Differential effects of angiostatin, endostatin and interferon-alpha(1) gene transfer on in vivo growth of human breast cancer cells

Spatial Distribution of Immune Cells Drives Resistance to Neoadjuvant Chemotherapy in Triple-Negative Breast Cancer

Neoadjuvant chemotherapy (NAC) alone or combined with target therapies represents the standard of care for localized triple-negative breast cancer (TNBC). However, only a fraction of patients have a response, necessitating better understanding of the complex elements in the TNBC ecosystem that establish continuous and multidimensional interactions. Resolving such complexity requires new spatially-defined approaches. Here, we used spatial transcriptomics to investigate the multidimensional organization of TNBC at diagnosis and explore the contribution of each cell component to response to NAC. Starting from a consecutive retrospective series of TNBC cases, we designed a case-control study including 24 patients with TNBC of which 12 experienced a pathologic complete response (pCR) and 12 no-response or progression (pNR) after NAC. Over 200 regions of interest (ROI) were profiled. Our computational approaches described a model that recapitulates clinical response to therapy. The data were validated in an independent cohort of patients. Differences in the transcriptional program were detected in the tumor, stroma, and immune infiltrate comparing patients with a pCR with those with pNR. In pCR, spatial contamination between the tumor mass and the infiltrating lymphocytes was observed, sustained by a massive activation of IFN-signaling. Conversely, pNR lesions displayed increased pro-angiogenetic signaling and oxygen-based metabolism. Only modest differences were observed in the stroma, revealing a topology-based functional heterogeneity of the immune infiltrate. Thus, spatial transcriptomics provides fundamental information on the multidimensionality of TNBC and allows an effective prediction of tumor behavior. These results open new perspectives for the improvement and personalization of therapeutic approaches to TNBCs.

Regulation of tumor angiogenesis by the crosstalk between innate immunity and endothelial cells

Endothelial cells and immune cells are major regulators of cancer progression and prognosis. Endothelial cell proliferation and angiogenesis are required for providing nutrients and oxygen to the nascent tumor and infiltration of immune cells to the tumor is dependent on endothelial cell activation. Myeloid cells and innate lymphocytes have an important role in shaping the tumor microenvironment by crosstalking with cancer cells and structural cells, including endothelial cells. Innate immune cells can modulate the activation and functions of tumor endothelial cells, and, in turn, endothelial cell expression of adhesion molecules can affect immune cell extravasation. However, the mechanisms underlying this bidirectional crosstalk are not fully understood. In this review, we will provide an overview of the current knowledge on the pathways regulating the crosstalk between innate immune cells and endothelial cells during tumor progression and discuss their potential contribution to the development of novel anti-tumor therapeutic approaches.

Crosstalk between angiogenesis and immune regulation in the tumor microenvironment

Cancer creates a complex tumor microenvironment (TME) composed of immune cells, stromal cells, blood vessels, and various other cellular and extracellular elements. It is essential for the development of anti-cancer combination therapies to understand and overcome this high heterogeneity and complexity as well as the dynamic interactions between them within the TME. Recent treatment strategies incorporating immune-checkpoint inhibitors and anti-angiogenic agents have brought many changes and advances in clinical cancer treatment. However, there are still challenges for immune suppressive tumors, which are characterized by a lack of T cell infiltration and treatment resistance. In this review, we will investigate the crosstalk between immunity and angiogenesis in the TME. In addition, we will look at strategies designed to enhance anti-cancer immunity, to convert “immune suppressive tumors” into “immune activating tumors,” and the mechanisms by which these strategies enhance effector immune cell infiltration.

Evaluation of antitumor effects of VEGFR-2 inhibitor F16 in a colorectal xenograft model

OBJECTIVES

Colorectal cancer (CRC) is the third most prevalent type of cancer in the United States. The treatment options for cancer include surgery, chemotherapy, radiation, and/or targeted therapy, which show significant improvement in overall survival. Among the various available treatments, antagonizing VEGF/VEGFR-2 pathways have shown effectiveness in limiting colorectal cancer growth and improving clinical outcomes. In this regard, we hypothesized that F16, a novel VEGFR-2 inhibitor, would control colorectal cancer growth by blocking the VEGFR-2 singling pathway in both in vitro and in vivo conditions. Therefore, the current study was aimed to analyze the efficacy of F16 on the growth of Colo 320DM cells under in vitro and in vivo conditions.

RESULTS

Human RT² profiler PCR array analysis results clearly showed that angiogenesis and anti-apoptosis-related gene expressions were significantly reduced in HUVEC cells after F16 (5 μM) treatment. In addition, Western blot results revealed that F16 attenuated the downstream signaling of the VEGFR-2 pathway in HUVEC cells by up-regulating the p53 and p21 levels and down-regulating the p-AKT and p-FAK levels. Accordingly, F16 confirmed potent cytotoxic effects against the cell viability of Colo 320DM tumors, with an IC₅₀ value of 9.52 ± 1.49 µM. Furthermore, treatment of mice implanted with Colo 320DM xenograft tumors showed a significant reduction in tumor growth and increases in survival rate compared to controls. Immunohistochemistry analysis of tumor tissues showed a reduction in CD31 levels also in F16 treated groups.

CONCLUSIONS

These results justify further evaluation of F16 as a potential new therapeutic agent for treating colorectal cancers.

Oncolytic Virotherapy: From Bench to Bedside

Oncolytic viruses are naturally occurring or genetically engineered viruses that can replicate preferentially in tumor cells and inhibit tumor growth. These viruses have been considered an effective anticancer strategy in recent years. They mainly function by direct oncolysis, inducing an anticancer immune response and expressing exogenous effector genes. Their multifunctional characteristics indicate good application prospects as cancer therapeutics, especially in combination with other therapies, such as radiotherapy, chemotherapy and immunotherapy. Therefore, it is necessary to comprehensively understand the utility of oncolytic viruses in cancer therapeutics. Here, we review the characteristics, antitumor mechanisms, clinical applications, deficiencies and associated solutions, and future prospects of oncolytic viruses.

Combination of anti-angiogenic therapy and immune checkpoint blockade normalizes vascular-immune crosstalk to potentiate cancer immunity

Cancer immunotherapy with immune checkpoint inhibitors (ICIs) has revolutionized the treatment of advanced cancers. However, the tumor microenvironment (TME) functions as a formidable barrier that severely impairs the efficacy of ICIs. While the crosstalk between tumor vessels and immune cells determines the nature of anti-tumor immunity, it is skewed toward a destructive cycle in growing tumors. First, the disorganized tumor vessels hinder CD8⁺ T cell trafficking into the TME, disable effector functions, and even kill T cells. Moreover, VEGF, the key driver of angiogenesis, interferes with the maturation of dendritic cells, thereby suppressing T cell priming, and VEGF also induces TOX-mediated exhaustion of CD8⁺ T cells. Meanwhile, a variety of innate and adaptive immune cells contribute to the malformation of tumor vessels. Protumoral M2-like macrophages as well as T_H2 and Treg cells secrete pro-angiogenic factors that accelerate uncontrolled angiogenesis and promote vascular immaturity. While CD8⁺ T and CD4⁺ T_H1 cells suppress angiogenesis and induce vascular maturation by secreting IFN-γ, they are unable to infiltrate the TME due to malformed tumor vessels. These findings led to preclinical studies that demonstrated that simultaneous targeting of tumor vessels and immunity is a viable strategy to normalize aberrant vascular-immune crosstalk and potentiate cancer immunotherapy. Furthermore, this combination strategy has been evidently demonstrated through recent pivotal clinical trials, granted approval from FDA, and is now being used in patients with kidney, liver, lung, or uterine cancer. Overall, combining anti-angiogenic therapy and ICI is a valid therapeutic strategy that can enhance cancer immunity and will further expand the landscape of cancer treatment.

Angiogenesis in Breast Cancer Progression, Diagnosis, and Treatment

Angiogenesis is a significant event in a wide range of healthy and diseased conditions. This process frequently involves vasodilation and an increase in vascular permeability. Numerous players referred to as angiogenic factors, work in tandem to facilitate the outgrowth of endothelial cells (EC) and the consequent vascularity. Conversely, angiogenic factors could also feature in pathological conditions. Angiogenesis is a critical factor in the development of tumors and metastases in numerous cancers. An increased level of angiogenesis is associated with decreased survival in breast cancer patients. Therefore, a good understanding of the angiogenic mechanism holds a promise of providing effective treatments for breast cancer progression, thereby enhancing patients' survival. Disrupting the initiation and progression of this process by targeting angiogenic factors such as vascular endothelial growth factor (Vegf)-one of the most potent member of the VEGF family- or by targeting transcription factors, such as Hypoxia-Inducible Factors (HIFs) that act as angiogenic regulators, have been considered potential treatment options for several types of cancers. The objective of this review is to highlight the mechanism of angiogenesis in diseases, specifically its role in the progression of malignancy in breast cancer, as well as to highlight the undergoing research in the development of angiogenesis-targeting therapies.

An Exploratory Search for Potential Molecular Targets Responsive to the Probiotic Lactobacillus salivarius PS2 in Women With Mastitis: Gene Expression Profiling vs. Interindividual Variability

Probiotics constitute an attractive alternative in the battle against microbial infections. Oral administration of certain strains of lactobacilli isolated from human milk has resulted in an effective reduction of the bacterial load as well as an improvement of the mastitis-associated symptoms. Nevertheless, little is yet known about the potential molecular mechanisms and specific targets implicated in these effects. Transcriptomic profiling has been used to search for disease-associated and therapy-responsive molecules in different disorders and experimental models. We have applied for the first time a gene expression-based molecular approach to explore for potential targets responsive to intervention with a probiotic in: (i) breast milk somatic cells (n = 17) and (ii) blood leukocytes (n = 19). Women with mastitis ingested a new strain of lactobacilli, Lactobacillus salivarius PS2 (3 × capsules per day, each capsule contained ~9.5 log10 CFU) for 21 days. We applied Affymetrix microarrays and Taqman one-step quantitative reverse transcription PCR (RT-qPCR) to analyze and compare gene expression changes between samples pre- and post-treatment. Our results substantiate the involvement of inflammatory and cell-growth related pathways and genes in the breast milk somatic cells following the intake of L. salivarius PS2. Individual analyses of selected genes: (1) supported the upregulation of STC1 and IL19 and the downregulation of PLAUR and IFNGR1 in the somatic cells of the patients as potential targets responsive to the probiotic, (2) detected a lack of a relationship between the gene expression responses in the two types of cells, and (3) evidenced a substantial interindividual variability in the gene expression changes in both types of cells. Our study provides an insight into the essentiality of incorporating the study of tissue-specific interindividual molecular responsivity into future clinical intervention trials to further understand the complexity of human gene expression responses to therapy and the potentiality of selecting appropriate responsive targets.

DEAE-Dextran coated paclitaxel nanoparticles act as multifunctional nano system for intranuclear delivery to triple negative breast cancer through VEGF and NOTCH1 inhibition

Triple negative breast cancer revolution has identified a plethora of therapeutic targets making it apparent that a single target for its treatment could be rare hence creating an urge to develop robust technologies for combination drug therapy. Paclitaxel, hailed as the most significant advancement in chemotherapy faces several underpinnings due to its low solubility and permeability. Advancing research has demonstrated the role of interferons in cancer. DEAE-Dextran, an emerging molecule with evidence of interferon induction was utilized in the present study to develop a nanoformulation in conjugation with paclitaxel to target multiple therapeutic pathways, with diminution of paclitaxel adverse effects and develop a specific targeted nano system. Evidently, it was demonstrated that DEAE-Dextran coated nanoformulation portrays significant synergistic cytotoxicity in the various cell lines. Moreover, overcoming the activation of ROS by paclitaxel, the combination drug therapy more effectively inhibited ROS through β-interferon induction. The nanoformulation was further conjugated to FITC for internalization studies which subsequently indicated maximum cellular uptake at 60min post treatment demonstrated by green fluorescence from FITC lighting up the nuclear membrane. Precisely, the mechanistic approach of nuclear-targeted nanoformulation was evaluated by in vivo xenograft studies which showed a synergistic release of β-interferon at the target organ. Moreover, the combination nanoformulation inculcated multiple mechanistic approaches through VEGF and NOTCH1 inhibition along with dual β and γ-interferon overexpression. Overall, the combination therapy may be a promising multifunctional nanomaterial for intranuclear drug delivery in TNBC.

Role of β-Interferon Inducer (DEAE-Dextran) in Tumorigenesis by VEGF and NOTCH1 Inhibition along with Apoptosis Induction

As a novel target for breast cancer, interferon inducers have found its role as anti-angiogenic agents with diethylaminoethyl dextran (DEAE-Dextran) being a molecule used for centuries as a transfection agent. Our results herein offer an explanation for the emergence of DEAE-Dextran as an anti-tumor agent for TNBC with in-depth mechanistic approach as an anti-angiogenic molecule. DEAE-Dextran has found to possess cytotoxic activity demonstrated during the various in vitro cytotoxicity assays; moreover, as an anti-oxidant, DEAE-Dextran has shown to possess excellent reactive oxygen species scavenging activity. The interferon inducing capacity of DEAE-Dextran was determined qualitatively as well as quantitatively specifically demonstrating overexpression of β-interferon. As a measure of anti-proliferative activity, DEAE-Dextran exhibited reduced ki67, p53, and PCNA levels. Also, overexpression of CK5/6 and p63 in DEAE-Dextran treated animals indicated improvement in breast cell morphology along with an improvement in cell–cell adhesion by virtue of upregulation of β-catenin and E-cadherin. Anti-angiogenic property of DEAE-Dextran was concluded by the downregulation of CD31, VEGF, and NOTCH1 both in vivo and in vitro. Further, apoptosis due to DEAE-Dextran, initially determined by downregulation of Bcl2, was confirmed with flow cytometry. Overall, results are defensive of DEAE-Dextran as an emerging anti-tumor agent with mechanisms pertaining to β-interferon induction with probable VEGF and NOTCH1 inhibition as well as apoptosis which still needs to be studied in further depth.

Mutations in Human Interferon α2b Gene and Potential as Risk Factor Associated with Female Breast Cancer

The current study explored the potential links between breast cancer and human interferon α-2b (hIFNα-2b) gene mutations. The hIFNα-2b gene was amplified from breast cancer tumor tissue samples (N = 60) by polymerase chain reaction (PCR) and the products were subjected to gene sequencing. A total of 38 (63.3%) samples showed positive PCR amplification results. Several of these also exhibited frequent alterations (mutations) after 400 bp and, in particular, adenine was replaced by other bases. A total of 19 selected mutated amino acids were analyzed for local/general fold pattern changes. Human IFNα-2b receptor (IFNAR): ligand (hIFNα-2b protein) interactions through a Z-DOCK (3.0.2) server were also evaluated to assess the binding patterns of each ligand to receptor to induce Janus-Kinase-signal transducer and activator of transcription antiproliferative signal transduction pathway inside the cancer cells. Certain local structural and conformational changes were predicted to be induced by mutations in the ligand. The variant models of the hIFNα-2b displayed structural and conformational changes that signified that changes to hIFNα-2b may be a risk factor in addition to other known factors associated with onset/progression of female breast carcinoma. It was hoped that others might build upon the research in this study evaluating protein structural models with mutations and their consequent interactions with receptors in the development of potent immune therapeutic drugs for breast cancer that are based on recombinant hIFNα-2b.

Antiangiogenic mechanisms and factors in breast cancer treatment

Breast cancer is known to metastasize in its latter stages of existence. The different angiogenic mechanisms and factors that allow for its progression are reviewed in this article. Understanding these mechanisms and factors will allow researchers to design drugs to inhibit angiogenic behaviors and control the rate of tumor growth.

Blockade of extracellular NM23 or its endothelial target slows breast cancer growth and metastasis

BACKGROUND

Nucleoside Diphosphate Kinase (NDPK), described as NM23 a metastasis suppressor, is found in the culture medium of cancer cells lines suggesting that the kinase may have an extracellular role. We propose that extracellular NM23 released from breast cancers in vivo stimulates tumor cell migration, proliferation and endothelial cell angiogenesis in support of metastasis development.

METHODS

NM23 in the bloodstream of immunocompromised mice carrying human triple-negative breast cancers or in breast cancer patients was measured by ELISA. Primary and metastatic tumor development, the impact of blockade of NM23 and/or its stimulation of nucleotide receptors were measured using in vivo imaging. NM23 expression data in the Curtis breast dataset was examined to test our hypothesis that NM23 may play a mechanistic role in breast cancer development.

RESULTS

SCID mice carrying metastatic MDA-MB-231Luc+ triple-negative human breast tumor cells elaborate NM23 into the circulation correlated with primary tumor growth. Treatment of mice with the NM23 inhibitor ellagic acid (EA) or the purinergic receptor antagonist MRS2179 slowed primary tumor growth. At 16 weeks following implantation, lung metastases were reduced in mice treated with EA, MRS2179 or the combination. Expression of NM23 in the Curtis breast dataset confirmed a likely role for NM23 in tumor metastasis.

CONCLUSIONS

Extracellular NM23 may constitute both a biomarker and a therapeutic target in the management of breast cancer.

Orchestration of angiogenesis by immune cells

It is widely accepted that the tumor microenvironment (TUMIC) plays a major role in cancer and is indispensable for tumor progression. The TUMIC involves many "players" going well beyond the malignant-transformed cells, including stromal, immune, and endothelial cells (ECs). The non-malignant cells can acquire tumor-promoting functions during carcinogenesis. In particular, these cells can "orchestrate" the "symphony" of the angiogenic switch, permitting the creation of new blood vessels that allows rapid expansion and progression toward malignancy. Considerable attention within the context of tumor angiogenesis should focus not only on the ECs, representing a fundamental unit, but also on immune cells and on the inflammatory tumor infiltrate. Immune cells infiltrating tumors typically show a tumor-induced polarization associated with attenuation of anti-tumor functions and generation of pro-tumor activities, among these angiogenesis. Here, we propose a scenario suggesting that the angiogenic switch is an immune switch arising from the pro-angiogenic polarization of immune cells. This view links immunity, inflammation, and angiogenesis to tumor progression. Here, we review the data in the literature and seek to identify the "conductors" of this "orchestra." We also suggest that interrupting the immune → inflammation → angiogenesis → tumor progression process can delay or prevent tumor insurgence and malignant disease.

NOTCH3 signaling regulates MUSASHI-1 expression in metastatic colorectal cancer cells

MUSASHI-1 (MSI-1) is a well-established stem cell marker in both normal and malignant colon cells and it acts by positively regulating the NOTCH pathway through inactivation of NUMB, a NOTCH signaling repressor. To date, the mechanisms of regulation of MSI-1 levels remain largely unknown. Here, we investigated the regulation of MSI-1 by NOTCH signaling in colorectal cancer cell lines and in primary cultures of colorectal cancer metastases. Stimulation by the NOTCH ligand DLL4 was associated with an increase of MSI-1 mRNA and protein levels, and this phenomenon was prevented by the addition of an antibody neutralizing NOTCH2/3 but not NOTCH1. Moreover, forced expression of activated NOTCH3 increased MSI-1 levels, whereas silencing of NOTCH3 by short hairpin RNA reduced MSI-1 levels in both colorectal cancer cells and CRC tumor xenografts. Consistent with these findings, enforced NOTCH3 expression or stimulation by DLL4 increased levels of activated NOTCH1 in colorectal cell lines. Finally, treatment of colorectal cancer cells with anti-NOTCH2/3 antibody increased NUMB protein while significantly reducing formation of tumor cell spheroids. This novel feed-forward circuit involving DLL4, NOTCH3, MSI-1, NUMB, and NOTCH1 may be relevant for regulation of NOTCH signaling in physiologic processes as well as in tumor development. With regard to therapeutic implications, NOTCH3-specific drugs could represent a valuable strategy to limit NOTCH signaling in the context of colorectal cancers overexpressing this receptor.

Treatment of medulloblastoma with oncolytic measles viruses expressing the angiogenesis inhibitors endostatin and angiostatin

Background

Medulloblastoma is the most common type of pediatric brain tumor. Although numerous factors influence patient survival rates, more than 30% of all cases will ultimately be refractory to conventional therapies. Current standards of care are also associated with significant morbidities, giving impetus for the development of new treatments. We have previously shown that oncolytic measles virotherapy is effective against medulloblastoma, leading to significant prolongation of survival and even cures in mouse xenograft models of localized and metastatic disease. Because medulloblastomas are known to be highly vascularized tumors, we reasoned that the addition of angiogenesis inhibitors could further enhance the efficacy of oncolytic measles virotherapy. Toward this end, we have engineered an oncolytic measles virus that express a fusion protein of endostatin and angiostatin, two endogenous and potent inhibitors of angiogenesis.

Methods

Oncolytic measles viruses encoding human and mouse variants of a secretable endostatin/angiostatin fusion protein were designed and rescued according to established protocols. These viruses, known as MV-hE:A and MV-mE:A respectively, were then evaluated for their anti-angiogenic potential and efficacy against medulloblastoma cell lines and orthotopic mouse models of localized disease.

Results

Medulloblastoma cells infected by MV-E:A readily secrete endostatin and angiostatin prior to lysis. The inclusion of the endostatin/angiostatin gene did not negatively impact the measles virus’ cytotoxicity against medulloblastoma cells or alter its growth kinetics. Conditioned media obtained from these infected cells was capable of inhibiting multiple angiogenic factors in vitro, significantly reducing endothelial cell tube formation, viability and migration compared to conditioned media derived from cells infected by a control measles virus. Mice that were given a single intratumoral injection of MV-E:A likewise showed reduced numbers of tumor-associated blood vessels and a trend for increased survival compared to mice treated with the control virus.

Conclusions

These data suggest that oncolytic measles viruses encoding anti-angiogenic proteins may have therapeutic benefit against medulloblastoma and support ongoing efforts to target angiogenesis in medulloblastoma.

Antitumor activities of human placenta-derived mesenchymal stem cells expressing endostatin on ovarian cancer

Endostatin is an important endogenous inhibitor of neovascularization that has been widely used in anti-angiogenesis therapy for the treatment of cancer. However, its clinical application is largely hampered by its low efficacy. Human placenta-derived mesenchymal stem cells (hpMSCs) are particularly attractive cells for clinical use in cell-based therapies. In the present study, hpMSCs were isolated and characterized. We then evaluated the tumor targeting properties and antitumor effects of hpMSCs as gene delivery vehicles for ovarian cancer therapy. We efficiently engineered hpMSCs to deliver endostatin via adenoviral transduction mediated by Lipofectamine 2000. The tropism capacity of the engineered hpMSCs toward tumor cells was then confirmed by in vitro migration assays and in vivo by intraperitoneal injection of hpMSCs into nude mice. The hpMSCs expressing the human endostatin gene demonstrated preferential homing to the tumor site and significantly decreased the tumor volume without apparent systemic toxic effects. These observations were associated with significantly decreased blood sprouts and tumor cell proliferation as well as a dramatically increased tumor apoptosis index. These results suggested that hpMSCs are potentially an effective delivery vehicle for therapeutic genes for the treatment of ovarian cancer.

Gene therapy with recombinant adenovirus encoding endostatin encapsulated in cationic liposome in coxsackievirus and adenovirus receptor-deficient colon carcinoma murine models

Adenovirus (Ad)-based antiangiogenesis gene therapy is a promising approach for cancer treatment. Downregulation or loss of coxsackievirus and adenovirus receptor (CAR) is often detected in various human cancers, which hampers adenoviral gene therapy approaches. Cationic liposome-complexed adenoviral vectors have been proven useful in CAR-deficient cells to enhance therapeutic gene transfer in vivo. Here, we investigated the antitumor effects of recombinant adenovirus encoding endostatin (Ad-hE) encapsulated in cationic liposome (Ad-hE/Lipo) on CAR-deficient CT26 colon carcinoma murine models. In vitro, Ad-hE/Lipo enhanced adenovirus transfection in CAR-deficient cells (CT26), and endostatin gene expression was measured by both qualitative and quantitative detection. In addition, an antibody neutralizing assay indicated that neutralizing serum inhibited naked adenovirus 5 (Ad5) at rather higher dilution than the complexes of Ad5 and cationic liposomes (Ad5-CL), which demonstrated that Ad5-CL was more capable of protecting Ad5 from neutralization. In vivo, Ad-hE/Lipo treatment in the murine CT26 tumor model by intratumoral injection resulted in marked suppression of tumor growth and prolonged survival time, which was associated with a decreased number of microvessels and increased apoptosis of tumor cells. In conclusion, recombinant endostatin adenovirus encapsulated with cationic liposome effectively inhibited CAR-deficient tumor growth through an antiangiogenic mechanism in murine models without marked toxicity, thus showing a feasible strategy for clinical applications.

Efficacy assessment of interferon-alpha-engineered mesenchymal stromal cells in a mouse plasmacytoma model

Bone marrow mesenchymal stromal cells (BM-MSCs) may survive and proliferate in the presence of cycling neoplastic cells. Exogenously administered MSCs are actively incorporated in the tumor as stromal fibroblasts, thus competing with the local mesenchymal cell precursors. For this reason, MSCs have been suggested as a suitable carrier for gene therapy strategies, as they can be genetically engineered with genes encoding for biologically active molecules that can inhibit tumor cell proliferation and enhance the antitumor immune response. We used BM-MSCs engineered with the murine interferon-alpha (IFN-α) gene (BM-MSCs/IFN-α) to assess in a mouse plasmacytoma model the efficacy of this approach toward neoplastic plasma cells. We found that IFN-α can be efficiently produced and delivered inside the tumor microenvironment. Subcutaneous multiple administration of BM-MSCs/IFN-α significantly hampered the tumor growth in vivo and prolonged the overall survival of mice. The antitumor effect was associated with enhanced apoptosis of tumor cells, reduction in microvessel density, and ischemic necrosis. By contrast, intravenous administration of BM-MSCs/IFN-α did not significantly modify the survival of mice, mainly as a consequence of an excessive entrapment of injected cells in the pulmonary vessels. In conclusion, BM-MSCs/IFN-α are effective in inhibiting neoplastic plasma cell growth; however, systemic administration of engineered MSCs needs to be improved to make this approach potentially suitable for the treatment of multiple myeloma.

Functional genomics of endothelial cells treated with anti-angiogenic or angiopreventive drugs

Angiogenesis is a highly regulated physiological process that has been studied in considerable detail given its importance in several chronic pathologies. Many endogenous factors and hormones intervene in the regulation of angiogensis and classical as well as targeted drugs have been developed for its control. Angiogenesis inhibition has come off the bench and entered into clinical application for cancer therapy, particularly for metastatic disease. While the clinical benefit is currently in terms of months, preclinical data suggest that novel drugs and drug combinations could lead to substantial improvement. The many targets of endogenous angiogenesis inhibitors reflect the complexity of the process; in contrast, current clinical therapies mainly target the vascular endothelial growth factor system. Cancer chemopreventive compounds can retard tumor insurgence and delay or prevent metastasis and many of these molecules hinder angiogenesis, a mechanism that we termed angioprevention. Angiopreventive drugs appear to prevalently act through the inhibition of the pro-inflammatory and anti-apoptotic player NFkappaB, thus contrasting inflammation dependent angiogenesis. Relatively little is known concerning the effects of these angiogenesis inhibitors on gene expression of endothelial cells, the main target of many of these molecules. Here we provide an exhaustive list of anti-angiogenic molecules, and summarize their effects, where known, on the transcriptome and functional genomics of endothelial cells. The regulation of specific genes can be crucial to preventive or therapeutic intervention. Further, novel targets might help to circumvent resistance to anti-angiogenic therapy. The studies we review are relevant not only to cancer but also to other chronic degenerative diseases involving endothelial cells, such as cardiovascular disorders, diabetes, rheumatoid arthritis and retinopaties, as well as vessel aging.

Antisense HIF-1alpha prevents acquired tumor resistance to angiostatin gene therapy

Angiostatin is a naturally occurring inhibitor of angiogenesis that is being developed as a drug to fight cancer. In this study we reveal that EL-4 tumors established in mice rapidly develop resistance to angiostatin gene therapy by upregulating hypoxia-inducible pathways. Angiostatin initially delayed tumor growth for 6 days by reducing blood vessel density. However, tumors quickly responded by upregulating the production of hypoxia-inducible factor-1alpha (HIF-1alpha) and its effector vascular endothelial growth factor (VEGF) in response to increasing tumor hypoxia, leading to restored angiogenesis and rapid tumor growth. Theoretically, blockade of HIF-1 should prevent resistance to anti-angiogenic therapy by preventing a tumor from responding to induced hypoxia. Antisense HIF-1alpha inhibited the expression of HIF-1alpha and of the HIF-1 effectors VEGF, glucose transporter-1 and lactate dehydrogenase. As a monotherapy, it was effective in eradicating small 0.1 cm diameter tumors, but only delayed the growth of large 0.4 cm diameter tumors. In contrast, timed injection of a combination of angiostatin and antisense HIF-1alpha plasmids completely eradicated large EL-4 tumors within 2 weeks, and prevented upregulation of hypoxia-inducible pathways induced by angiostatin. The data indicate that blocking hypoxia-inducible pathways by antisense HIF-1alpha can circumvent hypoxia-induced drug resistance and thereby augment the efficacy of anti-angiogenic therapies.

Administration route-dependent induction of antitumor immunity by interferon-alpha gene transfer

Type I interferon (IFN) protein is a cytokine with pleiotropic biological functions that include induction of apoptosis, inhibition of angiogenesis, and immunomodulation. We have demonstrated that intratumoral injection of an IFN-alpha-expressing adenovirus effectively induces cell death of cancer cells and elicits a systemic tumor-specific immunity in several animal models. On the other hand, reports demonstrated that an elevation of IFN in the serum following an intramuscular delivery of a vector is able to activate antitumor immunity. In this study, we compared the intratumoral and systemic routes of IFN gene transfer with regard to the effect and safety of the treatment. Intratumoral injection of an IFN-alpha adenovirus effectively activated tumor-responsive lymphocytes and caused tumor suppression not only in the gene-transduced tumors but also in distant tumors, which was more effective than the intravenous administration of the same vector. The expression of co-stimulatory molecules on CD11c(+) cells isolated from regional lymph nodes was enhanced by IFN gene transfer into the tumors. Systemic toxicity such as an elevation of hepatic enzymes was much lower in mice treated by intratumoral gene transfer than in those treated by systemic gene transfer. Our data suggest that the intratumoral route of the IFN vector is superior to intravenous administration, due to the effective induction of antitumor immunity and the lower toxicity.

Angiogenesis in cutaneous disease: part I

Angiogenesis is an important process in normal physiology and disease pathogenesis. Angiogenesis is controlled in a healthy body by a system of angiogenic growth factors and angiogenesis inhibitors. When angiogenic growth factors are predominantly expressed, blood vessel growth occurs and disease may result. Successful therapies have been developed that target growth factors, their receptors, or the cascade pathways that are activated by growth factor/receptor interactions. There is good evidence that angiogenesis plays an important role in a wide range of cutaneous maladies, and angiogenesis-targeting therapies are playing an increasing role in the management of dermatologic disease. Cutaneous angiogenesis offers an exciting new arena for targeted dermatologic therapeutics.

LEARNING OBJECTIVES

After completing this learning activity, participants should be able to distinguish angiogenic growth factors and inhibitors, recognize angiogenic mediating agents and compare their mechanisms of action, and apply the use of angiogenic mediating agents in clinical and research situations.

Interferon-alpha counteracts the angiogenic switch and reduces tumor cell proliferation in a spontaneous model of prostatic cancer

Interferon (IFN)-alpha is a cytokine with marked therapeutic activity in transplantable tumor models, that is in part due to angiogenesis inhibition. Aim of this study was to investigate the effects of IFN-alpha during the early phases of tumor development in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model. To provide sustained IFN-alpha production, TRAMP mice were injected intraperitoneally with lentiviral vectors. IFN-alpha administration resulted in rapid and protracted upregulation of IFN-alpha-regulated genes associated with antiangiogenic and antiproliferative functions in the prostate of TRAMP mice, including guanylate-binding protein 1 (GBP-1), IFI204 and CXCL10-11. These transcriptional changes were accompanied by effects on the tumor vasculature, including significant reduction of intraductal microvessel density and increased pericyte coverage, and marked reduction of tumor cell proliferation, without induction of tumor necrosis. Intriguingly, GBP-1 and myxovirus resistance A, two IFN-regulated proteins, were found expressed in approximately 40% of human prostate cancer samples analyzed, suggesting expression of endogenous IFN-alpha. Overall, these findings demonstrate that IFN-alpha is able to counteract the angiogenic switch and impairs tumor cell proliferation in preinvasive lesions. Since the angiogenic switch also marks progression of human prostatic cancer, these results highlight the potential of angiogenesis inhibitors for the development of chemoprevention strategies in high-risk individuals.

Nm23-H1/nucleoside diphosphate kinase as a key molecule in breast tumor angiogenesis

BACKGROUND

Neo-angiogenesis seems to be a critical feature of breast tumor growth, migration and metastasis. Inhibition of angiogenesis may provide information regarding treatment. Since angiogenesis is the result of complex processes, controlled by several angiogenic (pro- and/or -anti) factors and their receptors, multiple ways to prevent or retrogress tumor-induced angiogenesis have been proposed. The clinically significant activity of bevacizumab and other antiangiogenic treatments have attracted a great deal of interest.

OBJECTIVE/METHODS

We discuss biological aspects of breast cancer angiogenesis and nucleoside diphosphate kinase (NDPK) as a key molecule in this process.

RESULTS/CONCLUSIONS

In clinical and experimental trials, it was reported that NDPK is inversely related to breast cancer metastasis and angiogenesis. To inhibit the metastatic potential of cancer cells, Nm23-H1/NDP kinase appears to interact with many proteins involved in cellular signal transduction in angiogenesis and tumorigenesis, and therefore reduces the activation of the extracellular signal-regulated kinase (ERK)/MAPK in response to those signals.

Role of prolactin and vasoinhibins in the regulation of vascular function in mammary gland

The formation of new blood vessels has become a major focus of mammary gland research stimulated by the therapeutic opportunities of controlling angiogenesis in breast cancer. Normal growth and involution of the mammary gland are profoundly affected by the expansion and regression of blood vessels, whereas dysregulation of angiogenesis is characteristic of breast cancer growth and metastasis. Prolactin stimulates the growth and differentiation of the mammary gland under normal conditions, but its role in breast cancer is controversial. Its action is complicated by the fact that prolactin itself is angiogenic, but proteases cleave prolactin to generate vasoinhibins, a family of peptides that act on endothelial cells to suppress angiogenesis and vasodilation and to promote apoptosis-mediated vascular regression. This review summarizes our current knowledge about the vascular effects of prolactin and the generation and action of vasoinhibins, and discusses their possible contribution to the regulation of blood vessels in the normal and malignant mammary gland.

Targeting angiogenesis in pancreatic cancer: rationale and pitfalls

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer responsible for over 20% of deaths due to gastrointestinal malignancies. PDAC is usually diagnosed at an advanced stage which, in part, helps to explain its high resistance to chemotherapy and radiotherapy. In addition, the cancer cells in PDAC have a high propensity to metastasize and to aberrantly express several key regulators of angiogenesis and invasion. Chemotherapy has only provided a modest impact on mean survival and often induces side effects. Targeting angiogenesis alone or in combination with other modalities should be investigated to determine if it may provide for increased survival.

MATERIALS AND METHODS

This review summarizes the alterations in PDAC that play a critical role in angiogenesis and provides an overview of current and therapeutic strategies that may be useful for targeting angiogenesis in this malignancy.

The role of angiogenesis in endocrine liver metastases: an experimental study

Liver metastases are a major adverse event during the evolution of digestive endocrine tumors. However, little is known about their natural history and the determinants of their growth. In particular, whereas liver endocrine metastases, like their primary counterparts, are hypervascular, the role of tumor-associated angiogenesis has been little explored. We therefore designed an experimental model to study the intrahepatic growth of tumor endocrine cells; murine enteroendocrine STC-1 cells were injected into the spleen of nude mice to obtain their hepatic dissemination through the portal vein. Three stages of intrahepatic tumor growth were identified. Engraftment stage, until day 4 after intrasplenic injection of STC-1 cells, was avascular. Early growth, until day 17, resulted in small, infralobular nodules. Late growth, after day 17, was characterized by the development of large nodules associated with peritumoral vessels and containing abnormal intratumoral vessels. To test the effects of potentially anti-angiogenic agents on tumor growth, we then used STC-1 cells stably transfected with the endostatin-coding sequence. Intrahepatic tumor volume showed no significant change at days 4 and 8, but a dramatic decrease at day 28 (9.7 +/- 1.7% of liver tissue versus 25.2 +/- 2.4% in controls), because of a markedly lower number of large nodules (11 +/- 1.8% versus 42 +/- 5.8%) likely to result from an increased apoptotic index (39.4 +/- 5.6% versus 18.3 +/- 3.4). Our results suggest that active angiogenesis is not necessary for the engraftment and early growth of endocrine cells metastatic to the liver but is required at a later stage of progression.

Regulation of COX-2 mediated signaling by alpha3 type IV noncollagenous domain in tumor angiogenesis

Human alpha3 chain, a noncollagenous domain of type IV collagen [alpha3(IV)NC1], inhibits angiogenesis and tumor growth. These biologic functions are partly attributed to the binding of alpha3(IV)NC1 to alphaVbeta3 and alpha3beta1 integrins. alpha3(IV)NC1 binds alphaVbeta3 integrin, leading to translation inhibition by inhibiting focal adhesion kinase/phosphatidylinositol 3-kinase/Akt/mTOR/4E-BP1 pathways. In the present study, we evaluated the role of alpha3beta1 and alphaVbeta3 integrins in tube formation and regulation of cyclooxygenase-2 (COX-2) on alpha3(IV)NC1 stimulation. We found that although both integrins were required for the inhibition of tube formation by alpha3(IV)NC1 in endothelial cells, only alpha3beta1 integrin was sufficient to regulate COX-2 in hypoxic endothelial cells. We show that binding of alpha3(IV)NC1 to alpha3beta1 integrin leads to inhibition of COX-2-mediated pro-angiogenic factors, vascular endothelial growth factor, and basic fibroblast growth factor by regulating IkappaBalpha/NFkappaB axis, and is independent of alphaVbeta3 integrin. Furthermore, beta3 integrin-null endothelial cells, when treated with alpha3(IV)NC1, inhibited hypoxia-mediated COX-2 expression, whereas COX-2 inhibition was not observed in alpha3 integrin-null endothelial cells, indicating that regulation of COX-2 by alpha3(IV)NC1 is mediated by integrin alpha3beta1. Our in vitro and in vivo findings demonstrate that alpha3beta1 integrin is critical for alpha3(IV)NC1-mediated inhibition of COX-2-dependent angiogenic signaling and inhibition of tumor progression.

Gene modulatory effects, pharmacokinetics, and clinical tolerance of interferon-alpha1b: a second member of the interferon-alpha family

Interferon-alpha1 (IFN-alpha1), which may have a primary role in innate immunity, differs significantly in amino-acid sequence from IFN-alpha2, the only recombinant IFN-alpha with substantial clinical evaluation. Patients with metastatic malignancies received daily subcutaneous doses of 1.5-270 mug/m(2) of recombinant IFN-alpha1b. Gene modulation, pharmacokinetics, tolerability, and disease response were determined. Significant (P<0.01) dose and gene-dependent increases of 2-10 fold occurred in IFN-stimulated genes, including four (tumor necrosis factor-related apoptosis-inducing ligand, cig 5, p56, GEM) never previously identified as increased in patients; significant increases (P<0.01) resulted at the lowest dose (1.5 microg/m(2); 1.5 x 10(4) human antiviral units/m(2)). Increases (P<0.01) were sustainable for >4 weeks. Peak levels of IFN-alpha1b were at 3 h; an increase of approximately eightfold in both C(max) and AUC occurred between 15 microg/m(2) and 270 microg/m(2). Chronic toxicities of anorexia, weight loss, and fatigue were relatively uncommon. Eighteen patients were treated for >8 weeks; none experienced >grade 1 weight loss. Three patients at the highest dose developed grade 3 fatigue after > or =3 months, which required dose reduction or discontinuation. Patient acceptability of fatigue defined a dose for initiation of Phase II trials, 270 microg/m(2). Six patients (five with renal cell carcinoma) had progression-free survival for >1 year, including two who had partial responses. IFN-alpha1b resulted in potent stimulation of IFN-regulated genes and tumor regressions in renal cell carcinoma. Unique gene modulatory effects, when coupled with the moderate severity of side effects and a potentially central role in innate immunity, provide rationale for further clinical evaluation of IFN-alpha1 in virus infections and cancer.

Local interferon-? gene therapy elicits systemic immunity in a syngeneic pancreatic cancer model in hamster

The interferon (IFN) protein is a cytokine with pleiotropic biological functions that include induction of apoptosis, inhibition of angiogenesis and immunomodulation. We previously examined the two antitumor mechanisms, taking advantage of the fact that IFN-alpha did not show cross-species activity in its in vivo effect. In a nude mouse subcutaneous xenograft model using human pancreatic cancer cells, the expression of human IFN-alpha effectively induced cell death of human pancreatic cancer cells, whereas mouse IFN-alpha augmented antitumor immunity by stimulation of natural killer cells. Here, we extended our investigation to a syngeneic pancreatic cancer model, so that the integrated antitumor activity of local IFN-alpha gene therapy, including the antiproliferative, proapoptotic, antiangiogeneic and immunomodulatory effects, can be evaluated rigorously. When a recombinant hamster IFN-alpha adenovirus was injected into syngeneic subcutaneous tumors of hamster pancreatic cancer (PGHAM-1) cells in Syrian hamster, tumor growth was significantly suppressed due to cell death and T cell- and natural killer cell-mediated antitumor immunity. Moreover, in this case, tumor regression was observed not only for the injected subcutaneous tumors but also for the untreated tumors both in the peritoneal cavity and at distant sites. No significant systemic toxicity was observed in the treated hamsters. Moreover, the subcutaneous rechallenge of PGHAM-1 cells was rejected in three of four cured hamsters from the initial tumor challenge. This study further demonstrated that local IFN-alpha gene therapy is a promising therapeutic strategy for pancreatic cancer, due to its multiple mechanisms of antitumor activity and its lack of significant toxicity.

Identification of genes selectively regulated by IFNs in endothelial cells

IFNs are highly pleiotropic cytokines also endowed with marked antiangiogenic activity. In this study, the mRNA expression profiles of endothelial cells (EC) exposed in vitro to IFN-alpha, IFN-beta, or IFN-gamma were determined. We found that in HUVEC as well as in other EC types 175 genes were up-regulated (>2-fold increase) by IFNs, including genes involved in the host response to RNA viruses, inflammation, and apoptosis. Interestingly, 41 genes showed a >5-fold higher induction by IFN-alpha in EC compared with human fibroblasts; among them, the gene encoding the angiostatic chemokine CXCL11 was selectively induced by IFN-alpha in EC along with other genes associated with angiogenesis regulation, including CXCL10, TRAIL, and guanylate-binding protein 1. These transcriptional changes were confirmed and extended by quantitative PCR analysis and ELISA; whereas IFN-alpha and IFN-beta exerted virtually identical effects on transcriptome modulation, a differential gene regulation by type I and type II IFN emerged, especially as far as quantitative aspects were concerned. In vivo, IFN-alpha-producing tumors overexpressed murine CXCL10 and CXCL11, guanylate-binding protein 1, and TRAIL, with evidence of CXCL11 production by tumor-associated EC. Overall, these findings improve our understanding of the antiangiogenic effects of IFNs by showing that these cytokines trigger an antiangiogenic transcriptional program in EC. Moreover, we suggest that quantitative differences in the magnitude of the transcriptional activation of IFN-responsive genes could form the basis for cell-specific transcriptional signatures.

Angiogenesis meets immunology: Cytokine gene therapy of cancer

Delivery of cytokine genes at the tumor site in pre-clinical models has been shown to recruit host inflammatory cells followed by inhibition of tumor growth. This local effect is often accompanied by systemic protection mediated by the immune system, mainly by CD8(+) T and NK cells. On this basis, cytokine gene-transduced tumor cells have widely been used as vaccines in clinical trials, which have shown good safety profiles and some local responses but substantial lack of systemic efficacy. Are these findings the end of the story? Possibly not, if major improvements will be attained in the coming years. These should be directed at the level of gene selection and delivery, in order to identify the optimal cytokine and achieve efficient and durable cytokine expression, and at the level of improving immune stimulation, i.e. by co-administration of co-stimulatory molecules including B7 and CD40, or boosting the expression of tumor antigens or MHC class I molecules. Interestingly, some of the cytokines which have shown encouraging anti-tumor activity, including IFNs, IL-4, IL-12 and TNF-alpha, are endowed with anti-angiogenic or vasculotoxic effects, which may significantly contribute to local tumor control. Therapeutic exploitation of this property may result in the design of novel approaches which, by maximizing immune-stimulating and anti-angiogenic effects, could possibly lead to starvation of established tumors in patients.

Anti-angiogenic gene therapy of cancer: current status and future prospects

The discovery of endogenous inhibitors of angiogenesis has made it possible to test the hypothesis that blocking the angiogenic switch may keep tumor growth in check, and has added a new investigational arm to the field of cancer gene therapy. Angiogenesis inhibitors are heterogeneous in origin and potency, and their growing list includes proteolysis products of larger molecules with a different function, such as angiostatin, endostatin and vasostatin, modulators of vascular endothelial growth factor activity, such as sFLT-1, and some cytokines/chemokines with marked anti-endothelial activity, such as IL-12, IFN-alpha, and CXCL10. Pre-clinical studies have clearly indicated that these factors are essentially cytostatic and that they need long-term administration in order to obtain prolonged anti-tumor effects, representing a rational basis for their delivery by a gene therapy approach. The experimental approaches attempted to date, reviewed herein, indicate overall that anti-angiogenic gene therapy has efficacy mainly as an early intervention strategy and that a better understanding of the biological mechanisms underlying resistance to angiogenesis inhibition, as well as appropriate combined treatments, are required to generate a conceptual advancement which could drive the field towards successful management of established tumors.

Tumor-specific expression of the RGD-alpha3(IV)NC1 domain suppresses endothelial tube formation and tumor growth in mice

Angiogenesis plays an essential role in tumor growth. This study investigated expression of the noncollagenous domain of alpha3(IV) collagen (alpha3(IV)NC1) transduced into tumors and its inhibition of tumor growth. We hypothesized that if a human telomerase reverse transcriptase (hTERT) promoter-driven RGD motif containing alpha3(IV)NC1 (hTERT/RGD-alpha3(IV)NC1) were expressed in telomerase-expressing tumor cells, it would inhibit tumor growth by its anti-angiogenic property. Adenoviral transduction of hTERT/RGD-alpha3(IV)NC1 expressed RGD-alpha3(IV)NC1 in hTERT-positive tumor cell lines. However, hTERT/RGD-alpha3(IV)NC1 did not express RGD-alpha3(IV)NC1 in hTERT-negative cells such as keratinocytes and fibroblasts. The secreted RGD-alpha3(IV)NC1 in the conditioned medium from tumor cells inhibited cell proliferation as well as tube formation in cultured endothelial cells, but had no effect on other types of cells. In an in vivo model, adenoviral hTERT/RGD-alpha3(IV)NC1 gene therapy showed limited expression of RGD-alpha3(IV)NC1 in tumors and resulted in a significant decrease of vessel density in tumors. The growth of subcutaneous (s.c.) tumors in nude mice was significantly suppressed by treatment with hTERT/RGD-alpha3(IV)NC1. In addition, long-term inhibition of tumor growth was achieved by intermittent administration of hTERT/RGD-alpha3(IV)NC1. In conclusion, our findings demonstrate that tumor-specific anti-angiogenic gene therapy utilizing RGD-alpha3(IV)NC1 under the hTERT promoter inhibited angiogenesis in tumors, resulting in an antitumor effect.

Endostatin inhibits VEGF-A induced osteoclastic bone resorption in vitro

Background

Endostatin is a C-terminal fragment of collagen XVIII which is a component of basement membranes with the structural properties of both collagens and proteoglycans. Endostatin has a major role in angiogenesis which is intimately associated with bone development and remodeling. Signaling between the endothelial cells and the bone cells, for example, may have a role in recruitment of osteoclastic precursor cells. Our study aims at exploring a possibility that endostatin, either as a part of basement membrane or as a soluble molecule, may control osteoclastogenesis and osteoclastic bone resorption in vitro.

Methods

Rat pit formation assay was employed in order to examine the effect of endostatin alone or in combination with vascular endothelial growth factor-A (VEGF-A) on bone resorption in vitro. Effect of these agents on osteoclast differentiation in vitro was also tested. Osteoclastogenesis and the number of osteoclasts were followed by tartrate resistant acid phosphatase (TRACP) staining and resorption was evaluated by measuring the area of excavated pits.

Results

Endostatin inhibited the VEGF-A stimulated osteoclastic bone resorption, whereas endostatin alone had no effect on the basal resorption level in the absence of VEGF-A. In addition, endostatin could inhibit osteoclast differentiation in vitro independent of VEGF-A.

Conclusion

Our in vitro data indicate that collagen XVIII/endostatin can suppress VEGF-A induced osteoclastic bone resorption to the basal level. Osteoclastogenesis is also inhibited by endostatin. The regulatory effect of endostatin, however, is not critical since endostatin alone does not modify the basal bone resorption.

Liposome-mediated gene transfer of K1-5 suppresses tumor development and improves the prognosis of hepatocellular carcinoma in mice

It has been reported that kringle 1-5 (K1-5) has a potent and specific antiangiogenic activity. In the present study, we investigated the antitumor effect of gene transfer of K1-5 for hepatocellular carcinoma in mice. Inhibitory effect by the media of Cos-1 cells containing K1-5 on bovine capillary endothelial (BCE) cell proliferation was evaluated by a tetrazolium-based assay. For tumor growth, intrahepatic metastasis, and survival studies, intravenous injection of liposome-K1-5 cDNA complexes was performed to nude mice implanted with three hepatoma cell lines into the liver. Production of K1-5 was investigated by immunohistochemistry and Western blotting. The number of vessels in the tumor was counted in 0.125 mm2 fields. Expression of vascular endothelial growth factor (VEGF) and angiopoietin (Ang)-1 and -2 in tumors was investigated by Western blotting. Serum ALT levels and body weight of the mice were measured. Proliferation of BCE cells was inhibited by 44% in the media containing K1-5. Gene transfer of K1-5 suppressed tumor growth of the three hepatoma cell lines, respectively. In the K1-5-treated group, survival period was prolonged and the number of intrahepatic metastases was reduced. Expression of K1-5 protein was detected on hepatoma cells and hepatocytes. The number of vessels in tumor tissues was decreased by K1-5 transfection. Expression of angiopoietin-2 in tumor tissues was suppressed by K1-5 transfection. Serum ALT levels and body weight of mice were not influenced by K1-5 transfection. These findings suggest that antiangiogenic gene therapy with K1-5 cDNA will be a safe and effective strategy to suppress the growth of hepatocellular carcinoma.

A high risk of occurrence of sporadic breast cancer in individuals with the 104NN polymorphism of the COL18A1 gene

We investigated the influence of the polymorphism D104N of the COL18A1 gene, encoding endostatin, on the occurrence of sporadic breast cancer in 181 patients and 448 controls. The homozygous 104NN polymorphism was found in five patients but was absent in controls (2.8% vs 0.0%; P = 0.002). Individuals with this genotype had a significantly increased risk for disease. Our results suggest, for the first time, that the homozygous 104NN polymorphism, even at low frequency, constitutes an important inherited determinant of the disease.

Antitumor efficacy improved by local delivery of species-specific endostatin

OBJECT

Conflicting results have been reported concerning the antitumor efficacy of the angiogenesis inhibitor endostatin. This may be due to differences in the biological distribution of endostatin between studies or to the varying biological efficacies of the different protein forms that were examined. To address this issue, the authors used a local delivery approach in which each tumor cell secreted endostatin, providing uniform endostatin levels throughout the tumors. This allowed a direct assessment of the biological efficacy of soluble endostatin in vivo.

METHODS

The authors genetically engineered BT4C gliosarcoma cells so that they would stably express and secrete either the human or murine form of endostatin. Endostatin-producing cells or mock-infected cells were implanted intracerebrally in syngeneic BD-IX rats. The antitumor efficacy of endostatin was evaluated on the basis of survival data and tumor volume comparisons. In addition, microvascular parameters were assessed. The authors confirmed the continuous release of endostatin by the BT4C cells. A magnetic resonance imaging-assisted comparison of tumor volumes revealed that local production of murine endostatin significantly inhibited tumor growth. Notably, 40% of the animals in this treatment group experienced long-term survival without histologically verifiable tumors 7 months after cell implantation. After local treatment with murine endostatin, tumor blood plasma volumes were reduced by 71%, microvessel density counts by 84%, and vascular area fractions by 75%. In contrast, human endostatin did not inhibit tumor growth significantly in this model. Centrally located regions of necrosis were present in tumors secreting both the human and the murine species-specific form of endostatin.

CONCLUSIONS

The results suggest that endostatin inhibits tumor angiogenesis in vivo in a species-specific manner.

Interruption of tumor dormancy by a transient angiogenic burst within the tumor microenvironment

Tumor growth is currently viewed as a phenomenon associated with neovascularization and sustained production of angiogenic factors, but whether a transient angiogenic switch may trigger tumor growth remains unclear. Here, we report that leukemia cells (MOLT-3) were poorly angiogenic and remained dormant when injected s.c. into immunodeficient mice. However, progressive growth of lymphoid tumors was invariably recorded when irradiated angiogenic cells from Kaposi's sarcoma (KS-IMM) were locally coinjected with MOLT-3 cells or administered later. The persistence of KS-IMM cells in vivo was tracked by flow cytometry and real-time PCR analysis, and it was limited to a few days, during which angiogenesis was induced and preceded tumor growth. The engraftment of other types of poorly tumorigenic cancer cells was also greatly improved by irradiated KS-IMM cells. Moreover, short-term treatment with angiogenic factors, including basic FGF or VEGF, either given as recombinant factors or delivered by retroviral vectors, also accelerated tumor growth. These findings may emphasize that tumor angiogenesis is a process requiring a higher amount of angiogenic factors for its induction than maintenance.

Gene therapy of ovarian cancer with IFN-alpha-producing fibroblasts: comparison of constitutive and inducible vectors

Ovarian cancer represents a malignancy suitable for cell and gene therapy approaches owing to its containment within the peritoneal cavity, even at advanced tumor stages. As regulation of transgene expression would be preferable for conducting clinical trials for reasons of safety, we investigated whether intraperitoneal (i.p.) administration of retroviral vector-transduced fibroblasts encoding murine interferon-alpha (IFN-alpha) could have therapeutic activity, and compared its effect with the antitumor effects of fibroblasts producing IFN-alpha under a rapamycin analogue (AP21967)-inducible promoter. Human and murine fibroblasts were recruited into the solid component of transplantable ovarian cancer-grown i.p. in severe combined immunodeficiency mice. Multiple administrations of fibroblasts producing IFN-alpha in a constitutive manner showed therapeutic efficacy, leading to significant prolongation of survival in the majority of animals, associated with inhibition of tumor angiogenesis. Compared to cells transduced by the constitutive vector, fibroblasts transduced by the inducible vector released twofold higher IFN-alpha levels in vitro, following induction by AP21967, and production of the cytokine was under pharmacologic control both in vitro and in vivo. However, these cells elicited only modest therapeutic effects in vivo. Overall, these findings indicate that intracavitary IFN-alpha gene therapy using engineered fibroblasts requires sustained production of IFN-alpha to achieve durable antitumor effects.

Interferon-alpha gene therapy by lentiviral vectors contrasts ovarian cancer growth through angiogenesis inhibition

Ovarian cancer represents a suitable disease for gene therapy because of the containment of neoplastic cells in the peritoneal cavity even at advanced tumor stages. The aim of this study was to investigate whether intraperitoneal administration of a lentiviral vector encoding murine interferon-alpha (LV-IFN) could have therapeutic activity in a transplantable ovarian cancer model. Multiple injections of low amounts of LV-IFN into severe combined immunodeficiency (SCID) mice bearing IGROV-1 or OC316 ovarian cancer cells elicited remarkable antitumor activity, leading to prolongation of survival in the majority of animals. A definitive cure was obtained in animals bearing PD-OVA#1 tumors, generated by injecting tumor cells isolated from the ascitic fluid of a patient into SCID mice. Interferon-alpha levels were detected in the peritoneal fluids but not in the serum of treated mice, indicating that production of the cytokine is mainly local, by both tumor and normal cells of the host. Antitumor effects were associated with a remarkable decrease in the formation of hemorrhagic ascites, an increase in ischemic tumor necrosis, and a reduction in microvessel density. In conclusion, our findings show that intracavitary IFN-alpha gene therapy, using a lentiviral vector, provides strong antitumor effects in murine models of ovarian cancer and reinforces the evidence that angiogenesis inhibition is a promising strategy for the treatment of localized tumors.

Adenovirus-mediated interferon alpha gene transfer induces regional direct cytotoxicity and possible systemic immunity against pancreatic cancer

We previously demonstrated a characteristically high sensitivity of pancreatic cancer cells to interferon alpha (IFN-alpha) gene transfer, which induced a more prominent growth suppression and cell death in pancreatic cancer cells than in other types of cancers and normal cells. The IFN-alpha protein can exhibit both direct cytotoxicity and indirect immunological antitumour activity. Here, we dissected and examined the two mechanisms, taking advantage of the fact that IFN-alpha did not show any cross-species activity in its in vivo effect. When a human IFN-alpha adenovirus was injected into subcutaneous xenografts of human pancreatic cancer cells in nude mice, tumour growth was significantly suppressed due to cell death in an adenoviral dose-dependent manner. The IFN-alpha protein concentration was markedly increased in the injected subcutaneous tumour, but leakage of the potent cytokine into the systemic blood circulation was minimal. When a mouse IFN-alpha adenovirus was injected into the same subcutaneous tumour system, all mice showed significant tumour inhibition, an effect that was dependent on the indirect antitumour activities of IFN-alpha, notably a stimulation of natural killer cells. Moreover, in this case, tumour regression was observed not only for the injected subcutaneous tumours but also for the untreated tumours at distant sites. This study suggested that a local IFN-alpha gene therapy is a promising therapeutic strategy for pancreatic cancer, due to its dual mechanisms of antitumour activities and lack of significant toxicity.

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.

Endostatin cDNA/cationic liposome complexes as a promising therapy to prevent lung metastases in osteosarcoma: study in a human-like rat orthotopic tumor

Antiangiogenesis or destruction of tumor neovessels is an effective strategy to prevent tumor growth. Endostatin, one of the many inhibitors of angiogenesis that have been discovered, has shown conflicting results in preclinical assays. We studied the therapeutic potential of lipid/DNA complexes consisting of cationic liposomes and an endostatin-coding plasmid (Endo cDNA/CLP) in an orthotopic osteosarcoma model in rats. Empty plasmid without the endostatin gene complexed with cationic liposomes served as control. Animals were treated intravenously three times a week starting on the day tumors were detectable by (18)FDG tomoscintigraphy. During treatment, tumor progression was followed by PET scan and angioscintigraphy, and the effects of antivascular therapy on primary tumor, metastases, and tumor vascular density were confirmed by histologic analysis. Our results demonstrate that therapy using Endo cDNA/CLP is associated with pronounced delay in tumor growth. Moreover, it effectively prevented the occurrence of lung metastases, the major reason for bad prognosis and death in osteosarcoma patients. This approach could be used as an adjuvant therapy for osteosarcoma.