Angiogenesis meets immunology: Cytokine gene therapy of cancer

miR-23a-3p is a Key Regulator of IL-17C-Induced Tumor Angiogenesis in Colorectal Cancer

MicroRNAs (miRNAs) have emerged as key players in tumor angiogenesis. Interleukin-17C (IL-17C) was identified to promote colorectal cancer (CRC) progression. Therefore, we aimed to investigate the effect of IL-17C on tumor angiogenesis, the involvement of miR-23a-3p in IL-17C signaling, and the direct target gene of miR-23a-3p in CRC. In vitro and ex vivo angiogenesis, a mouse xenograft experiment, and immunostaining were performed to test the effect of IL-17C on tumor angiogenesis. ELISA, quantitative real time PCR, and gene silencing were used to uncover the underlying mechanism. IL-17C induced angiogenesis of intestinal endothelial cells, subsequently enhancing cell invasion and migration of DLD-1 cells. IL-17C-stimulated DLD-1 cells produced vascular endothelial growth factor (VEGF) to enhance angiogenesis. Moreover, IL-17C markedly accelerated xenograft tumor growth, which was manifested by substantially reduced tumor growth when treated with the VEGF receptor 2 inhibitor Ki8751. Accordingly, Ki8751 suppressed the expression of IL-17C-stimulated PECAM and VE-cadherin in xenografts. Furthermore, IL-17C activated STAT3 to increase the expression of miR-23a-3p that suppressed semaphorin 6D (SEMA6D) expression, thereby permitting VEGF production. Taken together, our study demonstrates that IL-17C promotes tumor angiogenesis through VEGF production via a STAT3/miR-23a-3p/SEMA6D axis, suggesting its potential as a novel target for anti-CRC therapy.

Retinal neurons curb inflammation and enhance revascularization in ischemic retinopathies via proteinase-activated receptor-2

Ischemic retinopathies are characterized by sequential vaso-obliteration followed by abnormal intravitreal neovascularization predisposing patients to retinal detachment and blindness. Ischemic retinopathies are associated with robust inflammation that leads to generation of IL-1β, which causes vascular degeneration and impairs retinal revascularization in part through the liberation of repulsive guidance cue semaphorin 3A (Sema3A). However, retinal revascularization begins as inflammation culminates in ischemic retinopathies. Because inflammation leads to activation of proteases involved in the formation of vasculature, we hypothesized that proteinase-activated receptor (Par)-2 (official name F2rl1) may modulate deleterious effects of IL-1β. Par2, detected mostly in retinal ganglion cells, was up-regulated in oxygen-induced retinopathy. Surprisingly, oxygen-induced retinopathy-induced vaso-obliteration and neovascularization were unaltered in Par2 knockout mice, suggesting compensatory mechanisms. We therefore conditionally knocked down retinal Par2 with shRNA-Par2-encoded lentivirus. Par2 knockdown interfered with normal revascularization, resulting in pronounced intravitreal neovascularization; conversely, the Par2 agonist peptide (SLIGRL) accelerated normal revascularization. In vitro and in vivo exploration of mechanisms revealed that IL-1β induced Par2 expression, which in turn down-regulated sequentially IL-1 receptor type I and Sema3A expression through Erk/Jnk-dependent processes. Collectively, our findings unveil an important mechanism by which IL-1β regulates its own endothelial cytotoxic actions by augmenting neuronal Par2 expression to repress sequentially IL-1 receptor type I and Sema3A expression. Timely activation of Par2 may be a promising therapeutic avenue in ischemic retinopathies.

Inhibition of vascular endothelial growth factor-mediated angiogenesis involved in reproductive toxicity induced by sesquiterpenoids of Curcuma zedoaria in rats

The use of herbal medicine has rapidly increased in recent decades, prompting an increase in toxicity concerns. Here we investigated whether and how essential oil of Curcuma zedoaria may induce reproductive and developmental toxicity. Whole embryo culture in rats revealed that the essential oil produced a concentration-dependent toxicity ex vivo in the embryos on gestation Day 9.5 (GD9.5). Weight loss, abnormal hematological and biochemical effects on dams and embryos were also observed in GD17 pregnant rats orally administrated with 100mgkg(-1) or 200mgkg(-1) essential oil from GD7 onward. Induction of embryotoxicity may be related to placental calcification attributed to inhibition of vascular endothelial growth factor (VEGF)-mediated angiogenesis. Analysis by gas chromatography-mass spectrometry demonstrated that the main toxic compounds in essential oil were sesquiterpenoids. Our results suggest that the reproductive toxicity of C. zedoaria may be caused by sesquiterpenoids in the essential oil blocking VEGF-mediated angiogenesis.

The role of peroxisome proliferator-activated receptors in colorectal cancer

Colorectal cancer is one of the most common cancers in the world. Dietary fat intake is a major risk factor for colorectal cancer. Some nuclear hormone receptors play an important role in regulating nutrient metabolism and energy homeostasis. Among these receptors, special attention has been focused on the role of peroxisome proliferator-activated receptors (PPARs) in colorectal cancer, because PPARs are involved in regulation of lipid and carbohydrate metabolism. PPARs are ligand-activated intracellular transcription factors. The PPAR subfamily consists of three subtypes encoded by distinct genes named PPARα, PPARβ/δ, and PPARγ. PPARγ is the most extensively studied subtype of PPARs. Even though many investigators have studied the expression and clinical implications of PPARs in colorectal cancer, there are still many controversies about the role of PPARs in colorectal cancer. In this paper, the recent progresses in understanding the role of PPARs in colorectal cancer are summarized.

The immunomodulatory effects of Sutherlandia frutescens extracts in human normal peripheral blood mononuclear cells

Sutherlandia frutescens (SF) is one of the medicinal plants used as an immune booster in the treatment of chronic ailments such as HIV/AIDS and cancer. Limited data suggest that its efficacy is based on its regulatory effect on cytokines, the critical components of the immune response. In this study, we investigated the in vitro immunomodulatory effects of SF extracts on normal human peripheral blood mononuclear cells (PBMCs). An ELISA-based assay was used to assess the levels of expression of 12 cytokines in treated cells. An adenosine triphosphate (ATP) assay was used to assess cell viability in relation to cytokine secretion. SF ethanol extracts induced changes in cytokine secretion relative to the dose of the extract. Generally cytokine expression and secretion was low in concentration because were not stimulated with any endotoxin. The high SFE dose (2.5 mg/ml) significantly (p<0.001) decreased some cytokines including TNF-α and IL 1β. Low doses of this extract (0.5 mg/ml) did not change TNF-α and IL 1β secretion from the baseline (untreated cells). Changes in cytokine secretion of SFE treated cells tracked changes in ATP levels (cell viability). The SFW extract-induced changes in cytokine secretion were independent of cell viability. TNF-α was decreased (p<0.001) by the high dose of SFW extract while IL 1β and IFNγ were increased (p<0.01) by the same dose. High doses decreased cell viability which was reflected in cytokine secretion. It is evident, from these results, that SF extracts can modulate cytokine secretion in unstimulated normal PBMCs in vitro. Further studies in animal models are recommended to advance understanding of this immunomodulatory activity.

Lycopene inhibits angiogenesis in human umbilical vein endothelial cells and rat aortic rings

Angiogenesis is important for tumour vascularisation and growth, and is therefore a promising target for cancer therapy. The present study reports inhibition ofin vitroangiogenesis in human umbilical vein endothelial cells (HUVEC) as well as in rat aortic rings at physiological concentrations of lycopene, that is, 1–2 μmol/l. At a final concentration of 1·15 μmol/l, a significant reduction (P < 0·05) in network branching, that is, junction numbers, the number of tubules and tubule length, was observed in both HUVEC as well as in the rat aortic rings. The inhibitory effect of lycopene was independent of the presence of the pro-angiogenic agents, vascular endothelial growth factor and TNF-α. The anti-angiogenic effects of lycopene in the present study were shown at a concentration that should be achievable by dietary means. These results extend our knowledge of one of the putative anti-cancer actions of lycopene.

Semliki Forest virus-mediated gene therapy of the RG2 rat glioma

AIMS

Glioblastoma multiforme is the most common and most malignant adult brain tumour. Despite numerous advances in cancer therapy there has been little change in the prognosis of glioblastoma multiforme, which remains invariably fatal. We examined the Semliki Forest virus virus-like particle (SFV VLP) expression system encoding interleukin-12 (IL-12) as a therapeutic intervention against the syngeneic RG2 rat glioma model.

METHODS

Glioma-bearing rats were treated with IL-12-encoding SFV VLPs via an implanted cannula. Animals were treated with 5 × 10⁷ (low-dose) or 5 × 10⁸ (high-dose) VLPs per treatment and the effect on glioma growth and survival was assessed.

RESULTS

Low-dose treatment produced a 70% reduction in tumour volume, associated with a significant extension (20.45%) in survival that was dependent upon IL-12 expression. High-dose treatment resulted in an 87% reduction in tumour volume, related to the oncolytic capacity of the SFV VLP system. VLP delivery to the central nervous system (CNS) demonstrated the potential of the vector system to induce lethal pathology that was unrelated to replication-competent virus or high-level IL-12 expression. Treatment-related death was pronounced in high dose-treated animals and appeared to be the result of inflammation, necrosis and oedema at the inoculation site.

CONCLUSION

The efficacy of an IL-12 gene therapy approach for the treatment of the RG2 glioma model has been demonstrated in addition to the oncolytic capacity of the VLP vector system. Despite this, the broad tropism of the SFV-based expression vector may limit use as a CNS gene therapy vector unless this inherent limitation can be overcome.

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.

Heme oxygenase-1 accelerates cutaneous wound healing in mice

Heme oxygenase-1 (HO-1), a cytoprotective, pro-angiogenic and anti-inflammatory enzyme, is strongly induced in injured tissues. Our aim was to clarify its role in cutaneous wound healing. In wild type mice, maximal expression of HO-1 in the skin was observed on the 2(nd) and 3(rd) days after wounding. Inhibition of HO-1 by tin protoporphyrin-IX resulted in retardation of wound closure. Healing was also delayed in HO-1 deficient mice, where lack of HO-1 could lead to complete suppression of reepithelialization and to formation of extensive skin lesions, accompanied by impaired neovascularization. Experiments performed in transgenic mice bearing HO-1 under control of keratin 14 promoter showed that increased level of HO-1 in keratinocytes is enough to improve the neovascularization and hasten the closure of wounds. Importantly, induction of HO-1 in wounded skin was relatively weak and delayed in diabetic (db/db) mice, in which also angiogenesis and wound closure were impaired. In such animals local delivery of HO-1 transgene using adenoviral vectors accelerated the wound healing and increased the vascularization. In summary, induction of HO-1 is necessary for efficient wound closure and neovascularization. Impaired wound healing in diabetic mice may be associated with delayed HO-1 upregulation and can be improved by HO-1 gene transfer.

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.

Combined immunogene therapy of IL-6 and IL-15 enhances anti-tumor activity through augmented NK cytotoxicity

Many tumors evade host immunity by lowering expression of major histocompatibility complex (MHC) molecules. Theoretically, low MHC expression should activate natural killer (NK) cells and in some cases suppress tumor growth; nevertheless, some tumors also produce high concentrations of immunosuppressive cytokines, such as transforming growth factor (TGF)-beta, to inhibit the activity of NK cells. Using a canine transmissible venereal tumor (CTVT) model, we have previously demonstrated that IL-6 is a strong antagonist for TGF-beta. Herein, we found that IL-6 alone was unable to significantly promote TGF-beta-inhibited NK activities. Conversely, IL-15 alone strongly promoted NK activities; however, NK activities were inhibited to baseline levels following the addition of TGF-beta. Therefore, a new strategy using combined immunogene therapy of both IL-6 and IL-15 mediated by electroporation was used in this study. This combined IL-6 and IL-15 treatment effectively relieved the inhibitory effect of TGF-beta and activated NK cell cytotoxicity of lymphokine-activated killer (LAK) cells. Similarly, in isolated DX5+ NK cells, only IL-6 and IL-15 in combination significantly overcame the inhibitory effect of TGF-beta and promoted NK cytotoxicity. The group of BALB/c mice injected with plasmids with IL-6 and IL-15 genes (pIL-6/pIL-15) had the highest percentages of DX5+ NK cells as compared with either the pIL-6 or pIL-15 groups. Further, in SCID mice inoculated with CTVT, electroporation-mediated delivery of pIL-6/pIL-15 was significantly more efficient in suppressing both tumor establishment and tumor growth as compared with pIL-6 or pIL-15 inoculation alone. In addition, the anti-asialo GM-1 antibody abolished NK activities in SCID mice and resulted in outgrowth of the tumors. Together, these results suggest that the TGF-beta-associated inhibition of NK cytotoxicity cannot be adequately restored by simply antagonizing TGF-beta with IL-6: the co-existence of NK activating factors such as IL-15 is also important in restoring TGF-beta-inhibited cytotoxicity. This study highlights the therapeutic potential of the pIL-6/pIL-15 combination by inhibiting TGF-beta activity and enhancing NK cytotoxicity.

The role of 15-deoxy-delta(12,14)-prostaglandin J(2), an endogenous ligand of peroxisome proliferator-activated receptor gamma, in tumor angiogenesis

Peroxisome proliferator-activated receptor gamma (PPARgamma), a nuclear hormone receptor, is a ligand-activated transcription factor involved in adipogenesis, glucose homeostasis and lipid metabolism. 15-Deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), an endogenous ligand of PPARgamma, has multifaceted cellular functions. Angiogenesis plays an important role in the pathophysiology of ischemic and neoplastic disorders, especially cancer. 15d-PGJ(2) is involved in regulation of angiogenic mediators including vascular endothelial growth factor and hence participates in the blood vessel formation by means of angiogenesis. However, depending on the experimental conditions, this cyclopentenone prostaglandin can exert opposite effects on angiogenesis. 15d-PGJ(2) inhibits angiogenesis via suppression of pro-inflammatory enzymes and cytokines, while it also stimulates angiogenesis via induction of heme oxygenase-1, endothelial nitric-oxide synthase, and hypoxia inducible factor-1alpha. The aim of this review is to highlight such dual effects of 15d-PGJ(2) on angiogenesis and underlying molecular mechanisms.