Calcium-induced Matrix Metalloproteinase 9 Gene Expression Is Differentially Regulated by ERK1/2 and p38 MAPK in Oral Keratinocytes and Oral Squamous Cell Carcinoma

Tolperisone hydrochloride improves motor functions in Parkinson's disease via MMP-9 inhibition and by downregulating p38 MAPK and ERK1/2 signaling cascade

The mitogen-activated protein kinase (MAPK) signaling pathway, particularly the p38 MAPK and ERK1/2, has been implicated in the pathogenesis of Parkinson's disease (PD). Recent studies have shown that MAPK signaling pathway can influence the expression of matrix metalloproteinase 9 (MMP-9), known for its involvement in various physiological and pathological processes, including neurodegenerative diseases. This study explores the modulation of MMP-9 expression via the MAPK/ERK signaling cascade and its potential therapeutic implications in the context of PD-associated motor dysfunction. Here, tolperisone hydrochloride (TL), a muscle relaxant that blocks voltage-gated sodium and calcium channels, was used as a treatment to observe its effect on MAPK signaling and MMP-9 expression. Rotenone (RT) exposure in mice resulted in a significant reduction in substantia nigra and primary motor cortex neurons, which were further evidenced by impairments in motor function. When TL was administered, neuron count was restored (89.0 ± 4.78 vs 117.0 ± 4.46/mm2), and most of the motor dysfunction was alleviated. Mechanistically, TL reduced the protein expression of phospho-p38MAPK (1.06 fold vs 1.00 fold) and phospho-ERK1/2 (1.16 fold vs 1.02 fold), leading to the inhibition of MAPK signaling, as well as reduced MMP-9 concentrations (2.76 ± 0.10 vs 1.94 ± 0.10 ng/mL) in the process of rescuing RT-induced neuronal cell death and motor dysfunction. Computational analysis further revealed TL's potential inhibitory properties against MMP-9 along with N and L-type calcium channels. These findings shed light on TL's neuroprotective effects via MMP-9 inhibition and MAPK signaling downregulation, offering potential therapeutic avenues for PD-associated motor dysfunction.

Methyltransferase-like 3-induced N6-methyladenosine upregulation promotes oral squamous cell carcinoma by through p38

BACKGROUND

Oral squamous cell carcinoma (OSCC), a main type of squamous cell cancer, is associated with considerable morbidity and mortality. Recent reports suggested methyltransferase-like 3 (METTL3)-mediated N6-methyladenosine (m6A) modification to be an essential regulator in the fate determination of stem cells. However, the functional significance of METTL3 in OSCC remains largely unknown.

METHODS

METTL3 expression was examined in OSCC patient samples, followed by correlation analysis against clinical tumor features. Functional assays, such as assessment of surface marker expression, colony forming, BrdU incorporation, tumor xenograft assay, and m6A dot blot, were conducted to study the impact of METTL3 knockdown (KD) in OSCC cells.

RESULTS

High METTL3 expression was positively correlated with more severe clinical features of OSCC tumors. METTL3 KD caused impairment of stem-like capacities in OSCC cells, such as tumorigenicity in vivo and colony-forming ability in vitro. Furthermore, METTL3-KD and cycloleucine, a methylation inhibitor, decreased m6A levels and down-regulated p38 expression in OSCC cells. On the contrary, the impaired cell proliferation capacity of OSCC cells after METTL3-KD was restored by exogenous expression of p38.

CONCLUSION

Our findings identified m6A methyltransferase METTL3 as a key element in the regulation of tumorigenesis in OSCC.

TRP channel expression correlates with the epithelial-mesenchymal transition and high-risk endometrial carcinoma

Transient receptor potential (TRP) channels excel in cellular sensing as they allow rapid ion influx across the plasma membrane in response to a variety of extracellular cues. Recently, a distinct TRP mRNA expression signature was observed in stromal cells (ESC) and epithelial cells (EEC) of the endometrium, a tissue in which cell phenotypic plasticity is essential for normal functioning. However, it is unknown whether TRP channel mRNA expression is subject to the phenotypic switching that occurs during epithelial to mesenchymal transition (EMT) and mesenchymal to epithelial transition (MET), and whether TRP channel mRNA expression is associated with aggressive phenotypes in endometrial cancer (EC). Here, we induced EMT and MET in vitro using in primary EEC and ESC, respectively, and analyzed expression and functionality of TRP channels using RT-qPCR and intracellular Ca²⁺ imaging. The outcome of these experiments showed a strong association between TRPV2 and TRPC1 mRNA expression and the mesenchymal phenotype, whereas TRPM4 mRNA expression correlated with the epithelial phenotype. In line herewith, increased TRPV2 and TRPC1 mRNA expression levels were observed in both primary and metastatic EC biopsies and in primary EC cells with a high EMT status, indicating an association with an aggressive tumor phenotype. Remarkably, TRPV2 mRNA expression in primary EC biopsies was associated with tumor invasiveness and cancer stage. In contrast, increased TRPM4 mRNA expression was observed in EC biopsies with a low EMT status and less aggressive tumor phenotypes. Taken together, this dataset proved for the first time that TRP channel mRNA expression is strongly linked to cellular phenotypes of the endometrium, and that phenotypic transitions caused by either experimental manipulation or malignancy could alter this expression in a predictable manner. These results implicate that TRP channels are viable biomarkers to identify high-risk EC, and potential targets for EC treatment.

Pharmacological Inhibition of Transient Receptor Potential Vanilloid 4 Reduces Vasogenic Edema after Traumatic Brain Injury in Mice

Vasogenic edema results from blood-brain barrier (BBB) disruption after traumatic brain injury (TBI), and although it can be fatal, no promising therapeutic drugs have been developed as yet. Transient receptor potential vanilloid 4 (TRPV4) is a calcium-permeable channel that is sensitive to temperature and osmotic pressure. As TRPV4 is known to be responsible for various pathological conditions following brain injury, we investigated the effects of pharmacological TRPV4 antagonists on TBI-induced vasogenic edema in this study. A TBI model was established by inflicting fluid percussion injury (FPI) in the mouse cerebrum and cultured astrocytes. Vasogenic brain edema and BBB disruption were assessed based on brain water content and Evans blue (EB) extravasation into brain tissue, respectively. After FPI, brain water content and EB extravasation increased. Repeated intracerebroventricular administration of the specific TRPV4 antagonists HC-067047 and RN-1734 dose-dependently reduced brain water content and alleviated EB extravasation in FPI mice. Additionally, real-time PCR analysis indicated that administration of HC-067047 and RN-1734 reversed the FPI-induced increase in mRNA levels of endogenous causal factors for BBB disruption, including matrix metalloproteinase-9 (MMP-9), vascular endothelial growth factor-A (VEGF-A), and endothelin-1 (ET-1). In astrocytes, TRPV4 level was observed to be higher than that in brain microvascular endothelial cells. Treatment with HC-067047 and RN-1734 inhibited the increase in mRNA levels of MMP-9, VEGF-A, and ET-1 in cultured astrocytes subjected to in vitro FPI. These results suggest that pharmacological inhibition of TRPV4 is expected to be a promising therapeutic strategy for treating TBI-induced vasogenic edema.

Rescuing mitochondria in traumatic brain injury and intracerebral hemorrhages - A potential therapeutic approach

Mitochondria are dynamic organelles responsible for cellular energy production. Besides, regulating energy homeostasis, mitochondria are responsible for calcium homeostasis, signal transmission, and the fate of cellular survival in case of injury and pathologies. Accumulating reports have suggested multiple roles of mitochondria in neuropathologies, neurodegeneration, and immune activation under physiological and pathological conditions. Mitochondrial dysfunction, which occurs at the initial phase of brain injury, involves oxidative stress, inflammation, deficits in mitochondrial bioenergetics, biogenesis, transport, and autophagy. Thus, development of targeted therapeutics to protect mitochondria may improve functional outcomes following traumatic brain injury (TBI) and intracerebral hemorrhages (ICH). In this review, we summarize mitochondrial dysfunction related to TBI and ICH, including the mechanisms involved, and discuss therapeutic approaches with special emphasis on past and current clinical trials.

Skin photo-protection with phytochemicals against photo-oxidative stress, photo-carcinogenesis, signal transduction pathways and extracellular matrix remodeling-An overview

Excessive exposure of skin to UV radiation triggers the generation of oxidative stress, inflammation, immunosuppression, apoptosis, matrix-metalloproteases production, and DNA mutations leading to the onset of photo ageing and photo-carcinogenesis. At the molecular level, these changes occur via activation of several protein kinases as well as transcription pathways, formation of reactive oxygen species, and release of cytokines, interleukins and prostaglandins together. Current therapies available on the market only provide limited solutions and exhibit several side effects. The present paper provides insight into scientific studies that have elucidated the positive role of phytochemicals in counteracting the UV-induced depletion of antioxidant enzymes, increased lipid peroxidation, inflammation, DNA mutations, increased senescence, dysfunctional apoptosis and immune suppression. The contribution of phytochemicals to the downregulation of expression of oxidative-stress sensitive transcription factors (Nrf2, NF-Kb, AP-1 and p53) and protein kinases (MSK, ERK, JNK, p38 MAPK, p90RSK2 and CaMKs) involved in inflammation, apoptosis, immune suppression, extracellular matrix remodelling, senescence, photo ageing and photo-carcinogenesis, is also discussed. Conclusively, several phytochemicals hold potential for the development of a viable solution against UV irradiation-mediated photo ageing, photo-carcinogenesis and related manifestations.

Characterization of fibroblasts from hypertrophied right ventricle of pulmonary hypertensive rats

Pulmonary arterial hypertension (PAH), which is characterized by an elevation of pulmonary arterial resistance, leads to a lethal right heart failure. It is an urgent issue to clarify the pathogenesis of PAH-induced right heart failure. The present study aimed to elucidate the characteristics of cardiac fibroblasts (CFs) isolated from hypertrophied right ventricles of monocrotaline (MCT)-induced PAH model rats. CFs were isolated from the right ventricles of MCT-injected rats (MCT-CFs) and saline-injected control rats (CONT-CFs). Expression of α-smooth muscle actin and collagen type I in MCT-CFs was lower than that in CONT-CFs. On the other hand, proliferation, migration, and matrix metalloproteinase (MMP)-9 production were significantly enhanced in MCT-CFs. In MCT-CFs, phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, c-Jun N-terminal kinase (JNK), and Ca²⁺/calmodulin-dependent protein kinase (CaMK) II was significantly enhanced. In addition to mRNA expression of Orai1, a Ca²⁺ release-activated Ca²⁺ channel, and stromal interaction molecules (STIM) 1, an endoplasmic reticulum Ca²⁺ sensor, the associated store-operated Ca²⁺ entry (SOCE) was significantly higher in MCT-CFs than CONT-CFs. Pharmacological inhibition of ERK1/2 pathway prevented the enhanced proliferation of MCT-CFs. The enhanced migration of MCT-CFs was prevented by a pharmacological inhibition of ERK1/2, JNK, CaMKII, or SOCE pathway. The enhanced MMP-9 production in MCT-CFs was prevented by a pharmacological inhibition of ERK1/2, CaMKII, or SOCE pathway but not JNK. The present results suggested that MCT-CFs exhibit proliferative and migratory phenotypes perhaps through multiple signaling pathways. This study for the first time determined the characteristics of CFs isolated from hypertrophied right ventricles of MCT-induced PAH model rats.

Glycogen synthase kinase-3β mediated regulation of matrix metalloproteinase-9 and its involvement in oral squamous cell carcinoma progression and invasion

PURPOSE

Oral squamous cell carcinoma (OSCC)-related deaths mainly result from invasion of the tumor cells into local cervical lymph nodes. It has been reported that progressive basement membrane loss promotes the metastatic and invasive capacities of OSCCs. Matrix metalloproteinase-9 (MMP-9) is known to play a central role in tumor progression and invasion. However, the role of MMP-9 in OSCC invasion has so far remained paradoxical and little is known about its regulation. Here, we aimed to assess MMP-9 expression regulation and its activation by glycogen synthase kinase-3β during human OSCC progression and invasion.

METHODS

In the present study, 178 human OSCC samples, including 118 fresh samples (18 adjacent normal, 42 noninvasive and 58 invasive tumor samples) and 60 archival human tissue microarray (TMA) tongue cancer samples, were included. mRNA expression, protein expression, MMP-9/-2 activity, protein-protein interaction and Snail, c-Myc, β-catenin and TIMP1 expression were assessed using RT-PCR, immunohistochemistry, Western blotting, co-immunoprecipitation and gelatin zymography analyses, respectively. Wnt5a and LPA mediated MMP-9 regulation was assessed in OCSCC-derived SCC-9 cells exogenously expressing GSK3β (WT) or non phosphoryable GSK3β (S9A).

RESULTS

We observed a progressive up-regulation/activation of MMP-9 at various stages of oral tumor progression/invasion. Positive correlations were observed between MMP-9 and c-Myc expression, MMP-9 and MMP-2 activity, MMP-9 and TIMP1 expression and MMP-9 activity and TIMP1-MMP-9 interaction. In contrast, a negative correlation between phosphorylated β-catenin and MMP-9 expression was observed. Conversely, we found that in oral tongue SCC MMP-9 expression was positively correlated with inactivation of GSK3 signaling. Finally, we found that Wnt5a and LPA mediated increased MMP-9 and decreased GSK3β activities in tongue SCC-derived SCC-9 cells. MMP-9 regulation by GSK3β was confirmed by using phosphoryable/regulatory GSK3β (WT construct) and not by non-phosphoryable GSK3β (S9A construct).

CONCLUSIONS

Collectively, our results show that MMP-9 overexpression and activation are important events occurring during OSCC progression/invasion and that this overexpression/activation is regulated by c-Myc, active MMP-2 and inactive GSK3β mediated pathways.

Novel Antitumor Invasive Actions of p-Cymene by Decreasing MMP-9/TIMP-1 Expression Ratio in Human Fibrosarcoma HT-1080 Cells

p-Cymene (4-isopropyltoluene) has been reported to have beneficial actions such as anti-inflammatory and antinociceptive activities. To evaluate whether p-cymene exhibits antitumor invasive actions, we examined the effects of p-cymene on the production of matrix metalloproteinase 9 (MMP-9)/gelatinase B and tissue inhibitor of metalloproteinases-1 (TIMP-1) in human fibrosarcoma HT-1080 cells. p-Cymene was found to dose-dependently inhibit the 12-O-tetradecanoylphorbol 13-acetate (TPA)-augmented production and gene expression of MMP-9 in HT-1080 cells. In contrast, p-cymene enhanced the TPA-augmented production and gene expression of TIMP-1 in HT-1080 cells. However, there was no change in the constitutive level of MMP-9 and TIMP-1 mRNAs and TIMP-1 protein in p-cymene-treated cells. In addition, we found that the in-vitro TPA-augmented invasiveness of HT-1080 cells was inhibited by p-cymene in a dose-dependent manner. Furthermore, p-cymene was found to suppress the constitutive and/or TPA-augmented phosphorylation of extracellular signal-regulated kinase (ERK)1/2 and p38 mitogen-activated protein kinase (MAPK) in HT-1080 cells. Thus, these results provide novel evidence that p-cymene is an effective candidate for the prevention of tumor invasion and metastasis through mechanisms that include the inhibition of MMP-9 expression and the augmentation of TIMP-1 production along with the suppression of ERK1/2 and p38 MAPK signal pathways in tumor cells.

Valencene from the Rhizomes of Cyperus rotundus Inhibits Skin Photoaging-Related Ion Channels and UV-Induced Melanogenesis in B16F10 Melanoma Cells

Ultraviolet (UV) radiation deeply penetrates skin and causes inflammation and pigmentary changes and triggers immune responses. Furthermore, accumulating evidence suggests that calcium ion channels, such as TRPV1 and ORAI1, mediate diverse dermatological processes including melanogenesis, skin wrinkling, and inflammation. The rhizomes of Cyperus rotundus have been used to treat inflammatory diseases including dermatitis. However, their effects on UV-induced photoaging-related ion channels remain unknown. Therefore, this study was undertaken to evaluate the antagonistic effects of C. rotundus extract and their constituents on TRPV1 and ORAI1 channels. Electrophysiological analysis revealed that valencene (1) isolated from the hexane fraction potently inhibited capsaicin-induced TRPV1 and ORAI1 currents at 90 μM (69 ± 15% and 97 ± 2% at -60 and -120 mV, respectively). The inhibitory effect of 1 on cytoplasmic Ca(2+) concentrations in response to ORAI1 activation (85 ± 2% at 50 μM) was also confirmed. Furthermore, 1 concentration-dependently decreased the melanin content after UVB irradiation in murine B16F10 melanoma cells by 82.66 ± 2.14% at 15 μg/mL. These results suggest that C. rotundus rhizomes have potential therapeutic effects on UV-induced photoaging and indicate that the therapeutic and cosmetic applications of 1 are worth further investigation.

TNF-α promotes breast cancer cell migration and enhances the concentration of membrane-associated proteases in lipid rafts

Purpose

Tumor progression is associated with cell migration, invasion and metastasis. These processes are accompanied by the activation of specific proteases that are either linked to cellular membranes or are secreted into extracellular spaces. TNF-α is known to play an important role in various aspects of tumor progression. The aim of this work was to assess the effect of TNF-α on the migration of breast cancer cells and, in addition, to assess its association with the location of membrane-associated proteases in lipid rafts.

Methods

Wound scratch healing and Transwell migration assays were used to study the effect of TNF-α on the migration of both hormone-dependent and hormone-independent breast cancer-derived cells, i.e., MCF7 and MDA-MB-231, respectively. The expression and secretion of three matrix metalloproteases, MMP9, MMP2 and MT1-MMP, and two dipeptidyl peptidases, CD26 and FAP-α, was investigated using RT-PCR, Western blotting and gelatin zymography. In addition, activation of the MAPK/ERK signaling pathway was investigated by Western blotting.

Results

We found that a TNF-α-induced enhancement of breast cancer cell migration was accompanied by an increased secretion of MMP9, but not MMP2, into the culture media. We also found that TNF-α upregulated the expression of the dipeptidyl peptidases CD26 and FAP-α in a dose-dependent manner and, in addition, enhanced the concentration of all five proteases in lipid rafts in the breast cancer-derived cells tested, regardless of cell type. Furthermore, we found that TNF-α activated the MAPK/ERK signaling pathway by increasing the ERK1/2 phosphorylation level. Application of the MEK/ERK1/2 inhibitor U-0126 resulted in down-regulation of TNF-α-induced MMP9 secretion and abrogation of the enhanced concentration of proteases in the lipid rafts.

Conclusions

From our results we conclude that TNF-α-induced activation of the MAPK/ERK signaling pathway may promote breast cancer cell migration via both upregulation of MMP9, CD26 and FAP-α and concentration of these proteases, as also MT1-MMP and MMP2, in the lipid rafts. TNF-α may serve as a potential therapeutic target in breast cancers susceptible to TNF-α stimulation.

Possible Mechanisms of Di(2-ethylhexyl) Phthalate-Induced MMP-2 and MMP-9 Expression in A7r5 Rat Vascular Smooth Muscle Cells

Proliferation and migration of vascular smooth muscle cells (VSMC) are important in the development and/or progression of many cardiovascular diseases, including atherosclerosis. Evidence shows that matrix metalloproteinase (MMP)-2 and MMP-9 are related to the pathogenesis of atherosclerosis. The expressions of MMP-2 and MMP-9 in atherosclerosis are regulated via various pathways, such as p38 mitogen activated protein kinase (MAPK), extracellular signal regulated kinase 1 and 2 (ERK1/2), Akt, and nuclear factor kappa (NF-κB). Di(2-ethylhexyl) phthalate (DEHP) has been shown to induce atherosclerosis by increasing tumor necrosis factor (TNF)-α, interleukin (IL)-6, and intercellular adhesion molecule (ICAM) productions. However, whether DEHP poses any effects on MMP-2 or MMP-9 expression in VSMC has not yet been answered. In our studies, rat aorta VSMC was treated with DEHP (between 2 and 17.5 ppm) and p38 MAPK, ERK1/2, Akt, NF-κB, and MMP-2 and MMP-9 proteins and activities were measured. Results showed that the presence of DEHP can induce higher MMP-2 and MMP-9 expression than the controls. Similar results on MMP-regulating proteins, i.e., p38 MAPK, ERK1/2, Akt, and NF-κB, were also observed. In summary, our current results have showed that DEHP can be a potent inducer of atherosclerosis by increasing MMP-2 and MMP-9 expression at least through the regulations of p38 MAPK, ERK1/2, Akt, and NF-κB.

Bisphenol A stimulates human prostate cancer cell migration via remodelling of calcium signalling

Bisphenol A (BPA), the principal constituent of reusable water bottles, metal cans, and plastic food containers, has been shown to be involved in human prostate cancer (PCa) cell proliferation. The aim of the present study was to explore the effect of BPA on PCa cell migration and the pathways involved in these processes. Using the transwell technique, we clearly show for the first time that the pre-treatment of the cells with BPA (1–10 nM) induces human PCa cell migration. Using a calcium imaging technique, we show that BPA pre-treatment induces an amplification of Store-Operated Calcium Entry (SOCE) in LNCaP cells. RT-PCR and Western blot experiments allowed the identification of the ion channel proteins which are up-regulated by BPA pre-treatments. These include the Orai1 protein, which is known as an important SOCE actor in various cell systems, including human PCa cells. Using a siRNA strategy, we observed that BPA-induced amplification of SOCE was Orai1-dependent. Interestingly, the BPA-induced PCa cell migration was suppressed when the calcium entry was impaired by the use of SOCE inhibitors (SKF96365, BTP2), or when the extracellular calcium was chelated. Taken together, the results presented here show that BPA induces PCa cells migration via a modulation of the ion channel protein expression involved in calcium entry and in cancer cell migration. The present data provide novel insights into the molecular mechanisms involved in the effects of an environmental factor on cancer cells and suggest both the necessity of preventive measures and the possibility of targeting ion channels in the treatment of PCa cell metastasis.

Kalopanaxsaponin A inhibits the invasion of human oral squamous cell carcinoma by reducing metalloproteinase-9 mRNA stability and protein trafficking

An inability to control cancer cell invasion and metastasis is the leading cause of death in patients with cancer. The present study was performed to determine the anti-invasive effect of Kalopanaxsaponin A (KPS-A) on matrix metalloproteinase-9 (MMP-9)-meidated invasion in phorbol 12-myristate 13-acetate (PMA)-stimulated human oral squamous cell carcinoma (OSCC) cells and a murine xenograft model of human OSCC. KPS-A, isolated from Kalopanax pictus, inhibited PMA-induced proliferation and invasion as well as PMA-induced MMP-9 expression and secretion at non-cytotoxic doses. KPS-A treatment reduced the stability of PMA-induced MMP-9 mRNA and inhibited the PMA-induced cytoplasmic translocation of HuR. In PMA-treated cells, KPS-A treatment resulted in the intracellular accumulation of MMP-9 and suppressed Ras-associated binding 1A (Rab1A) expression. KPS-A treatment suppressed PMA-induced phosphorylation of extracellular signal regulated kinase (ERK)1/2 and Akt. Furthermore, the oral administration of KPS-A led to substantial inhibition of tumor growth and the expression of proliferating cell nuclear antigen (PCNA), MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), HuR, and Rab1A in the tumor tissues of mice inoculated with YD-10B OSCC cells. Collectively, KPS-A inhibits the invasiveness of oral cancer by reducing HuR-mediated MMP-9 mRNA stability and Rab1A-mediated MMP-9 secretion via ERK1/2 and phosphatidylinositide 3-kinase (PI3K)/Akt. Therefore, KPS-A is a promising anti-invasive agent.

Suppression of matrix metalloproteinase-9 expression in undifferentiated, non-apoptotic keratinocytes is abrogated by the cleavage of poly(ADP-ribose) polymerase-1

Matrix metalloproteinase (MMP)-9, an enzyme that degrades the extracellular matrix, has been implicated as a key enzyme in the process of tissue remodeling. This study demonstrates the regulation of MMP-9 transcription through a gene regulatory element in its promoter (the KRE-M9 element). The KRE-M9-binding protein was purified and identified as poly(ADP-ribose) polymerase-1 (PARP-1), which inhibits the transcription of MMP-9 similar to involucrin. This regulation occurs in non-apoptotic keratinocytes using the distinctive culture conditions of high and low Ca(2+) levels. PARP cleavage, which occurs during apoptosis, results in de-repression of MMP-9 promoter activity. These data clarify a new role of PARP-1 and suggest a physiologically relevant connection between caspase activation and MMP-9 expression.

Integrin α3β1 as a breast cancer target

INTRODUCTION

Integrin receptors for cell adhesion to the extracellular matrix have important roles in all stages of cancer progression and metastasis. Since the integrin family was discovered in the early 1980's, many studies have identified critical adhesion and signaling functions for integrins expressed on tumor cells, endothelial cells and other cell types of the tumor microenvironment, in controlling proliferation, survival, migration and angiogenesis. In recent years, the laminin-binding integrin α3β1 has emerged as a potentially promising anti-cancer target on breast cancer cells.

AREAS COVERED

Studies from the past decade that implicate integrins as promising anti-cancer targets and the development of integrin antagonists as anti-cancer therapeutics. Recent preclinical studies that have identified the laminin-binding integrin α3β1 as an appealing anti-cancer target and the knowledge gaps that must be closed to fully exploit this integrin as a therapeutic target for breast cancer.

EXPERT OPINION

Although the tumor-promoting functions of α3β1 implicate this integrin as a promising therapeutic target on breast cancer cells, successful exploitation of this integrin as an anti-cancer target will require a better understanding of the molecular mechanisms whereby it regulates specific tumor cell behaviors and the identification of the most appropriate α3β1 functions to antagonize on breast cancer cells.

N-Acetylglucosamine suppress collagenases activation in ultraviolet B-irradiated human dermal fibroblasts: Involvement of calcium ions and mitogen-activated protein kinases

BACKGROUND

N-Acetylglucosamine (GlcNAc) and its derivates have been utilized in dietary supplements and for therapeutic development due to their unique characteristics. GlcNAc is recognized primarily for its function as a precursor to hyaluronic acid, which plays a significant role in the structure and hydration of the extracellular matrix in skin, in both the epidermis and the dermis.

OBJECTIVE

We investigated the protective effects of GlcNAc on immortalized human skin fibroblasts (HS68) against UVB damage. We then explored the inhibitory effects of GlcNAc on UVB-induced collagenases and investigated the molecular mechanism underlying those effects.

METHODS

Those effects were assessed by semi-quantitative PCR, Western blotting and enzymatic activity assays.

RESULTS

GlcNAc increased the viability of, and inhibited ROS production in, HS68 cells exposed to UVB irradiation. Pre-treatment of HS68 cells with GlcNAc inhibited UVB-induced production of the collagenases MMP-1 and MMP-13. Western blot analysis further revealed that GlcNAc markedly suppressed the enhancement of collagen degradation in UVB-exposed HS68 cells. GlcNAc also suppressed UVB-induced activation of c-Jun, c-Fos and NF-κB and the phosphorylation of MAPKs and PI3K/Akt, upstream modulators of AP-1 and NF-κB. Moreover, GlcNAc decreased the UVB-induced influx of Ca(2+) into HS68 cells and the phosphorylation of Ca(2+)/calmodulin-dependent kinases (CaMKs).

CONCLUSION

The results indicate that GlcNAc inhibited UVB-induced collagenolytic MMP production by interfering with Ca(2+)-dependent Akt and MAPKs/AP-1 and NF-κB signaling. They may thus be potentially useful in the prevention and treatment of skin photoaging.

Acteoside inhibits PMA-induced matrix metalloproteinase-9 expression via CaMK/ERK- and JNK/NF-κB-dependent signaling

SCOPE

Acteoside, an active phenylethanoid glycoside found in bitter tea and many medicinal plants, displays chemopreventive properties. The aim of our study was to determine the effect of acteoside on tumor invasion and migration; the possible mechanisms involved in this inhibition were investigated in human fibrosarcoma HT-1080 cells.

METHODS AND RESULTS

We employed invasion, migration and gelatin zymography assays to characterize the effect of acteoside on HT-1080 cells. Transient transfection assays were performed to investigate gene promoter activities, and immunoblot analysis to study its molecular mechanisms of action. We found that acteoside suppresses phorbol-12-myristate-13-acetate (PMA)-enhanced matrix metalloproteinase-9 (MMP-9) expression at the protein, mRNA, and transcriptional levels through the suppression of NF-κB activation. In addition, acteoside repressed the PMA-induced phosphorylation of ERK1/2 (ERK, extracellular regulated kinase) and JNK1/2. Further, we found that acteoside decreased the PMA-induced influx of Ca(2+) and repressed PMA-induced calmodulin-dependent protein kinase (CaMK) phosphorylation. Furthermore, treatment with BAPTA/AM, W7, or capsazepine markedly decreased PMA-induced MMP-9 secretion and cell migration, as well as ERK and JNK/NF-κB activation.

CONCLUSION

Acteoside inhibited PMA-induced invasion and migration of human fibrosarcoma cells via Ca(2+) -dependent CaMK/ERK and JNK/NF-κB-signaling pathways. Acteoside therefore has the potential to be a potent anticancer agent in therapeutic strategies for fibrosarcoma metastasis.

The flavonoids apigenin and luteolin suppress ultraviolet A-induced matrix metalloproteinase-1 expression via MAPKs and AP-1-dependent signaling in HaCaT cells

BACKGROUND

Ultraviolet (UV) irradiation causes major changes in skin connective tissues as a result of the degradation of collagen, a major structural component of the extracellular matrix. This process is likely mediated by matrix metalloproteinases (MMPs). Such changes in collagenous skin tissues have been suggested to be causes of cutaneous aging and skin cancer.

OBJECTIVE

We investigated the protective effects of apigenin and luteolin on immortalized human keratinocytes (HaCaT) against UVA damage. We then explored the inhibitory effects of apigenin and luteolin on UVA-induced MMP-1 and investigated the molecular mechanism underlying those effects.

METHODS

HaCaT cells were treated with apigenin and luteolin for the indicated times followed by irradiation with UVA. Those effects were assessed by semi-quantitative PCR, Western blotting and enzymic activity assays.

RESULTS

These two compounds, at concentrations of 1-5μM, increased the viability of, and inhibited ROS production in HaCaT cells exposed to UVA irradiation. Pre-treatment of HaCaT cells with apigenin and luteolin also inhibited UVA-induced production of the collagenases MMP-1. They also suppressed UVA-induced expression of c-Jun and c-Fos and the phosphorylation of three MAP kinases, upstream modulators of AP-1. Furthermore, the same two flavonoids decreased the UVA-induced influx of Ca(2+) into HaCaT cells and the phosphorylation of Ca(2+)/calmodulin-dependent kinases (CaMKs).

CONCLUSION

The results indicate that apigenin and luteolin inhibited UVA-induced collagenolytic MMP-1 production by interfering with Ca(2+)-dependent MAPKs and AP-1 signaling. They may thus be potentially useful in the prevention and treatment of skin photoaging.

Metformin blocks migration and invasion of tumour cells by inhibition of matrix metalloproteinase-9 activation through a calcium and protein kinase Calpha-dependent pathway: phorbol-12-myristate-13-acetate-induced/extracellular signal-regulated kinase/activator protein-1

BACKGROUND AND PURPOSE

Population studies have revealed that treatment with the anti-diabetic drug metformin is significantly associated with reduced cancer risk, but the underlying mode of action has not been elucidated. The aim of our study was to determine the effect of metformin on tumour invasion and migration, and the possible mechanisms, using human fibrosarcoma HT-1080 cells.

EXPERIMENTAL APPROACH

We employed invasion, migration and gelatin zymography assays to characterize the effect of metformin on HT-1080 cells. Transient transfection assays were performed to gene promoter activities, and immunoblot analysis to study its molecular mechanisms of action.

KEY RESULTS

Metformin inhibited migration and invasion by HT-1080 cells at sub-toxic concentrations. In these cells, metformin also suppressed phorbol-12-myristate-13-acetate (PMA)-enhanced levels of matrix metalloproteinases-9 (MMP-9) protein, mRNA and transcription activity through suppression of activator protein-1 (AP-1) activation. In addition, metformin strongly repressed the PMA-induced phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and protein kinase C(PKC)alpha, whereas the phosphorylation of p38 mitogen-activated protein kinase was not affected by metformin. Metformin decreased the PMA-induced Ca(2+) influx. Furthermore, treatment with an intracellular Ca(2+) chelator (BAPTA-AM) or a selective calmodulin antagonist (W7) markedly decreased PMA-induced MMP-9 secretion and cell migration, as well as activation of ERK and JNK/AP-1.

CONCLUSIONS AND IMPLICATIONS

Metformin inhibited PMA-induced invasion and migration of human fibrosarcoma cells via Ca(2+)-dependent PKCalpha/ERK and JNK/AP-1-signalling pathways. Metformin therefore has the potential to be a potent anti-cancer drug in therapeutic strategies for fibrosarcoma metastasis.

A novel role for the TRPV1 channel in UV-induced matrix metalloproteinase (MMP)-1 expression in HaCaT cells

Transient receptor potential vanilloid type 1 (TRPV1) is a molecular sensor for detecting adverse stimuli, such as capsaicin, heat, and acid. TRPV1 has been localized in keratinocytes and is suggested to be a mediator of heat-induced matrix metalloproteinase-1 (MMP-1). With regard to the multimodal activation of TRPV1, we hypothesize that TRPV1 might also mediate UV-induced MMP-1 in keratinocytes. In HaCaT, a human keratinocyte cell line, we initially confirmed capsaicin-induced membrane current and Ca(2+) influx. UV irradiation induced slow and persistent calcium influx and increased membrane current, which was inhibited by TRPV1 inhibitors (capsazepine and ruthenium red). The UV-induced MMP-1 expression in HaCaT was also decreased by TRPV1 inhibitors and was facilitated by capsaicin. Knock-down of TRPV1 using siRNA transfection also decreased MMP-1 expression, as well as UV-induced Ca(2+) influx in HaCaT. UV failed to induce MMP-1 expression in HaCaT cells cultured in Ca(2+)-free media. Both the UV-induced increase in [Ca(2+)](i) and MMP-1 were suppressed by Gö6976 (a calcium-dependent PKC inhibitor), but not by rottlerin (a calcium-independent PKC inhibitor). In addition to a plausible role of TRPV1 in UV-induced MMP-1 expression, we showed that UV increased TRPV1 expression in both HaCaT cells and human skin in vivo. From these results, we suggest that UV-induced MMP-1 expression might be mediated in part by PKC-dependent activation of TRPV1 and subsequent Ca(2+)-influx in human keratinocytes. J. Cell. Physiol. 219: 766-775, 2009. (c) 2009 Wiley-Liss, Inc.

An immortalization-dependent switch in integrin function up-regulates MMP-9 to enhance tumor cell invasion

Integrins, the major receptors for cell adhesion to the extracellular matrix, play important roles during tumor progression. However, it is still unclear whether genetic lesions that occur during carcinoma development can lead to altered integrin function, and how changes in integrin function contribute to subsequent carcinoma progression. Loss-of-function mutations in p53 and activating mutations in H-Ras, which immortalize and transform epithelial cells, respectively, are common causal events in squamous cell carcinoma (SCC). Phenotypes resulting from these two genetic lesions promote SCC progression and are, therefore, potential targets for anticancer therapies. We developed a model system of keratinocyte transformation that has allowed us to investigate the individual roles of p53 mutation and oncogenic Ras mutation in the acquisition of integrin alpha3beta1-regulated phenotypes that promote SCC progression. Using this model, we show that keratinocyte immortalization by p53-null mutation causes a switch in alpha3beta1 function that induces matrix metalloproteinase (MMP)-9 gene expression in tumorigenic cells. This acquired alpha3beta1-dependent regulation of MMP-9 was maintained during subsequent transformation by oncogenic Ras, and it promoted invasion of tumorigenic keratinocytes. Our results show that loss of p53 function leads to changes in integrin-mediated gene regulation that occur during SCC progression and play a critical role in tumor cell invasion.

Origin and pathogenesis of nodular lymphocyte-predominant Hodgkin lymphoma as revealed by global gene expression analysis

The pathogenesis of nodular lymphocyte–predominant Hodgkin lymphoma (NLPHL) and its relationship to other lymphomas are largely unknown. This is partly because of the technical challenge of analyzing its rare neoplastic lymphocytic and histiocytic (L&H) cells, which are dispersed in an abundant nonneoplastic cellular microenvironment. We performed a genome-wide expression study of microdissected L&H lymphoma cells in comparison to normal and other malignant B cells that indicated a relationship of L&H cells to and/or that they originate from germinal center B cells at the transition to memory B cells. L&H cells show a surprisingly high similarity to the tumor cells of T cell–rich B cell lymphoma and classical Hodgkin lymphoma, a partial loss of their B cell phenotype, and deregulation of many apoptosis regulators and putative oncogenes. Importantly, L&H cells are characterized by constitutive nuclear factor κB activity and aberrant extracellular signal-regulated kinase signaling. Thus, these findings shed new light on the nature of L&H cells, reveal several novel pathogenetic mechanisms in NLPHL, and may help in differential diagnosis and lead to novel therapeutic strategies.

S100B/RAGE-dependent activation of microglia via NF-kappaB and AP-1 Co-regulation of COX-2 expression by S100B, IL-1beta and TNF-alpha

Extracellular S100B is known to affect astrocytic, neuronal and microglial activities, with different effects depending on its concentration. Whereas at relatively low concentrations S100B exerts trophic effects on neurons and astrocytes, at relatively high concentrations the protein causes neuronal apoptosis and activates astrocytes and microglia, thus potentially representing an endogenous factor implicated in neuroinflammation. We have reported that RAGE ligation by S100B in BV-2 microglia results in the upregulation of expression of the pro-inflammatory cyclo-oxygenase 2 (COX-2) via parallel Ras-Cdc42-Rac1-dependent activation of c-Jun NH(2) terminal protein kinase (JNK) and Ras-Rac1-dependent stimulation of NF-kappaB transcriptional activity. We show here that: (1) S100B also stimulates AP-1 transcriptional activity in microglia via RAGE-dependent activation of JNK; (2) S100B upregulates IL-1beta and TNF-alpha expression in microglia via RAGE engagement; and (3) S100B/RAGE-induced upregulation of COX-2, IL-1beta and TNF-alpha expression requires the concurrent activation of NF-kappaB and AP-1. We also show that S100B synergizes with IL-1beta and TNF-alpha to upregulate on COX-2 expression in microglia. Given the crucial roles of COX-2, IL-1beta and TNF-alpha in the inflammatory response, we propose that, by engaging RAGE, S100B might play an important role in microglia activation in the course of brain damage.

Differential growth factor regulation of N-cadherin expression and motility in normal and malignant oral epithelium

Aberrant expression of N-cadherin is associated with tumor progression in squamous cell carcinomas (SCCs). Consequently, we examined the regulation of N-cadherin by TGFbeta1, an important mediator of keratinocyte and SCC function. N-cadherin expression was increased in oral SCC (OSCC) cell lines, regulating motility and correlating with TGFbeta1 production. Moreover, in normal keratinocytes TGFbeta1 increased expression of N-cadherin to regulate motility. TGFbeta1-mediated N-cadherin expression in the oral keratinocytes was blocked using siRNA targeting Smads. Unexpectedly, we found that EGF blocked TGFbeta1-mediated N-cadherin expression in oral keratinocytes and not in OSCC cells. Mechanistically, EGF enhanced Smad phosphorylation in the linker region, and attenuated TGFbeta1-mediated phosphorylation of Smad at the C-terminus, localization of Smad to the nucleus as well as Smad-driven promoter activity exclusively in oral keratinocytes but not in OSCC cells. The effect of EGF on TGFbeta1-mediated Smad-driven promoter activity and N-cadherin expression was reversed when activation of ERK1/2 was blocked. Although EGF and TGFbeta1 independently promoted migration of both oral keratinocytes and OSCC cells, EGF decreased TGFbeta1-mediated migration of oral keratinocytes but enhanced migration of OSCC cells. Together, these data support a model wherein EGF signaling has an important negative regulatory role on TGFbeta1-mediated N-cadherin expression and motility in normal oral keratinocytes, and in which loss of this regulatory mechanism accompanies malignant transformation of the oral epithelium.

Inhibition of Cell Proliferation and MAP Kinase and Akt Pathways in Oral Squamous cell Carcinoma by Genistein and Biochanin A

High morbidity and mortality associated with oral squamous cell carcinoma (OSCC) are largely attributable to late stage diagnosis. Despite significant advances in therapeutic strategies, the five-year survival rate for oral cancer remains at about 50%. A chemopreventive approach may be an effective alternative or adjunct to current therapies. Previous studies have shown anti-tumor effects of isoflavones in several cancers, including oral cancer. However, their mechanisms of action are still unclear. We hypothesized that isoflavones inhibit multiple signaling pathways implicated in oral carcinogenesis. To address our hypothesis, we investigated the effects of three isoflavone derivatives, genistein, biochanin A and daidzein, on SCC15 and SCC25 squamous cell carcinoma cell lines. In cell proliferation experiments, we found that genistein and biochanin A inhibited SCC15 and SCC25 cell growth with an IC50 of 50 μM. We also investigated the effect of isoflavones on ERK and Akt pathways. Our results, from western blot analysis, suggest that both genistein and biochanin A induced decreases in phosphorylation of ERK and Akt at treatment concentrations of 20, 50 and 100 μM. Taken together, our results clearly demonstrate a differential regulation of signaling pathways by various isoflavones in OSCC cell lines. Thus, tumor progression models can be utilized to study the preventive and therapeutic roles of isoflavones in oral cancer cell lines.

Anti-inflammatory effect of curcumin involves downregulation of MMP-9 in blood mononuclear cells

Curcumin (1, 7-bis (4-hydroxyl-3-methoxyphenyl)-1, 6 heptadiene-3, 5-dione) is a potent natural anti oxidant and anti-inflammatory agent, which mediates its effects mainly by inhibiting the activity of enzymes like cyclooxygenase, lipooxygenases and phospholipase A2. Here we examined the possibility of curcumin affecting the production of matrix metalloproteinases (MMPs) by peripheral blood mononuclear cells (PBMCs), which play an important role in inflammation. Zymographic analysis and ELISA showed that curcumin significantly inhibited the activity and level of MMPs produced by PBMCs isolated from human and inflammation-induced rabbit in a concentration dependent manner. The administration of curcumin to inflammation-induced rabbits also caused downregulation of MMP-9. Kinetic analysis showed that the effect of curcumin was a delayed one indicating inhibition of de novo protein synthesis. RT-PCR and immunoblot analysis showed inhibition of the production of MMP-9 mRNA and protein respectively by human PBMCs, which were activated in vitro by Artocarpus Lakoocha agglutinin (ALA) lectin. EMSA and super shift showed activation of classical NFkappaB in in vitro activated PBMCs and treatment with curcumin inhibited activation of NFkappaB. Immunoblot analysis suggested that ALA-induced activation of NFkappaB leading to the upregulation of MMP-9 was due to the degradation of IkappaB-alpha. Curcumin inhibited the degradation of IkappaB-alpha, which inhibited the ALA mediated activation of NFkappaB and upregulation of MMP-9. These results indicated that anti-inflammatory effect of curcumin also involves inhibition of the production of MMP-9 in PBMCs.

Transient receptor potential vanilloid-1 mediates heat-shock-induced matrix metalloproteinase-1 expression in human epidermal keratinocytes

Transient receptor potential vanilloid-1 (TRPV1), a heat-gated channel, was recently found on human keratinocytes and the activation of epidermal TRPV1 was known to induce release of proinflammatory mediators. However, the functional consequences of TRPV1 activation in cutaneous physiology and pathology have not been elucidated clearly. In this study, we investigated the role of TRPV1 on the matrix metalloproteinase (MMP)-1 expression induced by heat shock in human epidermal keratinocytes. Heat shock induced the expression of MMP-1 mRNA and protein in a temperature-dependent manner in an immortalized human keratinocyte cell line (HaCaT) and normal human epidermal keratinocytes (NHK). Heat-shock-induced MMP-1 expression was decreased by treatment of the TRPV1 inhibitors (capsazepine and ruthenium red) or knockdown of TRPV1 using RNA interference in HaCaT cells. Overexpression of TRPV1 greatly increased heat-shock-induced MMP-1 promoter activity in HEK 293 cells. Furthermore, direct activation of TRPV1 by capsaicin, a TRPV1 agonist, increased MMP-1 expression. We found that heat shock induced calcium influx through TRPV1 and that extracellular calcium was necessary for heat-shock-induced MMP-1 expression in HaCaT cells. Taken together, our results suggest that heat-shock-induced MMP-1 expression is mediated by activation of TRPV1 and is dependent on a calcium-dependent signaling process in human epidermal keratinocytes.

Activation dependent expression of MMPs in peripheral blood mononuclear cells involves protein kinase A

Monocyte/Macrophages are integral cellular components of inflammation. Matrix metalloproteinases (MMPs) produced by these cells play a crucial role in every aspect of inflammation. Results of the investigations on activation dependent upregulation of MMPs in human peripheral blood mononuclear cells in culture using different lectins as an in vitro model system to mimic inflammatory monocytes are presented. Under normal physiological conditions the monocytes produced only very low amount of MMPs in an indomethacin insensitive PG/cAMP independent manner. Zymographic analysis and ELISA showed that treatment of monocyte with lectins like concanavalin A (ConA), wheat germ agglutinin (WGA) and Artocarpus lakoocha agglutinin (ALA) caused upregulation of MMPs and the maximum effect was produced by ALA. ALA significantly upregulated MMP-9 in a concentration and time dependent manner. Immunoblot analysis and RT-PCR confirmed ALA mediated upregulation of MMP-9 production. Inhibition of ALA effect by indomethacin and reversal of the indomethacin effect by Bt(2)cAMP indicated involvement of cAMP dependent signaling pathway. Further support for the prostaglandin mediated effect was obtained by the upregulation of cyclooxygenase by ALA. H-89, an inhibitor of protein kinase A (PKA), inhibited the expression of MMP-9 indicating that ALA mediated upregulation of MMP-9 is mediated through PKA pathway. Increase in MMP production and increase in cyclooxygenase activity and inhibition of the effect of ALA on MMP production by indomethacin suggested that the ALA activated monocytes in culture can be used as an in vitro model system to study the intracellular signaling process involved in the mediation of inflammatory response.

RANK ligand signaling modulates the matrix metalloproteinase-9 gene expression during osteoclast differentiation

Osteoclast differentiation is tightly regulated by receptor activator of NF-kappaB ligand (RANKL) signaling. Matrix metalloproteinase-9 (MMP-9), a type IV collagenase is highly expressed in osteoclast cells and plays an important role in degradation of extracellular matrix; however, the molecular mechanisms that regulate MMP-9 gene expression are unknown. In this study, we demonstrate that RANKL signaling induces MMP-9 gene expression in osteoclast precursor cells. We further show that RANKL regulates MMP-9 gene expression through TRAF6 but not TRAF2. Interestingly, blockade of p38 MAPK activity by pharmacological inhibitor, SB203580 increases MMP-9 activity whereas ERK1/2 inhibitor, PD98059 decreases RANKL induced MMP-9 activity in RAW264.7 cells. These data suggest that RANKL differentially regulates MMP-9 expression through p38 and ERK signaling pathways during osteoclast differentiation. Transient expression of MMP-9 gene (+1 to -1174 bp relative to ATG start codon) promoter-luciferase reporter plasmids in RAW264.7 cells and RANKL stimulation showed significant increase (20-fold) of MMP-9 gene promoter activity; however, there is no significant change with respect to +1 bp to -446 bp promoter region and empty vector transfected cells. These results indicated that MMP-9 promoter sequence from -446 bp to -1174 bp relative to start codon is responsive to RANKL stimulation. Sequence analysis of the mouse MMP-9 gene promoter region further identified the presence of binding motif (-1123 bp to -1153 bp) for the nuclear factor of activated T cells 1 (NFATc1) transcription factor. Inhibition of NFATc1 using siRNA and VIVIT peptide inhibitor significantly decreased RANKL stimulation of MMP-9 activity. We further confirm by oligonucleotide pull-down assay that RANKL stimuli enhanced NFATc1 binding to MMP-9 gene promoter element. In addition, over-expression of constitutively active NFAT in RAW264.7 cells markedly increased (5-fold) MMP-9 gene promoter activity in the absence of RANKL. Taken together, our results suggest that RANKL signals through TRAF6 and that NFATc1 is a downstream effector of RANKL signaling to modulate MMP-9 gene expression during osteoclast differentiation.

Expression Cloning Identifies Transgelin (SM22) as a Novel Repressor of 92-kDa Type IV Collagenase (MMP-9) Expression

The 92-kDa gelatinase (MMP-9) expression is prerequisite for tissue remodeling in physiology and cancer. However, there are few known regulators of MMP-9 expression. Using an expression cloning strategy, we identified transgelin (SM22), a 22-25-kDa actin-binding protein localized to the cell membrane and cytoplasm, as a novel regulator of MMP-9 expression. Overexpression of a SM22 cDNA in HT1080 cells decreased MMP-9 mRNA/protein levels and diminished in vitro invasion of the latter rescued with exogenous MMP-9. Conversely, small interfering RNA-mediated knockdown of SM22 elevated MMP-9 synthesis, and uterus from SM22-null mice showed strong MMP-9 immunoreactivity compared with wild type animals. The ability of SM22 to repress MMP-9 expression required an intact amino terminus calponin homology domain. MMP-9 expression is driven by ERK signaling and SM22 targeted this pathway as evidenced by (a) the transience in MAPK activation and (b) blunted stimulation of the MMP-9 promoter by a constitutively active MEK expression vector. Progressive deletion analysis located the SM22 responsive region of the MMP-9 promoter to the proximal 90-bp region harboring an AP-1 motif subsequently implicated by site-directed mutagenesis. Furthermore, nuclear extract from the SM22 transfectants showed diminished c-Fos binding to this motif and SM22 expression reduced the activity of an AP-1-driven reporter by 75%. Thus, SM22 adds to a short list of repressors of MMP-9 expression, achieving this by reducing AP-1-dependent trans-activation of the gene by way of compromised ERK activation. Diminished transgelin expression in several cancers may thus partly account for the elevated MMP-9 expression evident in these tumors.

Metalloproteinases and their inhibitors: influence on tumor invasiveness and metastasis formation in head and neck squamous cell carcinomas

BACKGROUND

Matrix metalloproteinases (MMPs) play an important role in tumor invasiveness. This study investigates the expression status of MMPs and tissue inhibitors of metalloproteinases (TIMPs) in head and neck squamous cell carcinomas (HNSCC).

METHODS

Of 48 laryngeal squamous cell carcinoma (LSCC) biopsies and 10 HNSCC cell lines, mRNA was isolated, reversely transcribed, and subjected to polymerase chain reaction (PCR) amplifying MMP-1, MMP-2, MMP-9, MMP-10, TIMP-1, and TIMP-2. Silver nitrate-stained gel electrophoresis demonstrated MMP and TIMP expression status. Exemplary immunohistochemistry and zymography confirmed translation and enzyme activity.

RESULTS

Densitometric analysis revealed MMP-2 expression and lymph node metastases to be positively and TIMP-1 and TIMP-2 to be negatively correlated with lymph node metastases. TIMP-2 expression and tumor size were negatively correlated. MMP-1, MMP-9, and MMP-10 expression were not correlated to metastasis formation or tumor size.

CONCLUSIONS

Our results suggest that MMP-2 expression enhances, whereas TIMP-1 and TIMP-2 both suppress, cancer spread in LSCC.

Vascular endothelial growth factor-regulated ovarian cancer invasion and migration involves expression and activation of matrix metalloproteinases

Vascular endothelial growth factor (VEGF) expression is elevated in primary ovarian tumors and metastases. We examined the effect of VEGF on epithelial ovarian cancer (EOC) in vitro invasion and migration and underlying mechanisms. Using the Matrigel invasion assay and colloidal gold phagokinetic track assay, we found that VEGF induced EOC DOV13 invasion and migration in a matrix metalloproteinase (MMP)-dependent manner. Using Western blotting, we show that VEGF, at 20-80 ng/ml, induced secretion of pro-MMP-7 and pro-MMP-9 and activation of pro-MMP-2 in DOV13 conditioned medium in a concentration-dependent manner. However, gelatinolytic activity and total MMP-7 protein in DOV13 conditioned medium reached the maximum upon VEGF treatment at 20-40 ng/ml and decreased at higher-concentration VEGF treatment (80 ng/ml), as shown by DQ-gelatin degradation assay and ELISA. In addition to the effect on MMP secretion/activation, VEGF stimulated secretion of TIMP-2; and blocking TIMP-2 activity by an anti-TIMP-2 MAb significantly increased VEGF (80 ng/ml)-induced DOV13 invasion (p < 0.05), suggesting that VEGF may regulate MMP-2 activity in DOV13 conditioned medium through TIMP-2. Using real-time PCR, we found that VEGF, at 20 ng/ml, significantly increased the expression of VEGFR-1 and VEGFR-2 by approximately 4-fold and 31-fold, respectively, compared to untreated control (p < 0.05). However, the inducing effect of VEGF on VEGFR-2 expression and the internal expression of VEGF121 in DOV13 cells decreased with increasing of VEGF concentration, suggesting the existence of a negative feedback regulatory mechanism. In summary, our results indicate that VEGF may regulate EOC invasion and migration through VEGFR-mediated secretion and activation of MMPs.

Platelet-activating factor induces matrix metalloproteinase-9 expression through Ca2+- or PI3K-dependent signaling pathway in a human vascular endothelial cell line

Platelet-activating factor (PAF) augments angiogenesis by promoting the synthesis of a variety of angiogenic factors, via the nuclear factor (NF)-kappaB activation. Recently, we reported that PAF upregulates MMP-9 expression in a NF-kappaB-dependent manner. In this study, we investigated the signaling pathway involved in PAF-induced MMP-9 expression in ECV304 cells. Our current data indicate that the Ca(2+)- or phosphatidylinositol 3-kinase (PI3K)-dependent signaling pathway is necessary for PAF-induced MMP-9 expression. Furthermore, PAF-induced NF-kappaB activation was blocked by selective inhibitors of Ca(2+), PI3K, or extracellular signal-regulated kinase (ERK). Our results suggest that PAF-induced MMP-9 expression, in a NF-kappaB-dependent manner, is regulated by Ca(2+), PI3K and ERK signaling pathways.

Independent [Ca2+]i increases and cell proliferation induced by the carcinogen safrole in human oral cancer cells

The effect of the carcinogen safrole on intracellular Ca2+ movement and cell proliferation has not been explored previously. The present study examined whether safrole could alter Ca2+ handling and growth in human oral cancer OC2 cells. Cytosolic free Ca2+ levels ([Ca2+]i) in populations of cells were measured using fura-2 as a fluorescent Ca2+ probe. Safrole at a concentration of 325 microM started to increase [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced by 40% by removing extracellular Ca2+, and was decreased by 39% by nifedipine but not by verapamil or diltiazem. In Ca2+-free medium, after pretreatment with 650 microM safrole, 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) barely induced a [Ca2+]i rise; in contrast, addition of safrole after thapsigargin treatment induced a small [Ca2+]i rise. Neither inhibition of phospholipase C with 2 microM U73122 nor modulation of protein kinase C activity affected safrole-induced Ca2+ release. Overnight incubation with 1 microM safrole did not alter cell proliferation, but incubation with 10-1000 microM safrole increased cell proliferation by 60+/-10%. This increase was not reversed by pre-chelating Ca2+ with 10 microM of the Ca2+ chelator BAPTA. Collectively, the data suggest that in human oral cancer cells, safrole induced a [Ca2+]i rise by causing release of stored Ca2+ from the endoplasmic reticulum in a phospholipase C- and protein kinase C-independent fashion and by inducing Ca2+ influx via nifedipine-sensitive Ca2+ entry. Furthermore, safrole can enhance cell growth in a Ca2+-independent manner.

Analysis of activated EGFR signalling pathways and their relation to laminin-5 gamma2 chain expression in oral squamous cell carcinoma (OSCC)

Overexpression of epidermal growth factor receptor (EGFR) was shown for the majority of squamous cell carcinomas. The EGFR expression correlates to tumour size, stage and cytoplasmic accumulation of the laminin-5 gamma2 chain (Ln-5/gamma2), which is known as a marker of invading tumour cells. There is only limited knowledge if and how EGFR signalling pathways are important for invasion-associated processes and for the regulation of Ln-5/gamma2. Therefore the distribution of phosphorylated Erk1/2, p38 MAPK and Akt was immunohistochemically defined in oral squamous cell carcinoma (OSCC) of different histological grade and compared to histological criteria of invasion and cytoplasmic Ln-5/gamma2 deposition. With raising histological grade, there is a slight increase in nuclear pErk1/2-stained tumour cells (P=0.398) and a loss of nuclear (P=0.593) and increased cytoplasmic staining (P=0.144) of pAkt mainly in invading OSCC cells. Nuclear pp38 MAPK could only be sporadically detected in few cases. In case of pErk1/2 and pAkt, only a partial co-localisation could be revealed in cases with abundant kinases and Ln-5/gamma2. Among the investigated kinases, only pAkt shows a relation to histological grade and invasion in OSCC. pErk1/2, pp38 MAPK and pAkt do not represent a direct link between EGFR and Ln-5 synthesis. Therefore, enhanced Ln-5/gamma2 may be a secondary phenomenon of EGFR-induced tumour cell proliferation and dissemination.

Uncoupling of epidermal growth factor-dependent proliferation and invasion in a model of squamous carcinoma progression

Cell lines pairs were established from a primary squamous carcinoma of tongue and a lymph node metastasis and their biological behavior characterized. HN12 cells, derived from metastatic SCC, formed tumors upon subcutaneous transplantation to athymic mice, whereas HN4, derived from a primary lesion in the same individual, were non-tumorigenic in this assay. EGF stimulated proliferation of HN4 cells; in comparison, not only were metastatic HN12 cells refractory to the stimulatory effects of this growth factor but showed inhibition at higher growth factor concentrations. However, in contrast to the effects on proliferation, EGF (10 ng/ml) readily induced HN12 cells to invade in Boyden chamber assays whereas HN4 were non-invasive under these conditions. The invasive properties of HN12 cells were apparently independent of MMP-2 activity, as levels of active MMP-2 were higher in the non-invasive cells. However, EGF stimulated MMP-9 activity in invasive cells. Additionally, HN12 cells expressed constitutively high levels of active MMP-7 and MMP-3/10. The pharmacological agents LY294002, PD098059, SP600125, or SB202190 inhibited invasion of HN12 cells, suggesting requirement for phosphoinositide 3-OH kinase- and mitogen activated protein kinase-dependent pathways in the process. The data indicate that distinct biochemical differences distinguish metastatic squamous carcinoma cells from those derived from corresponding primary tumors, resulting in their contrasting biological properties.

Alpha3beta1 integrin regulates MMP-9 mRNA stability in immortalized keratinocytes: a novel mechanism of integrin-mediated MMP gene expression

Matrix metalloproteinases facilitate cell migration and tumor invasion through their ability to proteolyse the extracellular matrix. The laminin-binding integrin alpha3beta1 is expressed at high levels in squamous cell carcinomas and in normal keratinocytes during cutaneous wound healing. We showed previously that alpha3beta1 is required for MMP-9/gelatinase B secretion in immortalized mouse keratinocytes (MK cells) and that this regulation was acquired as part of the immortalized phenotype, suggesting a possible role for alpha3beta1 during malignant conversion. In the current study, we identify a novel mechanism whereby alpha3beta1 regulates the induction of MMP-9 expression that occurs in response to activation of a MAPK kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway. Inhibition of MEK/ERK signaling in wild-type MK cells with a pharmacological inhibitor, U0126, showed that ERK activation was necessary for high levels of endogenous MMP-9 gene expression and activity of a transfected MMP-9 promoter. Furthermore, activation of MEK/ERK signaling in these cells with an oncogenic mutant of Ras, RasV12, increased both endogenous MMP-9 gene expression and MMP-9 promoter activity. Experiments with alpha3beta1-deficient MK cells revealed that alpha3beta1 was required for both baseline levels and RasV12-induced levels of MMP-9 mRNA expression. However, alpha3beta1 was not required for RasV12-mediated activation of ERK or for ERK-dependent MMP-9 promoter activity. Direct comparison of mRNA turnover in the wild type and alpha3-null MK cells identified a requirement for alpha3beta1 in stabilization of MMP-9 mRNA transcripts. These results identify a novel function for integrins in promoting mRNA stability as a mechanism to potentiate MAPK-mediated gene expression. They also suggest a role for alpha3beta1 in maintaining high levels of MMP-9 mRNA expression in response to oncogenic activation of MEK/ERK signaling pathways.

A PSP94-derived peptide PCK3145 inhibits MMP-9 secretion and triggers CD44 cell surface shedding: implication in tumor metastasis

PURPOSE

PCK3145 is a synthetic peptide corresponding to amino acids 31-45 of prostate secretory protein 94, which can reduce experimental skeletal metastases and prostate tumor growth in vivo. Part of its biological action involves the reduction of circulating plasma matrix metalloproteinase (MMP)-9, a crucial mediator in extracellular matrix (ECM) degradation during tumor metastasis and cancer cell invasion. The antimetastatic mechanism of action of PCK3145 is however, not understood.

EXPERIMENTAL DESIGN

HT-1080 fibrosarcoma cells were treated with PCK3145, and cell lysates used for immunoblot analysis of small GTPase RhoA and membrane type (MT)1-MMP protein expression. Conditioned media was used to monitor soluble MMP-9 gelatinolytic activity by zymography and protein expression by immunoblotting. RT-PCR was used to assess RhoA, MT1-MMP, MMP-9, RECK, and CD44 gene expression. Flow cytometry was used to monitor cell surface expression of CD44 and of membrane-bound MMP-9. Cell adhesion was performed on different purified ECM proteins, while cell migration was specifically performed on hyaluronic acid (HA).

RESULTS

We found that PCK3145 inhibited HT-1080 cell adhesion onto HA, laminin-1, and type-I collagen suggesting the common implication of the cell surface receptor CD44. In fact, PCK3145 triggered the shedding of CD44 from the cell surface into the conditioned media. PCK3145 also inhibited MMP-9 secretion and binding to the cell surface. This effect was correlated to increased RhoA and MT1-MMP gene and protein expression.

CONCLUSIONS

Our data suggest that PCK3145 may antagonize tumor cell metastatic processes by inhibiting both MMP-9 secretion and its potential binding to its cell surface docking receptor CD44. Such mechanism may involve RhoA signaling and increase in MT1-MMP-mediated CD44 shedding. Together with its beneficial effects in clinical trials, this is the first demonstration of PCK3145 acting as a MMP secretion inhibitor.