broad-spectrum anti-MMP agents showed a lack of efficacy, our continually improving understanding of the complex physiologic and pathologic roles of MMPs might enable the development of new MMP-specific and tumor-specific therapies. Accordingly, MMPs will continue to be the subjects of intensive research in bladder cancer.

Role of matrix metalloproteinases and therapeutic benefits of their inhibition in spinal cord injury

This review will focus on matrix metalloproteinases (MMPs) and their inhibitors in the context of spinal cord injury (SCI). MMPs have a specific cellular and temporal pattern of expression in the injured spinal cord. Here we consider their diverse functions in the acutely injured cord and during wound healing. Excessive activity of MMPs, and in particular gelatinase B (MMP-9), in the acutely injured cord contributes to disruption of the blood-spinal cord barrier, and the influx of leukocytes into the injured cord, as well as apoptosis. MMP-9 and MMP-2 regulate inflammation and neuropathic pain after peripheral nerve injury and may contribute to SCI-induced pain. Early pharmacologic inhibition of MMPs or the gelatinases (MMP-2 and MMP-9) results in an improvement in long-term neurological recovery and is associated with reduced glial scarring and neuropathic pain. During wound healing, gelatinase A (MMP-2) plays a critical role in limiting the formation of an inhibitory glial scar, and mice that are genetically deficient in this protease showed impaired recovery. Together, these findings illustrate complex, temporally distinct roles of MMPs in SCIs. As early gelatinase activity is detrimental, there is an emerging interest in developing gelatinase-targeted therapeutics that would be specifically tailored to the acute injured spinal cord. Thus, we focus this review on the development of selective gelatinase inhibitors.

Proteolytic Activity Matrix Analysis (PrAMA) for simultaneous determination of multiple protease activities

Matrix metalloproteinases (MMPs) and A Disintegrin and Metalloproteinases (ADAMs) are two related protease families that play key roles in matrix remodeling and growth factor ligand shedding. Directly ascertaining the proteolytic activities of particular MMPs and ADAMs in physiological environments in a non-invasive, real-time, multiplex manner remains a challenge. This work describes Proteolytic Activity Matrix Analysis (PrAMA), an integrated experimental measurement and mathematical analysis framework for simultaneously determining the activities of particular enzymes in complex mixtures of MMPs and ADAMs. The PrAMA method interprets dynamic signals from panels of moderately specific FRET-based polypeptide protease substrates to deduce a profile of specific MMP and ADAM proteolytic activities. Deconvolution of signals from complex mixtures of proteases is accomplished using prior data on individual MMP/ADAM cleavage signatures for the substrate panel measured with purified enzymes. We first validate PrAMA inference using a compendium of roughly 4000 measurements involving known mixtures of purified enzymes and substrates, and then demonstrate application to the live-cell response of wildtype, ADAM10-/-, and ADAM17-/- fibroblasts to phorbol ester and ionomycin stimulation. Results indicate PrAMA can distinguish closely related enzymes from each other with high accuracy, even in the presence of unknown background proteolytic activity. PrAMA offers a valuable tool for applications ranging from live-cell in vitro assays to high-throughput inhibitor screening with complex enzyme mixtures. Moreover, our approach may extend to other families of proteases, such as caspases and cathepsins, that also can lack highly-specific substrates.

Efficient, enantioselective assembly of silanediol protease inhibitors

A five-step assembly of silicon-protected dipeptide mimics from commercially available reagents is described. This methodology makes silanediol protease inhibitors readily available for the first time. The sequence features asymmetric hydrosilylation, a novel reduction of a silyl ether to a silyllithium reagent, and addition of this dianion to a sulfinimine, to produce the complete inhibitor skeleton with full control of stereochemistry. Oxidation of the primary alcohol to an acid completes the synthesis.

Exploring the functional space of thiiranes as gelatinase inhibitors using click chemistry

A series of 4-[(triazolyl)methoxy]phenyl analogs of the phenoxyphenyl-substituted thiirane SB-3CT 1 was evaluated for its ability to inhibit gelatinases, members of the matrix metalloproteinase family of enzymes. The triazole segment of these inhibitors was assembled using the Meldal-Sharpless copper-catalyzed Huisgen dipolar cycloaddition of an azide and a terminal alkyne. While these triazole derivatives possessed fair activity as gelatinase inhibitors, an intermediate used in the dipolar cycloaddition, 4-(propargyloxy)phenyl derivative 2, showed very good activity (>50% inhibitory activity following a 3 h pre-incubation of 2 at a concentration of 3 μM) as an inhibitor of human matrix metalloproteinase-2.

Recently identified biomarkers that promote lymph node metastasis in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous cancer that arises in the upper aerodigestive tract. Despite advances in knowledge and treatment of this disease, the five-year survival rate after diagnosis of advanced (stage 3 and 4) HNSCC remains approximately 50%. One reason for the large degree of mortality associated with late stage HNSCC is the intrinsic ability of tumor cells to undergo locoregional invasion. Lymph nodes in the cervical region are the primary sites of metastasis for HNSCC, occurring before the formation of distant metastases. The presence of lymph node metastases is strongly associated with poor patient outcome, resulting in increased consideration being given to the development and implementation of anti-invasive strategies. In this review, we focus on select proteins that have been recently identified as promoters of lymph node metastasis in HNSCC. The discussed proteins are involved in a wide range of critical cellular functions, and offer a more comprehensive understanding of the factors involved in HNSCC metastasis while additionally providing increased options for consideration in the design of future therapeutic intervention strategies.

Sulfonate-containing thiiranes as selective gelatinase inhibitors

Matrix metalloproteinases (MMPs) are important zinc-dependent endopeptidases. Two members of this family of enzymes called gelatinases (MMP-2 and MMP-9) have been implicated in a number of human diseases, including cancer, neurological and cardiovascular diseases, and inflammation, to name a few. We describe in this report the preparation and evaluation of two structural types of thiirane inhibitors that show selectivity toward gelatinases. The biphenyl series targets both gelatinases, whereas the monophenyl analogues exhibit potent inhibition of only MMP-2. The latter structural type also exhibits improved water solubility and metabolic stability, both traits desirable for progress of these molecules forward in gelatinase-dependent animal models of disease.