Induction of tumour cell apoptosis by matrix metalloproteinase inhibitors: new tricks from a (not so) old drug

Matrix metalloproteinases (MMPs) regulate the turnover of extracellular matrix (ECM) components and play an important role in embryo development, morphogenesis and tissue remodelling, as well as in tumour invasion and metastasis. Synthetic MMP inhibitors (MMPIs) were designed to prevent tumour cell-induced changes in ECM and thereby achieve antitumour activity. Several MMPIs have entered clinical trials but the preliminary results did not meet the expectations. Recent evidence suggests that MMPs may have more diverse roles than originally believed, influencing angiogenesis, cytokine secretion, as well as tumour cell growth and survival. In particular, synthetic MMPIs may directly induce apoptosis of cancer cells via their inhibitory effect on the shedding of Fas Ligand (FasL), a transmembrane member of the TNF superfamily that kills susceptible cells through its receptor, Fas. Several types of cancers have been shown to express FasL and to shed it from their surface as a soluble form, which is significantly less potent in promoting apoptosis. MMP-7 was recently reported to catalyse this process. Conversely, inhibition of FasL-shedding by a synthetic MMPI results in apoptosis of Fas-sensitive cancer cells. More importantly, DNA-damaging anticancer agents, such as adriamycin, kill cancer cells, at least in part, by upregulating FasL. By inhibiting the proteolytic cleavage of FasL, MMPIs can potentiate the killing effect of traditional chemotherapeutic drugs. These studies therefore demonstrate a direct link between DNA-damaging chemotherapeutic drugs, the apoptosis-inducing Fas/FasL system and the proteolytic activity of MMPs and have important therapeutic implications. For example, the proteolytic activity of MMP-7, which is broadly expressed in primary and especially metastatic human malignancies, may contribute to tumour resistance to cytotoxic agents; targeting and inactivating MMP-7 may, therefore, enhance the efficacy of conventional cancer chemotherapy.     

Matrix metalloproteinases in cancer metastasis: molecular targets for prostate cancer prevention by green tea polyphenols and grape seed proanthocyanidins

Matrix metalloproteinases (MMP) play a crucial role in the development and metastatic spread of cancer. One of the earliest events in the metastatic spread of cancer is the invasion through the basement membrane and proteolytic degradation of the extracellular matrix proteins, such as, collagens, laminin, elastin and fibronectin etc, and non-matrix proteins. MMPs are the important regulators of tumor growth, both at the primary site and in distant metastases. Given the clear implications of MMPs in many human cancers, MMPs remain important targets of cancer therapy. Metastatic spread of cancer continues to be the greatest barrier in prevention or cure of cancer. The recognition that MMPs facilitate tumor cell growth, invasion and metastasis of cancer has led to the development of MMP inhibitors as cancer therapeutic agents. Understanding the molecular mechanism of metastasis is also crucial for the design and effective use of novel therapeutic strategies to combat metastases. In this short review article, we discuss the evidences that MMPs are associated with cancer metastasis and that they make a functional contribution to the process. Further, since considerable interest among human population is increasing with regard to the use of dietary botanical supplements for the prevention of age-associated diseases like some forms of cancer, we also discuss the beneficial effects of dietary botanicals, such as green tea polyphenols and grape seed proanthocyanidins, in chemoprevention of cancer with particular emphasis on the involvement of MMPs in prostate cancer.     

Tumour angiogenesis: a novel therapeutic target in patients with malignant disease

Angiogenesis refers to the formation of new blood vessels from an existing vasculature and is recognised as a necessary requirement for most tumours to grow beyond 1-2 mm in diameter. Factors established as playing a role in angiogenesis may be divided into two principal groups: (a) those that stimulate endothelial cell proliferation and/or elongation, migration and vascular morphogenesis including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet derived endothelial cell growth factor (PD-ECGF) and the tie and tek receptors, and (b) proteases and their receptors involved in the breakdown of basement membranes and the extracellular matrix (ECM) including the matrix metalloproteinases (MMPs), cathepsins and those involved in the plasmin cascade. Angiogenesis has been identified as a potential target for development of anticancer agents. The discovery of a range of naturally-occurring factors which negatively regulate angiogenesis, including the thrombospondins, angiostatin and endostatin, and the tissue inhibitors of MMPs (TIMPs), has given added impetus to this approach. Synthetic anti-angiogenic compounds have been developed, including TNP-470, carboxyamidotriazole, VEGF-tyrosine kinase inhibitors and MMP inhibitors (MMPI) which, like the naturally-occurring anti-angiogenic factors, inhibit angiogenesis in vitro and in vivo, and tumour development, growth and metastasis in vivo. Anti-angiogenic agents also enhance the antitumour activity of many conventional cytotoxic chemotherapeutic agents. Such combinations may have a particular role as adjuvant therapies following surgical resection of primary tumours. Unlike tumour cells, tumour associated endothelial cells do not develop resistance to anti-angiogenic agents. Furthermore, anti-angiogenic agents are generally cytostatic rather than cytotoxic. As such, these agents are, in general, likely to be administered over long periods of time. Therefore, as well as having proven antitumour efficacy, an anti-angiogenic compound will need to be well-tolerated if it is to become established in the clinical management of patients with malignant disease.     

Matrix Metalloproteinase Inhibitors: Do They Have a Place in Anticancer Therapy?

Matrix metalloproteinases (MMPs) are a family of enzymes involved in degradation of extracellular matrix. An imbalance between MMPs and naturally occurring MMP inhibitors may cause excess extracellular matrix destruction, allowing cancer cells to invade surrounding tissues and metastasize, and permitting angiogenesis to occur. Inhibition of certain key MMPs may prevent angiogenesis, tumor growth, invasion, and metastasis. Gelatinases MMP-2 and MMP-9 are expressed during carcinogenesis and angiogenesis. Synthetic MMP inhibitors were designed to target these enzymes and potentially prevent the tumor growth and metastases associated with cancer.     

Phase I trial of a novel matrix metalloproteinase inhibitor batimastat (BB-94) in patients with advanced cancer

Summary Degradation of basement membrane and extracellular matrix by matrix metalloproteinases (MMPs) is believed to be required for tumor invasion, tumor-induced angiogenesis and vascular invasion. A synthetic hydroxamate, batimastat (also known as BB-94), inhibits MMPs by binding the zinc ion in the active site of the MMP. Batimastat inhibits at least 50% of MMP activity at concentrations less than or equal to 10 ng/ml in vitro. Batimastat retarded ascites accumulation and increased survival in mice with human ovarian tumor xenografts. Acute and long-term toxicological studies revealed no major toxicity in animals. Batimastat is poorly soluble and was administered intraperitoneally (i.p.) as a suspension. Previous studies in patients with malignant ascites have shown no major toxicities at doses as high as 1350 mg/m².     

Therapeutic developments in matrix metalloproteinase inhibition

A family of zinc-dependent endopeptidases called matrix metalloproteinases (MMPs) have the capacity to degrade all elements of the extracellular matrix (ECM) and are required for homeostatic maintenance of the ECM. However, interest in MMPs predominantly arises from the accumulating evidence implicating that dysregulated MMP expression plays a role in mediating or accompanying a diverse array of pathologies. These include tumour invasion and metastasis and inflammatory diseases characterised by excessive tissue destruction, such as arthritis, periodontal disease, atherosclerosis, plaque rupture, arterial aneurysms, postmyocardial infarction, ventricular remodelling and cardiac rupture. Several patents representing therapeutic drugs and strategies to treat the associated conditions have been claimed, some resulting in clinical drug trials. This review will: i) summarise the current status of our understanding of MMPs and how they participate in normal and functional ECM degradation; ii) review therapeutic efforts to favourably alter the balance between MMP proteolysis and ECM sythesis; and iii) critically evaluate recent studies that have importantly advanced our understanding of the complexities of MMP function and propose areas where future efforts to develop therapeutic strategies might be most beneficial and productive.     

基质金属蛋白酶7在肿瘤中的作用及其机制研究进展

基质金属蛋白酶(Matrix Metalloproteinases,MMPs)是与肿瘤相关的一个蛋白酶家族,这个家族拥有29个成员,它们广泛参与肿瘤细胞的生长、侵袭和转移以及血管生成过程。基质金属蛋白酶7(MMP7)由于其结构特点和生理活性,被认为是这个家族中最重要的成员之一。在MMPs广谱抑制剂临床实验均不理想的情况下,对MMP7与肿瘤关系的深入研究,有助于更好的针对MMP7的肿瘤药物的研发。文章介绍了MMP7在肿瘤生长、侵袭转移和肿瘤血管生成中相关作用机制,并对MMP7在肿瘤诊断和治疗中的最新研究进展做了简要综述。     

Status of research on matrix metalloproteinases (MMPs) in India

INTRODUCTION: MMPs are extracellular matrix (ECM)-degrading enzymes that play a crucial role in embryogenesis, tissue remodeling, inflammation and angiogenesis. MMP-2 and -9 (also called type 2 and type 4 collagenase, or gelatinase A and B) are the key molecules that control invasion, tumor growth and metastasis. Tissue inhibitor of matrix metalloproteinase (TIMP) -2 and -1 are specific inhibitors of MMP-2 and MMP-9 respectively, and play a crucial role in regulation of MMP-2 and -9 activation, during pathophysiological processes. MMPs can specifically degrade native gelatin, collagens, fibronectin, ectactin and elastin. MMP-2 and -9 are overexpressed in almost all types of cancers, and so act as important therapeutic targets. AREAS COVERED: The status of MMP research in India from 1998 to 2010. In this review, the authors cover the role of matrix metalloproteinase inhibitors in cancer therapy. EXPERT OPINION: As compared with other parts of the world, Indian scientists have not generated a significant number of specific MMP inhibitors for the treatment of cancer, or other diseases. MMPs and membrane type (MT)-MMPs are potentially important therapeutic targets in many diseases, including cancers, therefore, designing specific inhibitors from natural products or through synthetic routes, is crucial.     

Matrix metalloproteinases and their inhibitors in vascular remodeling and vascular disease

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade various components of the extracellular matrix (ECM). Members of the MMP family include collagenases, gelatinases, stromelysins, matrilysins and membrane-type MMPs. ProMMPs are cleaved into active forms that promote degradation of ECM proteins. Also, recent evidence suggests direct or indirect effects of MMPs on ion channels in the endothelium and vascular smooth muscle, and on other mechanisms of vascular relaxation/contraction. Endogenous tissue inhibitors of metalloproteinases (TIMPs) reduce excessive proteolytic ECM degradation by MMPs. The balance between MMPs and TIMPs plays a major role in vascular remodeling, angiogenesis, and the uterine and systemic vasodilation during normal pregnancy. An imbalance in the MMPs/TIMPs activity ratio may underlie the pathogenesis of vascular diseases such as abdominal aortic aneurysm, varicose veins, hypertension and preeclampsia. Downregulation of MMPs using genetic manipulations of endogenous TIMPs, or synthetic pharmacological inhibitors such as BB-94 (Batimastat) and doxycycline, and Ro-28-2653, a more specific inhibitor of gelatinases and membrane type 1-MMP, could be beneficial in reducing the MMP-mediated vascular dysfunction and the progressive vessel wall damage associated with vascular disease.     

Metalloproteinase binding proteins: WO2009097397

MMPs are a group of metalloendopeptidases whose major role is in extracellular matrix (ECM) catabolism under physiological and pathological conditions. ECM catabolism is often associated with different diseases, and accumulated studies support the causal relationship between MMPs and different diseases especially with cancer and arthritis. Therefore, MMPs have been considered as therapeutic target molecules. However, multiple failures of MMP inhibitor drugs in clinical trials from late 1990s to early 2000s resulted in the consideration that wide inhibitory spectrum inhibitors of metalloproteinases may not be desirable for treatment of diseases. On the other hand, developing low molecular mass selective inhibitor(s) targeting the active site is not a very easy task. One way to overcome this problem is to develop biologic inhibitors, namely antibodies. In this patent application, Dyax Corp. reported that a binding protein (such as an antibody) against metalloproteinases, especially membrane-type 1 MMP (MMP-14) can be used as a therapeutic drug against different diseases including cancer. They succeeded in generating a selective MMP-14 inhibitory antibody with a K_i of 0.6 nM, which showed significant suppression of different tumour growth in mice. Further development of such an antibody as a drug may fulfil an unmet area of disease treatment targeting uncontrolled cell invasion and tissue destruction.     

Matrix metalloproteinase inhibitors

The matrix metalloproteinases (MMPs) are a family of at least fifteen secreted and membrane-bound zinc-endopeptidases. Collectively, these enzymes can degrade all of the components of the extracellular matrix, including fibrallar and non-fibrallar collagens, fibronectin, laminin and basement membrane glycoproteins. MMPs are thought to be essential for the diverse invasive processes of angiogenesis and tumor metastasis. Numerous studies have shown that there is a close association between expression of various members of the MMP family by tumors and their proliferative and invasive behavior and metastatic potential. In some of human cancers a positive correlation has also been demonstrated between the intensity of new blood vessel growth (angiogenesis) and the likelihood of developing metastases. Thus, control of MMP activity in these two different contexts has generated considerable interest as a possible therapeutic target.The tissue inhibitors of metalloproteinases (TIMPs) are naturally occurring proteins that specifically inhibit matrix metalloproteinases, thus maintaining balance between matrix destruction and formation. An imbalance between MMPs and the associated TIMPs may play a significant role in the invasive phenotype of malignant tumors. TIMP-1 has been shown to inhibit tumor-induced angiogenesis in experimental systems. These findings raised the possibility of using an agent that affects expression or activity of MMPs as an anti-cancer therapy. TIMPs are probably not suitable for pharmacologic applications due to their short half-life in vivo.Batimastat (BB-94) and marimastat (BB-2516) are synthetic, low-molecular weight MMP inhibitors. They have a collagen-mimicking hydroxamate structure, which facilitates chelation of the zinc ion in the active site of the MMPs. These compounds inhibit MMPs potently and specifically. Batimastat was the first synthetic MMP inhibitor studied in humans with advanced malignancies, but its usefulness has been limited by extremely poor water solubility, which required intraperitoneal administration of the drug as a detergent emulsion. Marimastat belongs to a second generation of MMP inhibitors. In contrast to batimastat, marimastat is orally available. Both of these agents are currently in Phase I/II trials in US, Europe and Canada.Some other new agents, currently in clinical trials, have been shown to inhibit MMP production. Bryostatins, naturally occurring macrocyclic lactones, have both in vitro and in vivo activity in numerous murine and human tumors. In culture, bryostatin-1 has been shown to induce differentiation and halt the growth of several malignant cell lines. While the exact mechanism responsible for anti-tumor activity is unclear, an initial event in the action of bryostatin-1 is activation of protein kinase C (PKC), followed by its down regulation. Bryostatin-1 does not directly affect the activity of MMPs, but it can inhibit the production of MMP-1, 3, 9, 10 and 11 by inhibiting PKC. TIMP-1 levels could also be modulated by bryostatin-1, as it is encoded by a PKC responsive gene.     

Natural bio-drugs as matrix metalloproteinase inhibitors: new perspectives on the horizon?

The matrix metalloproteinases (MMPs), belonging to the family of proteolytic enzymes, are well-known for their ability to degrade the extracellular matrix, and are involved in many aspects of both physiological cellular processes and pathological situations, such as tumor growth, invasion and metastasis. MMPs have been considered prognostic factors in various types of cancer as well as promising targets for cancer therapy. Although preclinical studies of a number of different synthetic MMP inhibitors have been identified as cytostatic and anti-angiogenic agents and have begun clinical testing, the past years have produced a consistent number of disappointments and limited successes. In view of their specific implication in malignant tissues, several natural compounds were utilized, and the results were so satisfactory as to encourage several clinical trials in order to improve efficacy and to reduce the side effect profile. The natural protection against cancer has been receiving a great deal of attention, and the critical examination of previous studies shed light on new information about the source and function of MMPs, focusing the attention on the identification of MMP targets in tumors. This review discusses the current knowledge and research in the field of natural MMP inhibitor as innovative therapeutic intervention in cancer.     

Status of research on matrix metalloproteinases (MMPs) in India

Introduction: MMPs are extracellular matrix (ECM)-degrading enzymes that play a crucial role in embryogenesis, tissue remodeling, inflammation and angiogenesis. MMP-2 and -9 (also called type 2 and type 4 collagenase, or gelatinase A and B) are the key molecules that control invasion, tumor growth and metastasis. Tissue inhibitor of matrix metalloproteinase (TIMP) -2 and -1 are specific inhibitors of MMP-2 and MMP-9 respectively, and play a crucial role in regulation of MMP-2 and -9 activation, during pathophysiological processes. MMPs can specifically degrade native gelatin, collagens, fibronectin, ectactin and elastin. MMP-2 and -9 are overexpressed in almost all types of cancers, and so act as important therapeutic targets.

Areas covered: The status of MMP research in India from 1998 to 2010. In this review, the authors cover the role of matrix metalloproteinase inhibitors in cancer therapy.

Expert opinion: As compared with other parts of the world, Indian scientists have not generated a significant number of specific MMP inhibitors for the treatment of cancer, or other diseases. MMPs and membrane type (MT)-MMPs are potentially important therapeutic targets in many diseases, including cancers, therefore, designing specific inhibitors from natural products or through synthetic routes, is crucial.     

Matrix metalloproteinase inhibitors: a review on bioanalytical methods, pharmacokinetics and metabolism

Enzymes are major drug targets in drug discovery and development processes in the pharmaceutical and biotechnology industry. A recent survey found that nearly half of all the marketed small-molecule drugs are inhibitors of enzymes. Matrix metalloproteinases (MMPs) are a family of 28 enzymes capable of degrading the constituents of the extracellular matrix (ECM) and the basement-membrane. MMPs play an essential role in several normal physiological processes including growth, wound healing and tissue repair. Over-expression and activation of MMPs has been linked to a range of diseases which include osteoarthritis, tumor metastasis, angiogenesis and cardiovascular diseases. The development of MMP inhibitors as therapeutic agents has kept an important place in drug discovery. Therefore, there is also an increasing need for robust analytical methods for evaluation of inhibitory potency and for the analysis of MMP inhibitors and their metabolites which can even play a more significant role than the parent drug. Modern analytical techniques and hyphenated instrumentations such as liquid chromatography-mass spectrometry with a function of structure elucidation can provide a profound insight into the research of MMP inhibitors and also serve as a complementary method to zymographic techniques for the analysis of biological samples. This review mainly summarizes bioanalytical methods, pharmacokinetics and related metabolites of MMP inhibitors over the last 12 years.     

Pharmacodynamic considerations in the use of matrix metalloproteinase inhibitors in cancer treatment

Introduction: Matrix metalloproteinases (MMPs) are classified in the family of zinc-dependent endopeptidases, which can degrade various components of an extracellular matrix and a basement membrane. Studies have demonstrated that MMPs relate to the development of malignant tumors and induce angiogenesis, resulting in the invasion and metastasis of tumor cells. MMPs are highly expressed in malignant tumors and are related to cancer patients’ malignant phenotype and poor prognosis. Therefore, blocking the expression or activity of MMPs may be a promising strategy for cancer treatment.

Areas Covered: This study aimed to explain the MMP structure, regulatory mechanism, and carcinogenic effect; investigate the matrix metalloproteinase-inhibitors (MMPIs) that are currently used in clinical trials for cancer treatment; and summarize the trial results.

Expert Opinion: Currently, the results of clinical trials that have used MMPIs as anticancer agents are unsatisfactory. However, MMPs remain an attractive target for cancer treatment. For example, development of the specific peptide or antibodies in targeting the hemopexin domain of MMP-2 may be a new therapeutic direction. The design and development of MMPIs that have selectivity will be the primary focus in future studies.     

Inhibition of invasion and angiogenesis by zinc-chelating agent disulfiram

Cell invasion and angiogenesis are crucial processes in cancer metastasis that require extracellular matrix (ECM) degradation. Proteolytic degradation of the ECM components is a central event of invasion and angiogenesis processes. During these processes, matrix metalloproteinases (MMPs) seem to be primarily responsible for much of the ECM degradation. Disulfiram is frequently used in the treatment of alcoholism and has been reported to possess antiretroviral activity and can eject intrinsic zinc out of human immunodeficiency virus (HIV) nucleocapsid protein. In this report, we show that disulfiram inhibited invasion and angiogenesis in both tumor and endothelial cells at nontoxic concentrations. The 3H-labeled type IV collagen degradation assay suggested that disulfiram has type IV collagenase inhibitory activity, and this inhibition was responsible for blocking invasion and angiogenesis through cell-mediated and non-cell-mediated pathways. However, the mechanisms underlying cell-mediated signal pathways are not fully characterized. Our data demonstrate that the non-cell-mediated pathway is dominant. Thus, disulfiram could directly interact with MMP-2 and MMP-9 and inhibit their proteolytic activity through a zincchelating mechanism. Addition of zinc could reverse the inhibition of invasiveness and collagenase inhibition through disulfiram treatment. This finding implies that MMP-2 and MMP-9 may be the inhibitory targets for a potential disulfiram treatment. These observations raise the possibility clinical therapeutic applications for disulfiram used as a potential inhibitor of metastatic cell invasion and angiogenesis.     

gem-Diamine 1-N-iminosugars and related iminosugars,candidate of therapeutic agents for tumor metastasis

Cancer metastasis is one of the major challenges in cancer research. Inhibitors of tumor metastasis are rapidly emerging as important new drug candidates for cancer therapy. Tumor metastasis formation occurs via a complex multistage process which involves a crucial step of tumor invasion through the basement membrane. Tumor cell invasion involves attachment of tumor cell to the basement membrane through laminin, degradation of the matrix by proteolytic enzymes from the tumor cell and cell migration through the basement membrane. New drugs aimed at the metabolism of tumor cell surface oligosaccharides and/or catabolism of glycoconjugates of extracellular matrix and basement membrane could inhibit tumor metastasis. In this article, current progress in the control of tumor metastasis by gem-diamine 1-N-iminosugars and related iminosugars (nojirimycin and d-glucaro-delta-lactam), which are potent and specific inhibitors of carbohydrate metabolism and catabolism, has been reviewed. gem-Diamine 1-N-iminosugars related to d-glucuronic acid and l-iduronic acid, nojirimycin and d-glucaro-delta-lactam suppress invasion of B16 melanoma variants and 3LL (lung carcinoma) cells through reconstituted basement membrane, and inhibit pulmonary metastasis of these tumor cells in mice and/or cKDH-8/11 (liver carcinoma) cells in rats. These results suggest that the metabolism of beta-d-glucuronide and alpha-l-iduronide of glycoconjugates and/or the processing of carbohydrates of tumor cell surface may participate in tumor metastasis. That these gem-diamine 1-N-iminosugars and related iminosugars are potent inhibitors of tumor metastasis holds promise of new drug candidates for cancer chemotherapy.     

Matrix metalloproteinases in cancer invasion, metastasis and angiogenesis

Matrix metalloproteinases (MMPs) are a family of proteinases that play an important role in cancer as well as in numerous other diseases. In this article, we summarize the current views on the role of MMPs in cancer with respect to invasion, metastasis and angiogenesis. A positive correlation between tumor progression and the expression of multiple MMP family members in tumor tissues has been demonstrated in numerous human and animal studies. It has been assumed that cancer cells are responsible for producing the MMPs in human tumors. However, recent evidence suggests that tumor cells have docking sites that bind stromal-cell-secreted MMPs. Furthermore, the role of MMPs produced by endothelial cells, especially MMP-2 and MT1-MMP, appear to be crucial for tumor angiogenesis, which is a requirement for cancer growth and dissemination.     

Matrix metalloproteinases as therapeutic targets in cancer

Degradation of extracellular matrix is crucial for malignant tumor growth, invasion, metastasis and angiogenesis. Matrix metalloproteinases (MMPs) are a family of zinc-dependent neutral endopeptidases collectively capable of degrading essentially all matrix components. Elevated levels of distinct MMPs can be detected in tumor tissue or serum of patients with advanced cancer, and their role as prognostic indicators in cancer has been widely examined. In addition, therapeutic intervention in tumor growth and invasion based on inhibition of MMP activity is under intensive investigation and several MMP inhibitors (MMPIs) are in clinical cancer trials. Even though results of the first clinical trials in advanced cancer have been mostly disappointing, there are also positive results. Recent observations show, that certain MMPs limit tumor growth. Therefore, identification of proper MMPs for therapeutic intervention with array-based molecular classifications of tumors and targeting these with more specific MMPIs in combination with conventional chemotherapy is expected to provide a feasible approach for cancer therapy. MMPIs represent a totally different therapeutic modality from proven anti-cancer drugs and thus traditional approaches to evaluate drug efficiency cannot be used without modification. In this review, we discuss the current view on the feasibility of MMPs as targets for therapeutic intervention in cancer.     

Clinical potential of matrix metalloprotease inhibitors in cancer therapy

Matrix metalloproteases (MMP) are a family of enzymes that contribute to the degradation of the extracellular matrix. The destruction of the extracellular matrix eventually leads to tumour invasion, metastasis and angiogenesis. Realising this mechanism of action, there is tremendous potential for inhibitors of MMP in cancer therapy. Extensive preclinical data have shown that administration of matrix metalloprotease inhibitors (MMPI) to different animal models results in a reduction in primary tumour growth as well as in the number and size of metastatic lesions. Based on promising preclinical studies, synthetic MMPI have been developed and taken into clinical trials. These include marimastat, BAY- 129566, CGS-27023A, prinomastat (AG-3340), BMS-275291 and metastat (COL-3). These drugs are all in different stages of clinical development, ranging from phase I to III. In general, musculoskeletal problems, such as joint stiffness and pain in hands, arms and shoulders seem to affect most patients in varying degrees, depending on the dose and type of compound administered. In addition to single agent therapy, several MMPI have entered trials of combination therapy. The objective of combining chemotherapy with an MMPI is to potentiate tumour cytotoxicity as well as to reduce the size and number of metastatic lesions. Several compounds have entered phase III combination therapy trials, but it is still too early to report any data. There is ongoing research in correlating biological endpoints, such as levels of MMP and markers of angiogenesis with clinical response. As the field of MMP and their inhibitors continues to mature, its role in cancer therapeutics will be better defined.