Angiostatin Gene Therapy Research Articles

Antisense HIF-1α 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.

Adenovirus mediated angiostatin gene therapy for ovarian cancer: experiment with nude mice

To built an expression vector of angiostatin (AG) gene with recombinated replication defective adenovirus and investigate the therapeutic effect of human AG gene on ovarian cancer. (1) Human AG K (1 - 3) cDNA was inserted into the vector pShuttle to build the recombinant plasmid pShttle-AG (K1-3). pAdeno-X-AG (K1-3) was built by double-cut and recombinated pShttle-AG (K1-3) to vector pAdeno-X, and then recombinant adenovirus was finally prepared by transfection of pAdeno-X-AG (K1-3) into to the human embryo kidney cells of the line 293. (2) Human ovarian cancer cells of the line SKOV3 were inoculated subcutaneously into nude mice of the line BALB/c nu/nu to establish model of human ovarian cancer. Then the mice were randomly divided into 3 groups to be injected with Ad = AG (K1-3), Ad-LacZ, or phosphate buffered saline (PBS) around the cancer every 5 days. The tumor size was measured every 5 days to calculate the tumor volume and tumor inhibition rate. Three days after the last injection the mice were killed. The tumor tissues, livers, and kidneys of the mice underwent immunohistochemistry to calculate the microvessel density (MVD) and expression of vessel endothelial growth factor (VEGF) and AG. The tumor volume and weight of the Ad-AG (K1-3) group were significantly less than those of the PBS and Ad-LacZ groups (all P < 0.01), however, there were not significant difference between the latter two groups (both P > 0.05). The expression levels of CD34 and VEGF of the Ad-AG (K1-3) group were both significantly lower than those of the PBS and Ad-LacZ groups (all P < 0.01), however (both P > 0.05). Human angiostatin mediated by adenovirus suppresses the angiogenesis and the growth of human ovarian cancer in the nude mice model, which suggests that it is promising in clinical application.

Effects of Sustained Antiangiogenic Therapy in Multistage Prostate Cancer in TRAMP Model

Antiangiogenic therapy is a promising alternative for prostate cancer growth and metastasis and holds great promise as an adjuvant therapy. The present study evaluated the potential of stable expression of angiostatin and endostatin before the onset of neoplasia and during the early and late stages of prostate cancer progression in transgenic adenocarcinoma of mouse prostate (TRAMP) mice. Groups of 5-, 10-, and 18-week-old male TRAMP mice received recombinant adeno-associated virus-6 encoding mouse endostatin plus angiostatin (E+A) by i.m. injection. The effects of therapy were determined by sacrificing groups of treated mice at defined stages of tumor progression and following cohorts of similarly treated mice for long-term survival. Results indicated remarkable survival after recombinant adeno-associated virus-(E+A) therapy only when the treatment was given at an earlier time, before the onset of high-grade neoplasia, compared with treatment given for invasive cancer. Interestingly, early-stage antiangiogenic therapy arrested the progression of moderately differentiated carcinoma to poorly differentiated state and distant metastasis. Immunohistochemical analysis of the prostate from treated mice indicated significantly lower endothelial cell proliferation and increased tumor cell apoptosis. Vascular endothelial growth factor receptor (VEGFR)-2 expression was significantly down-regulated in tumor endothelium after treatment but not VEGFR-1. Analysis of the neuroendocrine marker synaptophysin expression indicated that antiangiogenic therapy given at an early-stage disease reduced neuroendocrine transition of the epithelial tumors. These studies indicate that stable endostatin and angiostatin gene therapy may be more effective for minimally invasive tumors rather than advanced-stage disease.

Expression of angiostatin cDNA in human gallbladder carcinoma cell line GBC-SD and its effect on endothelial proliferation and growth

To explore the influence of angiostatin up-regulation on the biologic behavior of gallbladder carcinoma cells in vitro and in vitro, and the potential value of angiostatin gene therapy for gallbladder carcinoma. A eukaryotic expression vector of pcDNA3.1(+) containing murine angiostatin was constructed and identified by restriction endonuclease digestion and sequencing. The recombinant vector pcDNA3.1-angiostatin was transfected into human gallbladder carcinoma cell line GBC-SD with Lipofectamine 2000, and paralleled with the vector and mock control. The resistant clone was screened by G418 filtration. Angiostatin transcription and protein expression were examined by RT-PCR, immunofluorescence and Western-blot. The supernatant was collected to treat endothelial cells. Cell proliferation and growth in vitro were observed under microscope. Murine angiostatin cDNA was successfully cloned into the eukaryotic expression vector pcDNA3.1 (+). After 14 d of transfection and selection with G418, macroscopic resistant cell cloning was formed in the experimental group transfected with pcDNA 3.1(+)-angiostatin and vector control. But untreated cells died in the mock control. Angiostatin was detected by RT-PCR and protein expression was detected in the experimental group by immunofluorescence and Western-blot. Cell proliferation and growth in vitro in the three groups were observed respectively under microscope. No significant difference was observed in the growth speed of GBC-SD cells between groups that were transfected with and without angiostatin. After treatment with supernatant, significant differences were observed in endothelial cell (ECV-304) growth in vitro. The cell proliferation and growth were inhibited. Angiostatin does not directly inhibit human gallbladder carcinoma cell proliferation and growth in vitro, but the secretion of angiostatin inhabits endothelial cell proliferation and growth.

Angiostatin inhibits pancreatic cancer cell proliferation and growth in nude mice

To observe the biologic behavior of pancreatic cancer cells in vitro and in vivo, and to explore the potential value of angiostatin gene therapy for pancreatic cancer. The recombinant vector pcDNA3.1(+)-angiostatin was transfected into human pancreatic cancer cells PC-3 with Lipofectamine 2000, and paralleled with the vector and mock control. Angiostatin transcription and protein expression were determined by immunofluorescence and Western blot. The stable cell line was selected by G418. The supernatant was collected to treat endothelial cells. Cell proliferation and growth in vitro were observed under microscope. Cell growth curves were plotted. The troms-fected or untroms-fected cells overexpressing angiostatin vector were implanted subcutaneously into nude mice. The size of tumors was measured, and microvessel density count (MVD) in tumor tissues was assessed by immunohistochemistry with primary anti-CD34 antibody. After transfected into PC-3 with Lipofectamine 2000 and selected by G418, macroscopic resistant cell clones were formed in the experimental group transfected with pcDNA 3.1(+)-angiostatin and vector control. But untreated cells died in the mock control. Angiostatin protein expression was detected in the experimental group by immunofluorescence and Western-blot. Cell proliferation and growth in vitro in the three groups were observed respectively under microscope. After treatment with supernatant, significant differences were observed in endothelial cell (ECV-304) growth in vitro. The cell proliferation and growth were inhibited. In nude mice model, markedly inhibited tumorigenesis and slowed tumor expansion were observed in the experimental group as compared to controls, which was parallel to the decreased microvessel density in and around tumor tissue. Angiostatin does not directly inhibit human pancreatic cancer cell proliferation and growth in vitro, but it inhibits endothelial cell growth in vitro. It exerts the anti-tumor functions through antiangiogenesis in a paracrine way in vivo.

Combined effects of docetaxel and angiostatin gene therapy in prostate tumor model

The anti-tumor effects of adenovirus-delivered angiostatin (AdK3) in association with docetaxel (Taxotere) have been evaluated in a human-origin prostate tumor model. In vitro, human endothelial cells were 50- to 100-fold more sensitive to docetaxel than prostate cell lines (PC3, LNCaP, and DU145), and the combination regimen of docetaxel and AdK3 was significantly more cytotoxic for endothelial cells than either treatment alone. PC3 cells, which display the highest sensitivity to docetaxel, were then grafted onto athymic mice for an evaluation of the combined regimen as a therapy. The combination of a single intratumoral injection of AdK3 (2 × 109 pfu) and a single intravenous injection of docetaxel (15 mg/kg) was compared with the injection of AdK3 alone on preestablished mice bearing PC3-derived tumors with a mean tumor volume of 60 ± 11 or 205 ± 46 mm3. Significant antitumoral effects were observed only in mice receiving the combined treatment. We showed that all PC3 tumors regressed in the AdK3–docetaxel combination group and that 40 to 83% totally regressed. In all cases, this regimen was tightly correlated with a marked decrease in intratumoral vascularization. Our experimental data show that attacking both endothelial and tumoral compartments is an efficient and logical strategy, making this bitherapy approach clinically promising.

Angiostatin up-regulation in gastric cancer cell SGC7901 inhibits tumorigenesis in nude mice.

To explore the influence of angiostatin up-regulation on the biologic behavior of gastric cancer cells in vitro and in vivo, and the potential of angiostatin gene therapy in the treatment of human gastric cancer. Mouse angiostatin cDNA was subcloned into the eukaryotic expression vector pcDNA3.1(+) and identified by restriction endonucleases digestion and sequencing. The recombinant vector pcDNA3.1(+)-angio was transfected into human gastric cancer cells SGC7901 with liposome and paralleled with the vector control and the mock control. Angiostatin transcription and protein expression were examined by RT-PCR and Western blot in the stable cell lines selected by G418. Cell proliferation and growth in vitro of the three groups were observed respectively under microscope, cell number counting and FACS. The cells overexpressing angiostatin, vector transfected and untreated were respectively implanted subcutaneously into nude mice. After 30 days the size of tumors formed was measured, and microvessel density count (MVD) in the tumor tissues was assessed by immunohistochemistry with the primary anti-vWF antibody. The recombinant vector pcDNA3.1(+)-angio was confirmed with the correct sequence of mouse angiostatin under the promoter CMV. After 30 d of transfection and selection with G418, macroscopic resistant cell clones were formed in the experimental group transfected with pcDNA 3.1(+)-angio and the vector control. But no untreated cells survived in the mock control. Angiostatin mRNA transcription and protein expression were detected in the experimental group. No significant differences were observed among the three groups in cell morphology, cell growth curves and cell cycle phase distributions in vitro. However, in nude mice model, markedly inhibited tumorigenesis and slowed tumor expansion were observed in the experimental group as compared with the controls, which was paralleled with decreased microvessel density in and around tumor tissues (P<0.05). Angiostatin does not directly inhibit human gastric cancer cell proliferation and growth in vitro, but exerts its anti-tumor functions through antiangiogenesis in a paracrine way in vivo.

Expression of angiostatin cDNA in a murine renal cell carcinoma suppresses tumor growth in vivo

Objectives. To investigate the effectiveness of angiostatin gene therapy for renal cancer using a mouse model. The generally poor prognosis of advanced renal cancer indicates the need for new therapeutic modalities. The dependency of solid tumor growth on angiogenesis suggests that antiangiogenic therapy would be effective against renal cell carcinoma, which is generally a hypervascular tumor. Methods. Murine renal cancer cells (Renca) transfected with murine angiostatin cDNA (AST-Renca) were subcutaneously implanted in BALB/c mice. Subsequently, the macroscopic appearance and volume of tumors were evaluated once per week. Renca cells transfected with empty plasmid DNA (mock-Renca) were used as a control. In addition, histologic sections of tumor were analyzed for neovascularization on the basis of an immunohistochemical analysis for CD31. The antitumor effect of AST-Renca on a parental Renca tumor at a distant site was also evaluated. Results. The mean volume of AST-Renca tumors was significantly less than that of the control vector-transfected tumors 3 weeks after implantation. In the cell proliferation assay, the expression of angiostatin did not inhibit the proliferation of Renca cells in vitro. Immunohistochemical analysis of neovascularization by staining with anti-CD31 antibody revealed that angiostatin suppressed tumor vessel formation. Moreover, implantation of AST-Renca inhibited the growth of parental Renca implanted simultaneously at a distant site. Conclusions. Expression of an angiostatin transgene can suppress the growth of murine renal cancer through the inhibition of tumor-induced angiogenesis. Angiostatin gene therapy may be effective against renal cancer.

Growth of human squamous cell carcinoma xenografts in mice is inhibited by local angiostatin gene therapy

The possibility of inhibiting tumor growth by blocking the formation of new tumor vessels has recently received attention. Antiangiogenic tumor therapies have recently attracted intense interest because of their direct endothelial targeting and the absence of drug resistance. Local antiangiogenic gene therapy for cancer offers a potential way to achieve sustained therapeutic release of antiangiogenic substances. As a step toward this goal, we used liposomes complexed to angiostatin cDNA and targeted to human squamous cell carcinoma cell lines in vivo. Tumor cells expressing angiostatin after local gene transfer showed markedly reduced vascularity and contained many apoptotic tumor cells. These results demonstrate the potential utility of liposome-derived angiostatin for adjuvant therapy of oral cancer in humans.

Angiostatin enhances B7.1-mediated cancer immunotherapy independently of effects on vascular endothelial growth factor expression.

Tumors must develop an adequate vascular network to meet their increasing demands for nutrition and oxygen. Angiostatin, a multiple kringle (1-4)-containing fragment of plasminogen, is an effective natural inhibitor of tumor angiogenesis. Here we show that gene transfer of angiostatin into small (0.1 cm in diameter) solid EL-4 lymphomas established in syngeneic C57BL/6 mice led to reduced tumor angiogenesis and weak inhibition of tumor growth. In contrast, when angiostatin gene therapy was preceded by in situ gene transfer of the T-cell costimulator B7.1, large (0.4 cm in diameter) tumors were rapidly and completely eradicated, whereas B7.1 and angiostatin monotherapies were ineffective. Combined gene transfer of B7.1 and angiostatin generated potent systemic antitumor immunity that was effective in eradicating a systemic challenge of 10(7) EL-4 cells. Gene transfer of angiostatin expression plasmids led to overexpression of angiostatin in tumors, increased apoptosis of tumor cells, and decreased density of tumor blood vessels, which may allow the immune system to overcome tumor immune resistance. The latter effects were not the result of a decrease in vascular endothelial growth factor expression, as tumoral vascular endothelial growth factor expression increased slightly after angiostatin gene transfer, presumably in response to increasing hypoxia. These results suggest that combining immunogene therapy with a vascular attack by angiostatin is a particularly effective approach for eliciting antitumor immunity.

Growth of human melanoma xenografts is suppressed by systemic angiostatin gene therapy.

The effect of local and systemic delivery of the angiostatin gene on human melanoma growth was studied in nude mice. Liposome-coated plasmids carrying the cDNA coding for murine and human angiostatin (CMVang and BSHang) were injected weekly, locally or systemically, in mice transplanted with melanoma cells. The treatment reduced melanoma growth by 50% to 90% compared to that occurring in control animals treated with liposome-coated plasmid carrying the lacZ gene or in untreated controls. The growth of both locally injected and controlateral uninjected tumors in mice bearing two melanoma grafts was significantly suppressed after intratumoral treatment. Tumor growth inhibition was also observed in mice treated by intraperitoneal delivery, suggesting that angiostatin gene therapy acts through a systemic effect. Both melanoma growth suppression and delay in the onset of tumor growth were observed in treated mice. PCR performed on tumors and normal tissues showed that the lipofected DNA was present in tissues from treated mice, and angiostatin expression was demonstrated by RT-PCR. Histopathological analysis of melanoma nodules revealed an increase in apoptotic cells and a reduction in vessel density in tumors from treated mice. Our results suggest that systemic, liposome-mediated administration of genes coding for antiangiogenic factors represents a promising strategy for melanoma treatment in humans.

Angiostatin gene therapy inhibits the growth of murine squamous cell carcinoma in vivo.

Tumor growth is an angiogenesis-dependent process and therapeutic strategies aimed at inhibiting angiogenesis are theoretically attractive. Angiostatin has been shown to potently inhibit endothelial proliferation in vitro and tumor growth in vivo. We now show that a shift in the balance of tumor angiogenesis by gene transfer of a cDNA coding for mouse angiostatin into mouse squamous cell carcinoma NRS-1 and SCC-VII cells suppresses tumor growth in vivo. The inhibition of an angiostatin-transfected tumor was accompanied by a marked reduction in vascularity and the presence of many apoptotic tumor cells. However, transfected-angiostatin cDNA does not affect the expression of the vascular endothelial growth factor (VEGF) and VEGF-R2 in the vascular endothelium. The inhibition mechanisms of neovascularization may be mediated independent of VEGF:VEGF-R2 complex. Our data may provide a useful approach for human oral cancer therapy by gene therapy with angiostatin.

Cancer therapy by gene therapy with angiostatin.

Angiostatin, an internal fragment of plasminogen, has been shown to inhibit angiogenesis. A new area of cancer research that has generated excitement is the use of angiostatin to treat cancer. Angiostatin protein therapy has not been pursued because current technology is inadequate to manufacture the needed biologically active proteins in sufficient quantities. It is sufficient for effective therapy with angiostatin to establish angiostatin production in the vicinity of tumors by gene transfer of angiostatin cDNA. There are various methods by which to transfer angiostatin cDNA. One way is to use a viral vector to incorporate the gene into cells. Another way is to use nonviral vectors. In this review, evidence accumulated from many laboratories suggests that angiostatin gene therapy may be an important new cancer therapy as an adjuvant therapy to prevent recurrence. (c) 2001 Prous Science. All rights reserved.

Combined effects of radiotherapy and angiostatin gene therapy in glioma tumor model.

The objective of the present study was to evaluate the antitumor effect of a defective adenovirus expressing a secretable angiostatin-like molecule (AdK3) in combination with radiotherapy in rat C6 gliomas s.c. preestablished into athymic mice. In vitro, the combination regimen was significantly (P < 0.001) more cytotoxic for human microcapillary endothelial cells than either treatment alone, whereas survival of C6 glioma cells was not affected in the conditions used. Radiotherapy and AdK3 gene delivery was then studied on well established C6 xenografts (165 +/- 70 mm(3)). In these tumors, AdK3 intratumoral injections had only a marginal effect. Interestingly, when experimental radiotherapy was added, significantly higher (P < 0.005), and possibly synergistic, antitumoral effects were observed that tightly correlated a marked decrease of intratumoral vascularization. The combination of radiotherapy and AdK3 intratumoral injections also revealed a significant (P < 0.05) inhibition of tumor growth as compared with either treatment alone for larger tumors (467 +/- 120 mm(3)). Altogether, these data emphasize the potential of combining a destructive strategy directed against the tumor cells with an anti-angiogenic approach to fight cancer.