VEGF-Targeted RNA Interference Suppresses Angiogenesis and Tumor Growth of Retinoblastoma

PRMT5 promotes retinoblastoma development

Epigenetic mechanism, including DNA methylation and histone modifications, contributes to alterations in the expression patterns of genes regulating malignant phenotype of cancer cells. However, the epigenetic modulation of vascular endothelial growth factor-A (VEGFA) in retinoblastoma (RB) has not been clearly established. We aimed to examine the epigenetic regulation of VEGFA by protein arginine methyltransferase 5 (PRMT5) in RB. Using the GEO database, we identified VEGFA as a pathogenic gene in RB. Silencing of VEGFA in SO-RB50 and Y79 cells inhibited cell proliferation, angiogenesis, and migration, promoted apoptosis, and suppressed tumor growth in mice. Mechanistically, PRMT5 promoted H3K4me3 modification of the VEGFA promoter, thereby activating VEGFA expression. VEGFA could regulate the expression of MMP1, MMP2, and MMP9. Further silencing of VEGFA in RB cells overexpressing PRMT5 constrained the expression of MMP1, MMP2 and MMP9, and suppressed the growth of tumors in mice. In conclusion, this study clarifies that the depletion of PRMT5 reduces H3K4me3-mediated VEGFA transcription and retards the carcinogenesis of RB by suppressing the expression of MMPs.

Highly Efficient Photodynamic Therapy with Mitochondria-Targeting Aggregation-Induced Emission Photosensitizer for Retinoblastoma

Retinoblastoma (RB) is an aggressive eye cancer in infancy and childhood, lethal by metastasis if left untreated. Currently, the survival rate and the chance of saving vision depend on the severity of the disease. In this work, a highly efficient photodynamic ophthalmic therapy for RB is reported by employing an isoquinolinium-based aggregation-induced-emission (AIE) photosensitizer (PS) TPE-IQ-2O for photodynamic inactivation (PDI). TPE-IQ-2O is an efficient mitochondria-targeting photosensitizer as an efficient guided photodynamic therapy (PDT) agent against cancer cells. Maximizing cancer-selectively damage to tumors with minimized side effects on normal tissue is essential for effective anticancer PDT and provides long-lasting protection against metastasis. In addition, TPE-IQ-2O can effectively reduce the degree of tissue inflammation by inhibiting the expression of related inflammatory factors. TPE-IQ-2O also exhibits excellent biocompatibility with a neglectable hemolysis effect on mouse red blood cells and almost no killing effect on mammalian cells, which enables its potential applications in the treatment of RB.

Dual pH-Responsive and Tumor-Targeted Nanoparticle-Mediated Anti-Angiogenesis siRNA Delivery for Tumor Treatment

Purpose

In order to overcome the biological barriers at all levels and enhance the delivery efficiency of siRNA, we have prepared a multifunctional siRNA delivery system (CHCE/siRNA nanoparticles) through self-assembly of the carboxymethyl chitosan modified with histidine, cholesterol, and anti-EGFR antibody (CHCE).

Methods

The morphology of CHCE/siRNA NPs was detected by dynamic light scattering and scanning electron microscope. In vitro, we assessed the tumor-targeting, cellular uptake, and endosomal escape by flow cytometry and confocal laser scanning microscopy, confirming the CHCE/siRNA NPs functions in gene silencing and cell killing ability. In vivo, we examined the biodistribution of the CHCE/siRNA NPs by the IVIS imaging system and confirmed the therapeutic effect of NPs in the nude-mouse tumor model.

Results

The CHCE/siRNA NPs exhibited nanosized spherical with narrow size distribution. In vitro, the CHCE/siRNA NPs incorporated a dual capability of tumor targeting and pH response that could facilitate cellular bind, cellular uptake, and endosomal escape. The CHCE/siRNA NPs could effectively silence the vascular endothelial growth factor A (VEGFA) to cause cell apoptosis and inhibit proliferation. In vivo, the CHCE/siRNA NPs could target tumor sites to knock down VEGFA and achieve a better anti-tumor effect.

Conclusion

We successfully prepared a novel siRNA delivery system with the double capability of tumor targeting and pH response, which can break through the biological barriers to penetrate deep into tumors and achieve better therapeutic tumor effects, providing a new ideal delivery platform for siRNA.

Immunotherapy and Gene Therapy for Oncoviruses Infections: A Review

Immunotherapy has been shown to be highly effective in some types of cancer caused by viruses. Gene therapy involves insertion or modification of a therapeutic gene, to correct for inappropriate gene products that cause/may cause diseases. Both these types of therapy have been used as alternative ways to avoid cancers caused by oncoviruses. In this review, we summarize recent studies on immunotherapy and gene therapy including the topics of oncolytic immunotherapy, immune checkpoint inhibitors, gene replacement, antisense oligonucleotides, RNA interference, clustered regularly interspaced short palindromic repeats Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-based gene editing, transcription activator-like effector nucleases (TALENs) and custom treatment for Epstein-Barr virus, human T-lymphotropic virus 1, hepatitis B virus, human papillomavirus, hepatitis C virus, herpesvirus associated with Kaposi's sarcoma, Merkel cell polyomavirus, and cytomegalovirus.

INTRAVITREAL ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR FOR THE MANAGEMENT OF NEOVASCULARIZATION IN RETINOBLASTOMA AFTER INTRAVENOUS AND/OR INTRAARTERIAL CHEMOTHERAPY: Long-Term Outcomes in a Series of 35 Eyes

PURPOSE

To report the use of anti-vascular endothelial growth factor in the management of retinoblastoma.

METHODS

Retrospective review of 35 eyes (33 patients) treated with at least one intravitreal anti-vascular endothelial growth factor (ranibizumab and/or aflibercept) for new iris (n = 26) and/or retinal neovascularization (n = 21) after intravenous chemotherapy and/or intraarterial chemotherapy.

RESULTS

Most eyes (n = 31/35, 89%) were Group D or E. Previous treatments were salvage intraarterial chemotherapy after intravenous chemotherapy (n = 21/35, 60%), first-line intraarterial chemotherapy (n = 7/35, 20%), and first-line intravenous chemotherapy (n = 7/35, 20%). Associated clinical features were retinal ischemia (94%), retinal detachment (51%), active tumor (34%), intravitreal hemorrhage (43%), and/or glaucoma (17%). Mean 1.6 anti-vascular endothelial growth factor injections/eye were given; 28 eyes received ranibizumab, 2 aflibercept, and 5 both agents. Eight eyes underwent complementary treatments of ischemic retina. Resolution of neovascularization was observed in 28 eyes (n = 28/35, 80%). Globe salvage was achieved in 51% (n = 18/35), including 25% of those with active tumor (n = 3/12). One eye became phthisic. Sixteen eyes were enucleated, nine for tumor relapse/progression. Five eyes had high-risk histopathologic risk factors and received adjuvant intravenous chemotherapy. All patients are alive with no extraocular extension nor metastases (mean follow-up 3.7 years, range 1.1-7.6).

CONCLUSION

Intravitreal anti-vascular endothelial growth factor contributed to a globe salvage rate of 51% by providing conditions to continue conservative treatment.

Subretinal injection of ranibizumab in advanced pediatric vasoproliferative disorders with total retinal detachments

PURPOSE

To describe the surgical procedures, outcomes, and complications of a novel technique of subretinal injection of ranibizumab (SRR).

METHODS

Between September 2012 and September 2018, 37 eyes of 26 consecutive children with vascularly active total retinal detachments in 1 or both eyes treated with SRR as primary treatment were included in this retrospective study. All included eyes received subretinal injection of ranibizumab (0.25 mg/ 0.025 ml). Data included demographics, ocular examination, and anatomic outcomes, following treatment and complications of eyes after SRR were collected.

RESULTS

Eleven patients had bilateral SRR injections and 15 had monocular SRR injection. Thirteen patients were diagnosed as retinopathy of prematurity. Of all patients, the mean gestational age was 34.5 ± 5.1 weeks (range: 29.6~40.7 weeks), and birth weight was 2328.1 ± 1083.9 g (range: 940~3900 g). On 1-week postoperative follow-up, vascular activity decreased in all 37 eyes (100%). On the 1-month postoperative follow-up, vascular activity decreased but remained in 24 eyes (24/35, 68.6%) of 16 patients and vanished in 11 eyes (11/35, 31.4%) of 9 patients. No eye needed a secondary anti-VEGF therapy. Local subconjunctival hemorrhage was noted in two eyes (2/37, 5.4%). Localized wound leakage of subretinal fluid was also noted in one eye (1/37, 2.7%).

CONCLUSIONS

In this very limited study, we showed that SRR in vascularly active advanced pediatric vasoproliferative disorders with total retinal detachments is effective and promising, although more extensive controlled trials will be needed to confirm its safety and efficacy.

TRPM8 Activation via 3-Iodothyronamine Blunts VEGF-Induced Transactivation of TRPV1 in Human Uveal Melanoma Cells

In human uveal melanoma (UM), tumor enlargement is associated with increases in aqueous humor vascular endothelial growth factor-A (VEGF-A) content that induce neovascularization. 3-Iodothyronamine (3-T₁AM), an endogenous thyroid hormone metabolite, activates TRP melastatin 8 (TRPM8), which blunts TRP vanilloid 1 (TRPV1) activation by capsaicin (CAP) in human corneal, conjunctival epithelial cells, and stromal cells. We compare here the effects of TRPM8 activation on VEGF-induced transactivation of TRPV1 in an UM cell line (92.1) with those in normal primary porcine melanocytes (PM) since TRPM8 is upregulated in melanoma. Fluorescence Ca²⁺-imaging and planar patch-clamping characterized functional channel activities. CAP (20 μM) induced Ca²⁺ transients and increased whole-cell currents in both the UM cell line and PM whereas TRPM8 agonists, 100 μM menthol and 20 μM icilin, blunted such responses in the UM cells. VEGF (10 ng/ml) elicited Ca²⁺ transients and augmented whole-cell currents, which were blocked by capsazepine (CPZ; 20 μM) but not by a highly selective TRPM8 blocker, AMTB (20 μM). The VEGF-induced current increases were not augmented by CAP. Both 3-T₁AM (1 μM) and menthol (100 μM) increased the whole-cell currents, whereas 20 μM AMTB blocked them. 3-T₁AM exposure suppressed both VEGF-induced Ca²⁺ transients and increases in underlying whole-cell currents. Taken together, functional TRPM8 upregulation in UM 92.1 cells suggests that TRPM8 is a potential drug target for suppressing VEGF induced increases in neovascularization and UM tumor growth since TRPM8 activation blocked VEGF transactivation of TRPV1.

Targeting VEGF pathway to normalize the vasculature: an emerging insight in cancer therapy

Vascular normalization is a new concept of targeting angiogenesis to restore vessel structure and function and to increase blood perfusion and delivery of drugs. It has been confirmed that vascular normalization can decrease relapse and benefit other cancer therapy, including chemotherapy, radiotherapy, and immune cell therapy. The key point of this therapy is to inhibit pro-angiogenic factors and make it be balanced with anti-angiogenic factors, resulting in a mature and normal vessel characteristic. Vascular endothelial growth factor (VEGF) is a key player in the process of tumor angiogenesis, and inhibiting VEGF is a primary approach to tumor vessel normalization. Herein, we review newly uncovered mechanisms governing angiogenesis and vascular normalization of cancer and place emphasis on targeting VEGF pathway to normalize the vasculature. Also, important methods to depress VEGF pathway and make tumor vascular are discussed.

Development of Targeted siRNA Nanocomplexes to Prevent Fibrosis in Experimental Glaucoma Filtration Surgery

RNAi induced by double-stranded small interfering RNA (siRNA) molecules has attracted great attention as a naturally occurring approach to silence gene expression with high specificity. The myocardin-related transcription factor/serum response factor (MRTF/SRF) pathway is a master regulator of cytoskeletal gene expression and, thus, represents a promising target to prevent fibrosis. A major hurdle to implementing siRNA therapies is the method of delivery, and we have, thus, optimized lipid-peptide-siRNA (LPR) nanoparticles containing MRTF-B siRNAs as a targeted approach to prevent conjunctival fibrosis. We tested 15 LPR nanoparticle formulations with different lipid compositions, surface charges, and targeting or non-targeting peptides in human conjunctival fibroblasts. In vitro, the LPR formulation of the DOTMA/DOPE lipid with the targeting peptide Y (LYR) was the most efficient in MRTF-B gene silencing and non-cytotoxic compared to the non-targeting formulation. In vivo, subconjunctival administration of LYR nanoparticles containing MRTF-B siRNAs doubled bleb survival in a pre-clinical rabbit model of glaucoma filtration surgery. Furthermore, MRTF-B LYR nanoparticles reduced the MRTF-B mRNA by 29.6% in rabbit conjunctival tissues, which led to significantly decreased conjunctival scarring with no adverse side effects. LYR-mediated delivery of siRNA shows promising results to increase bleb survival and to prevent conjunctival fibrosis after glaucoma filtration surgery.

Anti-VEGF for ROP and Pediatric Retinal Diseases

Vascular endothelial growth factor (VEGF) is an important mediator of the pathological neovascularization and vascular permeability of the eye. The increasing use of intravitreal therapies targeting VEGF has revolutionized the treatment of pediatric vitreoretinal diseases. In retinopathy of prematurity (ROP), the role of VEGF in pathogenesis has been well recognized and the use of anti-VEGF treatment in phase 2 ROP has demonstrated promising results, particularly in severe cases of posterior disease. This has made VEGF an established target in the treatment of pediatric retinal diseases known to have abnormal vascular activity. However, questions remain about late systemic and neurodevelopmental effects after anti-VEGF therapy for children because intravitreal injection of anti-VEGF may result in systemic circulation of anti-VEGF agent and a corresponding suppression of systemic VEGF. We do not currently know whether the short-term suppression of systemic VEGF affects long-term neurodevelopmental outcomes because VEGF is a vital supporting factor during neurodevelopment. This review article focuses on the evidence for the use of anti-VEGF treatment in certain pediatric ocular diseases, including ROP, Coats disease, and retinoblastoma. More extensive and prospective studies are warranted to further elucidate the role of anti-VEGF therapy in these diseases and illustrate how we can optimally use these agents in pediatric patients.

A laser-activated multifunctional targeted nanoagent for imaging and gene therapy in a mouse xenograft model with retinoblastoma Y79 cells

Retinoblastoma (RB) is the most common intraocular malignancy of childhood that urgently needs early detection and effective therapy methods. The use of nanosized gene delivery systems is appealing because of their highly adjustable structure to carry both therapeutic and imaging agents. Herein, we report a folic acid (FA)-modified phase-changeable cationic nanoparticle encapsulating liquid perfluoropentane (PFP) and indocyanine green (ICG) (FA-CN-PFP-ICG, FCNPI) with good plasmid DNA (pDNA) carrying capacity, favorable biocompatibility, excellent photoacoustic (PA) and ultrasound (US) contrast, enhanced gene transfection efficiency and therapeutic effect. The liquid-gas phase transition of the FCNPI upon laser irradiation has provided splendid contrasts for US/PA dual-modality imaging in vitro as well as in vivo. More importantly, laser-mediated gene transfection with targeted cationic FCNPI nanoparticles demonstrated the best therapeutic effect compared with untargeted cationic nanoparticle (CN-PFP-ICG, CNPI) and neutral nanoparticle (NN-PFP-ICG, NNPI), both in vitro and in vivo. Such a multifunctional nanoagent is expected to combine dual-mode guided imaging with fewer side effects and proper therapeutic efficacy. These results establish an experimental foundation for the clinical detection of and therapy for RB.

STATEMENT OF SIGNIFICANCE

We successfully constructed a multifunctional targeted cationic nanoparticle (FCNPI) and meticulously compared the variations in the plasmid loading capacity and binding to Y79 cells with NNPI, CNPI, and FCNPI. FCNPI exhibited favorable plasmid loading capability, splendid ability for targeting and only it could provide optimal US and PA contrast to background during a considerable long time. The FCNPI/pDNA + Laser system also exhibited the best therapeutic effect in vivo; this finding proposes a potential strategy for the evaluation of an efficient gene delivery nanocarrier for gene targeting therapy of RB tumor. Our study showed that there are great advantages of targeting FCNPI to provide PA/US imaging and to enlighten laser-mediated gene transfection. FCNPI is a very helpful multifunctional agent with potential.

An optimized gene transfection system in WERI-Rb1 cells

The pathogenesis of Rb1 gene inactivation indicates that gene therapy could be a promising treatment for retinoblastoma. An appropriate gene transfer system is the basis for successful gene therapy; however, little attention has been given to an effective gene transfer system for retinoblastoma therapy in previous studies. This study was designed to provide an optimized transgene system for WERI-Rb1 cells (W-RBCs). Green fluorescent protein (GFP) was adopted as a reporter. Four classic viral vectors based on retroviruses, recombinant adeno-associated viruses (rAAV2, rAAV2/1), lentiviruses (LVs) and a novel non-viral vector X-treme HP reagent were adopted for W-RBC gene transfection. The efficacy and cytotoxicity were comprehensively compared among the different vectors through GFP expression and the trypan blue exclusion test. Furthermore, the serum and cell culture status were also optimized for better transfection. Cells transfected by rAAV2/1 expressed more GFP protein and exhibited less staining with trypan blue, compared to the rAAV2 counterpart. However, in comparison to the retroviral group, both the rAAV2/1 and LV groups had considerably less GFP⁺ cells. Interestingly, the X-treme HP presented a similar GFP transfection capacity to the retroviral vector, but with a much lower cytotoxicity. Furthermore, there were more GFP⁺ cells in a suspended condition than that in an adherent culture. Moreover, cells in a serum-positive system expressed more GFP, while cells in a serum-free system showed lower GFP expression and higher cytotoxicity. In conclusion, the retroviral vector and the X-treme HP are effective for W-RBC gene transfection, while the X-treme HP is more preferable due to its lower cytotoxicity. Moreover, the suspended cell culture system is superior to the adherent system, and the serum protects cell viability and facilitates the gene transfection of W-RBCs. This study presents an effective, convenient, and low toxic transfection system for gene delivery in W-RBCs and provides a promising system for further gene therapy of retinoblastoma.

Orchestrating epigenetic roles targeting ocular tumors

Epigenetics is currently one of the most promising areas of study in the field of biomedical research. Scientists have dedicated their efforts to studying epigenetic mechanisms in cancer for centuries. Additionally, the field has expanded from simply studying DNA methylation to other areas, such as histone modification, non-coding RNA, histone variation, nucleosome location, and chromosome remodeling. In ocular tumors, a large amount of epigenetic exploration has expanded from single genes to the genome-wide level. Most importantly, because epigenetic changes are reversible, several epigenetic drugs have been developed for the treatment of cancer. Herein, we review the current understanding of epigenetic mechanisms in ocular tumors, including but not limited to retinoblastoma and uveal melanoma. Furthermore, the development of new pharmacological strategies is summarized.

Receptor-targeted liposome-peptide-siRNA nanoparticles represent an efficient delivery system for MRTF silencing in conjunctival fibrosis

There is increasing evidence that the Myocardin-related transcription factor/Serum response factor (MRTF/SRF) pathway plays a key role in fibroblast activation and that knocking down MRTF can lead to reduced scarring and fibrosis. Here, we have developed a receptor-targeted liposome-peptide-siRNA nanoparticle as a non-viral delivery system for MRTF-B siRNA in conjunctival fibrosis. Using 50 nM siRNA, the MRTF-B gene was efficiently silenced by 76% and 72% with LYR and LER nanoparticles, respectively. The silencing efficiency was low when non-targeting peptides or siRNA alone or liposome-siRNA alone were used. LYR and LER nanoparticles also showed higher silencing efficiency than PEGylated LYR-P and LER-P nanoparticles. The nanoparticles were not cytotoxic using different liposomes, targeting peptides, and 50 nM siRNA. Three-dimensional fibroblast-populated collagen matrices were also used as a functional assay to measure contraction in vitro, and showed that MRTF-B LYR nanoparticles completely blocked matrix contraction after a single transfection treatment. In conclusion, this is the first study to develop and show that receptor-targeted liposome-peptide-siRNA nanoparticles represent an efficient and safe non-viral siRNA delivery system that could be used to prevent fibrosis after glaucoma filtration surgery and other contractile scarring conditions in the eye.

Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy: An analytical technique to understand therapeutic responses at the molecular level

Rapid monitoring of the response to treatment in cancer patients is essential to predict the outcome of the therapeutic regimen early in the course of the treatment. The conventional methods are laborious, time-consuming, subjective and lack the ability to study different biomolecules and their interactions, simultaneously. Since; mechanisms of cancer and its response to therapy is dependent on molecular interactions and not on single biomolecules, an assay capable of studying molecular interactions as a whole, is preferred. Fourier Transform Infrared (FTIR) spectroscopy has become a popular technique in the field of cancer therapy with an ability to elucidate molecular interactions. The aim of this study, was to explore the utility of the FTIR technique along with multivariate analysis to understand whether the method has the resolution to identify the differences in the mechanism of therapeutic response. Towards achieving the aim, we utilized the mouse xenograft model of retinoblastoma and nanoparticle mediated targeted therapy. The results indicate that the mechanism underlying the response differed between the treated and untreated group which can be elucidated by unique spectral signatures generated by each group. The study establishes the efficiency of non-invasive, label-free and rapid FTIR method in assessing the interactions of nanoparticles with cellular macromolecules towards monitoring the response to cancer therapeutics.

Epigenetics and ocular diseases: from basic biology to clinical study

Epigenetics is an emerging field in ophthalmology and has opened a new avenue for understanding ocular development and ocular diseases related to aging and environment. Epigenetic mechanisms, including DNA methylation, histone modifications, chromatin remodeling, and deployment of non-coding RNAs, result in the heritable silencing of gene expression without any change in DNA sequence. Accumulating evidence suggests a potential link between gene expression, chromatin structure, non-coding RNAs, and cellular differentiation during ocular development. Disruption of the balance of epigenetic networks could become the etiology of several ocular diseases. Here, we summarized the current knowledge about epigenetic regulatory mechanisms in ocular development and diseases.

Aminoimidazole carboxamide ribonucleotide (AICAR) inhibits the growth of retinoblastoma in vivo by decreasing angiogenesis and inducing apoptosis

5-Aminoimidazole-4-carboxamide-1-β-4-ribofuranoside (AICAR), an analog of AMP is widely used as an activator of AMP-kinase (AMPK), a protein that regulates the responses of the cell to energy change. Recently, we showed that AICAR-induced AMPK activation inhibits the growth of retinoblastoma cells in vitro by decreasing cyclins and by inducing apoptosis and S-phase arrest. In this study, we investigated the effects of AMPK activator AICAR on the growth of retinoblastoma in vivo. Intraperitoneal injection of AICAR resulted in 48% growth inhibition of Y79 retinoblastoma cell tumors in mice. Tumors isolated from mice treated with AICAR had decreased expression of Ki67 and increased apoptotic cells (TUNEL positive) compared with the control. In addition, AICAR treatment suppressed significantly tumor vessel density and macrophage infiltration. We also showed that AICAR administration resulted in AMPK activation and mTOR pathway inhibition. Paradoxically observed down-regulation of p21, which indicates that p21 may have a novel function of an oncogene in retinoblastoma tumor. Our results indicate that AICAR treatment inhibited the growth of retinoblastoma tumor in vivo via AMPK/mTORC1 pathway and by apoptogenic, anti-proliferative, anti-angiogenesis mechanism. AICAR is a promising novel non-chemotherapeutic drug that may be effective as an adjuvant in treating Retinoblastoma.

Combination of oncolytic adenovirus and endostatin inhibits human retinoblastoma in an in vivo mouse model

There is a critical need for new paradigms in retinoblastoma (RB) treatment that would more efficiently inhibit tumor growth while sparing the vision of patients. Oncolytic adenoviruses with the ability to selectively replicate and kill tumor cells are a promising strategy for cancer gene therapy. Exploration of a novel targeting strategy for RB utilizing combined oncolytic adenovirus and anti-angiogenesis therapy was applied over the course of the current study with positive results. The oncolytic adenoviruses Ad-E2F1 p-E1A and Ad-TERT p-E1 were constructed. The E1 region was regulated by the E2F-1 promoter or the human telomerase reverse transcriptase (hTERT) promoter, respectively. Effects on both replication and promotion of enhanced green fluorescent protein (EGFP) expression were observed in the replication-defective adenovirus Ad-EGFP in diverse cancer cell lines, HXO-RB44, Y79, Hep3B, NCIH460, MCF-7 and HLF. The cancer cell death induced by these agents was also explored. The in situ RB model demonstrated that mice with tumors treated with the oncolytic adenovirus and replication-defective adenovirus Ad-endostatin exhibited notable cancer cell death. This anticancer effect was further examined by stereo microscope, and the survival rate of experimental mice was determined. Both Ad-E2F1 p-E1A and Ad-TERT p-E1 replicated specifically in cancer cells in vitro and promoted EGFP expression in Ad-EGFP, although Ad-E2F1 p-E1A demonstrated superior EGFP promotion activity than Ad-TERT p-E1. In Hep3B, NCIH460 and MCF-7 cells, the number of Ad-TERT p-E1 copies was observed to exceed of the number of Ad-E2F1 p-E1A copies by a minimum of 10-fold. Furthermore, Ad-TERT p-E1 demonstrated significantly superior oncolytic effects in the RB mouse model, and Ad-endostatin effectively suppressed tumor growth and extended the overall lifespan of subjects; however, the Ad-E2F1 p-E1A was clearly less effective in attaining these goals. Most notably, the antitumor effect and survival rate of subjects in the combined Ad-TERT p-E1 + Ad-endostatin group were higher than those treated with either single Ad-TERT p-E1 (p=0.097, p=0.022, respectively) or Ad-endostatin (p=0.037, p=0.006, respectively). In conclusion, application of transcription factor E2F-1 and human telomerase reverse transcriptase (hTERT) promoters to control E1 offer some guarantee that not only is RB gene therapy effective, but it is also safe. Combination therapy using the oncolytic adenovirus Ad-TERT p-E1 and replication-defective adenovirus Ad-endostatin demonstrates desirable oncolysis in the in situ RB mouse model. Additionally, E1B19K is important in the RB tumor suppression effect of oncolytic adenoviruses.

Effect of VEGF-targeted antisense gene therapy on retinoblastoma cell line SO-RB50 in vitro and in vivo

AIM

To evaluate the possibility of generation 4 polyamidoamine (G4PAMAM) dendrimers acting as the delivery system of vascular endothelial growth factor (VEGF) antisense oligodeoxynucleotides (VEGFASODN), and to investigate the anti-tumor effect of G4PAMAM/VEGFASODN complex on the cultured cells and the mouse tumor xenograft model.

METHODS

The transfection efficiency was assessed by Flow cytometry (FCM). Thiazolyl tetrazolium (MTT) assay was performed to determine the relative growth rate (RGR) of the cells after transfection. Then a mouse tumor xenograft model of human retinoblastoma was established. Different interventions were given to the mice by intratumoral injection and the tumor growth was monitored. The expression of VEGF mRNA was detected by reverse transcription PCR (RT-PCR), the expression of VEGF protein was determined by western blot analysis, and the microvessel density (MVD) was measured by immunohistochemistry (IHC) staining.

RESULTS

G4PAMAM/VEGFASODN exhibited a high transfection rate in vitro, and the transfection rates of different doses of G4PAMAM/VEGFASODN groups increased with higher doses. This effect was accompanied by a dose-depended reduction in cell viability. The tumor growth in the tumor-bearing athymic mice was significantly inhibited in the G4PAMAM/VEGFASODN group. The expressions of VEGF mRNA and protein were obviously inhibited in the G4PAMAM/VEGFASODN group (P<0.05), and the MVD of the G4PAMAM/VEGFASODN group was lower than that of the other groups (P<0.05).

CONCLUSION

VEGFASODN can be delivered into the cultured and transplanted retinoblastoma cells efficiently by G4PAMAM, suppress the expressions of VEGF mRNA and protein, and reduce the MVD of tumor tissues. The G4PAMAM/VEGFASODN complex has antitumor properties in vitro and in vivo.

Retinoblastoma: Recent trends A mini review based on published literature

Retinoblastoma (RB) is the most common intraocular malignancy in children. Recently, there have been significant advances made in the molecular pathology and the management of the disease. Last decade has witnessed better understanding of the genetics of RB, the discovery of new tumor markers expressed by the RB tumors, the identification of high-risk histopathological factors following enucleation, and newer methods of treatment including periocular chemotherapy and superselective intraarterial chemotherapy. All these advances have translated in improved survival rates for the affected children, improved rates of eye salvage, and improved visual outcomes. This article briefly reviews these advances.Method of Literature Search: Literature on the Medline database was searched using the PubMed interface. The search strategy included MeSH and natural language terms using the keywords mentioned. Reference lists in retrieved articles and textbooks were also searched for relevant references.

Gene therapy for cancer: bacteria-mediated anti-angiogenesis therapy

Several bacterial species have inherent ability to colonize solid tumors in vivo. However, their natural anti-tumor activity can be enhanced by genetic engineering that enables these bacteria express or transfer therapeutic molecules into target cells. In this review, we summarize latest research on cancer therapy using genetically modified bacteria with particular emphasis on blocking tumor angiogenesis. Despite recent progress, only a few recent studies on bacterial tumor therapy have focused on anti-angiogenesis. Bacteria-mediated anti-angiogenesis therapy for cancer, however, is an attractive approach given that solid tumors are often characterized by increased vascularization. Here, we discuss four different approaches for using modified bacteria as anti-cancer therapeutics--bactofection, DNA vaccination, alternative gene therapy and transkingdom RNA interference--with a specific focus on angiogenesis suppression. Critical areas and future directions for this field are also outlined.

siRNA-mediated knockdown of VEGF-A, VEGF-C and VEGFR-3 suppresses the growth and metastasis of mouse bladder carcinoma in vivo

The growth of solid tumors is highly dependent on the formation of new blood and/or lymph vessels. Furthermore, metastases often disperse via newly formed blood or lymphatic vessels within the tumor, particularly in the case of epithelium-derived tumors. Since vascular endothelial growth factor (VEGF) signaling plays a vital role in angiogenesis and lymphangiogenesis, we used the small interfering RNA (siRNA) approach to selectively down-regulate VEGF-A, VEGF-C or VEGF receptor 3 (VEGFR-3) expression in bladder transitional carcinoma cells derived from T739 mice in an attempt to suppress tumor growth and metastasis in vivo. The synthetic siRNA was introduced into the tumor tissues by in vivo electroporation. The knockdown of VEGF-A, VEGF-C and VEGFR-3 expression significantly delayed tumor growth and reduced tumor metastasis compared to the negative controls. Thus, electroporation-mediated siRNA delivery to block the VEGF signaling pathway may provide a novel approach for the treatment or prevention of solid tumor growth and metastasis.

Experimental Research on Wild-type p53 Plasmid Transfected into Retinoblastoma Cells and Tissues using an Ultrasound Microbubble Intensifier

The transfection efficiency of wild-type p53 ( wtp53) was investigated in retinoblastoma (RB) Y79 cells using an ultrasound microbubble technique. A human RB nude mouse xenograft tumour model was also used to investigate whether this technique could deliver wtp53 into solid tumours. Reverse transcription–polymerase chain reaction (RT–PCR) demonstrated that wtp53 was successfully transfected into Y79 cells in the plasmid with microbubbles and ultrasound group and in the plasmid with liposomes group, but not in the plasmid with ultrasound group or in the untreated control group. Flow cytometry showed that apoptosis was highest in the microbubbles and ultrasound group (25.58%) compared with the plasmid with liposomes group (19.50%), and the other two groups (< 10%). RT–PCR also showed that the wtp53 gene was successfully transfected into solid tumours in the plasmid with microbubbles and ultrasound group. This study provides preliminary evidence in support of a potential new approach to RB gene therapy.

Differential expression of stem cell markers and vascular endothelial growth factor in human retinoblastoma tissue

Purpose

To investigate the relationship between vascular endothelial growth factor (VEGF) and the cancer stem cell-vascular niche complex in human retinoblastoma tissue.

Methods

Six human retinoblastoma specimens primarily enucleated for Reese-Ellsworth classification stage 5a were stained to detect cancer stem cell markers, including ABCG2 for the stem cell marker and MCM2 for the neural stem cell marker, as well as to detect VEGF for the angiogenic cytokine. Using immunofluorescence, the expression of these proteins was analyzed, and their relative locations noted.

Results

In non-neoplastic retina of tumor-bearing eyes, ABCG2 and MCM2 were sporadically expressed in the ganglion cell layer and the inner nuclear layer, whereas VEGF was sporadically expressed in inner retina where retinal vessels are abundantly distributed. In the tumor, ABCG2 was strongly expressed out of Wintersteiner rosettes, whereas MCM2 and VEGF were strongly stained in the rosettes. Interestingly, the outer portion of the rosettes was positive for MCM2, and the inner portion of the rosettes was positive for VEGF.

Conclusions

Our data demonstrated that MCM2 and VEGF are strongly expressed in the rosettes of the tumor, which were far from the area of ABCG2-positive cells. Although VEGF might not directly contribute to the cancer stem cell-vascular niche complex, it could play some role in the differentiation of tumor cells to build up the rosettes.

Direct effects of fascaplysin on human umbilical vein endothelial cells attributing the anti-angiogenesis activity

Novel anti-angiogenesis activity of fascaplysin via VEGF blockage was recently revealed by our previous study in addition to the reported cyclin-dependent kinase 4 (CDK4) selective inhibition. To uncover more details of this pharmacologically prospective property, this study further investigated whether fascaplysin had direct anti-proliferation effects on human umbilical vein endothelial cells (HUVEC), which might be contributing to anti-angiogenesis. The results showed that G1 cell cycle arrest was induced by 2.6 μM fascaplysin in a time-dependent manner, and exhibited more sensitive than hepatocarcinoma cells BeL-7402 and Hela cells. Approximately 56.09 ± 2.63% of the cells were arrested at the G1 phase after 24h, and 64.94 ± 2.07% after 36 h, comparing to the 22.82 ± 1.2% in methanol treated cells. Apoptosis of HUVEC cells was induced by 1.3 μM fascaplysin and indicated by the sub-G1, Hoechst staining, terminal deoxynucleotidyl transferase dUTP-mediated nicked end labeling (TUNEL) assay, and annexin-V and propidium (PI) label. This apoptosis response was further confirmed by the detection of active caspase-3 and by western blotting using antibodies against Bax, Bcl-2, procaspase-8, and Bid, indicating that apoptosis in HUVEC cells may involve a mitochondria pathway, by the demonstration of an increase in the Bax/Bcl-2 ratio. Together, our results suggest that the anti-angiogenesis activity of fascaplysin is through the direct effects of cell cycle arrest and apoptosis on HUVEC.

PEDF inhibits growth of retinoblastoma by anti-angiogenic activity

Pigment epithelium-derived factor (PEDF), an angiogenesis inhibitor with multiple other functions, balances angiogenesis in the eye and blocks tumor progression. Retinoblastoma, an angiogenesis-dependent tumor, is the most common ocular cancer in children without effective treatment. It has been reported that PEDF can induce neuronal differentiation of retinoblastoma cells; however, its anti-angiogenic potential for inhibition of retinoblastoma growth in vivo has not been elucidated. The present study was designed to investigate the effect of PEDF on growth of retinoblastoma and the possible molecular mechanism. Soluble and non-fusion recombinant PEDF were generated in E. coli. Recombinant PEDF dose-dependently inhibited proliferation and induced apoptosis of endothelial cells. PEDF had no effects on the proliferation and apoptosis of retinoblastoma cell line SO-Rb50. Intraperitoneal injection of PEDF resulted in growth inhibition of heterotopic retinoblastoma xenografts at 68.78%. MVD in tumor tissues treated with PEDF was significantly decreased. These results suggested that PEDF suppressed tumor growth by blocking angiogenesis instead of a direct cytotoxic effect on tumor cells. Vascular endothelial growth factor (VEGF), a major angiogenic stimulator, was down-regulated by PEDF in both SO-Rb50 cells and retinoblastoma xenografts. Hypoxia-inducible factor (HIF)-1alpha, a crucial transcriptional factor for VEGF expression, was also down-regulated by PEDF both in vitro and in vivo. PEDF reduced HIF-1alpha nuclear translocation, which may be responsible for the down-regulation of VEGF. Down-regulation of VEGF expression in tumor cells through inhibiting HIF-1alpha, thus attenuating the paracrine effect of VEGF on endothelial cell proliferation and vascular permeability in tumor tissues, may represent a mechanism for the anti-angiogenic activity of PEDF.

siRNA targeting VEGF inhibits hepatocellular carcinoma growth and tumor angiogenesis in vivo

BACKGROUND/AIMS

We have investigated whether siRNA targeted against VEGF inhibits functional properties of endothelial cells in vitro and HCC tumor growth and blood vessel formation in vivo.

METHODS

The influence of siRNA-VEGF on endothelial cell proliferation, apoptosis and tube formation were analyzed in vitro. Antitumoral effects were examined in an orthotopic tumor model after ex vivo transfer or intraperitoneal treatment of siRNA, respectively. Intratumoral microvessel density was assessed by CD31 staining.

RESULTS

VEGF expression was inhibited in Hepa129 by 70% and in SVEC4-10 by 48% within two days after transfection. In vitro, endothelial cell proliferation and tube formation was reduced by 23% and 38%, respectively. Interference with VEGF signaling was demonstrated by reduced pAKT in hepatoma cells. Tumor growth was inhibited by ex vivo transfer or intraperitoneal application of siRNA-VEGF by 83% or 63% in orthotopic tumors within 14 days. VEGF protein was reduced in both models by 29% and 44%. Microvessel density dropped to 34% for tumors from ex vivo transfected cells and 39% for systemic treated tumors.

CONCLUSIONS

The results show that VEGF knockdown can be associated with reduced endothelial cell proliferation and tube formation in vitro and decreased tumor growth and microvessel density in vivo.

Enhanced therapeutic efficacy by simultaneously targeting two genetic defects in tumors

Targeting tumor-specific gene abnormalities has become an attractive approach in developing therapeutics to treat cancer. Overexpression of Bcl2 and mutations of p53 represent two of the most common molecular defects in tumors. In the nucleus, p53 induces cell cycle arrest, while it interacts with Bcl2 outside of the nucleus to regulate signal pathways involved in apoptosis. To potentiate antitumor activity, we tested a "double target" approach to antitumor therapy by combining H101, a recombinant oncolytic adenovirus that targets the inactive p53 in tumors, with a small interfering RNA (siBCL2) that targets Bcl2. In cell culture, the combined treatment significantly enhanced apoptosis and cytotoxicity as compared with treatment with either H101 or siBCL2 alone. In animals carrying tumor xenographs, combined H101 and siBCL2 treatment significantly inhibited tumor growth and prolonged survival. At the end of the study, all animals in the combined therapy group survived and two of the five animals showed complete eradication of their tumors. Interestingly, siBCL2 treatment increased H101 viral replication in both treated cells and tumor tissues. Simultaneously targeting two tumor-specific gene abnormalities using an oncolytic adenovirus and siRNA potentiates total antitumor activity.

1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-formulated, immune-stimulatory vascular endothelial growth factor a small interfering RNA (siRNA) increases antitumoral efficacy in murine orthotopic hepatocellular carcinoma with liver fibrosis

Most experimental therapy studies are performed in mice that bear subcutaneous or orthotopic hepatoma but are otherwise healthy and nonfibrotic. The majority of hepatocellular carcinoma (HCC), however, develops in patients suffering from preexisting liver fibrosis. We investigated the efficacy of a standard experimental therapeutic approach to interrupt the vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) cascade via VEGF-A silencing, with or without 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP; cationic lipid) formulation, in HCC mice with preexisting liver fibrosis. The data show that intraperitoneal treatment with naked VEGF-A small interfering RNA (siRNA; 200 microg/kg) was inefficient to treat HCC implanted into fibrotic livers. VEGF-A siRNA containing an immunostimulatory motif in combination with DOTAP formulation significantly reduced hepatic VEGF-A expression and additionally activated the innate and adapted immune system as shown by an increased intrahepatic interferon type 1 response (68-fold increased beta-interferon expression). DOTAP-formulated VEGF-A siRNA markedly improved VEGF-A siRNA uptake and enhanced the antitumor response. This study shows for the first time the therapeutic feasibility of using synergistic effects (gene silencing and activation of the immune system) united in one siRNA sequence to reduce HCC growth and metastasis in mice with preexisting liver fibrosis. We expect that these results will help to direct and improve future experimental gene-silencing approaches and establish more efficient antitumoral therapies against HCC.