Inhibition of tumour growth by marimastat in a human xenograft model of gastric cancer: relationship with levels of circulating CEA

Cancer-Associated Fibroblasts: Accomplices in the Tumor Immune Evasion

Simple Summary

A growing number of studies suggest that cancer-associated fibroblasts (CAFs) modulate both myeloid and lymphoid cells through secretion of molecules (i.e., chemical function) and production of the extracellular matrix (ECM), i.e., physical function. Even though targeting functions CAFs is a relevant strategy, published clinical trials solely aimed at targeting the stroma showed disappointing results, despite being based on solid preclinical evidence. Our review dissects the interactions between CAFs and immune cells and explains how a deeper understanding of CAF subpopulations is the cornerstone to propose relevant therapies that will ultimately improve survival of patients with cancer.

Abstract

Cancer-associated fibroblasts (CAFs) are prominent cells within the tumor microenvironment, by communicating with other cells within the tumor and by secreting the extracellular matrix components. The discovery of the immunogenic role of CAFs has made their study particularly attractive due to the potential applications in the field of cancer immunotherapy. Indeed, CAFs are highly involved in tumor immune evasion by physically impeding the immune system and interacting with both myeloid and lymphoid cells. However, CAFs do not represent a single cell entity but are divided into several subtypes with different functions that may be antagonistic. Considering that CAFs are orchestrators of the tumor microenvironment and modulate immune cells, targeting their functions may be a promising strategy. In this review, we provide an overview of (i) the mechanisms involved in immune regulation by CAFs and (ii) the therapeutic applications of CAFs modulation to improve the antitumor immune response and the efficacy of immunotherapy.

The tumour microenvironment in pancreatic cancer - clinical challenges and opportunities

Metastatic pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid tumours despite the use of multi-agent conventional chemotherapy regimens. Such poor outcomes have fuelled ongoing efforts to exploit the tumour microenvironment (TME) for therapy, but strategies aimed at deconstructing the surrounding desmoplastic stroma and targeting the immunosuppressive pathways have largely failed. In fact, evidence has now shown that the stroma is multi-faceted, which illustrates the complexity of exploring features of the TME as isolated targets. In this Review, we describe ways in which the PDAC microenvironment has been targeted and note the current understanding of the clinical outcomes that have unexpectedly contradicted preclinical observations. We also consider the more sophisticated therapeutic strategies under active investigation - multi-modal treatment approaches and exploitation of biologically integrated targets - which aim to remodel the TME against PDAC.

Molecular Characterisation of Canine Osteosarcoma in High Risk Breeds

Dogs develop osteosarcoma (OSA) and the disease process closely resembles that of human OSA. OSA has a poor prognosis in both species and disease-free intervals and cure rates have not improved in recent years. Gene expression in canine OSAs was compared with non-tumor tissue utilising RNA sequencing, validated by qRT-PCR and immunohistochemistry (n = 16). Polymorphic polyglutamine (polyQ) tracts in the androgen receptor (AR/NR3C4) and nuclear receptor coactivator 3 (NCOA3) genes were investigated in control and OSA patients using polymerase chain reaction (PCR), Sanger sequencing and fragment analysis (n = 1019 Rottweilers, 379 Irish Wolfhounds). Our analysis identified 1281 significantly differentially expressed genes (>2 fold change, p < 0.05), specifically 839 lower and 442 elevated gene expression in osteosarcoma (n = 3) samples relative to non-malignant (n = 4) bone. Enriched pathways and gene ontologies were identified, which provide insight into the molecular pathways implicated in canine OSA. Expression of a subset of these genes (SLC2A1, DKK3, MMP3, POSTN, RBP4, ASPN) was validated by qRTPCR and immunohistochemistry (MMP3, DKK3, SLC2A1) respectively. While little variation was found in the NCOA3 polyQ tract, greater variation was present in both polyQ tracts in the AR, but no significant associations in length were made with OSA. The data provides novel insights into the molecular mechanisms of OSA in high risk breeds. This knowledge may inform development of new prevention strategies and treatments for OSA in dogs and supports utilising spontaneous OSA in dogs to improve understanding of the disease in people.

Matrix Metalloproteinases: A challenging paradigm of cancer management

Matrix metalloproteinases (MMPs) are members of zinc-dependent endopeptidases implicated in a variety of physiological and pathological processes. Over the decades, MMPs have been studied for their role in cancer progression, migration, and metastasis. As a result, accumulated evidence of MMPs incriminating role has made them an attractive therapeutic target. Early generations of broad-spectrum MMP inhibitors exhibited potent inhibitory activities, which subsequently led to clinical trials. Unexpectedly, these trials failed to meet the desired goals, mainly due to the lack of efficacy, poor oral bioavailability, and toxicity. In this review, we discuss the regulatory role of MMPs in cancer progression, current strategies in targeting MMPs for cancer treatment including prodrug design and tumor imaging, and therapeutic value of MMPs as biomarkers in breast, lung, and prostate cancers.

Preclinical Rationale for the Phase III Trials in Metastatic Pancreatic Cancer: Is Wishful Thinking Clouding Successful Drug Development for Pancreatic Cancer?

Prior phase III trials in advanced pancreatic cancer have been predominantly unsuccessful. In this review, we attempt to understand how past preclinical data were translated into phase III clinical trials in metastatic pancreatic cancer as described in the article. A systematic literature review conducted through the MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases, from January 1997 to June 2015 using key words-phase III clinical trials, metastatic/advanced pancreatic adenocarcinoma or pancreatic cancer identified 30 randomized controlled trials (RCTs) that met criteria. The trials were limited to RCTs in the first-line treatment of patients with metastatic pancreatic cancer. The success rate of first-line phase III studies in advanced pancreatic cancer was only 13%. In 60% of the RCTs, no preclinical experiments were referenced in biologically cognate pancreatic models. Nine (30%) of the RCTs were designed based on preclinical evidence from in vitro cell lines alone without additional in vivo validation in xenograft models. It remains uncertain how strongly the preclinical data influence the development of clinical regimens but so far the studies developed based on more solid preclinical evidence have been successful.

Involvement of matrix metalloproteinases (MMPs) and inflammasome pathway in molecular mechanisms of fibrosis

Fibrosis is a basic connective tissue lesion defined by the increase in the fibrillar extracellular matrix (ECM) components in tissue or organ. Matrix metalloproteinases (MMPs) are a major group of proteases known to regulate the turn-over of ECM and so they are suggested to be important in tissue remodelling observed during fibrogenic process associated with chronic inflammation. Tissue remodelling is the result of an imbalance in the equilibrium of the normal processes of synthesis and degradation of ECM components markedly controlled by the MMPs/TIMP imbalance. We previously showed an association of the differences in collagen deposition in the lungs of bleomycin-treated mice with a reduced molar pro-MMP-9/TIMP-1 ratio. Using the carbon tetrachloride (CCl₄) preclinical model of liver fibrosis in mice, we observed a significant increase in collagen deposition with increased expression and release of tissue inhibitors of metalloproteinase (TIMP)-1 both at 24 h and 3 weeks later. This suggests an early altered regulation of matrix turnover involved in the development of fibrosis. We also demonstrated an activation of NLRP3-inflammasome pathway associated with the IL-1R/MyD88 signalling in the development of experimental fibrosis both in lung and liver. This was also associated with an increased expression of purinergic receptors mainly P2X₇. Finally, these observations emphasize those effective therapies for these disorders must be given early in the natural history of the disease, prior to the development of tissue remodelling and fibrosis.

ADAM15 Is Functionally Associated with the Metastatic Progression of Human Bladder Cancer

ADAM15 is a member of a family of catalytically active disintegrin membrane metalloproteinases that function as molecular signaling switches, shed membrane bound growth factors and/or cleave and inactivate cell adhesion molecules. Aberrant metalloproteinase function of ADAM15 may contribute to tumor progression through the release of growth factors or disruption of cell adhesion. In this study, we utilized human bladder cancer tissues and cell lines to evaluate the expression and function of ADAM15 in the progression of human bladder cancer. Examination of genome and transcriptome databases revealed that ADAM15 ranked in the top 5% of amplified genes and its mRNA was significantly overexpressed in invasive and metastatic bladder cancer compared to noninvasive disease. Immunostaining of a bladder tumor tissue array designed to evaluate disease progression revealed increased ADAM15 immunoreactivity associated with increasing cancer stage and exhibited significantly stronger staining in metastatic samples. About half of the invasive tumors and the majority of the metastatic cases exhibited high ADAM15 staining index, while all low grade and noninvasive cases exhibited negative or low staining. The knockdown of ADAM15 mRNA expression significantly inhibited bladder tumor cell migration and reduced the invasive capacity of bladder tumor cells through Matrigel^TM and monolayers of vascular endothelium. The knockdown of ADAM15 in a human xenograft model of bladder cancer inhibited tumor growth by 45% compared to controls. Structural modeling of the catalytic domain led to the design of a novel ADAM15-specific sulfonamide inhibitor that demonstrated bioactivity and significantly reduced the viability of bladder cancer cells in vitro and in human bladder cancer xenografts. Taken together, the results revealed an undescribed role of ADAM15 in the invasion of human bladder cancer and suggested that the ADAM15 catalytic domain may represent a viable therapeutic target in patients with advanced disease.

Novel approach to analysis of in vitro tumor angiogenesis with a variable-pressure scanning electron microscope: suppression by matrix metalloproteinase inhibitor SI-27

Degradation of basement membrane by metalloproteinases (MMP) is a critical step in tumor angiogenesis. To evaluate in vitro angiogenesis, several models have been employed, including bovine cornea, fenestrated rat brain, Matrigel, and others. These models did not provide quantitative analysis of capillary formation. The current study aimed for a novel approach to in vitro assay of angiogenesis with a "wet scanning electron microscope (SEM)" to investigate suppression of tumor angiogenesis by the MMP inhibitor, SI-27. The effects of noncytotoxic concentrations of SI-27 (1-100 microM) were determined on nonmitogenic vascular endothelial growth factor (VEGF) (10 ng/ml)-mediated cell motility and in vitro angiogenesis of human umbilical vein endothelial cells (HUVECs). Activities of MMP and tissue inhibitor of metalloproteinase (TIMP) were determined by enzyme-linked immunosorbent assay (ELISA). Subsequently, the inhibitory effect of SI-27 was examined on in vitro angiogenesis stimulated by supernatants of human glioma cell lines (U87MG, U251MG, or U373MG). In vitro angiogenesis was quantitatively analyzed with a variable-pressure SEM. Cell motility and in vitro angiogenesis by HUVECs were significantly increased by VEGF along with elevated MMP-1 and -2 activity, whereas SI-27 significantly suppressed VEGF-mediated in vitro angiogenesis and inactivated both MMP-1 and MMP-2, but not inhibited cell motility. The angiogenesis promoted by glioma supernatants showed a significant reduction in the presence of SI-27. SI-27, a novel MMP inhibitor, inhibited tumor angiogenesis in vitro. It can be anticipated to prevent tumor growth through its angiosuppressive effect. Quantitative analysis with a variable-pressure SEM is a novel approach to in vitro angiogenesis assay.

Comparative enzyme immunoassay of matrix metalloproteinases-2, -7, -9 and their tissue inhibitor-2 in tumors and plasma of patients with gastric cancer

The content of matrix metalloproteinases (MMP) -2, -7, and -9 was significantly higher in tumors in comparison with the adjacent histologically intact gastric mucosa in 80, 70, and 72% patients with gastric cancer, respectively, the increase in the level of MMP tissue inhibitor-2 (TIMP-2) detected in 61% tumors was insignificant. Only plasma level of MMP-7 was elevated in primary patients in comparison with the control and positively correlated with the expression of this protein in the tumor. The concentration of MMP-7 was maximum in the blood of patients with tumor invasion in lymph vessels. These data suggest MMP-7 as a possible serological marker of gastric cancer.

Ocular neovascularization caused by herpes simplex virus type 1 infection results from breakdown of binding between vascular endothelial growth factor A and its soluble receptor

The normal cornea is transparent, which is essential for normal vision, and although the angiogenic factor vascular endothelial growth factor A (VEGF-A) is present in the cornea, its angiogenic activity is impeded by being bound to a soluble form of the VEGF receptor-1 (sVR-1). This report investigates the effect on the balance between VEGF-A and sVR-1 that occurs after ocular infection with HSV, which causes prominent neovascularization, an essential step in the pathogenesis of the vision-impairing lesion, stromal keratitis. We demonstrate that HSV-1 infection causes increased production of VEGF-A but reduces sVR-1 levels, resulting in an imbalance of VEGF-A and sVR-1 levels in ocular tissues. Moreover, the sVR-1 protein made was degraded by the metalloproteinase (MMP) enzymes MMP-2, -7, and -9 produced by infiltrating inflammatory cells that were principally neutrophils. Inhibition of neutrophils, inhibition of sVR-1 breakdown with the MMP inhibitor marimastat, and the provision of exogenous recombinant sVR-1 protein all resulted in reduced angiogenesis. Our results make the novel observation that ocular neovascularization resulting from HSV infection involves a change in the balance between VEGF-A and its soluble inhibitory receptor. Future therapies aimed to increase the production and activity of sVR-1 protein could benefit the management of stromal keratitis, an important cause of human blindness.

Novel investigational drugs for gastric cancer

BACKGROUND

Gastric cancer still represents a leading cause of death worldwide. Several cytotoxic agents have demonstrated activity and combination regimens improve progression-free survival, overall survival and quality of life. Nevertheless, now there is no standard therapy for advanced gastric cancer patients.

OBJECTIVE

To evaluate the role of new investigational agents.

METHODS

We analysed Phase I, II and III studies that evaluated tailored drugs directed against the epidermal growth factor receptor (EGFR), the c-erbB2, the vascular endothelial growth factor (VEGF), the vascular endothelial growth factor receptor (VEGFR), the matrix metalloproteinases (MMP) and the mammalian target of rapamycin (mTOR).

CONCLUSION

Data from Phase II trials indicate the potential of improved efficacy of chemotherapy when administered in combination with bevacizumab and cetuximab. Trastuzumab results are ongoing, while marimastat has not obtained clinical developments even if it has demonstrated to be an active drug in this setting of patients.

Role of matrix metalloproteinases in the inflammatory process of respiratory diseases

Matrix metalloproteinases (MMPs) are a group of proteases known to regulate the turnover of extracellular matrix and thus are suggested to be important in the process of several diseases associated with tissue remodeling. Furthermore, the concept that modulation of airway remodeling including excessive proteolysis damage of the tissue, may be of interest as a basis for future treatment. Degradation of extracellular matrix is currently associated with structural and recruited cell activation and release of inflammatory mediators and MMPs. Indeed, a marked increase in their expression is observed associated with a variety of inflammatory diseases, including respiratory pathologies. In these conditions, we have to consider MMPs as therapeutic targets which can be inhibited by non-selective and/or selective inhibitors as anti-inflammatory compounds. The present review aims to discuss the potential interest of the inhibition of MMP in inflammatory diseases with a focus on respiratory diseases.

The initial steps of ovarian cancer cell metastasis are mediated by MMP-2 cleavage of vitronectin and fibronectin

Most patients (80%) with ovarian cancer (OvCa) present with metastatic disease. Attachment of OvCa cells to peritoneum and omentum represents the first rate-limiting step for metastatic spread. Therefore, identifying factors regulating cell attachment in the abdominal cavity is critical to the development of therapeutic agents. We show here that MMP-2 expression was upregulated in OvCa cells upon attachment to their microenvironment. Downregulation of MMP-2 mRNA or pharmacological inhibition of MMP-2 proteolytic function, in both human OvCa primary cells and cell lines, reduced attachment of OvCa cells to a 3D organotypic model of metastatic OvCa, full human omentum or peritoneum, and in vivo to mouse peritoneum and omentum. Absence of MMP-2 in the host did not alter OvCa adhesion, as determined utilizing mice harboring homozygous null mutations in either the Mmp2 or Mmp9 genes. Conversely, adhesion induced upregulation of MMP-2 mRNA in OvCa cells. MMP-2 inhibition in OvCa cells through pharmacological or antibody treatment prior to i.p. dissemination in nude mice significantly decreased tumor growth and metastasis and extended survival. MMP-2 enhanced peritoneal adhesion of OvCa cells through cleavage of ECM proteins fibronectin (FN) and vitronectin (Vn) into small fragments and increased binding of OvCa cells to these FN and Vn fragments and their receptors, alpha5beta1 and alphaVbeta3 integrin. These findings indicate that MMP-2 expressed by metastatic OvCa cells functionally regulates their attachment to peritoneal surfaces.

Antiangiogenic strategies in pancreatic cancer

Since the introduction of gemcitabine in the treatment of pancreatic cancer, progress in the use of combination chemotherapies has been very limited. Of the different novel options, antiangiogenic treatment strategies are among those being intensively studied in preclinical and clinical settings of adenocarcinoma of the pancreas. Phase I and limited-size phase II studies using drugs with antiangiogenic properties have reported encouraging results. Overall, the results of phase III studies with some metalloprotease inhibitors and bevacizumab have so far failed to demonstrate a survival benefit for these drugs. Further investigations that will take into account the heterogeneity of pancreatic cancer are warranted using these or other antiangiogenic active substances.

Tackling EGFR signaling with TACE antagonists: a rational target for metalloprotease inhibitors in cancer

TNF-alpha converting enzyme (TACE/ADAM17) is a transmembrane metalloprotease that plays a key role in the cleavage and mobilization of receptor ligands that are initially synthesized as membrane-tethered precursors. For many years, attention has focused on the role of TACE-dependent TNF-alpha cleavage in arthritis and, more recently, it has become apparent that TACE also plays an important role in regulating epidermal growth factor receptor activity in several tumor types. This review presents the background to these findings and a rationale for the continued development of TACE inhibitors for the treatment of epidermal growth factor receptor-dependent epithelial tumors.

Novel targets in gastric and esophageal cancer

Esophageal cancer (EC) and gastric cancer (GC) constitute a major cause of cancer deaths worldwide. Recent improvements in both surgical techniques and adjuvant/neoadjuvant chemotherapy, radiotherapy or both have increased the survival of patients with loco-regional disease. However, most patients with GC or EC have advanced disease either at diagnosis or during the follow-up, and despite recent advances, these patients still do poorly. Understanding of the molecular pathways that characterize cell growth, cell cycle, apoptosis, angiogenesis and invasion has provided novel targets in cancer therapy. In this review we describe the current status of targeted therapies in the treatment of EC and GC, including EGFR inhibitors, antiangiogenic agents, cell cycle inhibitors, apoptosis promoters and matrix metalloproteinases inhibitors. The emerging data from the clinical development of these compounds has provided novel opportunities in the treatment of EC and GC that will probably translate into clinical benefit for patients with these common malignancies.

Inhibition of matrix metalloproteinase activity and growth of gastric adenocarcinoma cells by an angiotensin converting enzyme inhibitor in in vitro and murine models

INTRODUCTION

Angiotensin converting enzyme (ACE) shares structural homology with the matrix metalloproteinase family of proteolytic enzymes (MMPs) responsible for degradation of the extracellular matrix (ECM). ACE inhibitors have been reported to protect against cancer in patients. The aim of this study was to determine whether the ACE inhibitor, captopril, could impair the activity of MMPs and impact on tumour invasion and growth in a cell line and murine model.

METHODS

For proof of principle, the protein activity of human MMP-2 and MMP-9 produced by the HT1080 fibrosarcoma cell line was detected using gelatin zymography. Gene expression was determined by real time reverse transcriptase PCR and tumour cell invasion using Matrigel invasion chambers. The effect of captopril on the in vivo growth of MGLVA-1 human gastric adenocarcinoma xenografts was evaluated in a nude mouse model.

RESULTS

Captopril inhibited activity of secreted MMP-9 and MMP-2, however, gene expression in HT1080 remained unaltered. Invasion of HT1080 cells was inhibited by 48% (p<0.001). Tumour size was reduced by 40-50% with 0.4 mg/ml captopril (p<0.01) and when combined with cisplatin the inhibition increased to 71% (p<0.05).

DISCUSSION

ACE inhibitors inhibit the activity of secreted MMP-2 and -9 by a mechanism similar to synthetic MMP inhibitors. ACE inhibitors have previously been shown to inhibit tumour growth, however; this is the first study to demonstrate inhibition of a human gastric xenograft, both alone and in combination with cisplatin. These results support further investigation into the anticancer effects of ACE inhibitors.

Role of matrix metalloproteinases in melanoma cell invasion

Cutaneous melanomas are notorious for their tendency to metastasize. Essential steps in this process are the degradation of basement membranes and remodeling of the extracellular matrix (ECM) by proteolytic enzymes such as matrix metalloproteinases (MMPs), which are regulated by their tissue inhibitors (TIMPs). An MMP expression is not restricted to tumor cells but is also found in stromal cells, indicating that stroma-derived proteases may contribute to melanoma progression. The MMPs have been shown to interact with a broad range of non-matrix proteins including adhesion molecules, growth factors and mediators of angiogenesis and apoptosis. In this review, we evaluate new insights into the interplay of MMPs and their molecular partners in melanoma progression.

Novel targeted therapies in the treatment of gastric and esophageal cancer

Esophageal cancer (EC) and gastric cancer (GC) constitute a major cause of cancer deaths worldwide. Recent improvements in both surgical techniques and adjuvant/neoadjuvant radiotherapy and chemotherapy approaches have increased the survival of patients with loco-regional disease. However, most of the patients with GC or EC have advanced disease either at diagnosis or at follow-up. Despite recent advances in the treatment of advanced disease, these patients still do poorly. An emerging understanding of the molecular pathways that characterize cell growth, cell cycle, apoptosis, angiogenesis and invasion has provided novel targets in cancer therapy. In this review we describe the current status of targeted therapies in the treatment of EC and GC. These therapeutic strategies include EGFR inhibitors, antiangiogenic agents, cell cycle inhibitors, apoptosis promoters and matrix metalloproteinases inhibitors. The emerging data from the clinical development of these compounds has provided novel opportunities in the treatment of EC and GC that will probably translate into efficacy advantage in the treatment of these common malignancies.

Inhibition of glioma angiogenesis and invasion by SI-27, an anti-matrix metalloproteinase agent in a rat brain tumor model

OBJECTIVE

The matrix metalloproteinase (MMP) inhibitor SI-27 has undergone extensive development because of its effectiveness against glioma invasion and angiogenesis. However, previous studies have been performed in vitro. The present work investigates the potential of SI-27 to inhibit tumor invasion, slow angiogenesis, and prolong survival in rodent brain tumor models.

METHODS

Stable enhanced green fluorescent protein-expressing clones of a human malignant glioma cell line, U251MG, were stereotactically xenografted into the periphery of the anterior striatum and corpus callosum of Fischer 944 rats after immunosuppression with cyclosporin A. SI-27 (1 or 10 mg/kg) or carrier solution was administered on three successive days by intraperitoneal injection, and tumor invasion and angiogenesis were assessed 3 weeks later by quantitative image analysis. This was performed on whole brain sections analyzed either by direct observation of enhanced green fluorescent protein-expressing glioma cells or by additional immunohistochemistry to detect the endothelial cells with anti-factor VIII monoclonal antibody. In situ zymography on frozen sections was used to detect MMP activity.

RESULTS

The group receiving a total of 30 mg/kg showed a statistically significant (P < 0.001) increase in survival time compared with the controls receiving carrier (median survival, 47.3 versus 32.6 d). There was also a decrease in MMP activity, tumor cell invasion, and neovascularization. In contrast, animals given 3 mg/kg did not show these differences.

CONCLUSION

Systemic administration of the anti-MMP agent SI-27 is effective in the treatment of glioma in an animal model.

Drug-induced apoptosis by a matrix metalloproteinase inhibitor, SI-27 on human malignant glioma cell lines; in vitro study

Matrix metalloproteinase (MMP) plays important roles in cell invasion and tumor angiogenesis. SI-27, an anti-MMP agent, has already been shown to possess both in vitro anti-invasive and anti-angiogenic properties against malignant gliomas in non-cytotoxic dose concentrations. However, to the best of our knowledge, the molecular mechanism mediating the cytotoxic action by this agent and the molecular mechanism in the cytotoxic action against malignant glioma cell have not yet been clarified. Therefore, we assessed the effect in the cytotoxic dose concentrations to investigate whether this cytotoxic action is related to apoptosis in this study. The effect on human glioma cell lines (U87MG, U251MG, and U373MG) was examined by transmission electron microscope, agarose gel electrophoresis with the DNA fragmentation, flow cytometry with FITC-conjugated Annexin V, and detection of caspase activity. Drug-induced apoptosis was observed in the cytotoxic dose. The result indicated that the cytotoxity of SI-27 might be related to the drug-induced apoptosis mediated by caspase.

Reduced angiogenesis in peritoneal dissemination of gastric cancer through gelatinase inhibition

Marimastat is a broad-spectrum matrix metalloproteinase (MMP) inhibitor that inhibits almost all major MMPs, key enzymes in gastric cancer invasion and metastasis. We investigated the ability of marimastat to inhibit tumor angiogenesis in the severe combined immuno-deficient (SCID) mouse/human gastric cancer model of peritoneal dissemination. A human stomach adenocarcinoma cell line, TMK-1, was injected intraperitoneally into SCID mice. On the 7th day after tumor inoculation, the administration of marimastat (27 mg/kg/day) was initiated and the treatment was continued for 2 weeks using subcutaneously-inoculating mini-osmotic pumps. On the 21st day, the mice were killed and the disseminated nodules were evaluated. Total weights, numbers, and the microvascular density of the disseminating nodules were significantly lower in mice treated with marimastat compared to the control group. Film in situ zymography demonstrated that net gelatinolytic activity in the tissues was weaker in treated-group nodules than in control-group nodules. Thus, our results suggested that marimastat inhibited peritoneal dissemination of human gastric cancer cells through inhibition of tumor angiogenesis, possibly involving the down-regulation of gelatinases, in SCID mice injected with human gastric cancer cells.

Anti-invasive effect of an anti-matrix metalloproteinase agent in a murine brain slice model using the serial monitoring of green fluorescent protein-labeled glioma cells

OBJECTIVE

We aimed to analyze the anti-invasive effect of the anti-matrix metalloproteinase (anti-MMP) agent SI-27 by quantitative tracking of enhanced green fluorescent protein (EGFP)-labeled human malignant glioma cell lines in a brain slice model.

METHODS

Persistent expression of EGFP in human malignant glioma cell clones (U87MG, U251MG, and U373MG) was established with the use of the pEGFP-C1 vector. Tumor spheroid in 1 microl Matrigel was implanted into the caudate nucleus-putamen of a severe combined immunodeficient mouse brain slice. To allow the quantitative assessment of tumor cell invasion, the invasion area index was measured on Days 1, 3, 5, and 7 with a fluorescence stereomicroscope and an image analyzer in the presence of various concentrations of SI-27 (0, 1, 10, 50, or 100 microg/ml).

RESULTS

In the control group (0 microg/ml), all glioma cell lines invaded in a fingerlike fashion and reached the contralateral hemisphere through the corpus callosum. SI-27 at concentrations of 10, 50, and 100 microg/ml significantly suppressed the invasion area index on Days 5 and 7 in a dose-dependent manner, whereas 1 microg/ml had no effect. Transmission electron microscopy and laser confocal microscopy indicated that the tumor cells had penetrated the brain slice and that the normal structural integrity of the brain was maintained until Day 7.

CONCLUSION

This model enabled unequivocal periodic tracking of individual invading tumor cells in normal brain. The significant suppression of glioma cell invasion by noncytotoxic concentrations of SI-27 indicates that anti-MMP treatment may represent an important future therapeutic strategy for malignant cerebral neoplasms.

Inhibition of cervical lymph node metastasis by marimastat (BB-2516) in an orthotopic oral squamous cell carcinoma implantation model

Activation of matrix metalloproteinase-2 (MMP-2) is a common event in head and neck squamous cell carcinoma. An OSC-19 cell line, derived from human oral squamous cell carcinoma and known to metastasize to cervical lymph nodes, was implanted into the lingual margin of mice. The effect of marimastat (BB-2516), a broad MMP inhibitor, on the suppression of regional cervical lymph node metastasis was evaluated with an orthotopic implantation nude mice model. Marimastat was given immediately after OSC-19 implantation and continuously administered by an osmotic pump. The mice were divided into three groups by marimastat dose; Group A; 0 mg/kg/day, Group B; 30 mg/kg/day, and Group C; 150 mg/kg/day. Twenty-one days after implantation, primary oral tumors and cervical lymph nodes were resected. Cervical lymph node status was microscopically examined. Activation of MMP-2 in primary oral tumor was examined by gelatin zymography. Both cervical lymph node metastasis and activation of MMP-2 were significantly suppressed in Group C (P < 0.05). Moreover, the Group C mice had a significantly better survival than group A (P = 0.0026). There was a significant difference between Group A and Group C in terms of proliferation of tumor cells by proliferating cell nuclear antigen immunostaining (P = 0.0120). These results suggest a positive role for marimastat in the inhibition of MMP-2 activation and prevention of cervical lymph node metastasis in oral squamous cell carcinoma (OSCC). Improvement of survival in patients with OSCC could be expected using adjuvant therapy with marimastat.

A double-blind placebo-controlled, randomised study comparing gemcitabine and marimastat with gemcitabine and placebo as first line therapy in patients with advanced pancreatic cancer

Pancreatic cancer is the fifth most common cause of cancer death in the western world and the prognosis for unresectable disease remains poor. Recent advances in conventional chemotherapy and the development of novel 'molecular' treatment strategies with different toxicity profiles warrant investigation as combination treatment strategies. This randomised study in pancreatic cancer compares marimastat (orally administered matrix metalloproteinase inhibitor) in combination with gemcitabine to gemcitabine alone. Two hundred and thirty-nine patients with unresectable pancreatic cancer were randomised to receive gemcitabine (1000 mg m(-2)) in combination with either marimastat or placebo. The primary end-point was survival. Objective tumour response and duration of response, time to treatment failure and disease progression, quality of life and safety were also assessed. There was no significant difference in survival between gemcitabine and marimastat and gemcitabine and placebo (P=0.95 log-rank test). Median survival times were 165.5 and 164 days and 1-year survival was 18% and 17% respectively. There were no significant differences in overall response rates (11 and 16% respectively), progression-free survival (P=0.68 log-rank test) or time to treatment failure (P=0.70 log-rank test) between the treatment arms. The gemcitabine and marimastat combination was well tolerated with only 2.5% of patients withdrawn due to presumed marimastat toxicity. Grade 3 or 4 musculoskeletal toxicities were reported in only 4% of the marimastat treated patients, although 59% of marimastat treated patients reported some musculoskeletal events. The results of this study provide no evidence to support a combination of marimastat with gemcitabine in patients with advanced pancreatic cancer. The combination of marimastat with gemcitabine was well tolerated. Further studies of marimastat as a maintenance treatment following a response or stable disease on gemcitabine may be justified.

Marimastat as maintenance therapy for patients with advanced gastric cancer: a randomised trial

This randomised, double-blind, placebo-controlled study was designed to evaluate the ability of the orally administered matrix metalloproteinase inhibitor, marimastat, to prolong survival in patients with non-resectable gastric and gastro-oesophageal adenocarcinoma. Three hundred and sixty-nine patients with histological proof of adenocarcinoma, who had received no more than a single regimen of 5-fluorouracil-based chemotherapy, were randomised to receive either marimastat (10 mg b.d.) or placebo. Patients were treated for as long as was tolerable. The primary endpoint was overall survival with secondary endpoints of time to disease progression and quality of life. At the point of protocol-defined study completion (85% mortality in the placebo arm) there was a modest difference in survival in the intention-to-treat population in favour of marimastat (P=0.07 log-rank test, hazard ratio=1.23 (95% confidence interval 0.98-1.55)). This survival benefit was maintained over a further 2 years of follow-up (P=0.024, hazard ratio=1.27 (1.03-1.57)). The median survival was 138 days for placebo and 160 days for marimastat, with 2-year survival of 3% and 9% respectively. A significant survival benefit was identified at study completion in the pre-defined sub-group of 123 patients who had received prior chemotherapy (P=0.045, hazard ratio=1.53 (1.00-2.34)). This benefit increased with 2 years additional follow-up (P=0.006, hazard ratio=1.68 (1.16-2.44)), with 2-year survival of 5% and 18% respectively. Progression-free survival was also significantly longer for patients receiving marimastat compared to placebo (P=0.009, hazard ratio=1.32 (1.07-1.63)). Marimastat treatment was associated with the development of musculoskeletal pain and inflammation. Events of anaemia, abdominal pain, jaundice and weight loss were more common in the placebo arm. This is one of the first demonstrations of a therapeutic benefit for a matrix metalloproteinase inhibitor in cancer patients. The greatest benefit was observed in patients who had previously received chemotherapy. A further randomised study of marimastat in these patients is warranted.

Suppression of matrix metalloproteinase activity by SI-27: detection by a new activity assay with S-2444, a specific chromogenic peptide

We have previously reported on the anti-invasive and angiosuppressive effects of SI-27, an anti-matrix metalloproteinase (MMP) agent. The molecular mechanism of its anti-MMP action, however, has not yet been determined. The purpose of this study was to investigate the effects of SI-27 on MMP- 1, -2, -3, -9, and TIMP-1, -2 secreted by human glioma cell lines (U87MG, U251MG, U373MG, and Y98G). When cells were exposed to non-cytotoxic concentrations of SI-27 (preliminarily determined by the MTT assay), expressions of mRNAs for the enzymes was not inhibited. For an MMP activity assay, we employed the fact that active MMPs could cleave modified pro-urokinase to form active urokinase, which then acted on S-2444 peptide to create a chromogenic product. Secretion of all pro-MMPs from glioma cells was not significantly reduced by SI-27. However, activation of pro-MMPs was significantly inhibited in a dose-dependent manner ((IC50 values for MMP-2; U87MG, 3.5 microg/ml; U25 IMG, 4.2 microg/ml; U373MG, 4.8 microg/ml; Y98G, 4.0 degreesg/ml); (IC50 values for MMP-9; 251MG, 7.2 microg/ml, U373MG, 2.8 microg/ml). In addition, active MMPs were not inhibited by SI-27. These findings were supported by zymographic analysis and by collagenolysis assay data. TIMP-1 and -2 were also not inactivated by SI-27. These findings suggest that SI-27 targets the activation process of pro-MMP. S-2444, a specific chromogenic peptide, was useful for quantitative analysis of the activity of MMP subtypes in this study.

SI-27, a novel inhibitor of matrix metalloproteinases with antiangiogenic activity: detection with a variable-pressure scanning electron microscope

OBJECTIVE

Degradation of basement membrane is one the of crucial steps in tumor angiogenesis and is performed by matrix metalloproteinases (MMPs). This study was designed to investigate the suppression of tumor angiogenesis by SI-27, an MMP inhibitor.

METHODS

SI-27 was applied at noncytotoxic concentrations (1-100 micromol/L), and its effect on nonmitogenic vascular endothelial growth factor (VEGF)-enhanced cell motility and in vitro angiogenesis by human umbilical vein endothelial cells was determined. The activity of MMP-1, MMP-2, and tissue inhibitor of metalloproteinase 1 was determined by enzyme-linked immunosorbent assay. The effect of SI-27 on in vitro angiogenesis stimulated by supernatants of human glioma cell lines (U87MG, U251MG, and U373MG) also was examined. Angiogenesis was detected with variable vacuum scanning electron microscopy.

RESULTS

Cell motility and in vitro angiogenesis by human umbilical vein endothelial cells were significantly increased by VEGF. The maximal effect on cell motility by VEGF was noted at 5 ng/ml (P < 0.001), and the maximal effect on the capillary network was observed at 10 ng/ml (P < 0.001), along with elevated MMP-1 and MMP-2 activity. Whereas SI-27 significantly suppressed VEGF-mediated in vitro angiogenesis (50 micromol/L; P < 0.001) and inactivated both MMP-1 and MMP-2, the expression of tissue inhibitor of metalloproteinase 1 and VEGF-mediated cell motility were not affected by SI-27. The angiogenesis promoted by glioma supernatants showed a significant reduction in the presence of SI-27 (10 micromol/L; U87MG, P < 0.01; U251MG, P < 0.01; U373MG, P < 0.01).

CONCLUSION

SI-27 inhibited in vitro tumor angiogenesis by suppression of MMP. This agent may be anticipated to prevent tumor growth through an angiosuppressive effect.

Prevention of liver metastasis of human colon cancer by selective matrix metalloproteinase inhibitor MMI-166

MMI-166 is a selective inhibitor of matrix metalloproteinase (MMP)-2 and MMP-9. Mice implanted a human colon cancer orthotopically received 200 mg/kg of MMI-166 orally for 5 weeks. Gelatin zymography demonstrated that the administration of MMI-166 remarkably decreased the active MMP-2 expression. Histological examination revealed that MMI-166 showed prominent effect on reduction of the invasive feature of the cancer cells and showed inhibitory effect on tumor vasculature, resulting in the significant decrease of microvessel density of the implanted tumor and liver metastasis compared with the control group. Conclusively, MMI-166 is a potent antiangiogenic oral agent for a human colon cancer.

Marimastat as first-line therapy for patients with unresectable pancreatic cancer: a randomized trial

PURPOSE

The prognosis for unresectable pancreatic cancer remains dismal (1-year survival rate, < 10%; 5-year survival rate, < 5%). Recent advances in conventional chemotherapy and novel molecular treatment strategies warrant investigation. This, the largest randomized study in pancreatic cancer performed to date, compares marimastat, the first of a new class of agents, with gemcitabine.

PATIENTS AND METHODS

Four hundred fourteen patients with unresectable pancreatic cancer were randomized to receive marimastat 5, 10, or 25 mg bid or gemcitabine 1,000 mg/m2. The primary end point was survival. Progression-free survival, patient benefit, and safety were also assessed.

RESULTS

There was no significant difference in survival between 5, 10, or 25 mg of marimastat and gemcitabine (P =.19). Median survival times were 111, 105, 125, and 167 days, respectively, and 1-year survival rates were 14%, 14%, 20%, and 19%, respectively. There was a significant difference in survival rates between patients treated with gemcitabine and marimastat 5 and 10 mg (P <.003). Both agents were well tolerated, although grade 3 or 4 toxicities were reported in 22% and 12% of the gemcitabine- and marimastat-treated patients, respectively. The major toxicity of marimastat was musculoskeletal (44% of marimastat patients, compared with 12% of gemcitabine patients; musculoskeletal toxicity was severe in only 8% of marimastat patients).

CONCLUSION

The results of this study provide evidence of a dose response for marimastat in patients with advanced pancreatic cancer. The 1-year survival rate for patients receiving marimastat 25 mg was similar to that of patients receiving gemcitabine. In view of the manageable tolerability of marimastat and its ease of administration, further studies are warranted.

Effect of combination therapy with matrix metalloproteinase inhibitor MMI-166 and mitomycin C on the growth and liver metastasis of human colon cancer

Several synthetic inhibitors of matrix metalloproteinases (MMPs) show antitumor, antimetastasis and antiangiogenesis effects in various models. Synergistic effects of combinations with conventional cytotoxic agents were reported previously. In this study, we examined the effects of a new selective MMP inhibitor, MMI-166, on tumor growth, angiogenesis and metastasis in a liver metastatic model of human xenotransplanted colon cancer (TK-4). We also investigated the synergistic effects of MMI-166 and a conventional cytotoxic agent, mitomycin C (MMC), in this model. Mice transplanted orthotopically with TK-4 were divided into 4 groups; a control group (treated with vehicle solution), an MMI-166 group in which MMI-166 was orally administered (p.o.) at a dose of 200 mg / kg, 6 days / week for 5 weeks, an MMC group in which MMC was administered intraperitoneally (i.p.) at a dose of 2 mg / kg / week for 5 weeks, and a combination group (treated with MMI-166 and MMC). MMI-166 did not inhibit transplanted tumor growth, but significantly inhibited liver metastasis compared with the control group and MMC group (P < 0.01). Significant antitumor and antimetastatic effects of the combination therapy were demonstrated. The microvessel density (MVD) detected by immunohistochemical staining with ER-MP12 antibody tended to be lower in the MMI-166 and the combination groups. These results suggest that MMI-166 has potential antimetastatic ability and a synergistic effect with MMC.

Matrix metalloproteinases in human melanoma

Cutaneous melanoma is a highly invasive and metastatic tumor. Degradation of basement membranes and extracellular matrix is an essential step in melanoma cell migration, invasion, and metastasis formation. Matrix metalloproteinases and their tissue inhibitors play a crucial role in these complex multistep processes. Melanoma cells may express a number of matrix metalloproteinase family members (MMP-1, MMP-2, MMP-9, MMP-13, and MT1-MMP) as well as their tissue inhibitors (TIMP-1, TIMP-2, and TIMP-3). Numerous studies have examined matrix metalloproteinases, their tissue inhibitors, and the molecules that regulate their expression and/or activation in melanoma cell lines in vitro and in vivo, and in human melanocytic lesions. Recent results have indicated that adhesion molecules such as CD44 and integrin alphavbeta3 are involved in positioning activated matrix metalloproteinase molecules on the cell surface of invasive tumor cells. In this review we evaluate these novel aspects of the role of matrix metalloproteinases and their tissue inhibitors in melanoma progression. We conclude that the balance between levels of activated matrix metalloproteinases and expression levels of their tissue inhibitors, and the coexpression of activated matrix metalloproteinases and adhesion molecules are important factors in determining melanoma cell invasion, tumor growth, and metastasis formation.

Ongoing trials with matrix metalloproteinase inhibitors

Excessive or poorly regulated matrix metalloproteinase (MMP) activity has been implicated as a pathogenic factor in a range of diseases where the extracellular matrix is degraded or remodelled. Synthetic, potent, low molecular weight MMP inhibitors (MMPIs) have been developed and, over the past five years, these agents have begun clinical testing in patients with cancer, rheumatoid arthritis, osteoarthritis and acute macular degeneration. The past year has seen a number of disappointments with the halting of clinical trials of Ro 32-3555 in patients with rheumatoid arthritis and of BAY 12-9566 in patients with cancer. There have, however, been some successes with perhaps the clearest indication of efficacy being seen in the results of a Phase III trial of marimastat in patients with advanced gastric cancer. Clinical trials are continuing with marimastat and other MMPIs, including prinomastat, solimastat, BMS 275291, metastat and neovastat. Results from these trials are expected in the next two years and it is likely that clinical trials with MMPIs will begin in patients with other diseases where MMPs are believed to be involved, such as restenosis, cerebral haemorrhage and multiple sclerosis. Future research is likely to focus on the identification of specific MMP targets in different diseases, both in order to improve efficacy and to reduce the musculoskeletal side effect profile that has characterised several of the first generation oral MMPIs.

Matrix metalloproteinases: molecular aspects of their roles in tumour invasion and metastasis

The matrix metalloproteinases (MMPs) are a family of proteolytic enzymes, whose physiological functions include tissue remodelling and embryogenesis. The importance of this group of proteins in the processes of tumour invasion and metastasis is now widely acknowledged, and has led to the search for MMP inhibitors for use as anticancer treatments in a clinical setting. This review aims to bring the reader up-to-date with current research relating to MMPs, with particular emphasis on emerging mechanisms of regulation of these enzymes, and their interaction with cell adhesion molecules. The therapeutic inhibition of MMPs will also be discussed.