Differential expression of matrix metalloproteinases in activated c-ras-Ha-transfected immortalized human keratinocytes

The Endogenous Tryptophan-derived Photoproduct 6-formylindolo[3,2-b]carbazole (FICZ) is a Nanomolar Photosensitizer that Can be Harnessed for the Photodynamic Elimination of Skin Cancer Cells in Vitro and in Vivo

UV-chromophores contained in human skin may act as endogenous sensitizers of photooxidative stress and can be employed therapeutically for the photodynamic elimination of malignant cells. Here, we report that 6-formylindolo[3,2-b]carbazole (FICZ), a tryptophan-derived photoproduct and endogenous aryl hydrocarbon receptor agonist, displays activity as a nanomolar sensitizer of photooxidative stress, causing the photodynamic elimination of human melanoma and nonmelanoma skin cancer cells in vitro and in vivo. FICZ is an efficient UVA/Visible photosensitizer having absorbance maximum at 390 nm (ε = 9180 L mol^-1  cm^-1 ), and fluorescence and singlet oxygen quantum yields of 0.15 and 0.5, respectively, in methanol. In a panel of cultured human squamous cell carcinoma and melanoma skin cancer cells (SCC-25, HaCaT-ras II-4, A375, G361, LOX), photodynamic induction of cell death was elicited by the combined action of solar simulated UVA (6.6 J cm^-2 ) and FICZ (≥10 nm), preceded by the induction of oxidative stress as substantiated by MitoSOX Red fluorescence microscopy, comet detection of Fpg-sensitive oxidative genomic lesions and upregulated stress response gene expression (HMOX1, HSPA1A, HSPA6). In SKH1 "high-risk" mouse skin, an experimental FICZ/UVA photodynamic treatment regimen blocked the progression of UV-induced tumorigenesis suggesting feasibility of harnessing FICZ for the photooxidative elimination of malignant cells in vivo.

A Topical Zinc Ionophore Blocks Tumorigenic Progression in UV-exposed SKH-1 High-risk Mouse Skin

Nonmelanoma skin cancer (NMSC) is the most common malignancy in the United States representing a considerable public health burden. Pharmacological suppression of skin photocarcinogenesis has shown promise in preclinical and clinical studies, but more efficacious photochemopreventive agents are needed. Here, we tested feasibility of harnessing pharmacological disruption of intracellular zinc homeostasis for photochemoprevention in vitro and in vivo. Employing the zinc ionophore and FDA-approved microbicidal agent zinc pyrithione (ZnPT), used worldwide in over-the-counter (OTC) topical consumer products, we first demonstrated feasibility of achieving ZnPT-based intracellular Zn²⁺ overload in cultured malignant keratinocytes (HaCaT-ras II-4; SCC-25) employing membrane-permeable fluorescent probes. Zinc overload was accompanied by induction of intracellular oxidative stress, associated with mitochondrial superoxide release as substantiated by MitoSOX Red™ fluorescence microscopy. ZnPT-induced cell death observable in malignant keratinocytes was preceded by induction of metal (MT2A), proteotoxic (HSPA6, HSPA1A, DDIT3, HMOX1) and genotoxic stress response (GADD45A, XRCC2) gene expression at the mRNA and protein levels. Comet analysis revealed introduction of formamidopyrimidine-DNA glycosylase (Fpg)-sensitive oxidative DNA lesions. In a photocarcinogenesis model (UV-exposed SKH-1 high-risk mouse skin), topical ZnPT administration post-UV caused epidermal zinc overload and stress response gene expression with pronounced blockade of tumorigenesis. Taken together, these data suggest feasibility of repurposing a topical OTC drug for zinc-directed photochemoprevention of solar UV-induced NMSC.

UVB-irradiated keratinocytes induce melanoma-associated ganglioside GD3 synthase gene in melanocytes via secretion of tumor necrosis factor α and interleukin 6

Although expression of gangliosides and their synthetic enzyme genes in malignant melanomas has been well studied, that in normal melanocytes has been scarcely analyzed. In particular, changes in expression levels of glycosyltransferase genes responsible for ganglioside synthesis during evolution of melanomas from melanocytes are very important to understand roles of gangliosides in melanomas. Here, expression of glycosyltransferase genes related to the ganglioside synthesis was analyzed using RNAs from cultured melanocytes and melanoma cell lines. Quantitative RT-PCR revealed that melanomas expressed high levels of mRNA of GD3 synthase and GM2/GD2 synthase genes and low levels of GM1/GD1b synthase genes compared with melanocytes. As a representative exogenous stimulation, effects of ultraviolet B (UVB) on the expression levels of 3 major ganglioside synthase genes in melanocytes were analyzed. Although direct UVB irradiation of melanocytes caused no marked changes, culture supernatants of UVB-irradiated keratinocytes (HaCaT cells) induced definite up-regulation of GD3 synthase and GM2/GD2 synthase genes. Detailed examination of the supernatants revealed that inflammatory cytokines such as TNFα and IL-6 enhanced GD3 synthase gene expression. These results suggest that inflammatory cytokines secreted from UVB-irradiated keratinocytes induced melanoma-associated ganglioside synthase genes, proposing roles of skin microenvironment in the promotion of melanoma-like ganglioside profiles in melanocytes.

Immunohistochemical analysis of TIMP-3 and MMP-9 in actinic keratosis, squamous cell carcinoma of the skin, and basal cell carcinoma

The expression of metalloproteinases and their inhibitors has been related to different invasive and metastatic potentials in cancer. This study aims to investigate the immunohistochemical expression of TIMP-3 and MMP-9 in samples of basal cell carcinoma (BCC), squamous cell carcinoma of the skin (SCC), and actinic keratosis (AK). Immunohistochemistry was performed to evaluate the expression of TIMP-3 and MMP-9 in samples of BCC (n=22), SCC (n=10), and AK (n=15). Ten fields of both tumor parenchyma and tumor stroma were photographed and counted in image software. The ratio of positive cells to total cells was used to quantify the staining. A higher expression of MMP-9 was found in tumor stroma of SCC compared to BCC and AK. No significant differences in TIMP-3 expression were observed among the groups. Considering the well-described differences between these neoplasms, these results provide additional evidence of the role of MMP-9 in tumor invasiveness of keratinocyte-derived tumors.

Complex Regulation of the Pericellular Proteolytic Microenvironment during Tumor Progression and Wound Repair: Functional Interactions between the Serine Protease and Matrix Metalloproteinase Cascades

Spatial and temporal regulation of the pericellular proteolytic environment by local growth factors, such as EGF and TGF-β, initiates a wide repertoire of cellular responses coupled to a plasmin/matrix metalloproteinase (MMP) dependent stromal-remodeling axis. Cell motility and invasion, tumor metastasis, wound healing, and organ fibrosis, for example, represent diverse events controlled by expression of a subset of genes that encode various classes of tissue remodeling proteins. These include members of the serine protease and MMP families that functionally constitute a complex system of interacting protease cascades and titrated by their respective inhibitors. Several structural components of the extracellular matrix are upregulated by TGF-β as are matrix-active proteases (e.g., urokinase (uPA), plasmin, MMP-1, -3, -9, -10, -11, -13, -14). Stringent controls on serine protease/MMP expression and their topographic activity are essential for maintaining tissue homeostasis. Targeting individual elements in this highly interactive network may lead to novel therapeutic approaches for the treatment of cancer, fibrotic diseases, and chronic wounds.

TGF-beta1 + EGF-initiated invasive potential in transformed human keratinocytes is coupled to a plasmin/MMP-10/MMP-1-dependent collagen remodeling axis: role for PAI-1

The phenotypic switching called epithelial-to-mesenchymal transition is frequently associated with epithelial tumor cell progression from a comparatively benign to an aggressive, invasive malignancy. Coincident with the emergence of such cellular plasticity is an altered response to transforming growth factor-beta (TGF-beta) as well as epidermal growth factor (EGF) receptor amplification. TGF-beta in the tumor microenvironment promotes invasive traits largely through reprogramming gene expression, which paradoxically supports matrix-disruptive as well as stabilizing processes. ras-transformed HaCaT II-4 keratinocytes undergo phenotypic changes typical of epithelial-to-mesenchymal transition, acquire a collagenolytic phenotype, and effectively invade collagen type 1 gels as a consequence of TGF-beta1 + EGF stimulation in a three-dimensional physiologically relevant model system that monitors collagen remodeling. Enhanced collagen degradation was coupled to a significant increase in matrix metalloproteinase (MMP)-10 expression and involved a proteolytic axis composed of plasmin, MMP-10, and MMP-1. Neutralization of any one component in this cascade inhibited collagen gel lysis. Similarly, addition of plasminogen activator inhibitor type 1 (SERPINE1) blocked collagen degradation as well as the conversion of both proMMP-10 and proMMP-1 to their catalytically active forms. This study therefore identifies an important mechanism in TGF-beta1 + EGF-initiated collagen remodeling by transformed human keratinocytes and proposes a crucial upstream role for plasminogen activator inhibitor type 1-dependent regulation in this event.

Involvement of matrix metalloproteinase 2 and 9 in gambogic acid induced suppression of MDA-MB-435 human breast carcinoma cell lung metastasis

Cancer cell invasion is one of the crucial events in local spreading, growth, and metastasis of tumors. The present study investigated the antiinvasive and antimetastatic action of gambogic acid (GA) in MDA-MB-435 human breast carcinoma cells. GA caused a concentration-dependent suppression of cell invasion through Matrigel and significantly inhibited lung metastases of the cells transplanted in vivo. The potent effects of GA have been attributed to its ability to reduce the expression of matrix metalloproteinases (MMP) 2 and 9 in vitro and in vivo both at the protein and mRNA levels, which were associated with protein kinase C (PKC) signaling pathway as supported by the diminished antiinvasive effect of GA in the presence of specific activator of the pathway. Collectively, our data demonstrated that GA exhibited antiinvasion properties on highly invasive cancer cells via PKC mediated MMP-2/9 expression inhibition. This indicated that GA can be served as a potential novel therapeutic candidate for the treatment of cancer metastasis.

The chemopreventive polyphenol Curcumin prevents hematogenous breast cancer metastases in immunodeficient mice

Dissemination of metastatic cells probably occurs long before diagnosis of the primary tumor. Metastasis during early phases of carcinogenesis in high risk patients is therefore a potential prevention target. The plant polyphenol Curcumin has been proposed for dietary prevention of cancer. We therefore examined its effects on the human breast cancer cell line MDA-MB-231 in vitroand in a mouse metastasis model. Curcumin strongly induces apoptosis in MDA-MB-231 cells in correlation with reduced activation of the survival pathway NFkappaB, as a consequence of diminished IotakappaB and p65 phosphorylation. Curcumin also reduces the expression of major matrix metalloproteinases (MMPs) due to reduced NFkappa B activity and transcriptional downregulation of AP-1. NFkappa B/p65 silencing is sufficient to downregulate c-jun and MMP expression. Reduced NFkappa B/AP-1 activity and MMP expression lead to diminished invasion through a reconstituted basement membrane and to a significantly lower number of lung metastases in immunodeficient mice after intercardiac injection of 231 cells (p=0.0035). 68% of Curcumin treated but only 17% of untreated animals showed no or very few lung metastases, most likely as a consequence of down-regulation of NFkappa B/AP-1 dependent MMP expression and direct apoptotic effects on circulating tumor cells but not on established metastases. Dietary chemoprevention of metastases appears therefore feasible.

Silencing of the metastasis suppressor RECK by RAS oncogene is mediated by DNA methyltransferase 3b-induced promoter methylation

RECK is a membrane-anchored glycoprotein that may negatively regulate matrix metalloproteinase activity to suppress tumor invasion and metastasis. Our previous study indicated that oncogenic RAS inhibited RECK expression via a histone deacetylation mechanism. In this study, we address whether DNA methyltransferases (DNMT) participate in the inhibition of RECK by RAS. Induction of Ha-RAS(Val12) oncogene increased DNMT3b, but not DNMT1 and DNMT3a, expression in 2-12 cells. In addition, induction of DNMT3b by RAS was through the extracellular signal-regulated kinase signaling pathway. Oncogenic RAS increased the binding of DNMT3b to the promoter of RECK gene and this binding induced promoter methylation, which could be reversed by 5'-azacytidine and DNMT3b small interfering RNA (siRNA). The MEK inhibitor U0126 also reversed RAS-induced DNMT3b binding and RECK promoter methylation. Treatment of 5'-azacytidine and DNMT3b siRNA restored RECK expression in 2-12 cells and potently suppressed RAS-stimulated cell invasion. In addition, the inhibitory effect of 5'-azacytidine on RAS-induced cell invasion was attenuated after knockdown of RECK by siRNA. Interestingly, human lung cancer cells harboring constitutively activated RAS exhibited lower RECK expression and higher promoter methylation of RECK gene. 5'-Azacytidine and DNMT3b siRNA restored RECK expression in these cells and effectively suppressed invasiveness. Collectively, our results suggest that RAS oncogene induces RECK gene silencing through DNMT3b-mediated promoter methylation, and DNMT inhibitors may be useful for the treatment of RAS-induced metastasis.

Expression of laminin 5 by parental and c-Ha-ras-transformed HaCaT keratinocytes in organotypic cultures

Tumor cells traverse the basement membrane zone and gain access to the underlying mesenchyme to eventually form metastases. Laminin 5 is a major component of the basement membrane and connects keratinocytes at the level of hemidesmosomes to the mesenchyme. Underneath invading tumor cells anti-laminin 5 staining is diminished, and laminin 5 degradation products can stimulate cell migration and epidermal growth factor (EGF) receptor signaling. To investigate laminin 5 expression in parental HaCaT and tumorigenic c-Ha-ras-transformed HaCaT II-4rt keratinocytes, the cells were cultivated under monolayer and organotypic culture conditions. In monolayer cultures, HaCaT and c-Ha-ras-transformed HaCaT II-4rt keratinocytes secreted comparable amounts of laminin 5. After 7 days of organotypic cultures, collagen IV, beta4-integrin, nidogen and laminin 5 were detected along the epithelial-mesenchymal interface of parental HaCaT keratinocytes, while staining for these proteins was patchy or absent in the organotypic cultures with c-Ha-ras-transformed HaCaT II-4rt cells. Immunoblotting analysis confirmed absence of laminin 5 deposition in organotypic cultures of c-Ha-ras-transformed HaCaT II-4rt while the protein was detected in organotypic cultures of HaCaT keratinocytes. Surprisingly, however, the alpha3 and gamma2 laminin chain transcripts were strongly induced in c-Ha-ras-transformed HaCaT II-4rt cells by organotypic culture conditions, indicating that invasive epidermal tumor cells retain high mRNA levels for laminin 5 chains and suggesting an autocrine/paracrine induction of the laminin chain mRNAs. Moreover, as laminin 5 was absent in organotypic cultures of c-Ha-ras-transformed HaCaT II-4rt cells, it suggests immediate degradation of the protein. Degradation products may further contribute to the malignant phenotype by enhancing cellular migration and EGF-receptor activation.

Invasion and metastasis markers in cancers

Over 90% of all adults human cancers are of epithelial origin comprising mainly of skin and aero-digestive tract cancers. A significant proportion of our discipline's workload consists of management of these cancers. This review article is to provide clinicians with a summary of the current research findings in invasion and metastasis of epithelial cancers and the translation of some of this information to clinical use particularly related to skin and head and neck cancers (HNSCC). Metastasis is the leading cause of death in cancer patients. Although surgical resection of isolated metastases is beneficial for some patients, the overall efficacy of surgery, chemotherapy or radiotherapy is limited. Clearly, with today's advances in surgery a majority of these primary cancers are resectable and a cure attainable if surgeons could control or inhibit metastasis.

Ultraviolet radiation and skin cancer: molecular mechanisms

Every living organism on the surface of the earth is exposed to the ultraviolet (UV) fraction of the sunlight. This electromagnetic energy has both life-giving and life-endangering effects. UV radiation can damage DNA and thus mutagenize several genes involved in the development of the skin cancer. The presence of typical signature of UV-induced mutations on these genes indicates that the ultraviolet-B part of sunlight is responsible for the evolution of cutaneous carcinogenesis. During this process, variable alterations of the oncogenic, tumor-suppressive, and cell-cycle control signaling pathways occur. These pathways include (a) mutated PTCH (in the mitogenic Sonic Hedgehog pathway) and mutated p53 tumor-suppressor gene in basal cell carcinomas, (b) an activated mitogenic ras pathway and mutated p53 in squamous cell carcinomas, and (c) an activated ras pathway, inactive p16, and p53 tumor suppressors in melanomas. This review presents background information about the skin optics, UV radiation, and molecular events involved in photocarcinogenesis.

Farnesyltransferase inhibitor SCH-66336 downregulates secretion of matrix proteinases and inhibits carcinoma cell migration

The ras oncogenes are among those most frequently found in human cancers. Blocking Ras farnesylation is a promising strategy for arresting cancer growth. Ras activates several signaling pathways with key roles in cellular proliferation, invasion, metastasis and angiogenesis. Furthermore, proteolytic activities of matrix proteinases such as urokinase-type plasminogen activator (uPA) and matrix metalloproteinases (MMPs) are regulated by Ras isoforms. Thus, we investigated the effects of SCH-66336, a farnesyltransferase inhibitor, on secretion of components of the plasminogen activation system as well as on the gelatinases MMP-2 and MMP-9, which play pivotal roles in matrix remodeling. SCH-66336 up to 5 microM did not significantly alter the viability of prostate (PC-3) and renal (Caki-1) cancer cells incubated in serum-depleted medium. SCH-66336 partly inhibited the processing of H-Ras, while levels of mature N-Ras and K-Ras remained unaffected. Under these noncytotoxic conditions, uPA and tPA levels were lowered in culture medium but raised in cell lysates, suggesting inhibition of trafficking pathways. In contrast, SCH-66336 had no effect on uPAR expression or on secreted PAI-1 levels. As expected, the reduction of uPA and tPA activities by SCH-66336 inhibited the conversion of plasminogen to plasmin by about 25% in PC-3 cells. SCH-66336 also inhibited the levels of secreted pro-MMP-2 and pro-MMP-9 as well as the release of their inhibitors TIMP-1 and TIMP-2. SCH-66336 decreased both the adhesion and even more so the migration of PC-3 cells on gelatin. Thus, SCH-66336 inhibited farnesylation in both cancer cell types, and H-Ras functions should be reduced by the drug. In addition, the lower levels of secreted proteinases in the presence of SCH-66336 suggest that reduced matrix remodeling and cell migration should occur in treated tumors.

The inhibition of MAPK pathway is correlated with down-regulation of MMP-9 secretion induced by TNF-alpha in human keratinocytes

MMP-9 (92 kDa) is the major gelatinase able to degrade collagen IV, secreted by keratinocytes that are actively involved in wound-healing or tumorigenesis. Since the invasive phenotype of cancers is dependent on MMP-9 expression, it appeared of interest to precisely characterize which signal transduction pathways activated by TNF-alpha are involved in MMP-9 up-regulation induced by TNF-alpha. In HaCaT cells, activation of MMP-9 occurs at the transcriptional level. Inhibition of the MAPK pathway using specific inhibitors of the Ras, Raf, MEK1/2, and Erk1/2 cascade was correlated with a marked inhibition of MMP-9 activity, as determined by gene and protein expression. MAPK pathway activation via TNF-alpha was confirmed by marked AP-1 activation detected in EMSA. Under our experimental conditions, p38 MAPK and SAPK/JNK pathways were not activated. Gene and protein expression of other MMPs that regulate MMP-9, such as MMP-1 and MMP-13, were also up-regulated by TNF-alpha and inhibited by UO126, providing evidence that the MAPK pathway plays a fundamental role in the regulation of MMP-9 secretion by keratinocytes. As TNF-alpha is known to be a main activator of NF-kappaB pathway, the effects of campthothecin and caffeic acid were investigated, such as, TNF-alpha campthothecin up-regulated MMP-9 activity but caffeic acid only weakly inhibited MMP-9 activation induced by TNF-alpha. However, NF-kappaB is activated as shown from immunostaining data, a nuclear staining and higher Western blotting expression of p50 and p65 NF-kappaB subunits were detected after TNF-alpha treatment. A higher specific signal was also detected in EMSA for TNF-alpha-treated cells.

Tumor-stroma interactions directing phenotype and progression of epithelial skin tumor cells

Tumor-stroma interactions play a significant role in tumor development and progression. Alterations in the stromal microenvironment, including enhanced vasculature (angiogenesis), modified extracellular matrix composition, inflammatory cells, and dys-balanced protease activity, are essential regulatory factors of tumor growth and invasion. Differential modulation of stromal characteristics is induced by epithelial skin tumor cells depending on their transformation stage when grown as surface transplants in vivo. Tumor cells can regulate the development of a "tumor-stroma" via the aberrant expression of growth factors or induction of growth factor receptors in the stromal compartment. In this context, secretion of the hematopoietic growth factors G-CSF and GM-CSF, constituitively expressed in enhanced malignant tumors, may be good candidates for induction of a tumor stroma through their effect on inflammatory cells. Upon its induction, the tumor stroma will reciprocally influence the differentiation status of tumor cells resulting in a normalization of benign tumor epithelia and the maintenance of a malignant phenotype, respectively. In the HaCaT model for squamous cell carcinoma of the skin, stromal activation and angiogenesis are transient in pre-malignant transplants, however they remain persistent in malignant transplants where progressive angiogenesis is closely correlated with tumor invasion. While continued expression of VEGF and PDGF are associated with benign tumor phenotypes, activation of VEGFR-2 is a hallmark of malignant tumors and accompanies ongoing angiogenesis and tumor invasion. As a consequence the inhibition of ongoing angiogenesis by blocking VEGFR-2 signalling resulted in dramatically impaired malignant tumor expansion and invasion. Comparably, tumor vascularization and invasion was blocked by disturbing the balance of matrix protease activity caused by a lack of PAI-1 in the stromal cells of the knockout mouse hosts. A similar inhibition of tumor vascularization was caused by TSP-1 over-expression in skin carcinoma cells, which also blocked tumor invasion and expansion. On the other hand, when granulation tissue and angiogenesis were only transiently activated as a result of stable transfection of PDGF into non-tumorigenic HaCaT cells, the target cells formed benign, but not malignant, tumors. Collectively, these data show that tumor vascularization, providing intimate association of blood vessels with tumor cells, is a prerequisite for tumor invasion. A potential mechanism for this interrelationship may be the differential regulation of MMP-expression in tumors of different grades of malignancy. In vitro MMP expression did not discriminate between benign and malignant tumor cells unless they were co-cultured with stromal fibroblasts. However, in vivo regulation of MMP expression was clearly dependent on tumor phenotype. While MMP-1 and MMP-13 were down-regulated in benign transplants, they were persistently up-regulated in malignant ones. A tight balance between proteases and their inhibitors is crucial for both the formation and infiltration of blood vessels and for tumor cell invasion, thus again emphasizing the importance of the stromal compartment for the development and progression of carcinomas.

Role of interleukin-8 secreted from human oral squamous cell carcinoma cell lines

Interleukin-8 (IL-8) is an important cytokine involved in tumor growth and angiogenesis in a variety of malignancies. Furthermore, matrix metalloptoteinases (MMPs) also play important roles in the invasion and metastasis of carcinomas including oral squamous cell carcinoma (OSCC). We studied whether IL-8 and MMPs participate in tumorigenesis and metastasis of OSCC. First, we investigated the gene and protein expressions of IL-8 and IL-8 receptor (IL-8R), and the effect of IL-8 on proliferation, migration and invasion of OSCC. Second, we thus also investigated the effect of IL-8 on MMP release in OSCC cells. OSCC cell lines NA and HSC-4 constitutively expressed IL-8 mRNA and secreted its protein in vitro. The production of IL-8 was significantly enhanced by the addition of tumor necrosis factor (TNF)-alpha and IL-beta, but not interferon (IFN)-gamma, granulocyte-macrophage colony-stimulating factor (GM-CSF) or IL-2. Flow cytometric analysis revealed the constitutive expression of both receptors of IL-8, IL-8RA and IL-8RB, in OSCC cell lines. The expression of IL-8 receptors in HSC-4 cells was stronger than that in NA cells. The intensity of IL-8RA expression was stronger than that of IL-8RB expression in each cell line. The expression of IL-8 receptors was not altered by the addition of cytokines such as TNF-alpha and IL-1beta. The conditioned medium containing IL-8 from OSCC cell lines induced migration and invasion of OSCC cells, but did not change cell proliferation. The differences in migrational and invasive ability between NA cells and HSC-4 cells were correlated with the expression intensity of IL-8 receptors in each cell line. Neutralizing antibodies to IL-8, IL-8RA and IL-8RB partially inhibited the chemotactic activity induced by conditioned medium. The expression of MMP-2, -7 and -9 was detected in culture supernatants from these OSCC cell lines. The expressions of MMP-7 protein and mRNA were enhanced by the addition of rIL-8, but that of other MMPs was not observed in a similar manner. These results suggest that IL-8 secreted from OSCC may contribute to the invasion of OSCC through the regulation of MMP-7 expression.

The role of matrix metalloproteinase genes in glioma invasion: co-dependent and interactive proteolysis

Matrix metalloproteinases (MMPs) are cation-dependent endopeptidases which have been implicated in the malignancy of gliomas. It is thought that the MMPs play a critical role in both metastasis and angiogenesis, and that interference with proteases might therefore deter local tumor dissemination and neovascularization. However, the attempt to control tumor-associated proteolysis will rely on better definition of the normal tissue function of MMPs, an area of study still in its infancy in the central nervous system (CNS). Understanding the role of MMP-mediated proteolysis in the brain relies heavily on advances in other areas of molecular neuroscience, most notably an understanding of extracellular matrix (ECM) composition and the function of cell adhesion molecules such as integrins, which communicate knowledge of ECM composition intracellularly. Recently, protease expression and function has been shown to be strongly influenced by the functional state and signaling properties of integrins. Here we review MMP function and expression in gliomas and present examples of MMP profiling studies in glioma tissues and cell lines by RT-PCR and Western blotting. Co-expression of MMPs and certain integrins substantiates the gathering evidence of a functional intersection between the two, and inhibition studies using recombinant TIMP-1 and integrin antisera demonstrate significant inhibition of glioma invasion in vitro. Use of promising new therapeutic compounds with anti-MMP and anti-invasion effects are discussed. These data underline the importance of functional interaction of MMPs with accessory proteins such as integrins during invasion, and the need for further studies to elucidate the molecular underpinnings of this process.

Stromelysin-1 activation correlates with invasiveness in squamous cell carcinoma

The expression of selected metalloproteinases and tissue inhibitors of metalloproteinases (TIMP) was examined in three squamous cell carcinoma (SCC) cell lines (FaDu, SiHa, A431) and a keratinocyte cell line (HaCaT) to determine which metalloproteinases function in SCC invasiveness. A Matrigel invasion assay was used to assess invasiveness of the cell lines. Only the FaDu cell line showed invasiveness in this assay, and invasion of Matrigel by FaDu cells was inhibited by treatment with the metalloproteinase inhibitor, batimastat. No correlation was found between mRNA expression for matrilysin, stromelysins 1-3, TIMP-1, or TIMP-3 and secretion of these proteins, indicating that the extracellular activity of these molecules is regulated post-transcriptionally. The SCC cell lines differed from the HaCaT line in that matrilysin and TIMP-1 proteins were detected in conditioned medium from all SCC cell lines, but not in medium from HaCaT cells. Only the invasive cell line, FaDu, released active stromelysin-1 into the culture medium. These results indicate that while matrilysin contributes to the invasive phenotype, activation of stromelysin-1 is a key regulatory step for invasiveness in SCC cells.

The role of matrix metalloproteinase genes in glioma invasion: co-dependent and interactive proteolysis

Matrix metalloproteinases (MMPs) are cation-dependent endopeptidases which have been implicated in the malignancy of gliomas. It is thought that the MMPs play a critical role in both metastasis and angiogenesis, and that interference with proteases might therefore deter local tumor dissemination and neovascularization. However, the attempt to control tumor-associated proteolysis will rely on better definition of the normal tissue function of MMPs, an area of study still in its infancy in the central nervous system (CNS). Understanding the role of MMP-mediated proteolysis in the brain relies heavily on advances in other areas of molecular neuroscience, most notably an understanding of extracellular matrix (ECM) composition and the function of cell adhesion molecules such as integrins, which communicate knowledge of ECM composition intracellularly. Recently, protease expression and function has been shown to be strongly influenced by the functional state and signaling properties of integrins. Here we review MMP function and expression in gliomas and present examples of MMP profiling studies in glioma tissues and cell lines by RT-PCR and Western blotting. Co-expression of MMPs and certain integrins substantiates the gathering evidence of a functional intersection between the two, and inhibition studies using recombinant TIMP-1 and integrin antisera demonstrate significant inhibition of glioma invasion in vitro. Use of promising new therapeutic compounds with anti-MMP and anti-invasion effects are discussed. These data underline the importance of functional interaction of MMPs with accessory proteins such as integrins during invasion, and the need for further studies to elucidate the molecular underpinnings of this process.

Membrane-type 1 matrix metalloproteinase-mediated progelatinase A activation in non-tumorigenic and tumorigenic human keratinocytes

Elevated expression of type IV collagenases (MMP-2 and MMP-9) has been strongly correlated with tumour progression and metastasis in various tumours. Here, we analysed expression and activation of these MMPs in non-tumourigenic HaCaT cells and the malignant HaCaT variant II-4(rt). In monolayer cultures, both cell types secreted latent MMP-2 (proMMP-2) in comparable amounts, while MMP-9 production was clearly higher in II-4(rt)cells. Upon contact with fibrillar collagen type I the malignant II-4(rt)cells, but not the HaCaT cells, gained the capability to activate proMMP-2. This process is shown to be membrane-associated and mediated by MT1-MMP. Surprisingly, all membrane preparations from either HaCaT cells or II-4(rt)cells grown as monolayers, as well as within collagen gels, contained considerable amounts of active MT1-MMP. However, within collagen gels HaCaT cells showed significantly higher TIMP-2 levels compared to II-4(rt)cells. This indicates that TIMP-2 might play a central role for MT1-MMP-mediated gelatinolytic activity. Indeed, collagen type I-induced MT1-MMP-mediated proMMP-2 activation by II-4(rt)membranes could be completely abolished by an excess of TIMP-2. In conclusion, our data suggest that MT1-MMP-mediated proMMP-2 activation might be associated with malignant progression of epidermal tumour cells.

Ras-transfection up-regulated HaCaT cell migration: inhibition by Marimastat

Cell migration is an essential process in physiological and pathological conditions such as wound healing and tumor invasion. This phenomenon involves cell adhesion on the extracellular matrix mediated by integrins, and cell detachment promoted in part by metalloproteinases (MMPs). In the present study, the migration of two HaCaT-ras clones (metastatic or not), was compared with HaCaT cells, and normal human primary cultured keratinocytes. Using colloidal gold migration assay, the migration index on type I and type IV collagen was similar for primary cultured keratinocytes and HaCaT, whereas it was markedly higher for the HaCaT-ras clones. High motility of ras-transfected cells was confirmed from an in vitro wound healing assay. It was not correlated with changes in integrin expression or related to a different adhesion on extracellular matrix. The Marismastat (BB-2516), a MMP inhibitor, inhibited in a dose-dependent effect the migration in both assays, demonstrating the important role of MMPs in the migration process. Under our experimental conditions, MMP-1 activity was not detected in HaCaT and MMP-9 activity was secreted by these cells only after their stimulation by EGF. Here, MMP-2 was the major gelatinolytic activity secreted by all the cells and its secretion was markedly higher for HaCaT-nis clones compared with HaCaT. In addition, Western blotting results confirmed a higher expression of MMP-2 associated with a lower expression of TIMP-2 in HaCaT-ras compared with HaCaT. These results suggest that Ha-ras oncogene could be a stimulating factor of migration and might modified the balance between MMP-2 and TIMP-2 in keratinocyte cell lines.

Differential expression of matrix metalloproteinases and their inhibitors in non-small cell lung cancer

In a comprehensive immunohistochemical study of the expression of ten metalloproteinases (MMPs) and their four inhibitors (TIMPs) in 115 non-small cell lung carcinomas (NSCLCs), the findings have been correlated with the histological and clinical features of the tumours. All MMPs and TIMPs were expressed in tumours, with frequencies ranging from 41% for MMP-2 to 68% for MMP-13. Stromal immunoreactivity ranged from 6% for TIMP-4 to 87% for MMP-13. In some tumours, an overexpression of these proteins, as revealed by stronger staining in cancer cells than in adjacent normal bronchial epithelium, was also observed. The frequency ranged from 1% for MMP-3 to 28% for MMP-13. Compared with squamous cell carcinoma (SqCC), adenocarcinoma (AdC) more frequently overexpressed MMP-1, -11, -13, -14, and TIMP-2, and TIMP-1 and/or TIMP-2 overexpression positively correlated with more advanced stage disease. None of the MMP or TIMP expression correlated with the ras genotype of the tumours. The higher frequency of MMP overexpression in AdC than in SqCC may relate to the greater tendency of the former for systemic metastasis. The association of TIMP-1 overexpression with more advanced disease may suggest a role in prognosis.

Expression of multiple matrix metalloproteinases and urokinase type plasminogen activator in cultured Kaposi sarcoma cells

Kaposi's sarcoma (KS) cells are considered to be of endothelial origin. KS lesions are characterized by hyperproliferation and an invasive phenotype. We have determined that KS cell cultures constitutively secrete multiple forms of several matrix metalloproteinases (MMPs) and an altered form of urokinase plasminogen activator (uPA) by zymogram and Western analysis of the culture media. MMPs are a family of secreted endoproteinases which degrade components of the extracellular matrix. Their enhanced expression and activity are strongly correlated with cellular processes involving tissue remodeling and invasion. The KS cells secrete increased levels of gelatinase A and B and a high molecular weight uPA in vitro when compared with non-KS endothelial or epithelial cells. Multiple forms of gelatinases A and B were observed on gelatin zymograms. Caseinolytic bands observed were confirmed by Western blot analysis to be due to stromelysin activity, whereas matrilysin was not detected by casein zymography. Western blot analysis also detected secretion of interstitial collagenase and high molecular weight uPA. Gelatinolytic activity with the mobility of gelatinase B was detected on gelatin zymograms, but not by Western analysis. This unusual constitutive expression pattern of MMPs and uPA by KS cells in vitro is characterized by elevated levels of gelatinase A, gelatinase B, interstitial collagenase, stromelysin and a high molecular weight form of uPA, and the lack of expression of matrilysin. These secreted MMPs, taken together, are capable of digesting a broad range of components of the extracellular matrix. This unusual pattern is likely to contribute to the characteristic hyperproliferative and invasive phenotype of KS lesions.

Tumor and endothelial cell invasion of basement membranes. The matrigel chemoinvasion assay as a tool for dissecting molecular mechanisms

The spread of cancer cells from a primary tumor to distant organs is the major cause of death of cancer patients. Metastatic lesions are often resistent to cancer therapy because of the progressive phenotypic changes that they have undergone. Several genetic and epigenetic factors, both in the cell and in the host, contribute to the development of tumor progression towards metastases. In this review we will analyze the steps involved in tumor metastases, which can be potential targets for anti-metastatic therapy. One of the most critical events in cancer metastasis is the invasion of basement membranes. An assay which we developed over ten years ago, the matrigel "chemoinvasion" assay, has been a useful tool for studying the mechanisms involved in tumor and endothelial cell invasion of basement membranes and for the screening of anti-invasive agents. Here we will describe the assay and review some of the major results obtained with it.