Specific Interference of Urokinase-type Plasminogen Activator Receptor and Matrix Metalloproteinase-9 Gene Expression Induced by Double-stranded RNA Results in Decreased Invasion, Tumor Growth, and Angiogenesis in Gliomas

Genetic analysis of the molecular regulation of electric fields-guided glia migration

In a developing nervous system, endogenous electric field (EF) influence embryonic growth. We reported the EF-directed migration of both rat Schwann cells (SCs) and oligodendrocyte precursor cells (OPCs) and explored the molecular mechanism using RNA-sequencing assay. However, previous studies revealed the differentially expressed genes (DEGs) associated with EF-guided migration of SCs or OPCs alone. In this study, we performed joint differential expression analysis on the RNA-sequencing data from both cell types. We report a number of significantly enriched gene ontology (GO) terms that are related to the cytoskeleton, cell adhesion, and cell migration. Of the DEGs associated with these terms, nine up-regulated DEGs and 32 down-regulated DEGs showed the same direction of effect in both SCs and OPCs stimulated with EFs, while the remaining DEGs responded differently. Thus, our study reveals the similarities and differences in gene expression and cell migration regulation of different glial cell types in response to EF stimulation.

Effect of MMP-9 gene knockout on retinal vascular form and function

Retinal degeneration from inherited gene mutation(s) is a common cause of blindness because of structural and functional alterations in photoreceptors. Accordingly, various approaches are being tested to ameliorate or even cure neuroretinal blinding conditions in susceptible patients by employing neuroprotective agents, gene therapeutics, optogenetics, regenerative therapies, and retinal prostheses. The FVB/NJ mouse strain inherently has a common Pde6b rd1 homozygous allele that renders its progeny blind by the time pups reach weaning age. To study the role matrix metalloproteinase-9 (MMP-9) in retinal structure and function, we examined a global MMP-9 knockout (KO) mouse model that has been engineered on the same FVB/NJ background to test the hypothesis whether lack of MMP-9 activity diminishes neuroretinal degenerative changes and thus helps improve the vision. We compared side-by-side various aspects of the ocular physiology in the wild-type (WT) C57BL/6J, FVB/NJ, and MMP-9 KO strains of mice. The results suggest that MMP-9 KO mice display subdued changes in their retinae as reflected by both structural and functional enhancement in the overall ocular neurophysiological parameters. Altogether, the findings appear to have clinical relevance for targeting conditions wherein MMPs and their overactivities are suspected to play dominant pathophysiological roles in advancing neurodegenerative retinal diseases.

CRISPR/Cas9 nickase mediated targeting of urokinase receptor gene inhibits neuroblastoma cell proliferation

Neuroblastoma is a tumor arising from pluripotent sympathoadrenal precursor cells of neural cell origin. Neuroblastoma is one of the most aggressive childhood tumors with highly invasive and metastatic potential. The increased expression of urokinase and its receptor is often associated with a negative prognosis in neuroblastoma patients.

We have shown that targeting of the Plaur gene in mouse neuroblastoma Neuro 2A cells by CRISPR/Cas9n results in ~60% decrease in cell proliferation (p<0.05), reduction in the number of Ki-67 positive cells, caspase 3 activation and PARP-1 cleavage. Knockout of uPAR leads to downregulation of mRNA encoding full-length TrkC receptor, which is involved in p38^MAPK and Akt signalling pathways. This finding provides a rationale to study a role of uPAR in neuroblastoma progression, since uPAR could be considered a potential therapeutic target in neuroblastoma treatment.

Methylation regulates HEY1 expression in glioblastoma

Glioblastoma (GBM) remains one of the most lethal and difficult-to-treat cancers of the central nervous system. The poor prognosis in GBM patients is due in part to its resistance to available treatments, which calls for identifying novel molecular therapeutic targets. In this study, we identified a mediator of Notch signaling, HEY1, whose methylation status contributes to the pathogenesis of GBM. Datamining studies, immunohistochemistry and immunoblot analysis showed that HEY1 is highly expressed in GBM patient specimens. Since methylation status of HEY1 may control its expression, we conducted bisulphite sequencing on patient samples and found that the HEY1 promoter region was hypermethylated in normal brain when compared to GBM specimens. Treatment on 4910 and 5310 xenograft cell lines with sodium butyrate (NaB) significantly decreased HEY1 expression with a concomitant increase in DNMT1 expression, confirming that promoter methylation may regulate HEY1 expression in GBM. NaB treatment also induced apoptosis of GBM cells as measured by flow cytometric analysis. Further, silencing of HEY1 reduced invasion, migration and proliferation in 4910 and 5310 cells. Furthermore, immunoblot and q-PCR analysis showed the existence of a potential positive regulatory loop between HEY1 and p53. Additionally, transcription factor interaction array with HEY1 recombinant protein predicted a correlation with p53 and provided various bonafide targets of HEY1. Collectively, these studies suggest HEY1 may be an important predictive marker for GBM and potential target for future GBM therapy.

Targeting tumor-associated macrophages to combat pancreatic cancer

The tumor microenvironment is replete with cells that evolve with and provide support to tumor cells during the transition to malignancy. The hijacking of the immune system in the pancreatic tumor microenvironment is suggested to contribute to the failure to date to produce significant improvements in pancreatic cancer survival by various chemotherapeutics. Regulatory T cells, myeloid derived suppressor cells, and fibroblasts, all of which constitute a complex ecology microenvironment, can suppress CD8+ T cells and NK cells, thus inhibiting effector immune responses. Tumor-associated macrophages (TAM) are versatile immune cells that can express different functional programs in response to stimuli in tumor microenvironment at different stages of pancreatic cancer development. TAM have been implicated in suppression of anti-tumorigenic immune responses, promotion of cancer cell proliferation, stimulation of tumor angiogenesis and extracellular matrix breakdown, and subsequent enhancement of tumor invasion and metastasis. Many emerging agents that have demonstrated efficacy in combating other types of tumors via modulation of macrophages in tumor microenvironments are, however, only marginally studied for pancreatic cancer prevention and treatment. A better understanding of the paradoxical roles of TAM in pancreatic cancer may pave the way to novel preventive and therapeutic approaches. Here we give an overview of the recruitment and differentiation of macrophages, TAM and pancreatic cancer progression and prognosis, as well as the potential preventive and therapeutic targets that interact with TAM for pancreatic cancer prevention and treatment.

RNAi Based Approaches to the Treatment of Malignant Glioma

RNA interference (RNAi) is a recently discovered, powerful molecular mechanism that can be harnessed to engineer gene-specific silencing in mammalian tissues. A mechanism, where short double-stranded RNA (dsRNA) molecules, when introduced into cells elicit specific “knock-down” of gene expression via degradation of targeted messenger RNA, has lately become the technique of choice for analysis of gene function in oncology research. Thus, RNAi is currently being extensively evaluated as a potential therapeutic strategy against malignant gliomas, since surgical, radiological, and chemotherapeutic interventions during the past few decades have done little to improve the poor prognosis rate for patients with these dreaded tumors. This review summarizes the pre-clinical studies that are currently underway to test the validity of RNAi as a potential therapeutic strategy against malignant gliomas, and discusses the potential technical Hurdles that remain to be overcome before the technique can become a promising clinical therapy to combat this frequently lethal disease.

RNAi therapeutics for brain cancer: current advancements in RNAi delivery strategies

Malignant primary brain tumors are aggressive cancerous cells that invade the surrounding tissues of the central nervous system. The current treatment options for malignant brain tumors are limited due to the inability to cross the blood-brain barrier. The advancements in current research has identified and characterized certain molecular markers that are essential for tumor survival, progression, metastasis and angiogenesis. These molecular markers have served as therapeutic targets for the RNAi based therapies, which enable site-specific silencing of the gene responsible for tumor proliferation. However, to bring about therapeutic success, an efficient delivery carrier that can cross the blood-brain barrier and reach the targeted site is essential. The current review focuses on the potential of targeted, non-viral and viral particles containing RNAi therapeutic molecules as delivery strategies specifically for brain tumors.

GnRH-(1-5) activates matrix metallopeptidase-9 to release epidermal growth factor and promote cellular invasion

In the extracellular space, the gonadotropin-releasing hormone (GnRH) is metabolized by the zinc metalloendopeptidase EC3.4.24.15 (EP24.15) to form the pentapeptide, GnRH-(1-5). GnRH-(1-5) diverges in function and mechanism of action from GnRH in the brain and periphery. GnRH-(1-5) acts on the orphan G protein-coupled receptor 101 (GPR101) to sequentially stimulate epidermal growth factor (EGF) release, phosphorylate the EGF receptor (EGFR), and facilitate cellular migration. These GnRH-(1-5) actions are dependent on matrix metallopeptidase (MMP) activity. Here, we demonstrated that these GnRH-(1-5) effects are dependent on increased MMP-9 enzymatic activity in the Ishikawa and ECC-1 cell lines. Furthermore, the effects of GnRH-(1-5) mediated by GPR101 and the subsequent increase in MMP-9 enzymatic activity lead to an increase in cellular invasion. These results suggest that GnRH-(1-5) and GPR101 regulation of MMP-9 may have physiological relevance in the metastatic potential of endometrial cancer cells.

Extracellular matrix, gap junctions, and retinal vascular homeostasis in diabetic retinopathy

The vascular basement membrane (BM) contains extracellular matrix (ECM) proteins that assemble in a highly organized manner to form a supportive substratum for cell attachment facilitating myriad functions that are vital to cell survival and overall retinal homeostasis. The BM provides a microenvironment in which bidirectional signaling through integrins regulates cell attachment, turnover, and functionality. In diabetic retinopathy, the BM undergoes profound structural and functional changes, and recent studies have brought to light the implications of such changes. Thickened vascular BM in the retinal capillaries actively participate in the development and progression of characteristic changes associated with diabetic retinopathy. High glucose (HG)-induced compromised cell-cell communication via gap junctions (GJ) in retinal vascular cells may disrupt homeostasis in the retinal microenvironment. In this review, the role of altered ECM synthesis, compromised GJ activity, and disturbed retinal homeostasis in the development of retinal vascular lesions in diabetic retinopathy are discussed.

Invasive potential of melanoma cells correlates with the expression of MT1-MMP and regulated by modulating its association with motility receptors via N-glycosylation on the receptors

Matrix remodeling and invasion of basement membrane are the major determinants of malignant progression. Matrix degrading enzymes play a pivotal role in this process and have been shown to be regulated at multiple levels. Using high metastatic B16F10 and its invasive variant B16BL6 cells, we previously demonstrated that the expression of β1,6 branched N-oligosaccharides promotes cellular adhesion on different matrix components which in turn induces secretion of MMP9. The present investigations report that although the two cell lines do not differ in the expression of uPAR, expression of MT1-MMP is significantly higher on B16BL6 cells. Analysis of the transcripts of tissue inhibitors of matrix metalloproteinases (TIMPs) showed that expression of both TIMP1 and TIMP2 correlates negatively with the invasive potential of cells. CD44 and β1 integrin, the two important receptors involved in motility, were identified to carry β1,6 branched N-oligosaccharides in an invasive potential dependent manner. However, their glycosylation status did not appear to influence their surface expression. Although glycosylation on CD44 had no effect, that on β1 integrin significantly affected association of β1 integrin with MT1-MMP. The results thus demonstrate that the cancer cells use multiple mechanisms for degradation of matrix in a controlled manner to couple it with movement for effective invasion.

Galectin-3 and matrix metalloproteinase-9: Perspective in management of hepatocellular carcinoma

AIM

Hepatocellular carcinoma (HCC) is the fifth most common cancer in men and the seventh in women. HCC varies widely in incidence through the world, with rising incidence in Egypt. This study aimed to estimate the serum levels of matrix metalloproteinase-9 (MMP-9) and its substrate galectin-3 in order to evaluate their diagnostic accuracy and their relation to HCC-related clinical features.

METHODS

For this purpose, serum levels of these biochemical markers were assessed in 50 HCC patients, 30 cirrhotic patients in addition to 10 healthy subjects as a control group using enzyme linked immune-sorbent assay (ELISA).

RESULTS

In the present study, circulating level of galectin-3, MMP-9 increased significantly in HCC as compared to the control group (P = 0.044 and 0.04, respectively). However, no significant difference was observed between cirrhotic and HCC patients (P = 0.231 and 0.193, respectively). Our study found that HCC patients with metastatic spread had a significant elevation of both serum galectin-3 and MMP-9 levels (P = 0.028 and <0.0001, respectively). In addition, galectin-3 level significantly increased in HCC patients with poor prognosis suffering from portal vein invasion (P = 0.014). Moreover, MMP-9 increased significantly with increasing stage of Barcelona-Clinic Liver Cancer Group diagnostic and treatment strategy (P = 0.01).

CONCLUSION

MMP-9 and galectin-3 could be used as a guide for prognosis of HCC since they may play a role in HCC progression and metastasis. However, they are not useful markers for HCC diagnosis.

Involvement of nitric oxide synthase in matrix metalloproteinase-9- and/or urokinase plasminogen activator receptor-mediated glioma cell migration

BACKGROUND

Src tyrosine kinase activates inducible nitric oxide synthase (iNOS) and, in turn, nitric oxide production as a means to transduce cell migration. Src tyrosine kinase plays a key proximal role to control α9β1 signaling. Our recent studies have clearly demonstrated the role of α9β1 integrin in matrix metalloproteinase-9 (MMP-9) and/or urokinase plasminogen activator receptor (uPAR)-mediated glioma cell migration. In the present study, we evaluated the involvement of α9β1 integrin-iNOS pathway in MMP-9- and/or uPAR-mediated glioma cell migration.

METHODS

MMP-9 and uPAR shRNAs and overexpressing plasmids were used to downregulate and upregulate these molecules, respectively in U251 glioma cells and 5310 glioma xenograft cells. The effect of treatments on migration and invasion potential of these glioma cells were assessed by spheroid migration, wound healing, and Matrigel invasion assays. In order to attain the other objectives we also performed immunocytochemical, immunohistochemical, RT-PCR, Western blot and fluorescence-activated cell sorting (FACS) analysis.

RESULTS

Immunohistochemical analysis revealed the prominent association of iNOS with glioblastoma multiforme (GBM). Immunofluorescence analysis showed prominent expression of iNOS in glioma cells. MMP-9 and/or uPAR knockdown by respective shRNAs reduced iNOS expression in these glioma cells. RT-PCR analysis revealed elevated iNOS mRNA expression in either MMP-9 or uPAR overexpressed glioma cells. The migration potential of MMP-9- and/or uPAR-overexpressed U251 glioma cells was significantly inhibited after treatment with L-NAME, an inhibitor of iNOS. Similarly, a significant inhibition of the invasion potential of the control or MMP-9/uPAR-overexpressed glioma cells was noticed after L-NAME treatment. A prominent reduction of iNOS expression was observed in the tumor regions of nude mice brains, which were injected with 5310 glioma cells, after MMP-9 and/or uPAR knockdown. Protein expressions of cSrc, phosphoSrc and p130Cas were reduced with simultaneous knockdown of both MMP-9 and uPAR.

CONCLUSIONS

Taken together, our results from the present and earlier studies clearly demonstrate that α9β1 integrin-mediated cell migration utilizes the iNOS pathway, and inhibition of the migratory potential of glioma cells by simultaneous knockdown of MMP-9 and uPAR could be attributed to the reduced α9β1 integrin and iNOS levels.

Systematic review of protein biomarkers of invasive behavior in glioblastoma

Glioblastoma (GBM) is an aggressive and incurable brain tumor with a grave prognosis. Recurrence is inevitable even with maximal surgical resection, in large part because GBM is a highly invasive tumor. Invasiveness also contributes to the failure of multiple cornerstones of GBM therapy, including radiotherapy, temozolomide chemotherapy, and vascular endothelial growth factor blockade. In recent years there has been significant progress in the identification of protein biomarkers of invasive phenotype in GBM. In this article, we comprehensively review the literature and survey a broad spectrum of biomarkers, including proteolytic enzymes, extracellular matrix proteins, cell adhesion molecules, neurodevelopmental factors, cell signaling and transcription factors, angiogenic effectors, metabolic proteins, membrane channels, and cytokines and chemokines. In light of the marked variation seen in outcomes in GBM patients, the systematic use of these biomarkers could be used to form a framework for better prediction, prognostication, and treatment selection, as well as the identification of molecular targets for further laboratory investigation and development of nascent, directed therapies.

Epigenetic regulation of miRNA-211 by MMP-9 governs glioma cell apoptosis, chemosensitivity and radiosensitivity

Glioblastoma multiforme (GBM) is the most aggressive brain cancer, and to date, no curative treatment has been developed. In this study, we report that miR-211, a microRNA predicted to target MMP-9, is suppressed in grade IV GBM specimens. Furthermore, we found that miR-211 suppression in GBM involves aberrant methylation-mediated epigenetic silencing of the miR-211 promoter. Indeed, we observed a highly significant inverse correlation between miR-211 expression and MMP-9 protein levels, which is indicative of post-transcriptional control of gene expression. Additionally, shRNA specific for MMP-9 (pM) promoted miR-211 expression via demethylation of miR-211 promoter-associated CpG islands (-140 to +56). In independent experiments, we confirmed that miR-211 overexpression and pM treatments led to the activation of the intrinsic mitochondrial/Caspase-9/3-mediated apoptotic pathway in both glioma cells and cancer stem cells (CSC). We also investigated whether miR-211 is involved in the regulation of MMP-9 and thus plays a functional role in GBM. We found an acute inhibitory effect of miR-211 on glioma cell invasion and migration via suppression of MMP-9. Given the insensitivity of some GBMs to radiation and chemotherapy (temozolomide) along with the hypothesis that glioma CSC cause resistance to therapy, our study indicates that miR-211 or pM in combination with ionizing radiation (IR) and temozolomide significantly induces apoptosis and DNA fragmentation. Of note, miR-211- and pM-treated CSC demonstrated increased drug retention capacity, as observed by MDR1/P-gp mediated-Rhodamine 123 drug efflux activity assay. These results suggest that either rescuing miR-211 expression or downregulation of MMP-9 may have a new therapeutic application for GBM patients in the future.

Human adipose-derived stem cell adipogenesis induces paracrine regulation of the invasive ability of MCF-7 human breast cancer cells in vitro

The aim of this study was to determine the effects of paracrine regulation on the invasive ability of MCF-7 human breast cancer cells through human adipose-derived stem cell (hADSC) adipogenesis. hADSC differentiation of the third and fourth passages of cells was induced in different induction media: osteogenic, adipogenic and chondrogenic. Transwell migration assays in the differently conditioned media, flow cytometry, enzyme-linked immunosorbent assay and western blot analysis for selected cytokines were performed. The flow cytometric analysis demonstrated positive expression of CD29, CD44 and CD105, while expression of CD34 and CD45 was not identified. The transwell migration assay showed that the invasive ability of MCF-7 cells was significantly enhanced during hADSC adipogenesis. hADSCs exerted a significantly positive effect on the invasive activity of MCF-7 cells during adipo-genesis. The results indicate that the high expression levels of activating protein 2 (aP2) in MCF-7 and adipocytes induced for 12 days may be associated with cell growth, invasion and metastasis. Peroxisome proliferator-activated receptor γ may be involved in fatty syntheses during adipogenic initiation and following adipogenic differentiation, possibly acting as a protection factor resulting in cell maturation and differentiation. This study also demonstrated that the expression of vascular endothelial growth factor was repressed by hADSCs, while that of matrix metalloproteinase-2 and urokinase-type plasminogen activator was increased to a significant level.

MMP-9 and uPAR regulated glioma cell migration

Integrin-dependent and -independent MMP-9 and uPAR signaling plays a key role in glioma cell migration and invasion. In this article, we comment on all the possible pathways and molecules associated with MMP-9- and uPAR-mediated glioma cell migration with a special emphasis on integrins, a family of cell adhesion molecules. Our recent research investigations highlighted the substantial benefit of silencing both MMP-9 and uPAR together compared with their individual treatments in glioma. Simultaneous knockdown of both MMP-9 and uPAR regulated a majority of the molecules associated with glioma cell migration and significantly reduced the migration potential of glioma cells. Our results point out that the bicistronic construct, which can simultaneously silence both MMP-9 and uPAR offers a great therapeutic potential and is worth developing as a new drug for treating GBM patients.

A complete compilation of matrix metalloproteinase expression in human malignant gliomas

Glioblastomas are characterized by an aggressive local growth pattern, a marked degree of invasiveness and poor prognosis. Tumor invasiveness is facilitated by the increased activity of proteolytic enzymes which are involved in destruction of the extracellular matrix of the surrounding healthy brain tissue. Elevated levels of matrix metalloproteinases (MMPs) were found in glioblastoma (GBM) cell-lines, as well as in GBM biopsies as compared with low-grade astrocytoma (LGA) and normal brain samples, indicating a role in malignant progression. A careful review of the available literature revealed that both the expression and role of several of the 23 human MMP proteins is controversely discussed and for some there are no data available at all. We therefore screened a panel of 15 LGA and 15 GBM biopsy samples for those MMPs for which there is either no, very limited or even contradictory data available. Hence, this is the first complete compilation of the expression pattern of all 23 human MMPs in astrocytic tumors. This study will support a better understanding of the specific expression patterns and interaction of proteolytic enzymes in malignant human glioma and may provide additional starting points for targeted patient therapy.

Caveolin-1, caveolae, and glioblastoma

Glioblastoma multiforme (GBM) is the most common malignant brain tumor and is characterized by high invasiveness, poor prognosis, and limited therapeutic options. Biochemical and morphological experiments have shown the presence of caveolae in glioblastoma cells. Caveolae are flask-shaped plasma membrane subdomains that play trafficking, mechanosensing, and signaling roles. Caveolin-1 is a membrane protein that participates in the formation of caveolae and binds a multitude of signaling proteins, compartmentalizing them in caveolae and often directly regulating their activity via binding to its scaffolding domain. Caveolin-1 has been proposed to behave either as a tumor suppressor or as an ongogene depending on the tumor type and progress. This review discusses the existing information on the expression and function of caveolin-1 and caveolae in GBM and the role of this organelle and its defining protein on cellular signaling, growth, and invasiveness of GBM. We further analyze the available data suggesting caveolin-1 could be a target in GBM therapy.

Epigenetic diet: impact on the epigenome and cancer

A number of bioactive dietary components are of particular interest in the field of epigenetics. Many of these compounds display anticancer properties and may play a role in cancer prevention. Numerous studies suggest that a number of nutritional compounds have epigenetic targets in cancer cells. Importantly, emerging evidence strongly suggests that consumption of dietary agents can alter normal epigenetic states as well as reverse abnormal gene activation or silencing. Epigenetic modifications induced by bioactive dietary compounds are thought to be beneficial. Substantial evidence is mounting proclaiming that commonly consumed bioactive dietary factors act to modify the epigenome and may be incorporated into an 'epigenetic diet'. Bioactive nutritional components of an epigenetic diet may be incorporated into one's regular dietary regimen and used therapeutically for medicinal or chemopreventive purposes. This article will primarily focus on dietary factors that have been demonstrated to influence the epigenome and that may be used in conjunction with other cancer prevention and chemotherapeutic therapies.

Urokinase-type plasminogen activator receptor (uPAR)-mediated regulation of WNT/β-catenin signaling is enhanced in irradiated medulloblastoma cells

Urokinase plasminogen activator receptor (uPAR) is known to promote invasion, migration, and metastasis in cancer cells. In this report, we showed that ionizing radiation (IR)-induced uPAR has a role in WNT-β-catenin signaling and mediates induction of cancer stem cell (CSC)-like properties in medulloblastoma cell lines UW228 and D283. We observed that IR induced the expression of uPAR and CSC markers, such as Musashi-1 and CD44, and activated WNT-7a-β-catenin signaling molecules. Overexpression of uPAR alone or with IR treatment led to increased WNT-7a-β-catenin-TCF/LEF-mediated transactivation, thereby promoting cancer stemness. In contrast, treatment with shRNA specific for uPAR (pU) suppressed WNT-7a-β-catenin-TCF/LEF-mediated transactivation both in vitro and in vivo. Quercetin, a potent WNT/β-catenin inhibitor, suppressed uPAR and uPAR-mediated WNT/β-catenin activation, and furthermore, addition of recombinant human WNT-7a protein induced uPAR, indicating the existence of a mutual regulatory relationship between uPAR and WNT/β-catenin signaling. We showed that uPAR was physically associated with the WNT effector molecule β-catenin on the membrane, cytoplasm, and nucleus of IR-treated cells and CSC. Most interestingly, we demonstrated for the first time that localization of uPAR in the nucleus was associated with transcription factors (TF) and their specific response elements. We observed from uPAR-ChIP, TF protein, and protein/DNA array analyses that uPAR associates with activating enhancer-binding protein 2α (AP2a) and mediates β-catenin gene transcription. Moreover, association of uPAR with the β-catenin·TCF/LEF complex and various other TF involved during embryonic development and cancer indicates that uPAR is a potent activator of stemness, and targeting of uPAR in combination with radiation has significant therapeutic implications.

Regulation of DNA repair mechanism in human glioma xenograft cells both in vitro and in vivo in nude mice

BACKGROUND

Glioblastoma Multiforme (GBM) is the most lethal form of brain tumor. Efficient DNA repair and anti-apoptotic mechanisms are making glioma treatment difficult. Proteases such as MMP9, cathepsin B and urokinase plasminogen activator receptor (uPAR) are over expressed in gliomas and contribute to enhanced cancer cell proliferation. Non-homologous end joining (NHEJ) repair mechanism plays a major role in double strand break (DSB) repair in mammalian cells.

METHODOLOGY/PRINCIPAL FINDINGS

Here we show that silencing MMP9 in combination with uPAR/cathepsin B effects NHEJ repair machinery. Expression of DNA PKcs and Ku70/80 at both mRNA and protein levels in MMP9-uPAR (pMU) and MMP9-cathepsin B (pMC) shRNA-treated glioma xenograft cells were reduced. FACS analysis showed an increase in apoptotic peak and proliferation assays revealed a significant reduction in the cell population in pMU- and pMC-treated cells compared to untreated cells. We hypothesized that reduced NHEJ repair led to DSBs accumulation in pMU- and pMC-treated cells, thereby initiating cell death. This hypothesis was confirmed by reduced Ku70/Ku80 protein binding to DSB, increased comet tail length and elevated γH2AX expression in treated cells compared to control. Immunoprecipitation analysis showed that EGFR-mediated lowered DNA PK activity in treated cells compared to controls. Treatment with pMU and pMC shRNA reduced the expression of DNA PKcs and ATM, and elevated γH2AX levels in xenograft implanted nude mice. Glioma cells exposed to hypoxia and irradiation showed DSB accumulation and apoptosis after pMU and pMC treatments compared to respective controls.

CONCLUSION/SIGNIFICANCE

Our results suggest that pMU and pMC shRNA reduce glioma proliferation by DSB accumulation and increase apoptosis under normoxia, hypoxia and in combination with irradiation. Considering the radio- and chemo-resistant cancers favored by hypoxia, our study provides important therapeutic potential of MMP9, uPAR and cathepsin B shRNA in the treatment of glioma from clinical stand point.

Integrin α9β1-mediated cell migration in glioblastoma via SSAT and Kir4.2 potassium channel pathway

The α9β1 integrin accelerates cell migration through binding of the α9 cytoplasmic domain to SSAT, which catalyzes the catabolism of higher order polyamines, spermidine and spermine, to the lower order polyamine, putrescine. SSAT levels were downregulated at both the mRNA and protein levels by shRNA-mediated simultaneous knockdown of MMP-9 and uPAR/cathepsin B. In addition, we noted a prominent reduction in the expression of SSAT with MMP-9 and uPAR/cathepsin B knockdown in the tumor regions of 5310 injected nude mice brains. Further, SSAT knockdown in glioma xenograft cells significantly reduced their migration potential. Interestingly, MMP-9, uPAR and cathepsin B overexpression in these xenograft cells significantly elevated SSAT mRNA and protein levels. The migratory potential of MMP-9/uPAR/cathepsin B-overexpressed 4910 and 5310 cells was not affected by either glybenclamide (Kir 6.x inhibitor) or tertiapin-Q (Kir 1.1 and 3.x inhibitor) but instead was significantly inhibited by either barium or Kir4.2 siRNA treatments. Co-localization of α9 integrin with Kir4.2 was observed in both 4910 and 5310 xenograft cells. However, MMP-9 and uPAR/cathepsin B knockdown in these cells prominently reduced the co-localization of α9 with Kir4.2. Taken together, our results clearly demonstrate that α9β1 integrin-mediated cell migration utilizes SSAT and the Kir4.2 potassium channel pathway, and inhibition of the migratory potential of these glioma xenograft cells by simultaneous knockdown of MMP-9 and uPAR/cathepsin B could be attributed to the reduced SSAT levels and co-localization of α9 integrin with Kir4.2 inward rectifier potassium channels.

Gadd45a sensitizes medulloblastoma cells to irradiation and suppresses MMP-9-mediated EMT

Medulloblastomas are the most common malignant tumors of the central nervous system during childhood. Radiation-induced medulloblastoma tumor recurrences are aggressive and metastatic in nature. In the present study, we demonstrate that Gadd45a expression can sensitize medulloblastoma cells to radiotherapy. We have elucidated the role of Gadd45a in ionizing radiation (IR)-induced G2-M arrest and invasion and metastatic potential of the medulloblastoma cancer cell lines DAOY and D283. We demonstrate that Gadd45a is induced by IR and results in p53 phosphorylation. The role of IR-induced Gadd45a in G2-M arrest is demonstrated by fluorescence-activated cell sorting analysis in the cells treated with siRNA Gadd45a and Ov-exp Gadd45a. We show that Ov-exp Gadd45a aggravates G2-M blockage and also increases binding of Gadd45a to Cdc2 by immunocytochemistry analysis. Furthermore, we show the anti-tumorigenic role of Gadd45a to be mediated by the negative regulation of IR-induced cancer cell invasion and migration-associated proteins, such as matrix metallopeptidase (MMP)-9 and β-catenin. When compared with IR treatment alone, Ov-exp Gadd45a plus IR treatment resulted in decreased nuclear localization and increased membrane localization of β-catenin, and this was further confirmed by membrane distribution. We also show that Ov-exp Gadd45a resulted in downregulation of MMP-9 and suppression of epithelial-mesenchymal transition (EMT). Alternatively, inhibition of MMP-9 (pM) resulted in upregulation of Gadd45a and suppression of EMT. The anti-tumor effect of pM was correlated with increased expression of Gadd45a protein in nude mice intracranial tumors. Taken together, our studies demonstrate that upregulation of Gadd45a or suppression of MMP-9 (pM) with IR retards medulloblastoma tumor metastatic potential.

Overexpression of osteopontin in hepatocellular carcinoma and its relationships with metastasis, invasion of tumor cells

Osteopontin (OPN) plays an important role in metastasis and relapse of human cancer. However, the whole story of OPN relating to cancer has been far from clear untill now. To investigate the expression of OPN in hepatocellular carcinoma (HCC) and its relationships with recurrence and metastasis of HCC, normal and malignant liver tissues from patients with HCC were analyzed using immunohistochemical staining. OPN expression was inhibited by small interfering RNA (siRNA) in HCC cells lines, and then colony formation and matrigel invasion were examined. The results showed that expression of OPN was associated with metastasis of HCC with a positive rate of OPN in the tissue of HCC (70.00%), which was highly more obvious than those in paracarcinoma tissue and normal liver tissue (P < 0.01). In HCC cell lines, OPN depletion could reduce formed colony and metastasizing numbers in vitro. In conclusion, Expression of OPN in the tissue of HCC is related to metastasis or metastases. Specific siRNA could decrease expressions of OPN at both mRNA and protein levels, and abates the invasiveness of hepatocellular carcinoma cells, suggesting that OPN might be a promising agent for treatment of metastasis and recurrence of HCC.

siRNA-mediated downregulation of MMP-9 and uPAR in combination with radiation induces G2/M cell-cycle arrest in Medulloblastoma

Our previous work and that of other investigators strongly suggest a relationship between the upregulation of metalloproteinase-9 (MMP-9) and urokinase-type plasminogen activator receptor (uPAR) in tumor angiogenesis and metastasis. In this study, we evaluated the role of MMP-9 and uPAR in medulloblastoma cancer cell resistance to ionizing irradiation (IR) and tested the antitumor efficacy of siRNA (short interfering RNA) against MMP-9 [plasmid siRNA vector for MMP-9 (pM)] and uPAR [plasmid vector for uPAR (pU)] either alone or in combination [plasmid siRNA vector for both uPAR and MMP-9 (pUM)]. Cell proliferation (BrdU assay), apoptosis (in situ TUNEL for DNA fragmentation), and cell-cycle (FACS) analyses were carried out to determine the effect of siRNA either alone or in combination with IR on G2/M cell-cycle arrest in medulloblastoma cells. IR upregulated MMP-9 and uPAR expression in medulloblastoma cells; pM, pU, and pUM in combination with IR effectively reduced both MMP-9 and uPAR expression, thereby leading to increased radiosensitivity of medulloblastoma cells. siRNA treatments (pM, pU, and pUM) also promoted IR-induced apoptosis and enhanced IR-induced G2/M arrest during cell-cycle progression. While IR induces G2/M cell-cycle arrest through inhibition of the pCdc2- and cyclin B-regulated signaling pathways involving p53, p21/WAF1, and Chk2 gene expression, siRNA (pM, pU, and pUM) alone or in combination with IR induced G2/M arrest mediated through inhibition of the pCdc2- and cyclin B1-regulated signaling pathways involving Chk1 and Cdc25A gene expression. Taken together, our data suggest that downregulation of MMP-9 and uPAR induces Chk1-mediated G2/M cell-cycle arrest, whereas the disruption caused by IR alone is dependent on p53- and Chk2-mediated G2/M cell-cycle arrest.

Suppression of uPAR retards radiation-induced invasion and migration mediated by integrin β1/FAK signaling in medulloblastoma

BACKGROUND

Despite effective radiotherapy for the initial stages of cancer, several studies have reported the recurrence of various cancers, including medulloblastoma. Here, we attempt to capitalize on the radiation-induced aggressive behavior of medulloblastoma cells by comparing the extracellular protease activity and the expression pattern of molecules, known to be involved in cell adhesion, migration and invasion, between non-irradiated and irradiated cells.

METHODOLOGY/PRINCIPAL FINDINGS

We identified an increase in invasion and migration of irradiated compared to non-irradiated medulloblastoma cells. RT-PCR analysis confirmed increased expression of uPA, uPAR, focal adhesion kinase (FAK), N-Cadherin and integrin subunits (e.g., α3, α5 and β1) in irradiated cells. Furthermore, we noticed a ∼2-fold increase in tyrosine phosphorylation of FAK in irradiated cells. Immunoprecipitation studies confirmed increased interaction of integrin β1 and FAK in irradiated cells. In addition, our results show that overexpression of uPAR in cancer cells can mimic radiation-induced activation of FAK signaling. Moreover, by inhibiting FAK phosphorylation, we were able to reduce the radiation-induced invasiveness of the cancer cells. In this vein, we studied the effect of siRNA-mediated knockdown of uPAR on cell migration and adhesion in irradiated and non-irradiated medulloblastoma cells. Downregulation of uPAR reduced the radiation-induced adhesion, migration and invasion of the irradiated cells, primarily by inhibiting phosphorylation of FAK, Paxillin and Rac-1/Cdc42. As observed from the immunoprecipitation studies, uPAR knockdown reduced interaction among the focal adhesion molecules, such as FAK, Paxillin and p130Cas, which are known to play key roles in cancer metastasis. Pretreatment with uPAR shRNA expressing construct reduced uPAR and phospho FAK expression levels in pre-established medulloblastoma in nude mice.

CONCLUSION/SIGNIFICANCE

Taken together, our results show that radiation enhances uPAR-mediated FAK signaling and by targeting uPAR we can inhibit radiation-activated cell adhesion and migration both in vitro and in vivo.

Downregulation of uPARAP mediates cytoskeletal rearrangements and decreases invasion and migration properties in glioma cells

To identify molecular therapeutic targets for glioma, we performed gene expression profiling by using a complementary DNA (cDNA) microarray method and identified the urokinase plasminogen activator receptor-associated protein (uPARAP/Endo180) as a gene expressed highly in glioma tissue compared with the normal brain tissue. The uPARAP is an endocytic receptor for collagen. In certain cell types, uPARAP occurs in a complex with the urokinase plasminogen activator receptor (uPAR) where it fulfills other functions in addition to collagenolysis. Quantitative PCR analysis using a cDNA panel revealed higher expression levels of uPARAP in glioma tissue compared with normal brain tissue. Western blot analysis revealed that the uPARAP protein was expressed in glioma samples and two glioma cell lines, KNS42 and KNS81, but not expressed in control tissue from the normal brain. Introduction of small interfering RNA-targeted uPARAP into the two different glioma cell lines, KNS42 and KNS81, resulted in downregulation of uPARAP expression, and it significantly suppressed glioma cell migration and invasion in vitro. Control glioma cells showed small cell bodies, whereas uPARAP siRNA-treated glioma cells exhibited large and flat morphology. Most of the polymeric actin in the control glioma cells was concentrated in the lamellipodia that are observed in mobile cells. In contrast, in the uPARAP siRNA-treated glioma cells, polymeric actin became organized in stress fibers and the lamellipodia disappeared, characteristic of immobile cells. Our present study suggests that uPARAP may be involved in glioma cell invasiveness through actin cytoskeletal rearrangement. downregulation of uPARAP may be a novel anti-invasion therapeutic strategy for malignant gliomas.

Urokinase plasminogen activator receptor and/or matrix metalloproteinase-9 inhibition induces apoptosis signaling through lipid rafts in glioblastoma xenograft cells

Small interfering RNA (siRNA)-mediated transcriptional knockdown of urokinase plasminogen activator receptor (uPAR) and matrix metalloproteinase-9 (MMP-9), alone or in combination, inhibits uPAR and/or MMP-9 expression and induces apoptosis in the human glioblastoma xenograft cell lines 4910 and 5310. siRNA against uPAR (pU-Si), MMP-9 (pM-Si), or both (pUM-Si) induced apoptosis and was associated with the cleavage of caspase-8, caspase-3, and poly(ADP-ribose) polymerase. Furthermore, protein levels of the Fas receptor (APO-1/CD-95) were increased following transcriptional inactivation of uPAR and/or MMP-9. In addition, Fas siRNA against the Fas death receptor blocked apoptosis induced by pU-Si, pM-Si, or pUM-Si, thereby indicating the role for Fas signaling in pU-Si-, pM-Si-, or pUM-Si-mediated apoptotic cell death of human glioma xenograft cells. Thus, transcriptional inactivation of uPAR and/or MMP-9 enhanced localization of Fas death receptor, Fas-associated death domain-containing protein, and procaspase-8 into lipid rafts. Additionally, disruption of lipid rafts with methyl β cyclodextrin prevented Fas clustering and pU-Si-, pM-Si-, or pUM-Si-induced apoptosis, which is indicative of coclustering of Fas death receptor into lipid rafts in the glioblastoma xenograft cell lines 4910 and 5310. These data indicate the crucial role of the clusters of apoptotic signaling molecule-enriched rafts in programmed cell death, acting as concentrators of death receptors and downstream signaling molecules, and as the linchpin from which a potent death signal is launched in uPAR- and/or MMP-9-downregulated cells.

MMP-9, uPAR and cathepsin B silencing downregulate integrins in human glioma xenograft cells in vitro and in vivo in nude mice

BACKGROUND

Involvement of MMP-9, uPAR and cathepsin B in adhesion, migration, invasion, proliferation, metastasis and tumor growth has been well established. In the present study, MMP-9, uPAR and cathepsin B genes were downregulated in glioma xenograft cells using shRNA plasmid constructs and we evaluated the involvement of integrins and changes in their adhesion, migration and invasive potential.

METHODOLOGY/PRINCIPAL FINDINGS

MMP-9, uPAR and cathepsin B single shRNA plasmid constructs were used to downregulate these molecules in xenograft cells. We also used MMP-9/uPAR and MMP-9/cathepsin B bicistronic constructs to evaluate the cumulative effects. MMP-9, uPAR and cathepsin B downregulation significantly inhibits xenograft cell adhesion to several extracellular matrix proteins. Treatment with MMP-9, uPAR and cathepsin B shRNA of xenografts led to the downregulation of several alpha and beta integrins. In all the assays, we noticed more prominent effects with the bicistronic plasmid constructs when compared to the single plasmid shRNA constructs. FACS analysis demonstrated the expression of alphaVbeta3, alpha6beta1 and alpha9beta1 integrins in xenograft cells. Treatment with bicistronic constructs reduced alphaVbeta3, alpha6beta1 and alpha9beta1 integrin expressions in xenograft injected nude mice. Migration and invasion were also inhibited by MMP-9, uPAR and cathepsin B shRNA treatments as assessed by spheroid migration, wound healing, and Matrigel invasion assays. As expected, bicistronic constructs further inhibited the adhesion, migration and invasive potential of the xenograft cells as compared to individual treatments.

CONCLUSIONS/SIGNIFICANCE

Downregulation of MMP-9, uPAR and cathespin B alone and in combination inhibits adhesion, migration and invasive potential of glioma xenografts by downregulating integrins and associated signaling molecules. Considering the existence of integrin inhibitor-resistant cancer cells, our study provides a novel and effective approach to inhibiting integrins by downregulating MMP-9, uPAR and cathepsin B in the treatment of glioma.

An extensive invasive intracranial human glioblastoma xenograft model: role of high level matrix metalloproteinase 9

The lack of an intracranial human glioma model that recapitulates the extensive invasive and hypervascular features of glioblastoma (GBM) is a major hurdle for testing novel therapeutic approaches against GBM and studying the mechanism of GBM invasive growth. We characterized a high matrix metalloproteinase-9 (MMP-9) expressing U1242 MG intracranial xenograft mouse model that exhibited extensive individual cells and cell clusters in a perivascular and subpial cellular infiltrative pattern, geographic necrosis and infiltrating tumor-induced vascular proliferation closely resembling the human GBM phenotype. MMP-9 silencing cells with short hairpin RNA dramatically blocked the cellular infiltrative pattern, hypervascularity, and cell proliferation in vivo, and decreased cell invasion, colony formation, and cell motility in vitro, indicating that a high level of MMP-9 plays an essential role in extensive infiltration and hypervascularity in the xenograft model. Moreover, epidermal growth factor (EGF) failed to stimulate MMP-9 expression, cell invasion, and colony formation in MMP-9-silenced clones. An EGF receptor (EGFR) kinase inhibitor, a RasN17 dominant-negative construct, MEK and PI3K inhibitors significantly blocked EGF/EGFR-stimulated MMP-9, cell invasion, and colony formation in U1242 MG cells, suggesting that MMP-9 is involved in EGFR/Ras/MEK and PI3K/AKT signaling pathway-mediated cell invasion and anchorage-independent growth in U1242 MG cells. Our data indicate that the U1242 MG xenograft model is valuable for studying GBM extensive invasion and angiogenesis as well as testing anti-invasive and anti-angiogenic therapeutic approaches.

Progress on antiangiogenic therapy for patients with malignant glioma

Glioblastoma (GBM) is the most common primary brain tumor occurring in America. Despite recent advances in therapeutics, the prognosis for patients with newly diagnosed GBM remains dismal. As these tumors characteristically show evidence of angiogenesis (neovascularization) there has been great interest in developing anti-angiogenic therapeutic strategies for the treatment of patients with this disease and some anti-angiogenic agents have now been used for the treatment of patients with malignant glioma tumors. Although the results of these clinical trials are promising in that they indicate an initial therapeutic response, the anti-angiogenic therapies tested to date have not changed the overall survival of patients with malignant glioma tumors. This is due, in large part, to the development of resistance to these therapies. Ongoing research into key features of the neovasculature in malignant glioma tumors, as well as the general angiogenesis process, is suggesting additional molecules that may be targeted and an improved response when both the neovasculature and the tumor cells are targeted. Prevention of the development of resistance may require the development of anti-angiogenic strategies that induce apoptosis or cell death of the neovasculature, as well as an improved understanding of the potential roles of circulating endothelial progenitor cells and vascular co-option by tumor cells, in the development of resistance.

The pathobiology of glioma tumors

The ongoing characterization of the genetic and epigenetic alterations in the gliomas has already improved the classification of these heterogeneous tumors and enabled the development of rodent models for analysis of the molecular pathways underlying their proliferative and invasive behavior. Effective application of the targeted therapies that are now in development will depend on pathologists' ability to provide accurate information regarding the genetic alterations and the expression of key receptors and ligands in the tumors. Here we review the mechanisms that have been implicated in the pathogenesis of the gliomas and provide examples of the cooperative nature of the pathways involved, which may influence the initial therapeutic response and the potential for development of resistance.

Inhibition of MMP-9 transcription and suppression of tumor metastasis by pyrrole-imidazole polyamide

Matrix metalloproteinase (MMP)-9, the 92-kDa type IV collagenase, contributes to tumor invasion and metastases, and strategies to down-regulate its expression could ultimately be of clinical utility. A pyrrole-imidazole (PI) polyamide that targets the activator protein-1 (AP-1)-binding site of the MMP-9 promoter was designed and synthesized as a gene-silencing agent for tumor metastases. The synthesized product showed selective DNA binding ability. The MMP-9 PI polyamide significantly inhibited MMP-9's mRNA expression, protein level, and enzymatic activity in human breast adenocarcinoma cells (MDA-MB-231). Furthermore, the MMP-9 PI polyamide inhibited migration and invasion by in vitro wound-healing and matrigel-invasion assay. The FITC-labeled PI polyamide was localized in nuclei in 45 min of incubation with an MDA-MB-231 cell and remained in the nuclei for up to 96 h after incubation in vitro. It was also quickly localized in the mouse cellular nuclei of many tissues, including liver, kidney, and spleen, after intravenous injection without using any drug-delivery system. Moreover, the polyamide treatment significantly decreased metastasis in a mouse model of liver metastasis. Our results suggest that this PI polyamide, which targets the MMP-9 gene promoter, can be a novel MMP-9 down-regulating molecule for antimetastasis.

The role of MMP-9 in the anti-angiogenic effect of secreted protein acidic and rich in cysteine

Background:

Secreted protein acidic and rich in cysteine (SPARC), a matricellular glycoprotein, modulates cellular interaction with the extracellular matrix and is capable of altering the growth of various cancers. We therefore sought to determine the effect of SPARC expression on medulloblastoma tumour growth and angiogenesis.

Methods:

To this extent, we selected three SPARC full-length cDNA overexpressed clones (Daoy-SP). Consequences of SPARC overexpression were studied in terms of cell growth, angiogenesis using co-culture assay in vitro, dorsal skin-fold chamber assay in vivo, PCR Array for human angiogenic genes, as well as western blotting for angiogenic molecules and tumour growth, in an orthotopic tumour model.

Results:

The SPARC protein and mRNA levels were increased by approximately three-fold in Daoy-SP cells compared with parental (Daoy-P) and vector (Daoy-EV) controls. Daoy-SP clones reduced tumour cell-induced angiogenesis in vitro and in vivo, and formed small tumours with fewer blood vessels when compared with controls. Matrix metalloprotease-9 (MMP-9) and vascular endothelial growth factor (VEGF) expression were decreased in Daoy-SP clones. Further, inhibition of MMP-9 expression caused SPARC-mediated inhibition of angiogenesis and tumour growth as MMP-9 rescued SPARC-mediated anti-angiogenic effect in vitro and tumour growth inhibition in vivo.

Conclusion:

Overexpression of SPARC decreases angiogenesis, which leads to decreased tumour growth. Further, the role of MMP-9 could be attributed to the anti-angiogenic effect of SPARC.

Recent advances in the manipulation of murine gene expression and its utility for the study of human neurological disease

Transgenic mouse models have vastly contributed to our knowledge of the genetic and molecular pathways underlying the pathogenesis of neurological disorders that affect millions of people worldwide. Not only have they allowed the generation of disease models mimicking the human pathological state but they have also permitted the exploration of the pathological role of specific genes through the generation of knock-out and knock-in models. Classical constitutive transgenic mice have several limitations however, due to behavioral adaptation process occurring and conditional mouse models are time-consuming and often lack extensive spatial or temporal control of gene manipulation. These limitations could be overcome by means of innovative methods that are now available such as RNAi, viral vectors and large cloning DNA vectors. These tools have been extensively used for the generation of mouse models and are characterized by the superior control of transgene expression that has been proven invaluable in the assessment of novel treatments for neurological diseases and to further investigate the molecular processes underlying the etiopathology of neurological disorders. Furthermore, in association with classical transgenic mouse models, they have allowed the validation of innovative therapeutic strategies for the treatment of human neurological disorders. This review describes how these tools have overcome the limitations of classical transgenic mouse models and how they have been of value for the study of human neurological diseases.

Leveraging therapeutic potential of multi-targeted siRNA inhibitors

While the discovery of RNA interference (RNAi) has been considered one of the most significant breakthroughs in biomedicine, its prospects for novel therapeutic applications are even more exciting. The high specificity, exquisite selectivity and chemical homogeneity of small interfering RNAs (siRNA; intermediates in RNAi activity), provide unique advantages for these moieties as multi-targeted inhibitory drugs. Many such applications have demonstrated significant benefit compared with single gene-targeted siRNA inhibitors. In this article, we will review the current status of using a multi-targeted siRNA cocktail for novel therapeutic development in the treatment of cancer and viral infections. We will also propose the characteristics of various types of siRNA cocktails and their design, while recognizing the potential future impact of and challenges facing this unique therapeutic modality.

A suppressor of multiple extracellular matrix-degrading proteases and cancer metastasis

Cancer metastasis remains the most poorly understood process in cancer biology. It involves the degradation of extracellular matrix (ECM) proteins by a series of ‘tumour-associated’ proteases. Here we report the identification of a novel protease suppressor, NYD-SP8, which is located on human chromosome 19q13.2. NYD-SP8 encodes a 27 kD GPI-anchored cell surface protein, which shows structural homology to urokinase plasminogen activator receptor (uPAR). Co-immunoprecipitation experiments showed that NYD-SP8 binds to uPA/uPAR complexes and interfere with active uPA production. Overexpression of NYD-SP8 results in reducing activities of the three major classes of proteases known to be involved in ECM degradation, including uPA, matrix metalloproteinases (MMPs) and cathepsin B, leading to suppression of both in vitro and in vivo cancer cell invasion and metastasis. These data demonstrate an important role of NYD-SP8 in regulating ECM degradation, providing a novel mechanism that modulates urokinase signalling in the suppression of cancer progression.

Urokinase plasminogen activator system as a potential target for cancer therapy

Proteolysis of extracellular matrix (ECM) and basement membrane is an essential mechanism used by cancer cells for their invasion and metastasis. The ECM proteinases are divided into three groups: metalloproteinases, cysteine proteinases and serine proteinases. The urokinase plasminogen activator (uPA) system is one of the serine proteinase systems involved in ECM degradation. Members of this system, including uPA and its receptor (uPAR), are overexpressed in several malignant tumors. This system plays a major role in adhesion, migration, invasion and metastasis of cancer cells, thus making it an important target for anticancer drug therapy. Several strategies, including the use of antisense oligodeoxynucleotides, ribozymes, DNAzyme, RNAi, uPA inhibitors, soluble uPAR, catalytically inactive uPA fragments, synthetic peptides and synthetic hybrids are under study, as they interfere with the expression and/or activity of uPA or uPAR in tumor cells. Herein, we discuss the various pharmaceutical strategies under investigation to combat the uPA activity in cancer.

Pleiotropic roles of matrix metalloproteinases in tumor angiogenesis: contrasting, overlapping and compensatory functions

A number of extensive reviews are available discussing the roles of MMPs in various aspects of cancer progression from benign tumor formation to overt cancer present with deadly metastases. This review will focus specifically on the evidence functionally linking the MMPs and tumor-induced angiogenesis in various in vivo models. Emphasis has been placed on the cellular origin of the MMPs in tumor tissue, the requirement of proMMP activation and the resulting proteolytic activity for the induction and progression of tumor angiogenesis, and the pleiotropic roles for some of the MMPs. The functional mechanisms of the angiogenic MMPs are discussed as well as their catalytic detection in complex biological systems. In addition, the contribution of active MMPs to metastatic spread and establishment of secondary metastasis will be discussed in view of the findings indicating that MMPs are involved in the preparation of pre-metastatic niches. Finally, the most recent evidence, indicating the pro-metastatic consequences of anti-angiogenic therapies employing MMP inhibitors will be presented as examples highlighting possible outcomes of interfering with the pleiotropic nature of the MMP functionality.

Suppression of matrix metalloproteinase-9 expression by RNA interference inhibits SGC7901 gastric adenocarcinoma cell growth and invasion in vitro and in vivo

Matrix metalloproteinase-9 (MMP-9) is considered the key enzyme that degrades extracellular matrix (ECM) via breaking down type IV collagens. Up-regulated MMP-9 promotes growth and invasion of gastric adenocarcinomas. The present study is to block MMP-9 expression in gastric adenocarcinoma cells in order to inhibit tumor growth and invasion. The association between MMP-9 expression and tumor pathology was reconfirmed by applying immunohistochemistry on tissue arrays. Small interference RNAs (siRNA) targeted on human MMP-9 were used to suppress gene expression in SGC7901 human gastric adenocarcinoma cells. Cell growth and invasion were significantly inhibited in specific siRNA-targeted cells. In addition, we generate a SGC7901-subcutaneous mice model to observe anti-tumor effects from RNA interference (RNAi). Data showed tumor masses in MMP-9 siRNA-treated mice were significantly smaller than those in control mice. The expression of vascular endothelial growth factor and proliferating cell nuclear antigen were down-regulated in MMP-9 siRNA treated cells. Our results demonstrate that MMP-9 targeted RNAi is able to successfully suppress MMP-9 gene expression and inhibit cell growth and invasion of SGC7901 gastric adenocarcinoma in vitro and in vivo. MMP-9 is a potential therapeutic target for gastric adenocarcinomas.

Small interfering RNA-directed targeting of Toll-like receptor 4 inhibits human prostate cancer cell invasion, survival, and tumorigenicity

A major cause of tumor treatment failure is cancer cell metastasis. Toll-like receptor 4 (TLR4)-mediated signaling has been implicated in tumor cell invasion, survival, and metastasis in a variety of cancers. In this study, we investigated the biological roles of TLR4 in prostate metastatic cell invasion and survival, and the potential of gene silencing of TLR4 using small interfering RNA (siRNA) for treatment of cancer. In cultured human prostate cancer cell lines, TLR4 were higher PC3 and DU145 as compared with the poorly metastatic LNCaP indicating that up-regulation of TLR4 was positively correlated with metastasis of tumor cell. In the highly metastatic cancer cell PC3, gene silencing of TLR4 using siRNA significantly inhibited TLR4 mRNA expression and protein level. Knockdown of TLR4 in PC3 cells resulted in a dramatic reduction of tumor cell migration and invasion as indicated by a Matrigel invasion assay. Furthermore, TLR4 siRNA suppressed cell viability and ultimately caused the induction of apoptotic cell death. The effects were associated with abrogating TLR4-mediated signaling to downstream target molecules such as myeloid differentiation factor 88 (MyD88), adaptor-inducing IFN-beta (TRIF), and interferon regulatory factor-1 (IRF-1). In a mouse prostate cancer model, administration with the plasmid construct expressing siRNA for TLR4 obviously inhibited established tumor growth and survival. These studies revealed evidence of a multifaceted signaling network operating downstream of TLR4-mediated tumor cell invasion, proliferation, and survival. Thus, RNA interference-directed targeting of TLR4 may raise the potential of its application for cancer therapy.