Expression and activity of matrix metalloproteases in human malignant mesothelioma cell lines

Targeting SRC Family Kinases in Mesothelioma: Time to Upgrade

Malignant mesothelioma (MM) is a deadly tumor mainly caused by exposure to asbestos. Unfortunately, no current treatment is able to change significantly the natural history of the disease, which has a poor prognosis in the majority of patients. The non-receptor tyrosine kinase SRC and other SRC family kinase (SFK) members are frequently hyperactivated in many cancer types, including MM. Several works have indeed suggested that SFKs underlie MM cell proliferation, survival, motility, and invasion, overall affecting multiple oncogenic pathways. Consistently, SFK inhibitors effectively counteracted MM cancerous features at the preclinical level. Dasatinib, a multi-kinase inhibitor targeting SFKs, was also assessed in clinical trials either as second-line treatment for patients with unresectable MM or, more recently, as a neoadjuvant agent in patients with resectable MM. Here, we provide an overview of the molecular mechanisms implicating SFKs in MM progression and discuss possible strategies for a more successful clinical application of SFK inhibitors. Our aim is to stimulate discussion and further consideration of these agents in better designed preclinical and clinical studies to make the most of another class of powerful antitumoral drugs, which too often are lost in translation when applied to MM.

MicroRNA‑21 contributes to renal cell carcinoma cell invasiveness and angiogenesis via the PDCD4/c‑Jun (AP‑1) signalling pathway

Accumulating evidence has demonstrated that microRNAs are associated with malignant biological behaviour, including tumorigenesis, cancer progression and metastasis via the regulation of target gene expression. Our previous study demonstrated that programmed cell death protein 4 (PDCD4), which is a tumour suppressor gene, is a target of microRNA‑21 (miR‑21), which affects the proliferation and transformation capabilities of renal cell carcinoma (RCC) cells. However, the role of miR‑21 in the molecular mechanism underlying the migration, invasion and angiogenesis of RCC remains poorly understood. The effects of miR‑21 on the invasion, migration and angiogenesis of RCC cells was determined through meta‑analysis and regulation of miR‑21 expression in vitro. After searching several databases, 6 articles including a total of 473 patients met the eligibility criteria for this analysis. The combined results of the meta‑analysis revealed that increased miR‑21 expression was significantly associated with adverse prognosis in patients with RCC, with a pooled hazard ratio estimate of 1.740. In in vitro experiments, we demonstrated that a miR‑21 inhibitor decreased the number of migrating and invading A498 and 786‑O RCC cells, along with a decrease in PDCD4, c‑Jun, matrix metalloproteinase (MMP)2 and MMP9 expression. Additionally, inhibition of miR‑21 was revealed to reduce tube formation and tube junctions in the endothelial cell line HMEC‑1 by affecting the expression of angiotensin‑1 and vascular endothelial growth factor A, whereas PDCD4 small interfering RNA exerted opposite effects on the same cells. Overall, these findings, along with evidence‑based molecular biology, demonstrated that miR‑21 expression promoted the migration, invasion and angiogenic abilities of RCC cells by directly targeting the PDCD4/c‑Jun signalling pathway. The results may help elucidate the molecular mechanism underlying the development and progression of RCC and provide a promising target for microRNA‑based therapy.

Adenosine diphosphate regulates MMP2 and MMP9 activity in malignant mesothelioma cells

Although an association between cancer progression and matrix metalloproteinase (MMP) 2 and MPP9 expression has been known, the expression, nuclear localization, and physiologically controlled activation of these two MMPs have not been investigated in malignant mesothelioma cells. We examined the expression and intracellular localization of MMP2/9 in ZL55 malignant mesothelioma cells, as well as their regulation by ADP. Using real-time PCR, we showed that activation of the P2Y1 receptor by ADP increased the expression of MMP2/9 mRNAs; MMP2/9 collected from conditioned media also showed an increase in activity; and ADP induced the nuclear localization of MMP2/9. The effects of ADP on transcription of the MMPs were due to activation of c-Src, Akt, and NF-κB, while ERK1/2 phosphorylation was needed for the increase in enzymatic activity and the regulation of nuclear import. We also showed that the nuclear localization of MMP2/9 induced by ADP causes the cleavage and inactivation of poly-ADP-ribose polymerase-1. These findings may help to elucidate the mechanisms regulating MMP2/9 activation in ZL55 human epithelioid mesothelioma cells, and perhaps other cells. Therapeutic approaches that promote ADP accumulation in a tumor environment may constitute an effective means to induce anticancer activity.

Regulation of microRNA using promising dietary phytochemicals: Possible preventive and treatment option of malignant mesothelioma

Malignant mesothelioma (MM) is a very aggressive, lethal cancer, and its incidence is increasing worldwide. Development of multi-drug resistance, therapy related side-effects, and disease recurrence after therapy are the major problems for the successful treatment of MM. Emerging evidence indicates that dietary phytochemicals can exert anti-cancer activities by regulating microRNA expression. Until now, only one dietary phytochemical (ursolic acid) has been reported to have MM microRNA regulatory ability. A large number of dietary phytochemicals still remain to be tested. In this paper, we have introduced some dietary phytochemicals (curcumin, epigallocatechin gallate, quercetin, genistein, pterostilbene, resveratrol, capsaicin, ellagic acid, benzyl isothiocyanate, phenethyl isothiocyanate, sulforaphane, indole-3-carbinol, 3,3'-diindolylmethane, diallyl disulphide, betulinic acid, and oleanolic acid) which have shown microRNA regulatory activities in various cancers and could regulate MM microRNAs. In addition to microRNA regulatory activities, curcumin, epigallocatechin gallate, quercetin, genistein, resveratrol, phenethyl isothiocyanate, and sulforaphane have anti-mesothelioma potentials, and pterostilbene, capsaicin, ellagic acid, benzyl isothiocyanate, indole-3-carbinol, 3,3'-diindolylmethane, diallyl disulphide, betulinic acid, and oleanolic acid have potentials to inhibit cancer by regulating the expression of various genes which are also known to be aberrant in MM.

Nanoparticles for modulating tumor microenvironment to improve drug delivery and tumor therapy

Tumor microenvironment (TME) plays a critical role in tumorigenesis, tumor invasion and metastasis. TME is composed of stroma, endothelial cells, pericytes, fibroblasts, smooth muscle cells, and immune cells, which is characterized by hypoxia, acidosis, and high interstitial fluid pressure. Due to the important role of TME, we firstly reviewed the composition of TME and discussed the impact of TME on tumor progression, drug and nanoparticle delivery. Next, we reviewed current strategies developed to modulate TME, including modulating tumor vasculature permeability, tumor associated macrophage phenotypes, tumor associated fibroblasts, tumor stroma components, tumor hypoxia, and multiple interventions simultaneously. Also, potential problems and future directions of TME modulation strategy have been discussed.

Reactive oxygen species a double-edged sword for mesothelioma

It is well known that oxidative stress can lead to chronic inflammation which, in turn, could mediate most chronic diseases including cancer. Oxidants have been implicated in the activity of crocidolite and amosite, the most powerful types of asbestos associated to the occurrence of mesothelioma. Currently rates of mesothelioma are rising and estimates indicate that the incidence of mesothelioma will peak within the next 10-15 years in the western world, while in Japan the peak is predicted not to occur until 40 years from now. Although the use of asbestos has been banned in many countries around the world, production of and the potentially hazardous exposure to asbestos is still present with locally high incidences of mesothelioma. Today a new man-made material, carbon nanotubes, has arisen as a concern; carbon nanotubes may display 'asbestos-like' pathogenicity with mesothelioma induction potential. Carbon nanotubes resulted in the greatest reactive oxygen species generation. How oxidative stress activates inflammatory pathways leading to the transformation of a normal cell to a tumor cell, to tumor cell survival, proliferation, invasion, angiogenesis, chemoresistance, and radioresistance, is the aim of this review.

Influence of Immune Myeloid Cells on the Extracellular Matrix During Cancer Metastasis

The extracellular matrix (ECM) is one of the most important components within the tumor microenvironment that supports cancer development and metastasis. Under normal physiological conditions, the ECM is a tightly regulated network providing structural and biochemical support. However, the ECM becomes highly disorganized during neoplastic progression and consequently, stimulates cancer cell transformation, growth and spread. Cancer development and progression is also known to greatly benefit from the support of immune myeloid cells, which have multiple pro-tumorigenic functions including promoting tumor growth, migration and invasion, stimulating angiogenesis and suppressing anti-tumor responses. An increasing number of studies have shown that myeloid cells alter the ECM to support metastatic cancer progression and in turn, the ECM can influence the function of infiltrating myeloid cells. However, the exact nature of this relationship, such as the mechanisms employed and their molecular targets remains unclear. This review discusses evidence for the reciprocal dependence of myeloid cells and the tumor ECM for efficient tumor development and explores potential mechanisms involved in these interactions. A better understanding of this relationship has exciting implications for the development of new therapeutic treatments for metastatic cancer.

Differential expression of extracellular matrix constituents and cell adhesion molecules between malignant pleural mesothelioma and mesothelial hyperplasia

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a highly aggressive neoplasm associated with asbestos exposure. Currently, the molecular mechanisms that induce MPM development are still unknown. The purpose of this study was to identify new molecular biomarkers for mesothelial carcinogenesis.

METHODS

We analyzed a panel of 84 genes involved in extracellular matrix remodeling and cell adhesion by polymerase chain reaction (PCR) array in 15 samples of epithelioid mesothelioma and 10 samples of reactive mesothelial hyperplasia (MH; 3 of 25 samples were inadequate for mRNA analysis). To validate the differentially expressed genes identified by PCR array, we analyzed 27 more samples by immunohistochemistry, in addition to the 25 samples already studied.

RESULTS

Twenty-five genes were differentially expressed in MPM and MH by PCR array. Of these we studied matrix metalloproteinase 7 (MMP7), MMP14, CD44, and integrin, alpha3 expression by immunohistochemistry in 26 epithelioid MPM and 26 MH samples from the entire series of 52 cases. We observed higher MMP14 and integrin, alpha3 expression in MPM samples compared with MH samples (p = 0.000002 and p = 0.000002, respectively). Conversely, CD44 expression was low in most (57.7%) mesothelioma samples but only in 11.5% of the MH samples (p = 0.0013). As regards MMP7, we did not observe differential expression between MH and MPM samples.

CONCLUSIONS

We have extensively studied genes involved in cell adhesion and extracellular matrix remodeling in MPM and MH samples, gaining new insight into the pathophysiology of mesothelioma. Moreover, our data suggest that these factors could be potential biomarkers for MPM.

In vitro modulation of MMP-2 and MMP-9 in pediatric human sarcoma cell lines by cytokines, inducers and inhibitors

The highly aggressive pediatric sarcomas are characterized by high levels of matrix metalloproteinase (MMP)-2 and MMP-9, which play crucial roles in tumor invasion and metastasis by degradation of the extracellular membrane leading to cancer cell spread to distal organs. We examined the effects of cytokines, mitogens, inducers and inhibitors on MMP-2 and -9 expression in osteosarcoma (U2OS) and rhabdomyosarcoma (RD). The selected compounds included natural cytokines and growth factors, as well as chemical compounds applied in therapy of sarcoma and natural compounds that have demonstrated anticancer therapeutic potential. These cell lines were cultured in their respective media to near confluence and the cells were washed with PBS and incubated in serum-free medium with various concentrations of several cytokines, mitogens and inhibitors. After 24 h the media were removed and analyzed for MMP-2 and -9 by gelatinase zymography and quantitated by densitometry. Osteosarcoma and rhabdomyosarcoma showed bands corresponding to MMP-2 and -9 with dose-dependent enhancement of MMP-9 with phorbol 12-myristate 13-acetate (PMA) treatment. Tumor necrosis factor-α, interleukin-1β and LPS enhanced osteosarcoma U2OS MMP-9 secretion but had no effect on MMP-2 secretion. Tumor necrosis factor-α stimulated rhabdomyosarcoma MMP-2 expression, but had no effect on MMP-9 secretion. Doxycycline, epigallocatechin gallate, nutrient mixture (NM), actinomycin-D, cyclohex-amide, retinoic acid and dexamethasone inhibited MMP-2 and -9 in U2OS osteosarcoma cells. PMA-treated RD cells showed dose-response inhibition of MMP-9 by doxycycline and epigallocatechin gallate and both MMPs by NM. Dexamethasone and actinomycin-D showed inhibition of MMP-2 secretion of RD cells. Our results show that cytokines, mitogens and inducers show variable upregulation of U2OS osteosarcoma and RD rhabdomyosarcoma MMP-2 and -9 secretion, and inhibitors demonstrate downregulation under stimulatory conditions, suggesting the application of these agents for the development of effective therapies in pediatric sarcomas.

In vitro modulation of MMP-2 and MMP-9 in adult human sarcoma cell lines by cytokines, inducers and inhibitors

The highly aggressive adult sarcomas are characterized by high levels of matrix metalloproteinase (MMP)-2 and -9, which play crucial roles in tumor invasion and metastasis by degradation of the extracellular membrane leading to cancer cell spread to distal organs. We examined the effect of cytokines, mitogens, inducers and inhibitors on MMP-2 and MMP-9 secretion in chondrosarcoma (SW-1353), fibrosarcoma (HT-1080), liposarcoma (SW-872) and synovial sarcoma (SW-982) cell lines. The selected compounds included natural cytokines and growth factors, as well as chemical compounds applied in therapy of sarcoma and natural compounds that have demonstrated anticancer therapeutic potential. MMP-2 and MMP-9 secretions were analyzed by gelatinase zymography following 24-h exposure to the tested agents and quantitated by densitometry. Fibrosarcoma, chondrosarcoma, liposarcoma and synovial sarcoma showed bands corresponding to MMP-2 and MMP-9 with dose-dependent enhancement of MMP-9 with phorbol 12-myristate 13-acetate (PMA) treatment. In chondrosarcoma cells, tumor necrosis factor (TNF)-α had a stimulatory effect on MMP-9 and insignificant effect on MMP-2 and interleukin (IL)-1β stimulated MMP-9 and MMP-2. In fibrosarcoma and liposarcoma cells, TNF-α had a profound stimulatory effect on MMP-9, but no effect on MMP-2 and in synovial sarcoma an inhibitory effect on MMP-2 and no effect on MMP-9. IL-1β had a slight inhibitory effect on fibrosarcoma, liposarcoma and synovial sarcoma MMP-2 and MMP-9 except for MMP-9 in synovial sarcoma which showed slight stimulation. Lipopolysaccharide (LPS) stimulated expression of MMP-2 in fibrosarcoma and chondrosarcoma while inhibited it in liposarcoma. Doxycycline, epigallocatechin gallate and the nutrient mixture inhibited MMP-2 and MMP-9 in all cell lines. Actinomycin-D, cyclohexamide, retinoic acid, and dexamethasone inhibited MMP-2 and -9 in chondrosarcoma and fibrosarcoma cells. Our results show that cytokines, mitogens, inducers and inhibitors have an up or down regulatory effect on MMP-2 and MMP-9 expression in adult sarcoma cell lines, suggesting these agents may be effective strategies to treat these cancers.

Using functional nanomaterials to target and regulate the tumor microenvironment: diagnostic and therapeutic applications

Malignant tumors remain a major health burden throughout the world and effective therapeutic strategies are urgently needed. Cancer nanotechnology, as an integrated platform, has the potential to dramatically improve cancer diagnosis, imaging, and therapy, while reducing the toxicity associated with the current approaches. Tumor microenvironment is an ensemble performance of various stromal cells and extracellular matrix. The recent progress in understanding the critical roles and the underlying mechanisms of the tumor microenvironment on tumor progression has resulted in emerging diagnostic and therapeutic nanomaterials designed and engineered specifically targeting the microenvironment components. Meanwhile, the bio-physicochemical differences between tumor and normal tissues have recently been exploited to achieve specific tumor-targeting for cancer diagnosis and treatment. Here, the major players in the tumor microenvironment and their biochemical properties, which can be utilized for the design of multifunctional nanomaterials with the potential to target and regulate this niche, are summarized. The recent progress in engineering intelligent and versatile nanomaterials for targeting and regulating the tumor microenvironment is emphasized. Although further investigations are required to develop robust methods for more specific tumor-targeting and well-controlled nanomaterials, the applications of tumor microenvironment regulation-based nanotechnology for safer and more effective anticancer nanomedicines have been proven successful and will eventually revolutionize the current landscape of cancer therapy.

Matrix metalloproteinase and its drug targets therapy in solid and hematological malignancies: an overview

Matrix metalloproteinase (MMP) comprises a family of zinc-dependent endopeptidases that degrade various components of the extracellular matrix (ECM) and basement membrane. MMPs are involved in solid and hematological malignancy through modification of cell growth, activation of cancer cells and modulation of immune functions. Several polymorphisms of different MMPs such as MMP-1 (-1607 1G/2G), MMP-2 (-1306 C/T), MMP-3 (-1171 5A/6A) & MMP-9 (-1562 C/T) and their expression levels have been well documented in different types of solid cancer. These polymorphic variations were found to be associated with angiogenesis, cancer progression, invasion and metastasis. There is paucity of data available in the field of hematological malignancies. Hence the field of matrix biology of hematological malignancies is an area of active exploration. A number of MMP inhibitors (MMPIs) have been developed for the cancer treatment. The most extensively studied classes of MMP inhibitors include Batimastat, Marismastat, Salimatat, Prinomastat and Tanomastat. However, their efficacy and action have not been confirmed and more data is required. The application of one or more selective targeted MMPIs in combination with conventional anti-leukemic treatment may represent a positive approach in combat against hematopoietic malignancies. Balance of MMPs and TIMPs is altered in different malignancies and biochemical pathways. These alternations will add another dimension in the matrix biology of both solid tumor and leukemia. MMP and TIMP singly and in combination are increasingly being recognized as an important player in basic cellular biology. Exploration and exploitation of MMP and TIMP balance in various malignant and nonmalignant lesions is going to be one of the most interesting facets of future use of this system for human health care.

Clinical role of pleural effusion MMP-3 levels in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive malignant tumor of mesothelial origin associated with asbestos exposure. MPM exhibits a limited response to conventional chemotherapy and radiotherapy. This, early diagnosis of MPM is essential. Malignant tumor progression requires the destruction of the basement membrane, which is constructed from extracellular matrix (ECM) materials. Various types of human tumor cells are reported to produce ECM-degrading proteases that are important in tumor progression. Among this group of proteolytic enzymes, matrix metalloproteinases (MMPs) are thought to be important due to their wide degrading function. We investigated the pleural effusion MMP-3 levels of patients with MPM and compared them with those of a population with non-malignant pleuritis or lung cancer involving malignant pleural effusion. The pleural effusion MMP-3 concentrations of 52 MPM patients and 67 non-MPM patients were measured. The results showed that the MPM patients had significantly higher pleural effusion MMP-3 levels than the population with non-malignant pleuritis. The overall survival of the MPM patients with lower pleural effusion MMP-3 levels was longer than that of patients with higher pleural effusion MMP-3 levels. Our data therefore suggest a clinical role of pleural effusion MMP-3 levels in malignant pleural mesothelioma.

Galectin-3 facilitates cell motility in gastric cancer by up-regulating protease-activated receptor-1 (PAR-1) and matrix metalloproteinase-1 (MMP-1)

BACKGROUND

Galectin-3 is known to regulate cancer metastasis. However, the underlying mechanism has not been defined. Through the DNA microarray studies after galectin-3 silencing, we demonstrated here that galectin-3 plays a key role in up-regulating the expressions of protease-activated receptor-1 (PAR-1) and matrix metalloproteinase-1 (MMP-1) PAR-1 thereby promoting gastric cancer metastasis.

METHODOLOGY/PRINCIPAL FINDINGS

We examined the expression levels of Galectin-3, PAR-1, and MMP-1 in gastric cancer patient tissues and also the effects of silencing these proteins with specific siRNAs and of over-expressing them using specific lenti-viral constructs. We also employed zebrafish embryo model for analysis of in vivo gastric cancer cell invasion. These studies demonstrated that: a) galectin-3 silencing decreases the expression of PAR-1. b) galectin-3 over-expression increases cell migration and invasion and this increase can be reversed by PAR-1 silencing, indicating that galectin-3 increases cell migration and invasion via PAR-1 up-regulation. c) galectin-3 directly interacts with AP-1 transcriptional factor, and this complex binds to PAR-1 promoter and drives PAR-1 transcription. d) galectin-3 also amplifies phospho-paxillin, a PAR-1 downstream target, by increasing MMP-1 expression. MMP-1 silencing blocks phospho-paxillin amplification and cell invasion caused by galectin-3 over-expression. e) Silencing of either galectin-3, PAR-1 or MMP-1 significantly reduced cell migration into the vessels in zebrafish embryo model. f) Galectin-3, PAR-1, and MMP-1 are highly expressed and co-localized in malignant tissues from gastric cancer patients.

CONCLUSIONS/SIGNIFICANCE

Galectin-3 plays the key role of activating cell surface receptor through production of protease and boosts gastric cancer metastasis. Galectin-3 has the potential to serve as a useful pharmacological target for prevention of gastric cancer metastasis.

Cell-growth and migration inhibition of human mesothelioma cells induced by 3-O-methylfunicone from Penicillium pinophilum and cisplatin

Malignant pleural mesothelioma is a fatal malignancy linked to asbestos exposure. The main challenge for mesothelioma treatment is to go beyond the drug resistance, in particular against cisplatin (CDDP), one of the most used chemotherapeutic drug. 3-O-methylfunicone (OMF) is a metabolite produced by the fungus Penicillium pinophilum; its antiproliferative properties have been previously studied in vitro. Particularly, OMF is able to inhibit mesothelioma cell motility. To improve the effects of CDDP by-passing the resistance of mesothelioma cells to this drug, in the present study we investigated the combined treatment of OMF with CDDP respectively in an established mesothelioma cell line (NCI) and primary mesothelioma cells (Mest). As compared to the effect of single treatments, the combination of OMF and CDDP resulted in a stronger inhibition of NCI and Mest cell proliferation. OMF combination with CDDP was also able to affect the migratory ability of NCI and Mest cells by down-regulating αv and β5 expression and reducing metalloproteinase 2 (MMP-2) production. In addition, this association was effective in modulating VEGF gene expression. This finding highlights the possibility to use OMF and CDDP together to regulate angiogenesis and tumour progression in mesothelioma.

MT1-MMP plays an important role in an invasive activity of malignant pleural mesothelioma cell

Malignant pleural mesothelioma (MPM) has a poor prognosis and is a treatment resistant tumor, which is increasing in frequency throughout the world. The poor prognosis is due to the aggressive local invasiveness rather than distant metastasis. In this study, we established a cell line of malignant mesothelioma from a clinical specimen and assessed the relationship between the expression of MT1-MMP and the invasion ability of that line, as well as the cultured cells of several other lines, using the simple method that we created previously. We established a cell line from a clinical specimen from a patient with malignant mesothelioma. We assessed the invasive activities of MPM cells in an easy-to-prepare double-layered collagen gel hemisphere (DL-CGH) system that enabled us to visualize cell movements during invasion. To assess the role of MT1-MMP in the invasive activity of MPM cells, we knocked down its expression by RNA interference (RNAi). The invasion assay with DL-CGH revealed that a high expression of MT1-MMP in MPM cells was associated with aggressive invasive activity. The RNAi of MT1-MMP indicated that the expression of MT1-MMP might have a crucial role in the invasiveness of MPM cells. The MT1-MMP expression in MPM cells is related to their capacity for locally aggressive spreading into the pleura and the surrounding tissues, and MT1-MMP should be a suitable molecular target for the suppression of the invasiveness of MPM.

3-O-Methylfunicone, a metabolite produced by Penicillium pinophilum, modulates ERK1/2 activity, affecting cell motility of human mesothelioma cells

OBJECTIVES

3-O-methylfunicone (OMF), a secondary metabolite produced by Penicillium pinophilum, affects cell proliferation and motility in a variety of human solid tumours. The aim of this study was to demonstrate whether OMF has the ability to arrest cell division and motility, in a human mesothelioma cell line. Malignant mesothelioma is an aggressive cancer that does not respond to standard therapies the cells of which are considered to be highly resistant to apoptosis.

MATERIAL AND METHODS

Cell motility and invasion were measured using a modified Boyden chamber. Gene expression was examined by RT-PCR, while ERK1/2 was investigated by Western blot analysis. All experiments were also performed on primary cultures of mesothelial cells.

RESULTS

The present study shows that OMF inhibited motility of the NCI mesothelioma cell line by modulating ERK signalling activity, and affected alphaVbeta5 integrin and MMP-2 expression, inducing marked downregulation at both mRNA and protein levels. Substantial downregulation of VEGF gene expression was also demonstrated. These effects were not observed in normal mesothelial cell cultures.

CONCLUSION

OMF may have potential as a naturally derived anti-tumour drug for treatment of mesothelioma.

Global gene expression profiling of human pleural mesotheliomas: identification of matrix metalloproteinase 14 (MMP-14) as potential tumour target

BACKGROUND

The goal of our study was to molecularly dissect mesothelioma tumour pathways by mean of microarray technologies in order to identify new tumour biomarkers that could be used as early diagnostic markers and possibly as specific molecular therapeutic targets.

METHODOLOGY

We performed Affymetrix HGU133A plus 2.0 microarray analysis, containing probes for about 39,000 human transcripts, comparing 9 human pleural mesotheliomas with 4 normal pleural specimens. Stringent statistical feature selection detected a set of differentially expressed genes that have been further evaluated to identify potential biomarkers to be used in early diagnostics. Selected genes were confirmed by RT-PCR. As reported by other mesothelioma profiling studies, most of genes are involved in G2/M transition. Our list contains several genes previously described as prognostic classifier. Furthermore, we found novel genes, never associated before to mesotheliom that could be involved in tumour progression. Notable is the identification of MMP-14, a member of matrix metalloproteinase family. In a cohort of 70 mesothelioma patients, we found by a multivariate Cox regression analysis, that the only parameter influencing overall survival was expression of MMP14. The calculated relative risk of death in MM patients with low MMP14 expression was significantly lower than patients with high MMp14 expression (P = 0.002).

CONCLUSIONS

Based on the results provided, this molecule could be viewed as a new and effective therapeutic target to test for the cure of mesothelioma.

New diagnostic and molecular characteristics of malignant mesothelioma

Malignant mesothelioma is a primary cancer of the serosal cavities, an anatomic site that is also frequently affected by metastatic disease, predominantly from primary carcinomas of the lung, breast, and ovary. Advances in immunohistochemistry have resulted in improved diagnostic sensitivity and specificity in the differential diagnosis between metastatic adenocarcinoma and malignant mesothelioma in both cytological and histological material. Recently, the author's group applied high throughput technology to the identification of new markers that may aid in differentiating malignant mesothelioma from ovarian and peritoneal serous carcinoma, tumors with closely related histogenesis and antigenic profile. In addition to the improved tools available for serosal cancer diagnosis, knowledge regarding the biology of malignant mesothelioma has been accumulating in recent years. This review presents current data regarding the diagnostic and biological aspects of malignant mesothelioma.

Pathogenesis of malignant pleural mesothelioma and the role of environmental and genetic factors

BACKGROUND

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor for which no effective therapy exists despite the discovery of many possible molecular and genetic targets. The late stage of MPM diagnosis and the long latency that exist between some exposures and diagnosis have made it difficult to comprehensively evaluate the role of risk factors and their downstream molecular effects.

METHODS

This manuscript is a review of current literature about the pathogenesis of malignant mesothelioma. In this overview, current published studies concerning pathogenesis of malignant mesothelioma are reviewed, with insights into its etiology and pathogenesis. We searched pubmed using the following subjects: mesothelioma, radiation, genetics, pediatric malignant mesothelioma, SV40 virus, and growth factors. We selected 350 valuable articles of which 152 sources were used to complete this review.

CONCLUSION

Many risk factors for MPM development have been recognized including environmental exposures, genetic susceptibility, viral contamination, and radiation. In this review, we discuss the current molecular and genetic contributors to MPM pathogenesis and the risk factors associated with these carcinogenic processes.

Pathogenesis of malignant pleural mesothelioma and the role of environmental and genetic factors

Malignant pleural mesothelioma (MPM) is a rare, aggressive tumor for which no effective therapy exists despite the discovery of many possible molecular and genetic targets. Many risk factors for MPM development have been recognized including environmental exposures, genetic susceptibility, viral contamination, and radiation. However, the late stage of MPM diagnosis and the long latency that exists between some exposures and diagnosis have made it difficult to comprehensively evaluate the role of risk factors and their downstream molecular effects. In this review, we discuss the current molecular and genetic contributors in MPM pathogenesis and the risk factors associated with these carcinogenic processes.

Aberrant splicing and protease involvement in mesothelin release from epithelioid mesothelioma cells

Elevated amounts of soluble mesothelin-related proteins (SMRP) have already been reported in sera and pleural effusions from mesothelioma patients, providing a useful diagnostic marker for malignant pleural mesothelioma (MPM). However, the origin of SMRP is not yet understood. Production of SMRP could be related to abnormal splicing events leading to synthesis of a secreted protein (release) or to an enzymatic cleavage from membrane-bound mesothelin (ectodomain shedding). To test these hypotheses, we used a panel of mesothelioma cells established in culture from pleural effusions of MPM patients. Our in vitro results confirmed specific mesothelin expression and SMRP production in supernatants from epithelioid MPM cell lines, thus providing a relevant cellular model to study soluble mesothelin production mechanisms. The expression of mesothelin-encoding RNA variants was screened by reverse transcription-polymerase chain reaction experiments. Protease involvement in mesothelin cleavage from the cellular surface was investigated by treatment of MPM cells with GM6001, a broad-spectrum MMP- and ADAM-family inhibitor. GM6001 treatment significantly impaired SMRP production by MPM cell lines, in favor of an enzymatic-mediated shedding process. In addition, a splice variant transcript of mesothelin (variant 3) was detected in these MPM cell lines, in accordance with the release of a secreted part of the protein. Our results indicate that both mechanisms could be implicated in soluble mesothelin production by epithelioid mesothelioma cells.

Human T cells stimulate fibroblast-mediated degradation of extracellular matrix in vitro

Several chronic diseases are characterized by inflammation, T cell recruitment and tissue remodelling. We hypothesized that activated T cells may stimulate remodelling of extracellular matrix (ECM) in vitro. Total T cells (CD3+) as well as CD4+ and CD8+ subsets were isolated from peripheral blood and stimulated, after which conditioned media (CM) were obtained. CM was added to human lung fibroblasts in three-dimensional collagen gels and the area of gels was measured daily. Hydroxyproline was determined as a measure of collagen degradation in the gels. Matrix metalloproteinase (MMP) activity in the culture media was analysed by gelatine zymography. Cytokine secretion of stimulated CD4+ and CD8+ T cells was analysed. CD3+ CM augmented collagen gel contraction in a time- and dose-dependent manner (P < 0.0001). CD4+ T cell CM was more potent than CD8+ T cell CM (P < 0.001). CD3+ CM and CD4+ T cell CM, but not CD8+ T cell CM, stimulated fibroblast-mediated collagen degradation and MMP-9 activity. A broad-spectrum MMP-inhibitor added to the culture system inhibited both gel contraction and MMP activity. Activated CD4+ T cells secreted significantly more tumour necrosis factor (TNF) and interleukin (IL)-6 compared to CD8+ T cells. CD3+ CM from patients with chronic obstructive pulmonary disease stimulated fibroblast-mediated collagen gel contraction to the same magnitude as CD3+ CM from healthy controls. In conclusion, activated CD4+ T cells can stimulate fibroblast-mediated degradation of ECM in vitro. This could be a mechanism by which activated T cells stimulate degradation of lung tissue leading to pulmonary emphysema.

siRNA targeted against matrix metalloproteinase 11 inhibits the metastatic capability of murine hepatocarcinoma cell Hca-F to lymph nodes

Matrix metalloproteinase-11 (MMP-11) belongs to the particular member of MMP family, a group of zinc-dependent endopeptidases involved in tumor progression, invasion and metastasis. MMP-11 is strongly expressed in tumor cells and stromal fibroblasts located in the immediate vicinity of tumor. This study investigated the possible role of MMP-11 expression in mouse hepatocarcinoma cell line Hca-F with highly lymphatic metastasis potential by RNA interference (RNAi) approach. The results showed that a small interfering RNA (siRNA) targeted against MMP-11 significantly impeded Hca-F cells proliferation and colony formation in soft agar, as well as resulted in Hca-F cell apoptosis. This reduction of MMP-11 expression also led to the decreased migration and adhesion of Hca-F cells dramatically both in vitro and in vivo. Furthermore, in vivo metastasis assay indicated that down-regulation of MMP-11 expression in Hca-F cells attenuated the metastatic potential of Hca-F cells to peripheral lymph nodes. These data together provide compelling evidence into the function of MMP-11 and suggest that MMP-11 act as a tumor lymphatic metastasis-associated gene, and could represent a new potential target for gene therapy.

Anticancer Effects of Four Varieties of Muscadine Grape

The initiating event in carcinogenesis is a somatic mutation. During progression of the disease, additional mutations accumulate as the transformed cells develop the ability to proliferate and metastasize. These mutations can be produced by reactive oxygen species (ROS) generated through metabolism, or environmental insult. Metastasis involves tissue degradative enzymes, many of which are members of the matrix metalloproteinase family. Hence, substances that can neutralize ROS, inhibit mutagenesis, or block activity of the matrix metalloproteinases should prove to be anticarcinogenic. This study was performed to evaluate the possible anticarcinogenic characteristics of muscadine grapes. These grow wild in the southeast United States and have not been subjected to extensive breeding, as have most commercially cultivated fruits. The extracts tested were from pomace remaining after wine production. This is usually discarded, but the results obtained in this study indicate that pomace water extracts could be used as sources for purification of anticarcinogenic compounds. Four varieties of muscadine grape were tested for their abilities to affect mutagenesis by the metabolically activated carcinogen 2-aminoanthracene. Each extract was also assayed for antioxidant activity and for its ability to inhibit activity of matrix metalloproteinases-2 and -9. Each of the four extracts showed significant inhibition of 2-aminoanthracene mutagenesis, high antioxidant activity, and the ability to inhibit activities of both metalloproteinases, implying that these extracts could be good inhibitors of carcinogenesis. Two of the extracts showed little activity when tested for their effects on mutagenesis by the direct-acting mutagen methyl methanesulfonate.

Expression of Cancer-Associated Molecules in Malignant Mesothelioma

Malignant mesothelioma (MM) is a malignant tumor derived from mesothelial cells, native cells of the body cavities. Exposure to asbestos is the most strongly established etiologic factor, predominantly for the most common disease form, pleural mesothelioma. The pathogenesis of MM involves the accumulation of extensive cytogenetic changes, as well as cancer-related phenotypic alterations that facilitate tumor cell survival, invasion and metastasis. This review presents current knowledge regarding the biological characteristics of this disease that are linked to the so-called hallmarks of cancer. In addition, data suggesting that the anatomic site (solid tumor vs. effusion) affects the expression of metastasis-associated and regulatory molecules in MM are presented. Finally, recent work in which high-throughput methodology has been applied to MM research is reviewed. The data obtained in the reviewed research may aid in defining new prognostic markers and therapeutic targets for this aggressive disease in the future.

Crocidolite asbestos and SV40 are cocarcinogens in human mesothelial cells and in causing mesothelioma in hamsters

Only a fraction of subjects exposed to asbestos develop malignant mesothelioma (MM), suggesting that additional factors may render some individuals more susceptible. We tested the hypothesis that asbestos and Simian virus (SV40) are cocarcinogens. Asbestos and SV40 in combination had a costimulatory effect in inducing ERK1/2 phosphorylation and activator protein-1 (AP-1) activity in both primary Syrian hamster mesothelial cells (SHM) and primary human mesothelial cells (HM). Ap-1 activity caused the expression and activation of matrix metalloprotease (MMP)-1 and MMP-9, which in turn led to cell invasion. Experiments using siRNA and chemical inhibitors confirmed the specificity of these results. The same effects were observed in HM and SHM. Experiments in hamsters showed strong cocarcinogenesis between asbestos and SV40: SV40 did not cause MM, asbestos caused MM in 20% of hamsters, and asbestos and SV40 together caused MM in 90% of hamsters. Significantly lower amounts of asbestos were sufficient to cause MM in animals infected with SV40. Our results indicate that mineral fibers and viruses can be cocarcinogens and suggest that lower amounts of asbestos may be sufficient to cause MM in individuals infected with SV40.

Inhibition of malignant mesothelioma cell matrix metalloproteinase production and invasion by a novel nutrient mixture

Malignant mesothelioma (MM), an asbestos-associated cancer with no known cure, is a highly aggressive tumor causing profound morbidity and nearly universal mortality. Extracellular matrix (ECM) matrix metalloproteinases (MMPs) produced by tumor and stromal cells play a key role in tumor invasion and metastasis. Prevention of ECM degradation by MMP inhibition has been shown to be a promising therapeutic approach to inhibition of cancer development. Based on reported anticancer properties, the authors investigated the effect of a mixture (NM) containing lysine, proline, ascorbic acid, and green tea extract on MM cell line MSTO-211 H proliferation (by [MTT] [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay), MMP secretion (by gelatinase zymography), invasion (through Matrigel), and morphology (by hematoxylin and eosin [H&E] staining). MMP-2 and phorbol 12-myristate 13-acetate (PMA)-induced MMP-9 secretion were inhibited by NM in a dose-dependent fashion, with virtual total inhibition at 500 microg/ml NM. Invasion through Matrigel was inhibited at 50, 100, and 500 microg/ml by 27%, 36%, and 100%, respectively. NM was not toxic to the MM cell line, and H&E staining did not indicate any changes at and below 100 microg/ml concentration. In conclusion, NM significantly inhibited MM cell MMP secretion and invasion-both important parameters for cancer prevention, suggesting NM is an effective treatment strategy for MM.

ERK1/2 and p38 MAP kinase control MMP-2, MT1-MMP, and TIMP action and affect cell migration: a comparison between mesothelioma and mesothelial cells

Pleural malignant mesothelioma is a locally aggressive tumor of mesothelial cell origin. In other tumor types high expression of matrix metalloproteinase (MMP)-2, together with membrane-type1-MMP (MT1-MMP), and low levels of the tissue inhibitor of MMP (TIMP)-2 have been correlated with aggressive tumor progression and low survival rates. Therefore, we compared the expression and activation of these three factors and their regulation by two mesothelioma associated growth factors, platelet-derived growth factor (PDGF)-BB, and transforming growth factor (TGF)-beta1 in six human mesothelioma and one mesothelial cell line. Polymerase chain reaction (PCR), immunoblotting, zymography, and small inhibitory RNAs (siRNA) were used to study gene expression, protein activation, and signal transduction. To proof the relevance of our in vitro data immunohistochemistry was performed in tissue sections. PDGF-BB induced, while TGF-beta1 inhibited cell proliferation. PDGF-BB was a chemoattractant for mesothelial cells, and its effect was increased in the presence of TGF-beta1. TGF-beta1 stimulated the de novo synthesis of pro-MMP-2 in both cell types. Pro-MMP-2 synthesis involved p38 MAP kinase. In cell culture and tissue sections only mesothelial cells expressed MT1-MMP. Migration of mesothelioma cells was dependent on the presence of MT1-MMP. Migration, but not proliferation of mesothelioma cells was inhibited by oleoyl-N-hydroxylamide, TIMP-2, and siRNA for MT1-MMP. Our data suggest that in mesothelioma cells the phosphorylation of p38 MAP kinase is deregulated and is involved in pro-MMP-2 expression. Mesothelioma progression depends on an interaction with mesothelial cells that provide MT1-MMP necessary to activate pro-MMP-2 to facilitate migration through an extracellular matrix (ECM) layer.

Prognostic analysis of clinicopathologic factors in 49 patients with diffuse malignant peritoneal mesothelioma treated with cytoreductive surgery and intraperitoneal hyperthermic perfusion

BACKGROUND

Diffuse malignant peritoneal mesothelioma (DMPM) is a subset of peritoneal mesothelioma with a poor clinical outcome. We performed a prognostic analysis in a cohort of DMPM patients treated homogeneously by cytoreductive surgery and intraperitoneal hyperthermic perfusion (IPHP).

METHODS

Forty-nine DMPM patients who underwent 52 consecutive procedures were enrolled onto the study. Cytoreductive surgery was performed according to the peritonectomy technique, and the IPHP was performed with cisplatin plus doxorubicin or cisplatin plus mitomycin C. We assessed the correlation of the clinicopathologic variables (previous surgical score, age, sex, performance status, previous systemic chemotherapy, carcinomatosis extension, completeness of cytoreduction, IPHP drug schedule, mitotic count [MC], nuclear grade, and biological markers [epidermal growth factor receptor, p16, matrix metalloproteinase 2 and matrix metalloproteinase 9]) with overall and progression-free survival.

RESULTS

The mean age was 52 years (range, 22-74 years). The mean follow-up was 20.3 months (range, 1-89 months). Regarding the biological markers, the rates of immunoreactivity of epidermal growth factor receptor, p16, matrix metalloproteinase 2, and matrix metalloproteinase 9 were 94%, 60%, 100%, and 85%, respectively. The strongest factors influencing overall survival were completeness of cytoreduction and MC, whereas those for progression-free survival were performance status and MC. No biological markers were shown to be of prognostic value.

CONCLUSIONS

Completeness of cytoreduction, performance status, and MC seem to be the best determinants of outcome. These data warrant confirmation by a further prospective formal trial. No biological markers presented a significant correlation with the outcome. The overexpression of epidermal growth factor receptor, matrix metalloproteinase 2, and matrix metalloproteinase 9 and absent or reduced expression of p16 might be related to the underlining tumor kinetics of DMPM and warrant further investigation with other methods.

Diffuse malignant mesothelioma of the peritoneum: a clinicopathological study of 35 patients treated locoregionally at a single institution

BACKGROUND

In the current study, the authors report the clinicopathologic features of patients with peritoneal diffuse malignant mesothelioma (DMM) who were treated in a uniform fashion at a single institution to assess prognostic factors.

METHODS

Thirty-five patients were treated with cytoreductive surgery (CRS) and intraperitoneal hyperthermic perfusion (IPHP). The tumors were classified into epithelial, sarcomatoid, and biphasic types. Immunohistochemistry stains were performed for calretinin, WT-1, pCEA, Ber-EP4, epidermal growth factor receptor (EGFR), p16, matrix metalloprotease-2 (MMP-2), and MMP-9. Statistical correlation was evaluated for age, gender, completeness of cytoreduction (CC), tumor histotype, mitotic count (MC), necrosis, nuclear grade (NG), and biologic markers with regard to overall survival (OS) and progression-free survival (PFS).

RESULTS

The patient group was comprised of 15 men and 20 women with a median age of 52 years (range, 24-73 yrs). Twenty-five patients underwent optimal cytoreduction. There were 32 epithelial tumors and 3 biphasic tumors, and 3 patients had an NG of 1, 19 had an NG of 2, and 13 had an NG of 3. The mean MC was 14.1 (range, 0-160 per 50 high-power fields). Necrosis was present in 11 cases. All the tumors were found to be positive for calretinin and WT-1 and were negative for pCEA and Ber-EP4. The NG and MC were found to be significantly associated with OS (P = 0.02 and P = 0.01, respectively) whereas CC was found to be associated with both OS (P = 0.05) and PFS (P = 0.03). No biologic markers were found to be of prognostic significance.

CONCLUSIONS

The results of the current study indicate that NG, MC, and CC may be useful prognostic factors in patients treated with CRS and IPHP. The expression of EGFR, MMP-2, and MMP-9 and absent and/or reduced expression of p16 in DMMs confirms the results of previous studies suggesting their role in tumor pathogenesis and kinetics.

A Comparison of Airway and Serum Matrix Metalloproteinase-9 Activity Among Normal Subjects, Asthmatic Patients, and Patients With Asthmatic Mucus Hypersecretion

BACKGROUND

The rate of decline in lung function is increased in asthmatic patients, particularly in those with coexisting asthmatic mucus hypersecretion (AMH), in whom inflammation and the activity of matrix metalloproteinase (MMP)-9 and tissue inhibitor of metalloproteinase (TIMP)-1 in serum and BAL fluid (BALF) may be increased.

METHODS

Seven nonasthmatic subjects and 22 asthmatic subjects completed a questionnaire, and underwent lung function testing and bronchoscopy, during which AMH was diagnosed by the presence of mucus plugging. Subjects were classified as follows: mild/moderate asthma; severe asthma; and AMH. In BALF, we measured the differential WBC counts and MMP-9 activity by zymography. We measured total MMP-9 and TIMP-1 activity by enzyme-linked immunosorbent assay in BALF and serum.

RESULTS

The mean (+/- confidence interval) FEV1 was lower in AMH patients (73 +/- 13% predicted) compared with nonasthmatic subjects (95 +/- 7%) and patients with mild/moderate asthma (73 +/- 9%; p < 0.05), and was similar to that of patients with severe asthma (80 +/- 20%). MMP-9 activity was greater in AMH patients and in patients with severe asthma compared with nonasthmatic subjects (p = 0.05 and p = 0.01, respectively), as were TIMP-1 activities (p = 0.001 and p = 0.04, respectively), but MMP-9/TIMP-1 ratios were not. MMP-9 activity increased across the four groups from nonasthmatic subjects to AMH patients (r = 0.58; p = 0.0009), but the differential and total WBC counts were similar. There were no relationships between FEV1 percent predicted and either MMP-9 activity or MMP-9/TIMP-1 ratio. There were no differences in serum MMP-9 activity, which did not correlate with MMP-9 activity in BALF.

CONCLUSIONS

AMH and severe asthma were associated with greater proteolytic enzyme activities despite similar airway inflammation, which might play a role in remodeling and accelerated the decline in lung function in these patients.

Inhibition of proliferation, migration, and matrix metalloprotease production in malignant mesothelioma cells by tyrosine kinase inhibitors

The epidermal growth factor receptor (EGFR) is expressed in a variety of human solid tumors, including malignant mesothelioma. EGFR has been implicated in regulation of cell proliferation, survival, angiogenesis, and metastasis, making it an ideal target for drug development. ZD1839 (gefitinib) and OSI-774 (erlotinib) are new, low-molecular-weight, EGFR-selective tyrosine kinase (TK) inhibitors, whereas CI-1033 is a pan-EGFR family TK inhibitor. In the present study, we used ZD1839, OSI-774, and CI-1033 and investigated the effect of these drugs on proliferation, migration, and matrix metalloprotease (MMP) production in three malignant mesothelioma cell lines (M14K, ZL34, and SPC212). Using [3H]thymidine incorporation, DNA synthesis assay, we found that all three drugs inhibited transforming growth factor-alpha (TGF-alpha)-induced cellular proliferation in a dose-dependent manner. In addition, all three drugs induced apoptosis in ZL34 cells as determined by flow cytometry using annexin-V staining. Furthermore, all three drugs inhibited TGF-alpha-induced cell migration (chemotaxis) in a dose-dependent manner as determined by Boyden chamber assay. TGF-alpha-induced MMP-9 production was also inhibited in a dose-dependent manner as determined by gelatin zymography in three cell lines tested. In conclusion, our study demonstrates inhibitory effectiveness of EGFR-TK inhibitors in malignant mesothelioma cells and suggests that these drugs may be an effective treatment strategy for malignant mesothelioma.

Matrix metalloproteinase 11 depletion inhibits cell proliferation in gastric cancer cells

Our previous study has shown that matrix metalloproteinase 11 (MMP11) is highly expressed in tumor cell lines and primary tumor of gastric cancer (GC). In order to reveal the correlation between expression of MMP11 and biological features of GC cell, we have constructed the recombinant plasmids producing hairpin small interfering RNA (siRNA) to target MMP11 mRNA using a vector-based RNA interference technology. Stable transfection of recombinants into GC cell line BGC823 specifically depleted the mRNA and protein of MMP11 as demonstrated by RT-PCR and Western blotting analysis. The siRNA-treated cells exhibited significantly decreased growth ability compared with mock transfectants and parental BGC823 cells. Furthermore, colony formation of MMP11 deficient cells was dramatically inhibited in soft agar and tumorigenicity was reduced in nude mice, respectively. These results provide new insights into the function of MMP11 and suggest that MMP11 may play an important role in the control of cell proliferation and tumor development in GC.

Metastasis in pleural mesothelioma. Immunohistochemical markers for disseminated disease

AIMS

To examine 13 cases of mesothelioma with metastases and compare these with 29 biopsy samples of patients without metastases. Metastatic disease was defined as tumour in which tumour appeared in a different cavity/tissue of the body and which showed no direct spread. Consequently, mediastinal nodal and parenchymal lung spread was excluded.

METHODS AND RESULTS

Standard sections were prepared and stained according to the manufacturers' protocols. The antibodies used were MIB-1, nm23, Bcl-2, MMP-9, EMMPRIN (CD147) and alpha-catenin. Scoring employed a grading system (0/1/2/3), and was performed by two pathologists independently. The tissues revealed no significant staining differences for MIB-1, Bcl-2, MMP-9 or EMMPRIN, and therefore no linkage to metastatic potential was determined. Alpha-Catenin showed a diminished level of expression in cases of metastatic mesothelioma (P = 0.024), possibly reflecting dimished catenin-cadherin binding and paralleling data from other tumours. nm23 showed greater staining in metastatic tumours when compared with the controls (P = 0.001). Intriguingly, the nm23 staining pattern was the reverse of that expected. This reversed pattern has been noted before in other tumours and therefore a biological prognostic event may exist for this antibody test and mesothelioma metastasis.

CONCLUSION

There may be a place for nm23 and possibly alpha-catenin in immunohistochemical assessment of mesothelioma metastatic potential. However, MIB-1, Bcl-2, MMP-9 and EMMPRIN (CD147) do not show significant staining results.

Stromelysin-2 (Matrix Metalloproteinase 10) Is Inducible in Lymphoma Cells and Accelerates the Growth of Lymphoid Tumors In Vivo

Matrix metalloproteinase (MMP) 10 (stromelysin-2) is known to degrade various components of the extracellular matrix; however, the signals that regulate its expression and its role in lymphoma growth remain unknown. In the present work, we report the up-regulated expression of MMP10 in T lymphoma cells following contact with endothelial cells. The induction of MMP10 was found to be dependent on the specific interaction between LFA-1 and ICAM-1, which play a central role in regulating the expression of genes involved in the rate-limiting steps of lymphoma development. MMP10, but not MMP3 (stromelysin-1), was also up-regulated in human B lymphoma cells following exposure to IL-4, IL-6, and IL-13, but not to IL-1. To gain further insight into the role of MMP10 in lymphoma development, we generated lymphoma cell lines constitutively expressing high levels of MMP10 and studied these cells for their ability to form thymic lymphoma in vivo. Mice injected with lymphoma cells constitutively expressing MMP10 developed thymic lymphoma more rapidly than those injected with control lymphoma cells. These results provide the first in vivo evidence that overexpression of MMP10 promotes tumor development, and indicate that MMP10 induction is an important pathway activated not only upon ICAM-1/LFA-1-mediated intercellular contact, but also following activation of tumor cells with inflammatory cytokines.

Cell protection, resistance and invasiveness of two malignant mesotheliomas as assessed by 10K-microarray

Malignant pleural mesothelioma (MPM) is an aggressive serosal tumor, strongly associated with former exposure to asbestos fibers and for which there is currently no effective treatment available. In human, MPM is characterized by a high local invasiveness, poor prognosis and therapeutic outcomes. In order to assess molecular changes that specify this phenotype, we performed a global gene expression profiling of human MPM. Using a 10,000-element microarray, we analyzed mRNA relative gene expression levels by comparing a mesothelioma cell line to either a pleural cell line or tumor specimens. To analyze these gene expression data, we used various bioinformatics softwares. Hierarchical clustering methods were used to group genes and samples with similar expression in an unsupervised mode. Genes of known function were further sorted by enzyme, function and pathway clusters using a supervised software (IncyteGenomics). Taken together, these data defined a molecular fingerprint of human MPM with more than 700 up- or down-regulated genes related to several traits of the malignant phenotype, specially associated with MPM invasiveness, protection and resistance to anticancer defenses. This portrait is meaningful in disease classification and management, and relevant in finding new specific markers of MPM. These molecular markers should improve the accuracy of mesothelioma diagnosis, prognosis and therapy.

Activity of the matrix metalloproteinase-9 promoter in human normal and tumor cells

Matrix metalloproteinases (MMPs) belong to a family of proteins essential for those processes involving extracellular matrix degradation, such as embryonic development, morphogenesis, and tissue resorption and remodeling. Some members of this family play a crucial role also in tumor invasion. Most notably, MMP-9 is expressed in invasive tumors, and represents a key protein in brain tumor progression, whereas it is not expressed in adult normal tissues. The expression of the MMP-9, like other members of the family, is transcriptionally regulated. We, therefore, postulated that the MMP-9 promoter could be useful in driving selective expression of exogenous genes in tumor cells. This represents a key feature for gene therapy applications, since currently employed viral promoters induce severe organ toxicity, limiting the clinical benefits. In this study, we investigated the activity of the MMP-9 promoter in driving exogenous gene expression in human cell lines. High levels of reporter gene expression were detected in tumor derived cell lines, whereas the MMP-9 promoter activity in non-tumor cells was negligible. Furthermore, we show that tumor necrosis factor alpha (TNFalpha) is able to enhance considerably the MMP-9 promoter activity only in tumor cells. Since recent studies have indicated that MMP-9 enzymatic activity is detectable in the blood, it would be possible to screen potential responsive patients for a tumor gene therapy approach based on the MMP-9 promoter. Taken together these data suggest that MMP-9 promoter has the characteristics for transcritpionally targeted and inducible gene therapy applications.

Matrix metalloproteinases 2 and 9 (gelatinases A and B) expression in malignant mesothelioma and benign pleura

Matrix metalloproteinases (MMPs), in particular the gelatinases (MMP-2 and -9), play a significant role in tumour invasion and angiogenesis. The expression and activities of MMPs have not been characterised in malignant mesothelioma (MM) tumour samples. In a prospective study, gelatinase activity was evaluated in homogenised supernatants of snap frozen MM (n=35), inflamed pleura (IP, n=12) and uninflammed pleura (UP, n=14) tissue specimens by semiquantitative gelatin zymography. Matrix metalloproteinases were correlated with clinicopathological factors and with survival using Kaplan-Meier and Cox proportional hazard models. In MM, pro- and active MMP-2 levels were significantly greater than for MMP-9 (P=0.006, P<0.001). Active MMP-2 was significantly greater in MM than in UP (P=0.04). MMP-2 activity was equivalent between IP and MM, but both pro- and active MMP-9 activities were greater in IP (P=0.02, P=0.009). While there were trends towards poor survival with increasing total and pro-MMP-2 activity (P=0.08) in univariate analysis, they were both independent poor prognostic factors in multivariate analysis in conjunction with weight loss (pro-MMP-2 P=0.03, total MMP-2 P=0.04). Total and pro-MMP-2 also contributed to the Cancer and Leukemia Group B prognostic groups. MMP-9 activities were not prognostic. Matrix metalloproteinases, and in particular MMP-2, the most abundant gelatinase, may play an important role in MM tumour growth and metastasis. Agents that reduce MMP synthesis and/or activity may have a role to play in the management of MM.

Regulation of matrix metalloprotease activity in malignant mesothelioma cell lines by growth factors

BACKGROUND

The extracellular matrix metalloproteases (MMPs) produced by tumour and stromal cells are believed to play a key role in tumour cell invasion and metastasis. Malignant mesothelioma is a highly aggressive tumour. Previous studies have shown that malignant mesothelioma cells express MMP-1, -2, -3, -7 and -9. However, the regulation of MMP expression in malignant mesothelioma cells has not been thoroughly investigated.

METHODS

The effects of a number of growth factors on the secretion of MMP-2, -3 and -9 in malignant mesothelioma cells were studied by substrate zymography. The expression of relevant growth factor receptors in malignant mesothelioma cells was also examined using RT-PCR.

RESULTS

The exposure of malignant mesothelioma cells to different growth factors including epidermal growth factor (EGF), transforming growth factor-alpha, amphiregulin, heparin binding EGF, beta-cellulin (BTC), stem cell factor, insulin-like growth factors I and II, acidic and basic fibroblast growth factors, and hepatocyte growth factor increased secretion of MMP-9 and/or MMP-3. EGF receptor ligands BTC and EGF had the most potent effect on MMP-9 and MMP-3 production, respectively. Production of MMP-2 was not affected by any growth factors used in this study. We have also demonstrated mRNA expression of different growth factor receptors in malignant mesothelioma cells, and found that the tyrosine kinase inhibitor genistein inhibited the increased production of MMPs resulting from stimulation with different growth factors.

CONCLUSION

This study shows, for the first time, the broad extent of regulation of MMPs by various growth factors in malignant mesothelioma cells.

ETS-1 transcription factor binds cooperatively to the palindromic head to head ETS-binding sites of the stromelysin-1 promoter by counteracting autoinhibition

Stromelysin-1 (matrix metalloproteinase-3) is a member of the matrix metalloproteinase family. Regulation of its gene expression is critical for tissue homeostasis. Patterns of increased co-expression of stromelysin-1 and ETS-1 genes have been observed in pathological processes. Stromelysin-1 promoter is transactivated by ETS proteins through two palindromic head to head ETS-binding sites, an unusual configuration among metalloproteinase promoters. By using surface plasmon resonance, electrophoretic mobility shift assay, and photo-cross-linking, we showed that full-length human ETS-1 (p51) binds cooperatively to the ETS-binding site palindrome of the human stromelysin-1 promoter, with facilitated binding of the second ETS-1 molecule to form an ETS-1.DNA.ETS-1 ternary complex. The study of N-terminal deletion mutants allowed us to conclude that cooperative binding implied autoinhibition counteraction, requiring the 245-330-residue region of the protein that is encoded by exon VII of the gene. This region was deleted in the natural p42 isoform of ETS-1, which was unable to bind cooperatively to the palindrome. Transient transfection experiments showed a good correlation between DNA binding and promoter transactivation for p51. In contrast, p42 showed a poorer transactivation, reinforcing the significance of cooperative binding for full transactivation. It is the first time that ETS-1 was shown to be able to counteract its own autoinhibition.

The role of tumour-associated macrophages in tumour progression: implications for new anticancer therapies

The role of macrophages in tumour growth and development is complex and multifaceted. Whilst there is limited evidence that tumour-associated macrophages (TAMs) can be directly tumouricidal and stimulate the anti-tumour activity of T cells, there is now contrasting evidence that tumour cells are able to block or evade the activity of TAMs at the tumour site. In some cases, tumour-derived molecules even redirect TAM activities to promote tumour survival and growth. Indeed, evidence has emerged for a symbiotic relationship between tumour cells and TAMs, in which tumour cells attract TAMs and sustain their survival, with TAMs then responding to micro-environmental factors in tumours such as hypoxia (low oxygen tension) by producing important mitogens as well as various growth factors and enzymes that stimulate tumour angiogenesis. This review presents evidence for the number and/or distribution of TAMs being linked to prognosis in different types of human malignancy. It also outlines the range of pro- and anti-tumour functions performed by TAMs, and the novel therapies recently devised using TAMs to stimulate host immune responses or deliver therapeutic gene constructs to solid tumours.

Inhibition of mesothelioma cell growth in vitro by doxycycline

Malignant mesothelioma causes profound morbidity and nearly universal mortality that is often refractory to conventional treatment modalities of aggressive surgery, radiotherapy, or chemotherapy. Doxycycline, a commonly used antibiotic, has anti-tumor activity against several malignancies, but its anti-tumor effects on malignant mesothelioma have not been evaluated. We report here that concentrations of doxycycline achievable in serum with typical oral doses had cytostatic effects to varying extent on all eight of the mesothelioma cell lines studied but did not affect normal lung fibroblasts. Doxycycline inhibited the production of mitochondrial cytochrome c oxidase, especially in mesothelioma cells more sensitive to its cytostatic effects, and directly inhibited gelatinase A activity; both of these activities are putative mechanisms for the cytostatic activity of doxycycline in other tumor cells. Thus doxycycline may have a role as adjuvant therapy for malignant mesothelioma.