MMP and TIMP gene expression in head and neck squamous cell carcinomas and adjacent tissues

Human papillomavirus elevated genetic biomarker signature by statistical algorithm

Head and neck squamous cell carcinoma (HNSCC) is the one of the most frequently found cancers in the world. The aim of the study was to find the genes responsible and enriched pathways associated with HNSCC using bioinformatics and survival analysis methods. A total of 646 patients with HNSCC based on clinical information were considered for the study. HNSCC samples were grouped according to the parameters (RFS, DFS, PFS, or OS). The probe ID of these 11 genes was retrieved by Affymetrix using the NetAffx Query algorithm. The protein-protein interaction (PPI) network and Kaplan-Meier curve were used to find associations among the genes' expression data. We found that among these 11 genes, nine genes, CCNA1, MMP3, FLRT3, GJB6, ZFR2, PITX2, SYCP2, MEI1, and UGT8 were significant (p < .05). A survival plot was drawn between the p value and gene expression. This study helped us find the nine significant genes which play vital roles in HNSCC along with their key pathways and their interaction with other genes in the PPI network. Finally, we found the biomarker index for relapse time and risk factors for HNSCC in cancer patients.

High level of plasma matrix metalloproteinase-11 is associated with clinicopathological characteristics in patients with oral squamous cell carcinoma

Background

Matrix metalloproteinase-11 (MMP-11) is reported to be overexpressed in several cancers and may contribute to tumorigenesis. The current study investigated the association between the clinicopathological characteristics and plasma level of MMP-11 in oral squamous cell carcinoma (OSCC) patients.

Methodology and Principal Findings

The plasma MMP-11 concentration was determined by ELISA on 330 male OSCC patients. In addition, the metastatic effects of the MMP-11 knockdown on the oral cancer cells were investigated by cell migration assay. Our results showed that the plasma MMP-11 levels were significantly higher in patients with advanced T status (p = 0.001), lymph node metastasis (p = 0.006) and higher TNM stages (p<0.001). Moreover, treatment with the MMP-11 shRNA exerted an inhibitory effect on migration in SCC9 oral cancer cells.

Conclusion

Our study showed that plasma level of MMP-11 may be useful for assessment of the disease progression, especially lymph node metastasis, in patients with OSCC.

Tumor microenvironment in head and neck squamous cell carcinoma

The tumor microenvironment (TME) of head and neck squamous cell carcinoma (HNSCC) is comprised of cancer-associated fibroblasts (CAFs), immune cells, and other supporting cells. Genetic changes in the carcinoma cells, such as alterations to TP53, NOTCH1, and specific gene expression profiles, contribute to derangements in cancer and microenvironment cells such as increased ROS, overproduction of cytokines, and epithelial to mesenchymal transition (EMT). CAFs are among the most critical elements of the TME contributing to proliferation, invasion, and metastasis. The adaptive immune response is suppressed in HNSCC through overexpression of cytokines, triggered apoptosis of T cells, and alterations in antigen processing machinery. Overexpression of critical cytokines, such as transforming growth factor-β (TGF-β), contributes to EMT, immune suppression, and evolution of CAFs. Inflammation and hypoxia are driving forces in angiogenesis and altered metabolism. HNSCC utilizes glycolytic and oxidative metabolism to fuel tumorigenesis via coupled mechanisms between cancer cell regions and cells of the TME. Increased understanding of the TME in HNSCC illustrates that the long-held notion of "condemned mucosa" reflects a process that extends beyond the epithelial cells to the entire tissue comprised of each of these elements.

Matrix metalloproteinase-2 as a target for head and neck cancer therapy

INTRODUCTION

Matrix metalloproteinase (MMP)-2 is a zinc-dependent proteinase that is capable of cleaving all extracellular matrix (ECM) substrates. Degradation of the matrix is a key event in the progression, invasion, and metastasis of potentially malignant and malignant lesions of the head and neck. Therefore, blocking MMP-2 expression or activity may present a promising strategy for anticancer treatment.

AREAS COVERED

Current understanding of the molecular mechanisms that govern MMP-2 regulation and its tumorigenic effects, and that are involved in the initiation and progression of head and neck cancers, in particular the emerging role of MMP-2 in cell migration, which is a prerequisite for tumor metastasis. MMP-2 gene polymorphisms, cellular substrates, and interacting proteins are summarized. The current state of drugs that target this enzyme, either alone or in combination with other targeted agents are also discussed.

EXPERT OPINION

MMP-2 has long been a drug target. The current status of MMP-2 inhibitors as anticancer agents and their failure in the clinic is discussed in light of new data on the MMP-2s role as a cell surface transducer - data that may lead to the design and development of novel, MMP-2-targeting inhibitors.

LEF-1 regulates proliferation and MMP-7 transcription in breast cancer cells

Matrix metalloproteinase-7 (MMP-7) is a small secreted proteolytic enzyme with broad substrate specificity. Its expression is associated with tumor invasion, metastasis, and survival in a variety of cancers including breast cancer. Using bioinformatics analysis, a conserved LEF-1 binding site became obvious that is mapped at the promoter region of the genomic MMP-7 locus. Consequently, electrophoretic mobility shift assay demonstrated in vitro binding of LEF-1 to the predicted MMP-7 promoter binding site. Here, we demonstrate that lymphoid enhancer binding factor-1 (LEF-1) is associated with regulation of the proliferation-associated cyclin D1 and a gene encoding MMP-7 in breast cancer cells. Thus, a decrease of LEF-1 expression using LEF-1 siRNA resulted in down-regulation of cyclin D and MMP-7 expression, respectively. Moreover, cell cycle analysis of LEF-1 siRNA-transfected human breast cancer cells revealed a significant arrest in G2/M phase. Taken together, our results indicate a pivotal role of LEF-1 in the regulation of proliferation and MMP-7 transcription in breast cancer cells.

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

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

Efficient targeting of head and neck squamous cell carcinoma by systemic administration of a dual uPA and MMP-activated engineered anthrax toxin

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Although considerable progress has been made in elucidating the etiology of the disease, the prognosis for individuals diagnosed with HNSCC remains poor, underscoring the need for development of additional treatment modalities. HNSCC is characterized by the upregulation of a large number of proteolytic enzymes, including urokinase plasminogen activator (uPA) and an assortment of matrix metalloproteinases (MMPs) that may be expressed by tumor cells, by tumor-supporting stromal cells or by both. Here we explored the use of an intercomplementing anthrax toxin that requires combined cell surface uPA and MMP activities for cellular intoxication and specifically targets the ERK/MAPK pathway for the treatment of HNSCC. We found that this toxin displayed strong systemic anti-tumor activity towards a variety of xenografted human HNSCC cell lines by inducing apoptotic and necrotic tumor cell death, and by impairing tumor cell proliferation and angiogenesis. Interestingly, the human HNSCC cell lines were insensitive to the intercomplementing toxin when cultured ex vivo, suggesting that either the toxin targets the tumor-supporting stromal cell compartment or that the tumor cell requirement for ERK/MAPK signaling differs in vivo and ex vivo. This intercomplementing toxin warrants further investigation as an anti-HNSCC agent.

Functional expression of the chemokine receptor XCR1 on oral epithelial cells

Chemokines are chemoattractant cytokines which act on specific receptors and play an important role in leukocyte migration as well as physiological and pathological processes. We investigated the role of the chemokine receptor XCR1 and its ligand lymphotactin (Lptn/XCL1) in the regulation of oral epithelial cell behaviour. In vitro XCR1 mRNA and cell surface protein expression was detected in normal oral keratinocytes and oral squamous cell carcinoma cell lines. Lymphotactin mediated intracellular activation of the ERK1/2 signalling pathway and stimulated migration, invasion, and proliferation of all cells through XCR1. Oral cancer cells showed a greater response to lymphotactin than normal keratinocytes and a direct relationship between receptor expression and migration, invasion, and proliferation was observed. Exposure of normal keratinocytes to lymphotactin resulted in increased adhesion to fibronectin but not collagen and stimulated MMP-2 and MMP-9 but not MMP-7 release, whereas exposure of cancer cells resulted in increased adhesion to both collagen and fibronectin and stimulated production of MMP-2, MMP-9, and MMP-7. We observed XCR1 but not lymphotactin to be expressed by epithelial cells in normal oral mucosa in vivo, whilst both were expressed and up-regulated in inflammatory oral disease and oral cancer including primary and metastatic disease. Lymphotactin mRNA and constitutive intracellular protein were detected in normal keratinocytes and oral cancer cell lines in vitro. These findings show that XCR1 and its ligand, lymphotactin, are expressed by oral epithelial cells and suggest that they play a role in regulating the behaviour of these cells.

CCL25-CCR9 interaction modulates ovarian cancer cell migration, metalloproteinase expression, and invasion

BACKGROUND

Ovarian carcinoma (OvCa) is the most lethal gynecological malignancy among women and its poor prognosis is mainly due to metastasis. Chemokine receptor CCR9 is primarily expressed by a small subset of immune cells and its only natural ligand, CCL25, is largely expressed in the thymus, which involutes with age. Other than the thymus, CCL25 is expressed by the small bowel. Interactions between CCL25 and CCR9 have been implicated in leukocyte trafficking to the small bowel, a frequent metastatic site for OvCa cells. The current study shows OvCa tissue and cells significantly express CCR9, which interacts with CCL25 to support carcinoma cell migration and invasion.

METHODS

RT-PCR and flow cytometry techniques were used to quantify the expression CCR9 by OvCa cells. OvCa tissue microarrays (TMA) was used to confirm CCR9 expression in clinical samples. The Aperio ScanScope scanning system was used to quantify immunohistochemical staining. Cell invasion and migration assays were performed using cell migration and matrigel invasion chambers. Matrix metalloproteinase (MMP) mRNAs were quantified by RT-PCR and active MMPs were quantified by ELISA.

RESULTS

Our results show significantly (p<0.001) higher expression of CCR9 by mucinous adenocarcinoma, papillary serous carcinoma, and endometriod ovarian carcinoma cases, than compared to non-neoplastic ovarian tissue. Furthermore, CCR9 expression was significantly elevated in OvCa cell lines (OVCAR-3 and CAOV-3) in comparison to normal adult ovarian epithelial cell mRNA. OvCa cells showed higher migratory and invasive potential towards chemotactic gradients of CCL25, which was inhibited by anti-CCR9 antibodies. Expression of collagenases (MMP-1, -8, and -13), gelatinases (MMP-2 and -9), and stromelysins (MMP-3, -10, and -11) by OvCa cells were modulated by CCL25 in a CCR9-dependent fashion.

CONCLUSIONS

These results demonstrate both biological significance and clinical relevance of CCL25 and CCR9 interactions in OvCa cell metastasis.

Matrilysins may not predict the metastatic potential in squamous cell carcinoma of the tongue

OBJECTIVE

To examine immunoexpression of matrix metalloproteinase (MMP)-7 and -26 in squamous cell carcinoma (SCC) of the tongue and its relation with cervical metastasis.

MATERIAL AND METHODS

Twenty-four cases were selected and divided into two groups: a metastatic group (n = 12) and a non-metastatic group (n = 12). Cases were graded as either negative (score 0), positive (score +) or strongly positive (score ++).

RESULTS

MMP-7 expression was identical in both groups, with 17% of the cases graded as score 0, 50% as score + and 33% as score ++. MMP-26 expression was 25% score 0, 8% score + and 67% score ++ in the metastatic group, and 8% score 0, 50% score + and 42% score ++ in the non-metastatic group. Statistical analysis showed no differences between the studied groups and no correlations between proteins.

CONCLUSIONS

MMP-7 and -26 immunostaining is not a useful indicator of the metastatic potential of SCCs of the tongue. However, the role of these proteins in the process of invasion and metastasis cannot be ruled out since their more marked presence along the tumor invasion front compared to more central areas of the tumors indicates higher secretion of these proteases in this region, facilitating the invasion process.

Clinical and biological significance of CXCR5 expressed by prostate cancer specimens and cell lines

Chemokines and chemokine receptors have been shown to be involved in metastatic process of prostate cancer (PCa). In this study, we show primary PCa tissues and cell lines (LNCaP and PC3) express CXCR5, a specific chemokine receptor for CXCL13. Expression of CXCR5 was significantly higher (p < 0.001) in PCa cases than compared to normal match (NM) tissues. CXCR5 intensity correlated (R(2) = 0.97) with Gleason score. While prostate tumor tissues with Gleason scores >or= 7, displayed predominantly nuclear CXCR5 expression patterns, PCa specimens with Gleason scores <or= 6 showed predominantly membrane and cytoplasmic expression patterns that were comparable to benign prostatic hyperplasia (BPH). Similar to tissue expression, PCa cell lines expressed significantly more CXCR5 than normal prostatic epithelial cells (PrECs), and CXCR5 expression was distributed among intracellular and extracellular compartments. Functional in vitro assays showed higher migratory and invasive potentials toward CXCL13, an effect that was mediated by CXCR5. In both PCa cell lines, CXCL13 treatment increased the expression of collagenase-1 or matrix metalloproteinase-1 (MMP-1), collagenase-3 (MMP-13), stromelysin-1 (MMP-3), stromelysin-2 (MMP-10) and stromelysin-3 (MMP-11). These data demonstrate the clinical and biological relevance of the CXCL13-CXCR5 pathway and its role in PCa cell invasion and migration.

LPA receptor 2 mediates LPA-induced endometrial cancer invasion

OBJECTIVE

We have previously shown that lysophosphatidic acid (LPA) promotes the ovarian cancer metastatic cascade. In this study, we evaluated the role of LPA on endometrial cancer invasion.

METHODS

Transient mRNA knockdown was accomplished using pre-designed siRNA duplexes against LPA receptor 2 (LPA2) and human matrix metalloproteinase-7 (MMP-7). RT-PCR was used to characterize LPA receptor and MMP-7 expression. Analysis of in vitro invasion was performed with rat-tail collagen type I coated Boyden chambers. Gelatin zymography was used to evaluate the MMP activity in cell culture conditioned media. Cell-cell and cell-matrix attachment was also assessed upon LPA2 knockdown to further illuminate the LPA2 cascade.

RESULTS

LPA increases HEC1A cellular invasion at physiologic concentrations (0.1-1 muM). Of the four principle LPA receptors, LPA2 is predominantly expressed by HEC1A cells. Transient transfection of LPA2 siRNA reduced LPA2 mRNA expression in HEC1A cells by 93% (P<0.01). Silencing LPA2 eliminated the LPA-stimulated increase in invasion (P<0.05) and reduced LPA-induced MMP-7 secretion/activation, without significantly affecting cell-cell or cell-matrix adhesion. Silencing MMP-7 reduced overall invasion but did not eliminate LPA's pro-invasive effect on HEC1A cells, as compared to negative control (P<0.05). Gelatin zymography confirmed that LPA2 and MMP-7 knockdown reduced MMP-7 activation in HEC1A conditioned media.

CONCLUSION

LPA2 mediates LPA-stimulated HEC1A invasion and the subsequent activation of MMP-7.

Suppression of local invasion of ameloblastoma by inhibition of matrix metalloproteinase-2 in vitro

Background

Ameloblastomas are odontogenic neoplasms characterized by local invasiveness. This study was conducted to address the role of matrix metalloproteinase-2 (MMP-2) in the invasiveness of ameloblastomas.

Methods

Plasmids containing either MMP-2 siRNA or tissue inhibitor of metalloproteinase-2 (TIMP-2) cDNA were created and subsequently transfected into primary ameloblastoma cells. Zymography, RT-PCR, and Western blots were used to assess MMP-2 activity and expression of MMP-2 and TIMP-2, as well as protein levels.

Results

Primary cultures of ameloblastoma cells expressed cytokeratin (CK) 14 and 16, and MMP-2, but only weakly expressed CK18 and vimentin. MMP-2 mRNA and protein levels were significantly inhibited by RNA interference (P < 0.05). Both MMP-2 siRNA and TIMP-2 overexpression inhibited MMP-2 activity and the in vitro invasiveness of ameloblastoma.

Conclusion

These results indicate that inhibition of MMP-2 activity suppresses the local invasiveness of ameloblastoma cells. This mechanism may serve as a novel therapeutic target in ameloblastomas pursuant to additional research.

Requirement of MMP-3 in anchorage-independent growth of oral squamous cell carcinomas

BACKGROUND

Matrix metalloproteinase-3 (MMP-3) is expressed in various carcinomas; however, its function is not clearly established. This study was to assess its possible role in oral squamous cell carcinomas (OSCCs).

MATERIALS AND METHODS

Specimens of seven oral pre-malignant lesions (OPMLs) and 92 OSCCs were subjected to MMP-3 detection by RT-PCR and Western blot. Antisense oligodeoxynucleotides (AODNs) of MMP-3 were used to transfect OSCC (OECM-1 and SCC-9) and esophageal carcinoma (CE81T/VGH) cell lines, and their growth was subsequently analyzed by XTT and soft-agar colony assay.

RESULTS

MMP-3 transcript was preferentially expressed in OSCCs (71 of 92, 77%) than in OPMLs (two of seven, 29%; P = 0.012). Both MMP-3 transcript and protein levels were significantly higher in OSCC masses than in neighboring tissues (P < 0.0001 and P = 0.04, respectively). Growth of the three cell lines was not affected, while the colony numbers of OECM-1 and CE81T/VGH were significantly reduced by the transfection of MMP-3 AODNs (P = 0.002 and P = 0.004, respectively). SCC-9 did not form colonies in soft-agar/medium.

CONCLUSIONS

MMP-3 function may be required in most OSCCs, and it may support the anchorage-independent growth of both OSCC and esophageal carcinoma.

Increased expression of the collagen internalization receptor uPARAP/Endo180 in the stroma of head and neck cancer

Local growth, invasion, and metastasis of malignancies of the head and neck involve extensive degradation and remodeling of the underlying, collagen-rich connective tissue. Urokinase plasminogen activator receptor-associated protein (uPARAP)/Endo180 is an endocytic receptor recently shown to play a critical role in the uptake and intracellular degradation of collagen by mesenchymal cells. As a step toward determining the putative function of uPARAP/Endo180 in head and neck cancer progression, we used immunohistochemistry to determine the expression of this collagen internalization receptor in 112 human squamous cell carcinomas and 19 normal or tumor-adjacent head and neck tissue samples from the tongue, gingiva, cheek, tonsils, palate, floor of mouth, larynx, maxillary sinus, upper jaw, nasopharynx/nasal cavity, and lymph nodes. Specificity of detection was verified by staining of serial sections with two different monoclonal antibodies against two non-overlapping epitopes on uPARAP/Endo180 and by the use of isotype-matched non-immune antibodies. uPARAP/Endo180 expression was observed in stromal fibroblast-like, vimentin-positive cells. Furthermore, expression of the collagen internalization receptor was increased in tumor stroma compared with tumor-adjacent connective tissue or normal submucosal connective tissue and was most prominent in poorly differentiated tumors. These data suggest that uPARAP/Endo180 participates in the connective tissue destruction during head and neck squamous cell carcinoma progression by mediating cellular uptake and lysosomal degradation of collagen.

Matrix metalloproteinase gene expression in oral lichen planus: erosive vs. reticular forms

BACKGROUND

Oral lichen planus (OLP) is an autoimmune disease of unknown aetiology. The pathogenesis is characterized by apoptosis of basal keratinocytes, triggered by contact between CD8+ -activated lymphocytes and an unknown antigen expressed on the surface of the basal cells. Basement membrane (BM) degradation, which allows lymphocytes to migrate, involves proteolytic enzymes known as matrix metalloproteinases (MMPs).

OBJECTIVES

This study aimed to evaluate the expression of a series of MMPs in biopsies from OLP patients, to reveal correlations with different clinical forms of OLP.

METHODS

Twenty-six patients diagnosed with OLP (14 reticular and 12 erosive) were studied, together with seven healthy patients as negative controls.

RESULTS

Reverse transcriptase polymerase chain reaction (RT-PCR) showed that the overall levels of expression of MMP mRNAs were higher in erosive lichen planus (E-OLP) than in the reticular forms (R-OLP). Moreover, MMP-1 and MMP-3 may be principally associated with erosion development. The expression of specific tissue inhibitors of metalloproteinases (TIMPs) was also evaluated.

CONCLUSIONS

The different clinical appearances of OLP are associated with significant differences in MMP mRNA levels.

Matrix metalloproteases in head and neck cancer

Matrix metalloproteases (MMPs) are a collection of enzymes capable of cleaving extracellular matrix components, growth factors, and cell-surface receptors. MMPs modulate most aspects of tumorigenesis and are highly expressed in cancer compared with normal tissues. Preclinical studies have demonstrated that head and neck squamous cell carcinomas (HNSCCs) express high levels of MMPs in vivo and that inhibition of these enzymes in vitro and in mouse models decreases invasion and metastasis. However, the clinical trials for MMP inhibitors have failed to demonstrate a significant survival advantage in most cancers. The disparity between preclinical and clinical studies has led to the reevaluation of how MMP functions in cancer and the design of clinical trials for molecularly targeted agents. Mouse model data and analysis of HNSCC tumor specimens suggests that membrane type-1 MMP (MT1-MMP) may be a critical enzyme in tumor cell invasion and survival in vivo. This accumulated data provide evidence for development of selective MT1-MMP inhibitors as therapy in HNSCC.

Inhibition of Matrilysin Expression by Antisense or RNA Interference Decreases Lysophosphatidic Acid–Induced Epithelial Ovarian Cancer Invasion

Our previous reports show that matrilysin [matrix metalloproteinase (MMP)-7] is overexpressed in epithelial ovarian cancer (EOC) and recombinant MMP-7 promotes EOC invasion in vitro. In the present study, we further evaluated the correlation of MMP-7 expression to EOC invasiveness and examined its role in lysophosphatidic acid (LPA)-induced invasion. By sense and antisense gene transfection in vitro, we show that overexpression of MMP-7 in all MMP-7 stably transfected DOV13 clones significantly enhanced their invasiveness, although MMP-7 antisense transfection caused a 91% decrease of MMP-7 expression (P < 0.01) and 87% decrease of invasion (P < 0.05) in geneticin (G418)-selected DOV13 clone P47-M7As-3 compared with vector-transfected control. As assessed by MMP-7 ELISA, LPA treatment at 10 to 80 micromol/L significantly stimulated the secretion of total MMP-7 in DOV13 conditioned medium (P < 0.01). In addition, LPA apparently induced the activation of MMP-7 in DOV13 cells as detected by gelatin zymography. In the antisense MMP-7-transfected DOV13 clone (P47-M7As-3), LPA-increased invasion was significantly decreased compared with vector control. Moreover, knocking down of MMP-7 by small interfering RNA also suppressed LPA-induced invasion in two EOC cell lines (DOV13 and R182). Altogether, our results show that MMP-7 expression is correlated with EOC invasiveness and LPA-induced MMP-7 secretion/activation may represent a new mechanism that facilitates ovarian cancer invasion besides the well-known induction of MT1-MMP-mediated proMMP-2 activation by LPA.

The functional (-1171 5A-->6A) polymorphisms of matrix metalloproteinase 3 gene as a risk factor for oral submucous fibrosis among male areca users

BACKGROUND

Insertion/deletion (-1171 5A-->6A) polymorphisms in the promoter region of matrix metalloproteinase 3 (MMP3) gene result in different transcriptional activities. MMP3 is able to degrade collagens types II, V, IX, and X, and other extracellular matrix. The functional promoter polymorphism of MMP3 has been related to the susceptibility in some inflammatory diseases and metastasis of cancers.

METHODS

Oral submucous fibrosis (OSF) and oral squamous cell carcinoma (OSCC) are prevalent among Asian areca users. In this study, genomic DNA obtained from the blood of OSCC (n = 150), OSF (n = 71), and control non-diseased areca user (n = 98) in male were subjected to polymerase chain reaction (PCR)-based genotyping of MMP3.

RESULTS

The 5A genotype in MMP3 promoter was observed more frequently in OSF group than in control group (P = 0.01). No significant difference was noted between OSCC and control groups on the 5A genotype frequency (P = 0.18). No association was found between 5A genotype in MMP3 promoter and site or lymph node metastasis and stage of OSCC.

CONCLUSION

The results indicated that the 5A genotype of MMP3 promoter was associated with the risk of OSF but not OSCC.

Matrix metalloproteinases and their inhibitors as biomarkers for metal toxicity in vitro

Exposure to nickel and chromium, and their compounds, has been associated with adverse health effects. These metals are two human carcinogens whose pathogenesis involves active extracellular matrix degradation and remodelling. In this work we have compared the effects of in vitro exposure to nickel and chromium of a keratinocyte cell line (HaCat). The modulation of matrix metalloproteinase genes was used as biomarker of chemical damage. Confluent cells were constantly exposed to subtoxic chromium and nickel concentrations (10(-5) and 10(-7)M) up to 72 h. Total RNA was extracted and specific matrix metalloproteinase, and inhibitor, gene expression was analyzed by RT-PCR. Moreover, cell cycle alterations were evaluated by flow cytometry. Nickel and chromium showed different results, with an upregulation of MMP-2 mRNA production in nickel-treated cells while chromium exposure down-regulated MMP-2 mRNA production. This result could be correlated to the precocious (6h) over-expression of tissue inhibitor-1 (TIMP-1) mRNA in chromium-treated cells. Cell cycle analysis showed and increase of cells with 4N DNA. These results could be explained as a survival response of cells that escape metal induced apoptosis through the anti-apoptotic effects of TIMP-1. These cells that encompass the genotoxic insult may have a selective proliferation advantage, and therefore represent the precursor pool from which degenerating variants may emerge. To study if the chemical damage was reversible, subconfluent cells were stimulated only for 24 h, then the medium was replaced without metal. Cells were able to recover from nickel exposure, showing only weak alterations in specific mRNA expression and cell cycle alteration respect to control. Chromium-induced damage was irreversible. Our results demonstrated that there is an association between metal toxicity and expression of MMPs and their inhibitors. These biomarkers could be potentially useful to elaborate a prediction model of chemical toxicity.

The matrix metalloproteinase system in oral squamous cell carcinoma

BACKGROUND

The matrix metalloproteinase (MMP) system is responsible for degradation of tissue in both normal and pathological processes, including tumour invasion and metastasis.

AIM

To compare tissue concentrations of components of the MMP system between tumour tissue and normal tissue in patients with oral squamous cell carcinoma, and to correlate concentrations with pathological grade of tumour.

METHODS

Thirty-eight paired tissue samples from tumours and normal tissue were analysed by three laboratory techniques: firstly, enzyme linked immunosorbent assays (ELISA) in ng/mg protein for MMP-1, MMP-3, and tissue inhibitors of metalloproteinases (TIMPs) -1 and -2. Secondly, gelatinase activity assays to measure concentrations of total and endogenous active gelatinases, MMP-2 and MMP-9 (ng/mg protein). And thirdly to use quenched fluorescent substrate hydrolysis to measure total MMP activity (pM/min).

RESULTS

The concentration of all MMPs was significantly higher in tumour than in normal oral tissue (p < 0.05, Mann-Whitney U-test). Tissue concentrations of some of these factors correlated with clinical and pathological indices of aggressiveness of tumours, including T-stage, N-stage, tumour differentiation, and anatomical level of involved nodes. However, the study was not powered to show statistical significance.

CONCLUSION

It is the balance between proteinases and their inhibitors that controls tissue degradation at each stage of tumour invasion and metastasis. Measurement of MMPs in oral mucosal biopsy samples may establish the invasive potential of tumours at their initial presentation.

Expression and functional role of CCR9 in prostate cancer cell migration and invasion

PURPOSE

Metastasis is responsible for most cancer-related deaths; hence, therapies designed to minimize metastasis are greatly needed. The precise cellular and molecular mechanisms used by cancer cells for metastasis are not fully understood; however, the metastatic spread of neoplastic cells is probably related to the ability of these cells to migrate, invade, home, and survive locally. The migration of tumor cells shares many similarities with leukocyte trafficking, which is regulated by chemokine receptor-ligand interactions. The current study evaluates the molecular mechanisms of CCL25 and CCR9 in prostate cancer cell migration and invasion.

EXPERIMENTAL DESIGN

In the current study, real-time quantitative polymerase chain reaction, flow cytometry analysis, and in vitro migration as well as invasion chamber analysis (with and without antibody-mediated inhibition) were used to ascertain the biological and functional significance of CCR9 expression by normal prostatic epithelial cells (PrEC) or prostate cancer cell lines (LNCaP-10995 and PC3).

RESULTS

We report that functional CCR9 is highly expressed by LNCaP cells and modestly, yet significantly, expressed by PC3 cells when compared with PrEC cells. Neutralization of CCL25-CCR9 interactions impaired the migration and invasion potential of the LNCaP and PC3 cell lines. CCL25 differentially modulated the expression of collagenase-1 or matrix metalloproteinase (MMP)-1, collagenase-3 (MMP-13), stromalysin-2 (MMP-10), stromalysin-3 (MMP-11), and gelatinase-A (MMP-2), but not MMP-3, MMP-7, MMP-8, MMP-9, MMP-12, or MMP-14 in prostate cancer cells.

CONCLUSIONS

These studies suggest that the expression and activation of CCR9 affect cancer cell migration, invasion, and MMP expression, which together may affect prostate cancer metastasis.

Matrilysin over-expression in MCF-7 cells enhances cellular invasiveness and pro-gelatinase activation

Matrilysin (MMP-7) is over-expressed in various cancers and is thought to play important roles in tumor invasion and metastasis. However, the function of MMP-7 in breast cancer remains unclear. We therefore examined the expression of the MMP-7 gene in breast cancer (MCF-7) cells and the effect of its over-expression on cellular invasion. We transfected human MMP-7 into MCF-7 cells and selected clones that stably over-expressed the MMP-7 gene. The in vitro invasiveness of MCF-7 cells was quantified by use of the Matrigel invasion assay. Expression of MMP-7 mRNA was analyzed by quantitative RT-PCR. MMP secretion and activation were detected by gelatin zymography. We found that MMP-7-expressing clones had significantly increased invasion (P < 0.001), with increased MMP-7 expression and gelatinase activation as compared to the vector controls. We conclude that MMP-7 over-expression correlates with breast cancer in vitro invasiveness and that MMP-7 may promote invasion by increasing the secretion and activation of proMMP-2 and proMMP-9.

Immunoexpression and prognostic significance of TIMP-1 and -2 in oral squamous cell carcinoma

Matrix metalloproteinases (MMPs) are proteolytic enzymes that are capable of degrading different substrates within the extracellular matrix, and which are believed to be crucial for tumor invasion and metastasis. Tissue inhibitors of MMPs (TIMPs) can inhibit the action of MMPs but also can show a paradoxical poor prognostic effect. In order to evaluate the prognostic significance of TIMPs, we studied the expression of TIMP-1 and -2 in series of 68 oral squamous cell carcinomas (OSCC) by immunohistochemistry. Expression of TIMP-1 was detected in 45 cases (66.2%). In all of these TIMP-1 was expressed in tumoral tissue, and in 19 of them also in the surrounding stroma. In cancer tissue, TIMP-1 was observed in three patterns: homogeneous, central and irregular. Immunoreactivity for TIMP-2 was detected in 38 cases (56%) in tumoral tissue and 9 (13.2%) in the stroma. The expression pattern of TIMP-2 was the same three as TIMP-1 and one more: invasive front of tumoral nests. TIMP-1 expression was not correlated with clinical or pathological parameters. However, TIMP-2 was significantly correlated with T stage (p=0.03), TNM stage (p=0.01), local recurrence (p=0.04), and poor survival (p=0.03, odds ratio=2.75). TIMP-1 and TIMP-2 were significantly correlated with cyclin D1 (p=0.04; p=0.015, respectively) and p53 expressions (p=0.02; p=0.04, respectively). Finally, TIMP-1 but no TIMP-2 was associated with the nuclear antigen Ki-67 (p=0.001). These results suggest that TIMP-1 and -2 are expressed in tumoral and stromal tissue in OSCC. TIMP-2 is related to advanced disease, recurrence and poor prognosis.

Stromelysin 3, Ets-1, and vascular endothelial growth factor expression in oral precancerous and cancerous lesions: correlation with microvessel density, progression, and prognosis

PURPOSE

Identification of molecular changes characteristic of development and progression of oral cancer are of paramount importance for effective intervention. Stromelysin 3 (MMP11) is a unique matrix metalloproteinase shown to have dual function during cancer progression. The transcription factor Ets-1 and vascular endothelial growth factor (VEGF) are important proangiogenic factors in cancer. This study was designed to test the hypothesis that concomitant expression of stromelysin 3, Ets-1, and/or VEGF affects the development, progression, and prognosis of oral cancer.

PATIENTS AND METHODS

Immunohistochemical analysis of stromelysin 3, Ets-1, VEGF, and platelet/endothelial cell adhesion molecule 1 (a marker for intratumoral microvessel density) was carried out in serial paraffin embedded tissue sections of 220 oral squamous cell carcinomas (OSCC), 90 precancerous lesions (59 hyperplasias and 31 dysplasias), and 81 matched histologically normal oral tissues.

RESULTS

Ets-1, VEGF, and stromelysin 3 expression independently correlated with increased intratumoral microvessel density in precancerous lesions (P = 0.05, 0.001, and 0.026, respectively) as well as in SCCs (P = 0.005, 0.01, and 0.031, respectively). Logistic regression analysis revealed that concomitant expression of stromelysin 3 and Ets-1 (stromelysin 3(+)/ Ets-1(+) phenotype; odds ratio, 3.7; P = 0.001) was the most significant predictor for transition to precancerous stage, whereas dual expression of stromelysin 3 and VEGF (stromelysin 3(+)/ VEGF(+) phenotype; odds ratio, 2.07; P = 0.004) was the most important predictor for progression from precancerous stage to frank malignancy. Intriguingly, Ets-1 expression was significantly associated with VEGF expression and stromelysin 3 expression in precancerous tissues as well as OSCCs. Follow-up data for 144 patients for a maximum period of 115 months showed that VEGF [hazards ratio (HR), 4.532; P = 0.004] and Ets-1 (HR = 2.182; P = 0.049) expression significantly correlated with reduced disease-free survival in univariate analysis. In bivariate analysis, patients harboring Ets-1(+)/VEGF(+) phenotype had the worst survival (median disease-free survival, 50 months; HR, 2.943; P = 0.003). Multivariate analysis using Cox's proportional hazards model showed that increased VEGF expression was the most significant adverse prognosticator in OSCC patients (HR, 4.470; P = 0.004).

CONCLUSIONS

In conclusion, this study provides the first evidence of concomitant expression of stromelysin 3, VEGF, and Ets-1 in clinical specimens in different stages of development of oral cancer. In early stages, concomitant expression of stromelysin 3 and Ets-1 favors the development of a precancerous state, whereas dual expression of stromelysin 3 and VEGF is associated with progression from precancerous to cancerous state. VEGF expression is an adverse prognosticator for disease-free survival.

Detection of plasminogen activators in oral cancer by laser capture microdissection combined with zymography

Plasminogen activation is believed to be critical to the progression of oral squamous cell carcinoma by facilitating matrix degradation during invasion and metastasis, and high levels of urokinase plasminogen activator (uPA) and plasminogen activator (PA) inhibitor-1 (PAI-1) in tumors predict poor disease outcome. We describe the development of a novel method for studying PA in oral cancer that combines the sensitivity and specificity of zymography with the spatial resolution of immunohistochemistry. Laser capture microdissection (LCM) was combined with plasminogen-casein zymography to analyze uPA, tissue PA (tPA), uPA-PAI-1 complexes, and tPA-PAI-1 complexes in 11 tumors and adjacent non-malignant epithelium from squamous cell carcinomas of the tongue, floor of mouth, larynx, and vocal cord. uPA was detectable in all tumor samples analyzed, uPA-PAI-1 complexes in three samples, and tPA in nine. PA was detectable in as little as 0.5 microg protein lysate from microdissected tumors. In all specimens, uPA expression was highly increased in tumor tissue compared to adjacent non-malignant tissue. In conclusion, LCM combined with zymography may be excellently suited for analyzing the prognostic significance and causal involvement of the plasminogen activation system in oral cancer.

Activities of the matrix metalloproteinase stromelysin-2 (MMP-10) in matrix degradation and keratinocyte organization in wounded skin

The matrix metalloproteinase stromelysin-2 is expressed in keratinocytes of the epithelial tongue of skin wounds, suggesting a role in keratinocyte migration. Here, we show that stromelysin-2 enhances migration of cultured keratinocytes. To gain insight into the in vivo activities of stromelysin-2 in epithelial repair, we generated transgenic mice expressing a constitutively active stromelysin-2 mutant in keratinocytes. These animals had no alterations in skin architecture, and the healing rate of skin wounds was normal. Histologically, however, we found abnormalities in the organization of the wound epithelium. Keratinocytes at the migrating epidermal tip were scattered in most sections of mice with high expression level, and there was a reduced deposition of new matrix. In particular, the staining pattern of laminin-5 at the wound site was altered. This may be due to proteolytic processing of laminin-5 by stromelysin-2, because degradation of laminin-5 by this enzyme was observed in vitro. The inappropriate matrix contact of keratinocytes was accompanied by aberrant localization of beta1-integrins and phosphorylated focal adhesion kinase, as well as by increased apoptosis of wound keratinocytes. These results suggest that a tightly regulated expression level of stromelysin-2 is required for limited matrix degradation at the wound site, thereby controlling keratinocyte migration.

CXCL12-CXCR4 interactions modulate prostate cancer cell migration, metalloproteinase expression and invasion

The mechanisms responsible for prostate cancer metastasis are incompletely understood at both the cellular and molecular levels. In this regard, chemokines are a family of small, cytokine-like proteins that induce motility of neoplastic cells, leukocytes and cancer cells. The current study evaluates the molecular mechanisms of CXCL12 and CXCR4 in prostate cancer cell migration and invasion. We report that functional CXCR4 is significantly expressed by prostate cancer cell lines, LNCaP and PC3, when compared with normal prostatic epithelial cells (PrEC). As measured using motility and invasion chamber assays, prostate cancer cells migrated and invaded through extracellular matrix components in response to CXCL12, at rates that corresponded to CXCR4 expression. Anti-CXCR4 antibodies (Abs) significantly impaired the migration and invasive potential of PC3 and LNCaP cells. CXCL12 induction also enhanced collagenase-1 (metalloproteinase-1 (MMP-1)) expression by LNCaP and PC3 cells. Collagenase-3 (MMP-13) was expressed by prostate cancer cells, but it was not expressed by PrEC cells or modulated by CXCL12. CXCL12 increased MMP-2 expression by LNCaP and PC3; however, MMP-9 expression was elevated only in PC3 cells after CXCL12-CXCR4 ligation. PC3 cells also expressed high levels of stromelysin-1 (MMP-3) after CXCL12 stimulation. CXCL12 also significantly increased stromelysin-2 (MMP-10) expression by LNCaP cells. Stromelysin-3 (MMP-11) was expressed by LNCaP cells, but not by PC3 or PrEC cells and CXCL12 induced PC3 MMP-11 expression. Membrane type-1 MMP (MMP-14) was not expressed by PrEC or LNCaP cells, but CXCL12 significantly enhanced MMP-14 expression by PC3 cells. These studies reveal important cellular and molecular mechanisms of CXCR4/CXCL12-mediated prostate cancer cell migration and invasion.

The mRNA profile of genes in betel quid chewing oral cancer patients

Oral cancer is one of the most common types of human cancer in the world. Although the risk factors for oral cancer are well-recognized in different countries, the molecular mechanism responsible for this malignancy remains elusive particularly in the countries where betel quid chewing is prevalent. The cDNA microarray analysis was used to analyse the mRNA expression patterns of 1177 genes in ten oral cancer patients with betel quid chewing history. Eighty-four genes involving cell adhesion, cell shape, growth, apoptosis, angiogenesis, metastasis, and metabolism were deregulated. Although the expression profile of these genes was shared by certain clinical patients, there was no significant association of the expression profile with clinical staging. Functional implication of four validated genes including caspase-1, STAT-1, COX-2 and pleiotrophin was discussed. This study provides pilot data for understanding the pathogenesis of oral cancer in countries like Taiwan where betel quid chewing is prevalent.

Matrix Metalloproteinase 3 Polymorphism

PURPOSE

Treatment of head and neck cancer often associates different therapeutic modalities, including surgery, radiotherapy, and chemotherapy. In an attempt to optimize therapeutics, the identification of molecular markers linked to response to chemotherapy remains important. Recently, the involvement of metalloproteinases in resistance to chemotherapy was suggested through their interaction with the Fas/Fas ligand pathway. Indeed metalloproteinases enhance Fas ligand shedding modulating chemotherapy efficiency. On the basis of these findings, we tested the existence of a correlation between response to chemotherapy and four metalloproteinase polymorphisms in a prospective series of 148 head and neck cancer patients.

EXPERIMENTAL DESIGN

Patients were genotyped using automated fragment analysis and 5'-nuclease allelic discrimination assay. Response to chemotherapy was clinically assessed without knowledge of the genotype status.

RESULTS

A significant relation between the metalloproteinase type 3 (MMP3) -1612insA polymorphism and response to chemotherapy was identified. Indeed, patients with the 6A/6A genotype responded more frequently (86%) to treatment as compared with patients with the 5A/6A (65%) or 5A/5A (55%) genotypes (P = 0.04). A multivariate analysis, including tumor stage, gender, TP53 mutations, and MMP3 polymorphism, showed that the 6A/6A genotype was an independent factor of response to 5-fluorouracil-cisplatin chemotherapy in head and neck cancer patients with an odds ratio of 6.7 as compared with the 5A/5A genotype.

CONCLUSIONS

This work showed that genotyping the MMP3 gene enhancer polymorphism -1612insA could help predict chemosensitivity in head and neck cancer patients.

In vitro evaluation of matrix metalloproteinases as predictive testing for nickel, a model sensitizing agent

The identification of potential damage due to chemical exposure in the workplace is a major health and regulatory concern. Traditional tests that measure both sensitization and elicitation responses require the use of animals. An alternative to this widespread use of experimental animals could have a crucial impact on risk assessment, especially for the preliminary screening of new molecules. We developed an in vitro model for the screening of potential toxic compounds. Human keratinocytes (HaCat) were used as target cells while matrix metalloproteinases (MMP) were selected as responders because they are key enzymes involved in extracellular matrix (ECM) degradation in physiological and pathological conditions. Chemical exposure was performed using nickel sulphate as a positive tester. Nickel contact induced upregulation of MMP-2 and IL-8 mRNA production. Molecular activation occurred even at very low nickel concentrations even though no phenotypic changes were observed. MMP-9 accumulation was found in the medium of treated cells with respect to controls. These observations led to the hypothesis that even minimal exposure can accumulate transcriptional activity resulting in long-term clinical signs after contact. Our simple in vitro model can be applied as a useful preliminary complement to the animal studies to screen the effects of new potential toxic compounds.

Differential expression of matrilysin-1 (MMP-7), 92 kD gelatinase (MMP-9), and metalloelastase (MMP-12) in oral verrucous and squamous cell cancer

Squamous cell carcinoma (SCC) of the oral cavity is a highly invasive tumour of stratified squamous epithelium that spreads through degradation of the basement membrane (BM) and extracellular matrix (ECM). There are currently no reliable tissue or serum markers to predict whether the tumour has metastasized at the time of diagnosis. Verrucous carcinoma (VC) of the oral cavity is a rare low-grade variant of oral SCC that penetrates into the subepithelial connective tissue. Many matrix metalloproteinases (MMPs), such as MMP-1, -2, -7, -9, -13, and -14, as well as integrin receptors have been implicated in cancer invasion. Integrin alphavbeta6 is induced in SCC and appears to be involved in up-regulation of MMP-9 expression by oral keratinocytes and promotion of their migration. The aim of this study was to investigate whether the pattern of MMP expression or that of alphavbeta6 integrin contributes to the differences in the biological behaviour of oral SCC and VC. The results show that the less aggressive nature of oral VC may be connected to its MMP expression profile. Typically, VCs were devoid of epithelial MMP-3, -7, -9, -12 and -13 expression, compared with SCCs. MMP-19 was expressed by epithelial keratinocytes in hyperproliferative areas of verrucous hyperplasia, VC, and SCC, but was absent in the invasive cancer cell nests of SCC. MMP-26 was expressed by hyperproliferative keratinocytes in VC as well as by invasive cancer cells in SCCs. MMP-10 was expressed widely in the epithelium of all SCC specimens. alphavbeta6 integrin expression was also detected in some cases of epithelial hyperplasia but was significantly more abundant in cancers at the invasive front. The absence of MMP-7, -9 and -12 from epithelial cells may serve as a good prognostic marker of non-invasive oral carcinoma. Blocking the activity of invasion-specific MMPs or alphavbeta6 integrin might offer novel therapeutic modalities in early-stage oral carcinoma.

Stromelysin-3 expression is an early event in human oral tumorigenesis

Stromelysin-3 (ST3/MMP11) is associated with human tumour progression. To determine the clinical significance of ST3 in oral tumorigenesis, its expression was analysed in different stages of tobacco-associated oral cancer. Immunohistochemical analysis of ST3 expression in 79 oral precancerous lesions, 177 SCCs and 35 histologically normal oral tissues was carried out and corroborated by immunoblotting and RT-PCR. ST3/MMP11 protein expression was observed in 45/79 (57%) precancerous lesions [28/48 (58%) with hyperplasia and 17/31 (55%) with dysplasia] and in 123/177 (70%) oral SCCs. In precancerous lesions, ST3 expression was higher compared to normal oral tissues (p = 0.000) and associated with MVD (p = 0.05), a marker for angiogenesis. ST3 was also expressed in cells cultured from precancerous and cancerous lesions that had undergone epithelial-to-mesenchymal transition. In oral cancer patients, ST3 positivity was associated with lymph node involvement (p = 0.025) and increased intratumoral MVD (p = 0.009). Ninety-eight oral SCC patients were followed up for a period of 94 months (median 22.5 months). Kaplan-Meier survival analysis showed that ST3 expression was not a significant prognostic indicator. ST3 expression in oral hyperplastic and dysplastic lesions suggests its association with progression of phenotypic alterations acquired early during the malignant transformation pathway of oral epithelium and implicates it not only in angiogenesis and invasion but also in tumorigenesis. Thus, ST3 may serve as a potential target for developing molecular therapeutics for early intervention in oral tumorigenesis.

Prognostic relevance of molecular markers of oral cancer--a review

The aim of the present article was to review the current knowledge on the prognostic value of tumour marker in the treatment of oral squamous cell carcinoma (OSCC). The literature of the past 5 years (1997-August 2002) was screened. One hundred and sixty-nine articles were included in this review, twenty-nine molecular markers of relevance were identified. Tumour markers were allocated to four groups according to their function: (i) Enhancement of Tumour Growth: Cell cycle acceleration and proliferation, (ii) Tumour Suppression and Anti-Tumour Defence: Immune response and apoptosis, (iii) Angiogenesis, (iv) Tumour Invasion and Metastatic Potential: Adhesion molecules and matrix degradation. Data showed that the prognostic relevance of most tumour markers is still not quite clear. Only 12 of 23 reports on the prognostic relevance of markers for cell cycle acceleration and proliferation indicated a significant association with prognosis while 20 of 29 studies on markers for tumour suppression and anti-tumour response showed prognostic relevance. Markers of angiogenesis exhibited only minor importance for the prognosis and treatment of OSCC. Results on markers of tumour invasion and metastatic potential appeared to be too premature for a statement regarding their prognostic value. In general, the location of markers within the tumour and not their quantitative assessment as such is emphasized. Particularly, the analysis of the invasive front of the tumour with regard to the occurrence of molecular markers is supposed to be of great importance for prognostication.

Basic fibroblast growth factor induces the expression of matrix metalloproteinase-3 in human periodontal ligament cells through the MEK2 mitogen-activated protein kinase pathway

Basic fibroblast growth factor (bFGF, FGF-2) is one of the potent mitogens for periodontal ligament (PDL) cells. However, the role of bFGF on the matrix metalloproteinase-3 (MMP-3) expression in PDL cells is unknown. In this study, the effect of bFGF on MMP-3 expression in PDL cells and the mechanism of this process were examined. Human PDL cells were exposed to bFGF at various concentrations (0.01-10 ng/ml) in monolayer cultures. bFGF increased [3H]thymidine incorporation and suppressed proteoglycan synthesis concentration-dependently. However, similar concentration ranges of bFGF increased the release of the cell-associated proteoglycans into the medium. Furthermore, bFGF increased MMP-3 mRNA levels concentration-dependently as examined by reverse transcription-polymerase chain reaction (RT-PCR). Induction of MMP-3 after the stimulation with bFGF was observed as early as 12 h with maximal at 24 h. Thereafter, the MMP-3 mRNA level gradually decreased until 72 h. Cycloheximide blocked the induction of MMP-3 by bFGF, indicating the requirement of de novo protein synthesis for this stimulation. Furthermore, MMP-3 expression induced by bFGF was abrogated by U0126, a specific inhibitor of MEK1/2 and ERK1/2 in mitogen-activated protein (MAP) kinase pathway, not by PD98059, a specific inhibitor of MEK1. In addition, bFGF up-regulated the phosphorylated ERK1/2 in 5 min with the maximal at 20 min as examined by Western blotting, and U0126 inhibited the ERK1/2 phosphorylation induced by bFGF. These findings suggest that bFGF induces MMP-3 expression in PDL cells through the activation of the MEK2 in MAP kinase pathway. bFGF stimulation on MMP-3 synthesis may be involved in the control of the cell-associated proteoglycans in PDL cells during periodontal regeneration and degradation.