AdTIMP-2 inhibits tumor growth, angiogenesis, and metastasis, and prolongs survival in mice

Matrix metalloproteinases as therapeutic targets in breast cancer

Matrix metalloproteinases (MMPs) are the most prominent proteinases involved in tumorigenesis. They were initially recognized to promote tumor progression by remodeling the extracellular matrix through their proteolytic activity. However, accumulating evidence has revealed that some MMPs have protective roles in cancer progression, and the same MMP can exert opposing roles depending on the cell type in which it is expressed or the stage of cancer. Moreover, studies have shown that MMPs are involved in cancer progression through their roles in other biological processes such as cell signaling and immune regulation, independent of their catalytic activity. Despite the prognostic significance of tumoral or stromal expression of MMPs in breast cancer, their roles and molecular mechanisms in breast cancer progression remain unclear. As the failures of early clinical trials with broad-spectrum MMP inhibitors were mainly due to a lack of drug specificity, substantial efforts have been made to develop highly selective MMP inhibitors. Some recently developed MMP inhibitory monoclonal antibodies demonstrated promising anti-tumor effects in preclinical models of breast cancer. Importantly, anti-tumor effects of these antibodies were associated with the modulation of tumor immune microenvironment, suggesting that the use of MMP inhibitors in combination with immunotherapy can improve the efficacy of immunotherapy in HER2-positive or triple-negative breast cancer. In this review, the current understanding of the roles of tumoral or stromal MMPs in breast cancer is summarized, and recent advances in the development of highly selective MMP inhibitors are discussed.

Nanodrug Delivery Systems Modulate Tumor Vessels to Increase the Enhanced Permeability and Retention Effect

The use of nanomedicine for antitumor therapy has been extensively investigated for a long time. Enhanced permeability and retention (EPR) effect-mediated drug delivery is currently regarded as an effective way to bring drugs to tumors, especially macromolecular drugs and drug-loaded pharmaceutical nanocarriers. However, a disordered vessel network, and occluded or embolized tumor blood vessels seriously limit the EPR effect. To augment the EPR effect and improve curative effects, in this review, we focused on the perspective of tumor blood vessels, and analyzed the relationship among abnormal angiogenesis, abnormal vascular structure, irregular blood flow, extensive permeability of tumor vessels, and the EPR effect. In this commentary, nanoparticles including liposomes, micelles, and polymers extravasate through the tumor vasculature, which are based on modulating tumor vessels, to increase the EPR effect, thereby increasing their therapeutic effect.

p21-activated protein kinase 1 induces the invasion of gastric cancer cells through c-Jun NH2-terminal kinase-mediated activation of matrix metalloproteinase-2

Gastric cancer (GC) is one of the most common malignancies worldwide. The prognosis of GC is poor, mostly due to widespread metastasis. p21-activated kinase 1 (Pak1), the best characterized member of an evolutionarily conserved family of serine/threonine kinases, plays an important role in the regulation of cell morphogenesis, motility, mitosis and angiogenesis. By qRT-PCR and Gelatin zymograph assay, we demonstrated in the present study that stable overexpression of Pak1 induced matrix metalloproteinase (MMP)-2 mRNA expression and activity in the human MKN45 GC cell line. Conversely, knockdown of endogenous Pak1 expression by small interfering RNA (siRNA) decreased MMP-2 mRNA expression and activity in the MKN45 GC cells. Activation of c-Jun N-terminal kinase (JNK) was required for Pak1-induced upregulation of MMP-2 mRNA level and activity. Moreover, upregulation of MMP-2 by Pak1 via the JNK pathway notably promoted the invasion of MKN45 GC cells. Overexpression of MMP-2 mRNA was once again confirmed to be associated with GC metastasis. In conclusion, our results demonstrated for the first time that Pak1 stimulated MMP-2 mRNA expression and activity in MKN45 GC cells. The JNK signaling pathway was involved in Pak1 modulation of MMP-2, which was important for MKN45 GC cell invasiveness.

Promotion of astrocytoma cell invasion by micro RNA–22 targeting of tissue inhibitor of matrix metalloproteinase–2

OBJECTIVE

Diffuse astrocytomas (DAs) have a high recurrence rate due to diffuse infiltration into the brain and spinal cord. Micro RNAs (miRNAs) are small noncoding RNAs that regulate gene expression by binding to complementary sequences of target messenger RNA (mRNA). It has been reported that miRNA-22 (miR-22) is involved in the invasion of some cancer cell lines. The aim of this study was to identify the biological effects of miR-22 in regard to the invasion of human DAs.

METHODS

The authors evaluated whether the level of miR-22 is elevated in human spinal DAs by using miRNA chips. Next, the role of miR-22 in 1321N1 human astrocytoma cells was investigated. Finally, to elucidate whether miR-22 promotes invasion by astrocytoma cells in vivo, the authors transplanted miR-22 overexpressed astrocytoma cells into mouse thoracic spinal cord.

RESULTS

The miR-22 significantly upregulated the invasion capacity of 1321N1 cells. Computational in silico analysis predicted that tissue inhibitor of matrix metalloproteinase–2 (TIMP2) is a target gene of miR-22. This was confirmed by quantitative reverse transcription polymerase chain reaction and Western blotting, which showed that miR-22 inhibited TIMP2 mRNA and protein expression, respectively. Luciferase reporter assays demonstrated that miR-22 directly bound the 3′-untranslated regions of TIMP2. The authors further showed that miR-22 promoted invasiveness in 1321N1 astrocytoma cells when transplanted into mouse spinal cord.

CONCLUSIONS

These data suggest that miR-22 acts to regulate invasion of 1321N1 astrocytoma cells by targeting TIMP2 expression. Additional studies with more cases and cell lines are required to elucidate the findings of this study for a novel treatment target for spinal DAs.

TIMPs: versatile extracellular regulators in cancer

A compelling long-term goal of cancer biology is to understand the crucial players during tumorigenesis in order to develop new interventions. Here, we review how the four non-redundant tissue inhibitors of metalloproteinases (TIMPs) regulate the pericellular proteolysis of a vast range of matrix and cell surface proteins, generating simultaneous effects on tumour architecture and cell signalling. Experimental studies demonstrate the contribution of TIMPs to the majority of cancer hallmarks, and human cancers invariably show TIMP deregulation in the tumour or stroma. Of the four TIMPs, TIMP1 overexpression or TIMP3 silencing is consistently associated with cancer progression or poor patient prognosis. Future efforts will align mouse model systems with changes in TIMPs in patients, will delineate protease-independent TIMP function, will pinpoint therapeutic targets within the TIMP-metalloproteinase-substrate network and will use TIMPs in liquid biopsy samples as biomarkers for cancer prognosis.

Tissue inhibitor of metalloproteinase 2 inhibits activation of the β-catenin signaling in melanoma cells

The tissue inhibitor of metalloproteinase (TIMP) family, including TIMP-2, regulates the activity of multifunctional metalloproteinases in pathogenesis of melanoma. The Wnt/β-catenin pathway is constitutively activated and plays a critical role in melanoma progression. However, the relationship between TIMP-2 expression and β-catenin activity is still unclear. We hypothesize that TIMP-2 over expression inhibits the activation of the Wnt/β-catenin pathway in melanoma cells. Protein expression, distribution, and transcriptional activity of β-catenin were assayed in established stable melanoma cell lines: parental A2058 expressing, A2058 T2-1 over-expressing (T2-1), and A2058 T2R-7 under-expressing (T2R-7) TIMP-2. Compared to T2-1 cells at the basal level, T2R-7 showed significantly lower amount protein and weaker immunofluorescence staining of β-catenin. This regulation is through posttranslational level via ubiquitination. Functionally, proliferation and cell growth were lower in T2R-7 compared to A2058 and T2-1. Lithium treatment was used to mimics activation of the Wnt/β-catenin pathway. In T2R-7 cells under-expressing TIMP2, lithium significantly increased total β-catenin, nuclear β-catenin, and its downstream protein phosphor-c-Myc (S62). Nuclear β-catenin staining was enhanced in T2R-7. Beta-catenin transcriptional activity and cell proliferation were also increased significantly. Axins inhibit β-catenin pathway via GSK-3 β. We further found the ratio of p-GSK-3 β (S9) to β-catenin and protein levels of Axins were significantly lower, whereas downstream Wnt 11 was high in T2R-7 treated with lithium. Collectively, the high level of TIMP-2 protein inhibits the activation of the Wnt/β-catenin pathway, thus suppressing proliferation. Insights in the molecular mechanisms of TIMP-2 may provide promising opportunities for anti-proliferative therapeutic intervention.

MicroRNA involvement in a metastatic non-functioning pituitary carcinoma

PURPOSE

Pituitary carcinomas are extremely rare neoplasms, and molecular events leading to malignant pituitary transformation are largely unknown. Enhanced understanding of molecular mechanisms driving malignant pituitary progression would be beneficial for pituitary carcinoma diagnosis and treatment.

METHODS

Differential microRNA expression in paired primary and metastatic pituitary carcinoma specimens were detected using high-throughput human microRNA microarrays and TaqMan microRNA arrays. Three of significantly deregulated miRNAs were further confirmed using quantitative real-time PCR in the metastatic carcinoma, six atypical pituitary adenomas and eight typical pituitary adenomas. Target genes of microRNAs were bioinformatically predicated and verified in vitro by Western blotting and real-time PCR and in vivo by immunohistochemistry respectively.

RESULTS

We present a case of a 50-year-old woman harboring non-functioning pituitary carcinoma with multiple intracranial metastases, and identified up-regulation of miR-20a, miR-106b and miR-17-5p in the metastatic carcinoma as compared to the primary neoplasm. Furthermore, miR-20a and miR-17-5p were increased in the metastatic carcinoma and six atypical pituitary adenomas as compared to eight typical pituitary adenomas as measured by quantitative real-time PCR. Both PTEN and TIMP2 were bioinformatically predicated and confirmed in vitro as target genes of these three microRNAs. As semi-quantified by immunohistochemistry, PTEN was absent and TIMP2 was decreased in the metastatic pituitary carcinoma as compared to pituitary adenomas.

CONCLUSIONS

Our results suggest microRNA involvement in malignant pituitary progression, whereby increased miR-20a, miR-106b and miR-17-5p promote metastasis by attenuating PTEN and TIMP2 in pituitary carcinoma.

CleavPredict: A Platform for Reasoning about Matrix Metalloproteinases Proteolytic Events

CleavPredict (http://cleavpredict.sanfordburnham.org) is a Web server for substrate cleavage prediction for matrix metalloproteinases (MMPs). It is intended as a computational platform aiding the scientific community in reasoning about proteolytic events. CleavPredict offers in silico prediction of cleavage sites specific for 11 human MMPs. The prediction method employs the MMP specific position weight matrices (PWMs) derived from statistical analysis of high-throughput phage display experimental results. To augment the substrate cleavage prediction process, CleavPredict provides information about the structural features of potential cleavage sites that influence proteolysis. These include: secondary structure, disordered regions, transmembrane domains, and solvent accessibility. The server also provides information about subcellular location, co-localization, and co-expression of proteinase and potential substrates, along with experimentally determined positions of single nucleotide polymorphism (SNP), and posttranslational modification (PTM) sites in substrates. All this information will provide the user with perspectives in reasoning about proteolytic events. CleavPredict is freely accessible, and there is no login required.

Rac1/Pak1/p38/MMP-2 Axis Regulates Angiogenesis in Ovarian Cancer

PURPOSE

Zoledronic acid is being increasingly recognized for its antitumor properties, but the underlying functions are not well understood. In this study, we hypothesized that zoledronic acid inhibits ovarian cancer angiogenesis preventing Rac1 activation.

EXPERIMENTAL DESIGN

The biologic effects of zoledronic acid were examined using a series of in vitro [cell invasion, cytokine production, Rac1 activation, reverse-phase protein array, and in vivo (orthotopic mouse models)] experiments.

RESULTS

There was significant inhibition of ovarian cancer (HeyA8-MDR and OVCAR-5) cell invasion as well as reduced production of proangiogenic cytokines in response to zoledronic acid treatment. Furthermore, zoledronic acid inactivated Rac1 and decreased the levels of Pak1/p38/matrix metalloproteinase-2 in ovarian cancer cells. In vivo, zoledronic acid reduced tumor growth, angiogenesis, and cell proliferation and inactivated Rac1 in both HeyA8-MDR and OVCAR-5 models. These in vivo antitumor effects were enhanced in both models when zoledronic acid was combined with nab-paclitaxel.

CONCLUSIONS

Zoledronic acid has robust antitumor and antiangiogenic activity and merits further clinical development as ovarian cancer treatment.

Normalization of the tumor microenvironment: evidence for tissue inhibitor of metalloproteinase-2 as a cancer therapeutic

Matrix metalloproteinases (MMPs) are members of the Metzincin family of proteases responsible for degrading the extracellular matrix (ECM). In early studies, MMP degradation of the sub-epithelial basement membrane was thought to be tumor cell autonomous and contribute to the invasive behavior of malignant cells. It is now recognized that MMPs have multiple roles that can either promote or inhibit tumor progression and metastasis. The endogenous inhibitors of the MMPs are the tissue inhibitors of metalloproteinases (TIMPs). Early studies on the tumor microenvironment revealed TIMP function to be principally through the inhibition of MMPs, thereby blocking tumor cell migration and invasion. However, data from a number of laboratories are now reporting that TIMPs have direct cellular functions, independent of their MMP inhibitory activity. The TIMPs can modulate normal tissue physiology and development, as well as pathology and progression in a variety of acute and chronic disease states. In this review, we briefly describe the role of MMPs and TIMPs in ECM turnover and formation of the tumor microenvironment. Based on the evidence presented, we postulate that TIMP-2 and other soluble components of the normal ECM may provide a novel therapeutic approach to cancer treatment through "normalization" of the tumor microenvironment.

Influence of Stromal Components on Lung Cancer Carcinogenesis

The association between tumor growth and angiogenesis was first observed over 100 years ago. Since then, research has shown the dependence of tumor growth on angiogenesis and the ability of cancer cells to alter the stromal microenvironment. Technological advancements have enabled researchers to identify cell types within a tumor, identify chemokines, cytokines, and growth factors secreted by tumor cells, show the interaction between tumor cells and stroma, and investigate the function of distinct genes using knockout and transgenic mouse technology. This review provides an overview of tumor growth, emphasizing research using in vivo mouse models on vascular endothelial growth factor (VEGF), fibrinogen, fibronectin, plasminogen, and MMPs in primary tumor growth and metastasis of lung cancer in particular.

p38α MAPK mediates 17β-estradiol inhibition of MMP-2 and -9 expression and cell migration in human lovo colon cancer cells

Epidemiological studies demonstrate that the incidence and mortality rates of colorectal cancer in women are lower than in men. However, it is unknown if 17β-estradiol (E(2)) treatment is sufficient to inhibit cell proliferation and cell migration in human colon cancer cells. Up-regulation of urokinase plasminogen activator (uPA), tissue plasminogen activator (tPA), and matrix metallopeptidases (MMPs) is reported to associate with the development of cancer cell mobility, metastasis, and subsequent malignant tumor. In the present study, we treated human LoVo colon cancer cells with E(2) to explore whether E(2) down-regulates cell proliferation and migration, and to identify the precise molecular and cellular mechanisms behind the down-regulatory responses. Here, we found that E(2) treatment decreased cell proliferation and cell cycle-regulating factors such as cyclin A, cyclin D1 and cyclin E. At the same time, E(2) significantly inhibited cell migration and migration-related factors such as uPA, tPA, MMP-2, and MMP-9. However, E(2) treatment showed no effects on upregulating expression of plasminogen activator inhibitor-1 (PAI-1), tissue inhibitor of metalloproteinase-1, -2, -3, and -4 (TIMP-1, -2, -3, and -4). After administration of inhibitors including QNZ (NFκB inhibitor), LY294002 (Akt activation inhibitor), U0126 (ERK1/2 inhibitor), SB203580 (p38 MAPK inhibitor) or SP600125 (JNK1/2 inhibitor), E(2) -downregulated cell migration and expression of MMP-2 and MMP-9 in LoVo cells is markedly inhibited only by p38 MAPK inhibitors, SB203580. Application of specific target gene siRNA (ERα, ERβ, p38α, and p38β) to LoVo cells further confirmed that p38 MAPK mediates E(2) /ERs inhibition of MMP-2 and -9 expression and cell motility in LoVo cells. Collectively, these results suggest that E(2) treatment down-regulates cell proliferation by modulating the expression of cyclin A, cyclin D1 and cyclin E. E(2) treatment simultaneously impaired cell migration by inhibiting the expression of uPA, tPA, MMP-2, and MMP-9 through E(2) /ERs - p38α MAPK signaling pathway in human LoVo colon cancer cells.

E-cadherin as a predictive marker of brain metastasis in non-small-cell lung cancer, and its regulation by pioglitazone in a preclinical model

It remains unclear whether patients with non-small-cell lung cancer (NSCLC) develop brain metastasis during or after standard therapy. We attempted to identify biological markers that predict brain metastasis, and investigated how to modulate expression of such markers. A case-control study of patients who were newly diagnosed with NSCLC and who had developed brain metastasis during follow-up was conducted between 2004 and 2009. These patients were compared with a control group of patients who had NSCLC but no evidence of brain metastasis. Immunohistochemical analysis of expression of Ki-67, p53, Bcl-2, Bax, vascular endothelial growth factor, epidermal growth factor receptor, caspase-3, and E-cadherin was conducted. The methylation status of the genes for O(6)-methylguanine-DNA-methyltransferase, tissue inhibitor of matrix metalloproteinase (TIMP)-2, TIMP-3, and death-associated protein-kinase was also determined, by use of a methylation-specific polymerase chain reaction. A significantly increased risk of developing brain metastasis was associated with the presence of primary tumors with low E-cadherin expression in patients with NSCLC. We also investigated the effects of pioglitazone, a peroxisome proliferator-activated receptor γ-activating drug, in tumor-bearing mouse models. We found that E-cadherin expression was proportional to pioglitazone exposure time. Interestingly, pioglitazone pretreatment before cancer cell inoculation prevented loss of E-cadherin expression and reduced expression of MMP9 and fibronectin, compared with the control group. E-cadherin expression could be a predictor of brain metastasis in patients with NSCLC. Preventive treatment with pioglitazone may be useful for modulating E-cadherin expression.

TIMP-2 fusion protein with human serum albumin potentiates anti-angiogenesis-mediated inhibition of tumor growth by suppressing MMP-2 expression

TIMP-2 protein has been intensively studied as a promising anticancer candidate agent, but the in vivo mechanism underlying its anticancer effect has not been clearly elucidated by previous works. In this study, we investigated the mechanism underlying the anti-tumor effects of a TIMP-2 fusion protein conjugated with human serum albumin (HSA/TIMP-2). Systemic administration of HSA/TIMP-2 effectively inhibited tumor growth at a minimum effective dose of 60 mg/kg. The suppressive effect of HSA/TIMP-2 was accompanied by a marked reduction of in vivo vascularization. The anti-angiogenic activity of HSA/TIMP-2 was directly confirmed by CAM assays. In HSA/TIMP-2-treated tumor tissues, MMP-2 expression was profoundly decreased without a change in MT1-MMP expression of PECAM-1-positive cells. MMP-2 mRNA was also decreased by HSA/TIMP-2 treatment of human umbilical vein endothelial cells. Zymographic analysis showed that HSA/TIMP-2 substantially decreased extracellular pro-MMP-2 activity (94–99% reduction) and moderately decreased active MMP-2 activity (10–24% reduction), suggesting MT1-MMP-independent MMP-2 modulation. Furthermore, HSA/TIMP-2 had no effect on in vitro active MMP-2 activity and in vivo MMP-2 activity. These studies show that HSA/TIMP-2 potentiates anti-angiogenic activity by modulating MMP-2 expression, but not MMP-2 activity, to subsequently suppress tumor growth, suggesting an important role for MMP-2 expression rather than MMP-2 activity in anti-angiogenesis.

Differential expression patterns of MMPs and their role in the invasion of epithelial premalignant tumors and invasive cutaneous squamous cell carcinoma

Co-expression of several members of the matrix metalloproteinase (MMP) family is characteristic of human malignant tumors. MMP-2, MMP-9, TIMP-2, and MT1-MMP are thought to be involved in the process of destruction of basement membranes and stromal invasion by neoplastic epithelial cells. In this study, we investigated the expression and role of MMPs in cutaneous oncogenesis. Tissue microarray consisting of 62 squamous cell carcinomas (SCC), 32 Bowen's disease (BD) samples, 25 normal epidermis samples were obtained for the study. MMP-2,-9, MT1-MMP and TIMP-2 proteins were examined by immunohistochemical staining and mRNA level was detected by quantitative RT-PCR in fresh tissues consisting of 5 cutaneous SCCs and paired normal epidermis samples. Gelatinase activity of MMP-2 and MMP-9 was investigated by gelatin zymography and protein levels of MT1-MMP and TIMP-2 were measured by western blot in 2 human SCC cell lines. The invasive property was evaluated with invasion assays using Transwell filters. SCC exhibited significantly increased MMP-2, MT1-MMP and decreased TIMP-2 mRNA and protein expression compared to that of the normal epithelium. Immunohistochemical staining revealed that MT1-MMP was strongly expressed on the invasive front of SCCs, whereas BD exhibited higher expression around the dyskeratotic cells in the epithelium. In comparison with the expression observed in BD, SCC exhibited significantly increased MMP-2 expression. In addition, high MMP-2 and MT1-MMP expression and low TIMP-2 expression had a significant positive correlation with the invasiveness of SCC cell lines in vitro. Our results revealed significantly increased MT1-MMP and MMP-2 expression and decreased TIMP-2 expression in cutaneous SCC, and the expression correlated with the invasiveness of SCC cell lines. Therefore, the expression of these factors in cutaneous tumors may serve as an indicator of tumor aggressiveness and invasion.

Conditionally replicating adenovirus expressing TIMP2 increases survival in a mouse model of disseminated ovarian cancer

Ovarian cancer remains difficult to treat mainly due to presentation of the disease at an advanced stage. Conditionally-replicating adenoviruses (CRAds) are promising anti-cancer agents that selectively kill the tumor cells. The present study evaluated the efficacy of a novel CRAd (Ad5/3-CXCR4-TIMP2) containing the CXCR4 promoter for selective viral replication in cancer cells together with TIMP2 as a therapeutic transgene, targeting the matrix metalloproteases (MMPs) in a murine orthotopic model of disseminated ovarian cancer. An orthotopic model of ovarian cancer was established in athymic nude mice by intraperitonal injection of the human ovarian cancer cell line, SKOV3-Luc, expressing luciferase. Upon confirmation of peritoneal dissemination of the cells by non-invasive imaging, mice were randomly divided into four treatment groups: PBS, Ad-ΔE1-TIMP2, Ad5/3-CXCR4, and Ad5/3-CXCR4-TIMP2. All mice were imaged weekly to monitor tumor growth and were sacrificed upon reaching any of the predefined endpoints, including high tumor burden and significant weight loss along with clinical evidence of pain and distress. Survival analysis was performed using the Log-rank test. The median survival for the PBS cohort was 33 days; for Ad-ΔE1-TIMP2, 39 days; for Ad5/3-CXCR4, 52.5 days; and for Ad5/3-CXCR4-TIMP2, 63 days. The TIMP2-armed CRAd delayed tumor growth and significantly increased survival when compared to the unarmed CRAd. This therapeutic effect was confirmed to be mediated through inhibition of MMP9. Results of the in vivo study support the translational potential of Ad5/3-CXCR4-TIMP2 for treatment of human patients with advanced ovarian cancer.

JNK suppression is essential for 17β-Estradiol inhibits prostaglandin E2-Induced uPA and MMP-9 expressions and cell migration in human LoVo colon cancer cells

Background

Epidemiological studies demonstrate that the incidence and mortality rates of colorectal cancer in women are lower than in men. However, it is unknown if 17β-estradiol treatment is sufficient to inhibit prostaglandin E2 (PGE2)-induced cellular motility in human colon cancer cells.

Methods

We analyzed the protein expression of urokinase plasminogen activator (uPA), tissue plasminogen activator (tPA), matrix metallopeptidases (MMPs), plasminogen activator inhibitor-1 (PAI-1) and tissue inhibitor of metalloproteinases (TIMPs), and the cellular motility in PGE2-stimulated human LoVo cells. 17β-Estradiol and the inhibitors including LY294002 (Akt activation inhibitor), U0126 (ERK1/2 inhibitor), SB203580 (p38 MAPK inhibitor), SP600125 (JNK1/2 inhibitor), QNZ (NFκB inhibitor) and ICI 182 780 were further used to explore the inhibitory effects of 17β-estradiol on PGE2-induced LoVo cell motility. Student's t-test was used to analyze the difference between the two groups.

Results

Upregulation of urokinase plasminogen activator (uPA), tissue plasminogen activator (tPA) and matrix metallopeptidases (MMPs) is reported to associate with the development of cancer cell mobility, metastasis, and subsequent malignant tumor. After administration of inhibitors including LY294002, U0126, SB203580, SP600125 or QNZ, we found that PGE2 treatment up-regulated uPA and MMP-9 expression via JNK1/2 signaling pathway, thus promoting cellular motility in human LoVo cancer cells. However, PGE2 treatment showed no effects on regulating expression of tPA, MMP-2, plasminogen activator inhibitor-1 (PAI-1), tissue inhibitor of metalloproteinase-1, -2, -3 and -4 (TIMP-1, -2, -3 and -4). We further observed that 17β-estradiol treatment inhibited PGE2-induced uPA, MMP-9 and cellular motility by suppressing activation of JNK1/2 in human LoVo cancer cells.

Conclusions

Collectively, these results suggest that 17β-estradiol treatment significantly inhibits PGE2-induced motility of human LoVo colon cancer cells.

Significant relation of tissue inhibitor of matrix metalloproteinase-2 and its combination with matrix metalloproteinase-2 to survival of patients with cancer of uterine cervix

Tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) has high affinity for matrix metalloproteinase-2 (MMP-2). Few studies simultaneously investigate their implication in prognosis of patients with cervical cancer. We used reverse transcription-polymerase chain reaction and immunohistochemical method for cervical tissues and microarrays to investigate the association among TIMP-2, MMP-2, clinicopathological parameters, and prognosis of patients with cancer. Our results showed that cancer tissues exhibited less TIMP-2 expression and patients with pelvic lymph node metastasis had less TIMP-2 expression. Positive TIMP-2 constellated with negative MMP-2 indicated lower recurrence probability and better overall survival. The protective effect of TIMP-2 expression may overcome the adverse effect of MMP-2 expression in terms of disease-free interval and overall survival while neither TIMP-2 nor MMP-2 alone can be used to predict outcome. We suggest that following patients other than those with positive TIMP-2 and negative MMP-2 expression more closely and intensely may improve their prognosis.

The soluble fragment of VE-cadherin inhibits angiogenesis by reducing endothelial cell proliferation and tube capillary formation

Vascular endothelial-specific cadherin (VE-cadherin) is an endothelial cell-specific adhesion molecule, localized at cell-cell contact sites. It is involved in physiological and pathological angiogenesis. In this study, we showed that in vitro a soluble N-terminal fragment of VE-cadherin (EC1-3) corresponding to cadherin 1-3 ectodomains inhibited vascular endothelial growth factor-stimulated endothelial cell proliferation and capillary tube structure formation in the matrigel model. In vivo, EC1-3 was tested in a murine colon cancer model. EC1-3-expressing colon cancer C51 cells were subcutaneously grafted into nude mice, and tumor growth and angiogenesis were evaluated. At day 33, the mean volume of the tumors developed was reduced (510±104 versus 990±120 mm(3) for control). Similarly, injection of EC1-3 virus-producing cells into established C51 tumors resulted in an inhibition by 33% of tumor growth. Immunohistological staining of vessels on tumor sections showed a significantly reduced intratumoral angiogenesis. Furthermore, EC1-3 did not induce vessel injury in the lung, liver, spleen, heart and brain in the mice. These results suggest that the soluble N-terminal fragment of VE-cadherin EC1-3 could exert an antitumoral effect by targeting tumor angiogenesis, which included blocking endothelial cell proliferation and capillary tube formation with no obvious toxicity on normal organs.

Intake of grape-derived polyphenols reduces C26 tumor growth by inhibiting angiogenesis and inducing apoptosis

This study evaluated the in vivo antitumor activity of grape-derived polyphenols. BALB/c mice were subcutaneously implanted with C26 colon carcinoma cells, and 2 d later they received either solvent or red wine polyphenols (RWPs) (100 mg/kg/d, human equivalent dose approximately 500 mg/d) in the drinking water for 25 d. Wistar rats received either solvent or RWPs (100 mg/kg/d, human equivalent dose approximately 1000 mg/d) in the drinking water 1 wk before injection of azoxymethane and were studied 10 wk later. In mice, RWPs inhibited tumor growth by 31%, reduced tumor vascularization and the number of lung metastases, decreased proliferation as indicated by down-regulation of Ki67, cyclin D1, and UHRF1, and increased apoptosis as indicated by TUNEL staining and active caspase-3 levels in tumor cells. RWPs reduced expression of VEGF, matrix metalloproteinase (MMP)-2, MMP-9, and cyclooxygenase-2 and increased expression of tumor suppressor genes p16(INK4A), p53, and p73 in tumor cells. In rats, RWPs reduced by 49% the number of azoxymethane-induced aberrant crypt foci (preneoplastic lesions) in colon. Thus, RWPs effectively reduced the development of colon carcinoma tumors in vivo by blunting tumor vascularization and by inhibiting proliferation and promoting apoptosis of tumor cells subsequent to an up-regulation of tumor suppressor genes.

Increase in tissue inhibitor of metalloproteinase-2 (TIMP-2) levels and inhibition of MMP-2 activity in a metastatic breast cancer cell line by an anti-invasive small molecule SR13179

Tissue inhibitor of metalloproteinase-2 (TIMP-2), the endogenous inhibitor of matrix metalloproteinase-2 (MMP-2), regulates tumor invasion by modulating the activity of MMP-2. In addition, TIMP-2 is involved in the direct regulation of cell growth and angiogenesis, independent of MMP inhibition. Therefore, the development of therapeutic agents that increase TIMP-2 levels may offer a novel and broad approach to anti-neoplastic therapy. We report that a novel small molecule synthetic flavanoid SR13179, which inhibits the invasion of a highly metastatic human breast cancer cell line MCF-10CA1a through Matrigel, significantly increases protein and mRNA levels of TIMP-2 in a time- and dose-dependent manner. SR13179 inhibits the gelatinolytic activity of MMP-2 by >50% but has no effect on MMP-2 protein expression. SR13179 also possesses potent anti-tumor activity in several tumor cell lines regardless of their hormone receptor, p53 or multi-drug resistance status. Given the multifunctional inhibitory activity of TIMP-2 on tumor growth and invasion, the observed increase in TIMP-2 expression by SR13179 may play a central role in the anti-tumor and anti-invasive activity of this novel small molecule. Modulation of TIMP-2 protein expression may be a new molecular target for anti-metastatic adjuvant therapy for breast and other cancers.

Therapy of head and neck squamous cell carcinoma with replicative adenovirus expressing tissue inhibitor of metalloproteinase-2 and chemoradiation

Recent studies have demonstrated the efficacy of targeted therapy combined with radiotherapy in head and neck squamous cell carcinoma (HNSCC). We hypothesized that a combination treatment including a replicating adenovirus armed with tissue inhibitor of metalloproteinase-2 (TIMP-2), radiation and Cisplatin will augment treatment response and reduce tumor growth in vivo of HNSCC xenografts. Both single-agent (TIMP-2 virus, radiation and Cisplatin) and the combination therapies were evaluated in vitro and in vivo. The efficacy of both single-agent and combination therapies in vivo was determined by monitoring tumor growth and immunohistochemistry. Treatment with replicative Ad-TIMP-2 virus and radiation decreased cell viability in vitro and resulted in an additional antiangiogenic response in vivo. Tumor response rates to treatment with replicative Ad-TIMP-2, radiation, Cisplatin or combination therapies ranged from limited inhibition of tumor growth of the single-agent therapy to a statistically significant additive antitumor response with the combination therapies. Replicative Ad-TIMP-2+radiation+Cisplatin in the SCC1 nude mice demonstrated the greatest response rates in tumor growth and angiogenesis. Combination of Ad-TIMP-2 gene therapy with radiation and the triple treatment group resulted in an augmented therapeutic response. This is the first report of the potential benefits of combining radiation and MMP inhibitor treatment.

REIC/Dkk-3 overexpression downregulates P-glycoprotein in multidrug-resistant MCF7/ADR cells and induces apoptosis in breast cancer

The overexpression of reduced expression in immortalized cells (REIC)/Dickkopf-3 (Dkk-3), a tumor suppressor gene, induced apoptosis in human prostatic and testicular cancer cells. The aim of this study is to examine the potential of REIC/Dkk-3 as a therapeutic target against breast cancer. First, the in vitro apoptotic effect of Ad-REIC treatment was investigated in breast cancer cell lines and the adenovirus-mediated overexpression of REIC/Dkk-3 was thus found to lead to apoptotic cell death in a c-Jun-NH(2)-kinase (JNK) phosphorylaion-dependent manner. Moreover, an in vivo apoptotic effect and MCF/Wt tumor growth inhibition were observed in the mouse model after intratumoral Ad-REIC injection. As multidrug resistance (MDR) is a major problem in the chemotherapy of progressive breast cancer, the in vitro effects of Ad-REIC treatment were investigated in terms of the sensitivity of multidrug-resistant MCF7/ADR cells to doxorubicin and of the P-glycoprotein expression. Ad-REIC treatment in MCF7/ADR cells also downregulated P-glycoprotein expresssion through JNK activation, and sensitized its drug resistance against doxorubicin. Therefore, not only apoptosis induction but also the reversal of anticancer drug resistance was achieved using Ad-REIC. We suggest that REIC/Dkk-3 is a novel target for breast cancer treatment and that Ad-REIC might be an attractive agent against drug-resistant cancer in combination with conventional antineoplastic agents.

Adenovirus-mediated REIC/Dkk-3 gene transfer inhibits tumor growth and metastasis in an orthotopic prostate cancer model

We had previously reported that REIC/Dkk-3, a member of the Dickkopf (Dkk) gene family, works as a tumor suppressor. In this study, we evaluated the therapeutic effects of an intratumoral injection with adenoviral vector encoding REIC/Dkk-3 gene (Ad-REIC) using an orthotopic mouse prostate cancer model of RM-9 cells. We also investigated the in vivo anti-metastatic effect and in vitro anti-invasion effect of Ad-REIC gene delivery. We demonstrated that the Ad-REIC treatment inhibited prostate cancer growth and lymph node metastasis, and prolonged mice survival in the model. These therapeutic responses were consistent with the intratumoral apoptosis induction and in vitro suppression of cell invasion/migration with reduced matrix metalloprotease-2 activity. We thus concluded that in situ Ad-REIC/Dkk-3 gene transfer may be a promising therapeutic intervention modality for the treatment of prostate cancer.

Antitumor effects of non-replicative herpes simplex vectors expressing antiangiogenic proteins and thymidine kinase on Lewis lung carcinoma establishment and growth

There is growing evidence that combinations of antiangiogenic proteins with other antineoplastic treatments such as chemo- or radiotherapy and suicide genes-mediated tumor cytotoxicity lead to synergistic effects. In the present work, we tested the activity of two non-replicative herpes simplex virus (HSV)-1-based vectors, encoding human endostatin::angiostatin or endostatin::kringle5 fusion proteins in combination with HSV-1 thymidine kinase (TK) molecule, on endothelial cells (ECs) and Lewis lung carcinoma (LLC) cells. We observed a significant reduction of the in vitro growth, migration and tube formation by primary ECs upon direct infection with the two recombinant vectors or cultivation with conditioned media obtained from the vector-infected LLC cells. Moreover, direct cytotoxic effect of HSV-1 TK on both LLC and ECs was demonstrated. We then tested the vectors in vivo in two experimental settings, that is, LLC tumor growth or establishment, in C57BL/6 mice. The treatment of pre-established subcutaneous tumors with the recombinant vectors with ganciclovir (GCV) induced a significant reduction of tumor growth rate, while the in vitro infection of LLC cells with the antiangiogenic vectors before their implantation in mice flanks, either in presence or absence of GCV, completely abolished the tumor establishment.

MMP2 role in breast cancer brain metastasis development and its regulation by TIMP2 and ERK1/2

Matrix metalloproteinase 2 (MMP2) is important in breast cancer (BC) invasion and metastasis. We previously reported that BC brain metastases, in a rat syngeneic model developed in our laboratory, have high expression and activity of MMP2. The MMP2 mechanism of action in the brain is still under intense scrutiny. To study the role of MMP2 in the development of BC brain metastasis we transfected ENU1564 rat mammary adenocarcinoma cells with tissue inhibitor of MMP2 (TIMP2). Animals inoculated with ENU1564-TIMP2 cells had decreased orthotopic tumor growth, decreased orthotopic metastatic behavior and did not develop brain metastases. These results were associated with decreased MMP2 activity, demonstrated by gel zymography. Mitogen activated protein kinase (MAPK) pathway components, such as ERK1/2, have been correlated to MMP expression and/or astrocyte activity. We found that BC brain metastases have peripheral astrocyte reactivity and higher expression of glial fibrillary acidic protein (GFAP) and phosphorylated-ERK1/2 (p-ERK1/2). Additionally, rat astrocyte-conditioned media increased in vitro invasion of ENU1564 cancer cells and increased expression of MMP2 and p-ERK1/2. Blockage of ERK1/2 phosphorylation by treatment with MEK inhibitor (PD98059) decreased the expression of MMP2 in cancer cells grown in rat astrocyte-conditioned media. Our results are highly suggestive that MMP2 plays a role in the development of BC metastases, in particular to the brain. Furthermore, our results suggest that astrocyte factors and the ERK1/2 signaling pathway may be associated with BC brain metastasis development; and that ERK1/2 may regulate MMP2 in a way that is modifiable by astrocyte factors.

[The role of matrix metalloproteinases and tissue inhibitors of metalloproteinases in invasion of tumours of neuroepithelial tissue]

Tumour invasion requires degradation of extracellular matrix components and migration of cells through degraded structures into surrounding tissues. Matrix metalloproteinases (MMP) constitute a family of zinc and calcium-dependent endopeptidases that play a key role in the breakdown of extracellular matrix, and in processing of cytokines, growth factors, chemokines and cell surface receptors. Their activity is regulated at the levels of transcription, activation and inhibition by tissue inhibitors of metalloproteinases (TIMP). Changes in expression of MMP and TIMP are implicated in tumour invasion, because they may contribute to both migration of tumour cells and angiogenesis. Alterations of MMP expression observed in brain tumours arouse interest in the development and evaluation of synthetic matrix metalloproteinase inhibitors as antitumour agents.

A biologically active angiogenesis inhibitor, human serum albumin-TIMP-2 fusion protein, secreted from Saccharomyces cerevisiae

Tissue inhibitor of metalloproteinase-2 (TIMP-2) is an endogenous and bi-functional inhibitor of angiogenesis. TIMP-2 is expressed in an insoluble form in Escherichia coli and secreted at a very low level from yeast. Here, we report on a high level of secretion of TIMP-2 fused with human serum albumin (HSA) from the yeast Saccharomyces cerevisiae. The secreted HSA-TIMP-2 fusion protein (87kDa) was purified to greater than 95% homogeneity. The HSA-TIMP-2 protein inhibited approximately 81% of tube formation of human umbilical vein endothelial cells (HUVECs) when studied at a concentration of 187microM. The systemic administration of HSA-TIMP-2 at 40mg/kg to the C57B1/6 mouse inhibited the growth of B16BL6 tumors. Furthermore, a combination treatment of HSA-TIMP-2 with 5-fluorouracil (50mg/kg) showed significant effects on tumor growth in this model. The high level of secretion of the biologically active angiogenesis inhibitor from S. cerevisiae should facilitate fundamental research and application studies of HSA-TIMP-2, as an attractive candidate for therapeutic agents treating angiogenesis-related diseases.

The use of tissue inhibitors of matrix metalloproteinases to increase the efficacy of a tumor necrosis factor/interferonγ antitumor therapy

Owing to its impressive ability to kill tumor cells, especially in combination with interferon-gamma (IFNgamma), tumor necrosis factor (TNF) is widely appreciated as being a potential systemic therapeutic for the treatment of cancer. On the other hand, owing to its proinflammatory activities, administration of TNF leads to many systemic side effects and eventually to a potentially lethal systemic inflammatory response syndrome (SIRS). However, systemic treatment of tumor-bearing mice with TNF/IFNgamma in combination with BB-94 (a broad-spectrum metalloproteinase inhibitor) confers protection against TNF/IFNgamma-induced mortality, whereas preserving the antitumor activity. In this study, we investigated the effect of the adenoviral delivery of human tissue inhibitors of matrix metalloproteinase (hTIMP)-1 and hTIMP-2 genes on the outcome of TNF/IFNgamma antitumor therapy. The dose of adenovirus was limited to 10(8) PFU per mouse owing to the additive toxicity of combining it with TNF/IFNgamma therapy. Nevertheless, this dose was sufficient to achieve highly efficient adenoviral transfer and expression of hTIMP-1 and hTIMP-2 in the liver, but not the tumor. Treatment with this low dose of AdhTIMP-1 or AdhTIMP-2 was not enough to protect the host against the toxic effects of TNF/IFNgamma. However, it was sufficient to show a synergistic effect of hTIMPs with TNF/IFNgamma such that tumors regressed significantly faster. Interestingly, only AdTIMP-2 was able to prevent relapses after treatment.

Adenovirus-mediated expression of TIMP-1 and TIMP-2 in bone inhibits osteolytic degradation by human prostate cancer

Matrix metalloproteinases (MMPs) are proteolytic enzymes that play critical roles in the pathogenesis of human cancers. Clinical trials using synthetic small molecule MMP inhibitors have been carried out but with little success. Tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors that block the extracellular matrix-degrading activity of MMPs. Here, we investigated the possibilities of genetically modifying human bones with TIMPs to create a high-TIMP bone microenvironment, which is hostile to metastatic prostate cancer cells using adenovirus-mediated gene transfer technology and SCID-hu end-organ colonization mouse model. Two strategies were used to achieve bone-specific TIMP expression: (i) ex vivo bone adenoviral infection followed by in vivo bone implantation; and (ii) ex vivo BMS cell infection followed by injection into in vivo implanted human fetal bones. PC-3 prostate cancer cells were injected into human fetal bones 4 weeks after implantation in SCID mice. In vitro, adenovirus-mediated expression of TIMP-1 or TIMP-2 in bone fragments inhibited MMP-2 activity, bone turnover and prostate cancer cell-induced proteolytic degradation as determined by gelatin zymography, calcium measurement and DQ protein quenched fluorescence assay, respectively. In vivo, immunohistochemistry confirmed TIMP-2 expression in AdTIMP-2-infected bone implants 4 weeks after implantation in SCID mice. Mice receiving AdTIMP-treated bone fragments showed significantly reduced PC-3-induced osteolysis, osteoclast recruitment and bone turnover in the implanted bones. We propose that adenoviral gene transfer of TIMP-1 and TIMP-2 can prevent the proteolytic activity of prostate cancer cells in bone and that enhancing anti-proteolytic defense mechanisms in target organs represents a promising form of prostate cancer gene therapy.

Activation of proMMP-2 and Src by HHV8 vGPCR in human pulmonary arterial endothelial cells

Idiopathic pulmonary arterial hypertension (iPAH) is associated with human herpesvirus 8 (HHV8) infection and demonstrates pathological angiogenesis similar to that observed with another HHV8-linked disease, namely Kaposi Sarcoma (KS). Importantly, the HHV8 encoded viral G-protein-coupled receptor (vGPCR) induces KS lesions in a murine model. Investigating the impact of vGPCR expression on the angiogenic activity of human pulmonary arterial endothelial cells (HPAEC) can yield insight into the pathobiology of HHV8-associated vascular disorders, particularly PAH. Cultured HPAECs were transduced with retroviral vectors carrying either control or vGPCR coding regions. vGPCR expression selectively activated matrix metalloproteinase (MMP)-2, a pivotal matrix modulating enzyme during angiogenesis. A membrane type 1 MMP (MT1-MMP) neutralizing antibody and the tissue inhibitor of metalloproteinases-2 (TIMP-2) independently blocked vGPCR-induced MMP-2 activation. vGPCR expression concordantly promoted MMP-2 activation by increasing MT1-MMP expression while decreasing TIMP-2 expression. vGPCR activated Src kinase as demonstrated by phosphorylation of Src and its substrate focal adhesion kinase (FAK). vGPCR promoted angiogenesis of HPAECs as demonstrated by a substantial increase in tubulogenesis in vitro. The Src inhibitors PP2 and SU6656 significantly diminished vGPCR-induced MMP-2 activation and tubulogenesis. Our findings indicate that vGPCR induces MMP-2 activation in HPAECs through regulation of MT1-MMP and TIMP-2 expression. vGPCR activates Src and inhibition of such activation abrogates proMMP-2 activation and in vitro angiogenesis induced by vGCPR. The current study implicates vGPCR as an etiological agent in iPAH and identifies Src and MMP-2 as potential therapeutic targets in HHV8 associated KS and iPAH.

Tissue inhibitor of metalloproteinases-2 improves antitumor efficacy of a replicating adenovirus in vivo

Clinical studies of replicating adenoviruses for the treatment of cancer have demonstrated their safety but have yielded disappointing results, indicating the need for new strategies to improve their efficacy. We hypothesized that the efficacy of a replicating adenovirus could be improved by expression of tissue inhibitor of metalloproteinases-2 (TIMP-2), a 21-kDa unglycosylated secretory protein. TIMP-2 specifically inhibits the active forms of a number of matrix metalloproteinases (MMPs) that play a role in the degradation of basement membranes and the extracellular matrix and are therefore involved in the control of the growth, invasion and metastasis of tumor cells, as well as angiogenesis. In addition, TIMP-2 can abrogate tumor growth and angiogenesis by a variety of mechanisms independent of MMP inhibition. In this study, we demonstrate that expression of TIMP-2 enhanced the antitumor efficacy of a replicating adenovirus in vivo, by reducing both tumor growth and angiogenesis.

Intravenous Delivery of Anti-RhoA Small Interfering RNA Loaded in Nanoparticles of Chitosan in Mice: Safety and Efficacy in Xenografted Aggressive Breast Cancer

Overexpression of RhoA in cancer indicates a poor prognosis, because of increased tumor cell proliferation and invasion and tumor angiogenesis. We showed previously that anti-RhoA small interfering RNA (siRNA) inhibited aggressive breast cancer more effectively than conventional blockers of Rho-mediated signaling pathways. This study reports the efficacy and lack of toxicity of intravenously administered encapsulated anti-RhoA siRNA in chitosan-coated polyisohexylcyanoacrylate (PIHCA) nanoparticles in xenografted aggressive breast cancers (MDA-MB-231). The siRNA was administered every 3 days at a dose of 150 or 1500 microg/kg body weight in nude mice. This treatment inhibited the growth of tumors by 90% in the 150-microg group and by even more in the 1500-microg group. Necrotic areas were observed in tumors from animals treated with anti-RhoA siRNA at 1500 microg/kg, resulting from angiogenesis inhibition. In addition, this therapy was found to be devoid of toxic effects, as evidenced by similarities between control and treated animals for the following parameters: body weight gain; biochemical markers of hepatic, renal, and pancreatic function; and macroscopic appearance of organs after 30 days of treatment. Because of its efficacy and the absence of toxicity, it is suggested that this strategy of anti-RhoA siRNA holds significant promise for the treatment of aggressive cancers.

Recombinant AAV-mediated HSVtk gene transfer with direct intratumoral injections and Tet-On regulation for implanted human breast cancer

BACKGROUND

HSVtk/ganciclovir (GCV) gene therapy has been extensively studied in tumors and relies largely on the gene expression of HSVtk. Most studies, however, have failed to demonstrate any significant benefit of a controlled gene expression strategy in cancer treatment. The Tet-On system is commonly used to regulate gene expression following Dox induction. We have evaluated the antitumor effect of HSVtk/ganciclovir gene therapy under Tet-On regulation by means of adeno-associated virus-2 (AAV-2)-mediated HSVtk gene transfer with direct intratumoral injections in mice bearing breast cancer tumors.

METHODS

Recombinant adeno-associated virus-2 (rAAV) was constructed and transduced into MCF-7 cell line. GCV treatment to the rAAV infected MCF-7 cells was performed by MTT assay under the doxycycline (Dox) induction or without Dox induction at a vp (viral particle) number of > or =10(4)/cell. The virus was administered intratumorally to nude mice that had also received GCV intraperitoneally. The antitumor effects were evaluated by measuring tumor regression and histological analysis.

RESULTS

We have demonstrated that GCV treatment to the infected MCF-7 cells under the Dox induction was of more inhibited effects than those without Dox induction at > or =10(4) vp/cell. In ex vivo experiments, tumor growth of BALB/C nude mice breast cancer was retarded after rAAV-2/HSVtk/Tet-On was injected into the tumors under the Dox induction. Infiltrating cells were also observed in tumors after Dox induction followed by GCV treatment and cells were profoundly damaged. The expression of HSVtk gene in MCF-7 cells and BALB/C nude mice tumors was up-regulated by Tet-On under Dox induction with reverse transcription-PCR (RT-PCR) analysis.

CONCLUSION

The antitumor effect of rAAV-mediated HSVtk/GCV gene therapy under the Dox induction with direct intratumoral injections may be a useful treatment for breast cancer and other solid tumors.

Preparation and in vitro studies of microencapsulated cells releasing human tissue inhibitor of metalloproteinase-2

OBJECTIVE

To prepare microencapsulated cells releasing human tissue inhibitor of metalloproteinase-2 (TIMP-2), and investigate their biological characteristics in vitro.

METHODS

Chinese hamster ovary (CHO) cells were stably transfected with a human TIMP-2 expression vector, encapsulated in barium alginate microcapsules and cultured in vitro. Morphological appearance of the microcapsules was observed under a light microscope. Cell viability was assessed using MTT (3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide) assay. Enzyme linked immunosorbent assay (ELISA) and reverse zymography were used to confirm the release of biologically active TIMP-2 from the microcapsules. Cryopreservation study of the microencapsulated cells was carried out using dimethyl sulfoxide (DMSO) as preservative agent.

RESULTS

The microcapsules appeared like a sphere with diameter of 300 - approximately 600 microm. The surface of the capsule wall was clearly smooth. The microencapsulated cells survived well and kept proliferating over the 6 weeks observed. No significant difference in TIMP-2 secretion was found between encapsulated and unencapsulated cells. Reverse zymography confirmed the bioactivity of MMP (matrix metalloproteinase) inhibition of TIMP-2. The cryopreservation process did not damage the microcapsule morphology nor the viability of the cells inside.

CONCLUSION

Microencapsulated engineered CHO cells survive at least 6 weeks after preparation in vitro, and secrete bioactive TIMP-2 freely from the microcapsules.

Adeno-associated virus 2-mediated intratumoral prostate cancer gene therapy: long-term maspin expression efficiently suppresses tumor growth

Maspin is a member of the serine protease inhibitors and the maspin gene, a tumor suppressor gene, is down-regulated in a large fraction of prostate cancers. We evaluated the use of adeno-associated virus (AAV, serotype 2) vector encoding maspin as a means for in vivo gene therapy for human prostate cancer. TUNEL assay of subcutaneously formed LNCaP or DU145 tumors in nude mice showed that intratumoral AAV-mediated maspin expression significantly upregulated the number of apoptotic cells compared with AAV-LacZ treatment. Immunofluorescence double staining for maspin protein and apoptosis in LNCaP tumors showed that the percentage of apoptotic cells in AAV-maspin-mediated maspin-expressing cells was significantly high compared with that in AAV-GFP-mediated GFP-expressing cells. Moreover, significantly fewer CD31-positive microvessels were observed in AAV-maspin-treated tumors compared with the control tumors. These therapeutic responses were highly correlated to persistent maspin expression in tumors, confirmed by Western blot analysis until at least day 56 after treatment. Finally, intratumoral delivery of AAV-maspin significantly suppressed growth of LNCaP and DU145 tumors and improved survival of mice. We conclude that AAV-mediated prolonged maspin expression efficiently suppresses human prostate tumor growth in vivo by apoptosis induction and inhibition of angiogenesis.

Tumstatin, the NC1 domain of alpha3 chain of type IV collagen, is an endogenous inhibitor of pathological angiogenesis and suppresses tumor growth

Angiogenesis, the formation of new blood vessels, is required for physiological development of vertebrates and repair of damaged tissue, but in the pathological setting contributes to progression of cancer. During tumor growth, angiogenesis is supported by up-regulation of angiogenic stimulators (pro-angiogenic) and down-regulation of angiogenic inhibitors (anti-angiogenic). The switch to the angiogenic phenotype (angiogenic switch) allows the tumors to grow and facilitate metastasis. The bioactive NC1 domain of type IV collagen alpha3 chain, called tumstatin, imparts anti-tumor activity by inducing apoptosis of proliferating endothelial cells. Tumstatin binds to alphaVbeta3 integrin via a mechanism independent of the RGD-sequence recognition and inhibits cap-dependent protein synthesis in the proliferating endothelial cells. The physiological level of tumstatin is controlled by matrix metalloproteinase-9, which most effectively cleaves it from the basement membrane and its physiological concentration in the circulation keeps pathological angiogenesis and tumor growth in check. These findings suggest that tumstatin functions as an endogenous inhibitor of pathological angiogenesis and functions as a novel suppressor of proliferating endothelial cells and growth of tumors.

Membrane type-matrix metalloproteinases and tumor progression

Matrix metalloproteinases (MMPs) are a family of zinc endopeptidases that process growth factors, growth factor binding proteins, cell surface proteins, degrade extracellular matrix (ECM) components and thereby play a central role in tissue remodeling and tumor progression. Membrane-type matrix metalloproteinases (MT-MMPs) are a recently discovered subgroup of intrinsic plasma membrane proteins. Their functions have been extended from pericellular proteolysis and control of cell migration to cell signaling, control of cell proliferation and regulation of multiple stages of tumor progression including growth and angiogenesis. This review sheds light on the new functions of MT-MMPs and their inhibitors in tumor development and angiogenesis, and presents recent investigations that document their influence on various cell functions.

Metalloproteinases and their inhibitors in tumor angiogenesis

Angiogenesis is the process by which new blood vessels are formed from preexisting vasculature. It is an essential feature of the female reproductive cycle, embryonic development and wound repair. Angiogenesis has also been identified as a causal or contributing factor in several pathologies, including cancer, where it is a rate-limiting step during tumor progression. Matrix metalloproteinases (MMPs) are a family of soluble and membrane-anchored proteolytic enzymes that can degrade components of the extracellular matrix (ECM) as well as a growing number of modulators of cell function. Several of the MMPs, in particular the gelatinases and membrane-type 1 MMP (MT1-MMP), have been linked to angiogenesis. Potential roles for these proteases during the angiogenic process include degradation of the basement membrane and perivascular ECM components, unmasking of cryptic biologically relevant sites in ECM components, modulation of angiogenic factors and production of endogenous angiogenic inhibitors. This review brings together what is currently known about the functions of the MMPs and the closely related ADAM (a disintegrin and metalloproteinase domain) and ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) families in angiogenesis and considers how this information might be useful in manipulation of the angiogenic process, with a view to constraining tumor progression.

Anti-RhoA and anti-RhoC siRNAs inhibit the proliferation and invasiveness of MDA-MB-231 breast cancer cells in vitro and in vivo

Overexpression of RhoA or RhoC in breast cancer indicates a poor prognosis, due to increased tumor cell proliferation and invasion and tumor-dependent angiogenesis. Until now, the strategy of blockage of the Rho-signaling pathway has used either GGTI or HMG-CoA reductase inhibitors, but they are not specific to RhoA or RhoC inhibition. In this study, a new approach with anti-RhoA and anti-RhoC siRNAs was used to inhibit specifically RhoA or RhoC synthesis. Two transfections of either RhoA or RhoC siRNA (8.5 nM) into MDA-MB-231 human breast cancer cells or HMEC-1 endothelial cells induced extensive degradation of the target mRNA and led to a dramatic decrease in synthesis of the corresponding protein. In vitro, these siRNAs inhibited cell proliferation and invasion more effectively than conventional blockers of Rho cell signaling. Finally, in a nude mouse model, intratumoral injections of anti-RhoA siRNA (100 microl at 85 nM) every 3 days for 20 days almost totally inhibited the growth and angiogenesis of xenografted MDA-MB-231 tumors. One may infer from these observations that specific inhibition of the Rho-signaling pathway with siRNAs represents a promising approach for the treatment of aggressive breast cancers.

Replicating retroviral vectors mediating continuous production and secretion of therapeutic gene products from cancer cells

The successful application of cancer gene therapy has been hampered by the low efficiency of in vivo gene delivery by currently used replication-defective vectors. Accordingly, considerable efforts are now being directed toward development and use of vectors capable of replicating in cancer cells. However, for replicating retroviruses, insertion of additional reading frames into the viral genome often resulted in the generation of unstable viruses. Here, we report a novel concept for the generation of replication-competent murine leukemia virus (MLV) vectors capable of mediating the secretion of soluble therapeutic proteins from infected cells. As a proof of principle, we inserted transgene regions encoding either a single-chain variable region fragment (scFv), here, the laminin-specific L36-scFv, or the T-cell-specific 7A5-scFv, or the cytokine GM-CSF into the MLV envelope (env) gene after +1 codon of the envelope (Env) protein, followed by a sequence specifying a furin protease cleavage site. The resulting viruses, termed L36-furin-A, 7A5-furin-A and GMCSF-furin-Mo, respectively, infected a variety of human cell lines, including HMEC-1 (endothelial), A301 (lymphoid), MDA-MB231 and MDA-MB468 (breast cancer) and HT1080 (fibrosarcoma) cells. Western blot analysis of conditioned culture medium from HT1080 cells infected by replicating L36-furin A, as an example, revealed that more than 90% of the Env fusion protein molecules were indeed intracellularly cleaved. After 5 days of infection, up to 3-4 mug/ml of soluble L36-scFv accumulated in the supernatant of HT1080 cells. The eukaryotically produced L36-scFv and 7A5-scFv were able to recognize their native antigens with high avidity, as assessed by ELISA and flow cytometry. Furthermore, the replicating viruses were genetically stable for more than 12 cell passages. In conclusion, a new generation of replication-competent retroviral vectors capable of mediating long-term and efficient secretion of therapeutic proteins suitable for cancer therapy was generated.