Antiangiogenic Therapy Against Experimental Glioblastoma Using Genetically Engineered Cells Producing Interferon-α, Angiostatin, or Endostatin

Abstract

Inhibition of angiogenesis has been considered among the most promising approaches to treat highly vascularized solid tumors such as glioblastoma. In this study, we designed and validated a new in vitro assay system based on the implantation of tumor cells into organotypic brain slice cultures. We evaluated the effects of local production of three endogenous inhibitors of angiogenesis, angiostatin, endostatin, and interferon (IFN)-alpha(1), using stably transfected rat (9L) and human (GL15) glioblastoma cells on tumor vascularization and growth. Despite similar effectiveness of the three proteins in a classic in vitro endothelial cell migration assay, IFN-alpha(1) demonstrated the most potent antiangiogenic effect in organotypic brain slice cultures. In vivo, after intracerebral implantation of such genetically modified glioblastoma cells, IFN-alpha(1) caused a dramatic decrease in tumor volume revealed by magnetic resonance imaging and by postmortem histology. The mechanisms of this antitumor effect were most likely caused by the major antiangiogenic action of the cytokine, because IFN-alpha(1) expression provoked a pronounced decrease in blood vessel density, which was accompanied by extensive necrosis in the body mass of the tumors. The median survival time of rats implanted intracerebrally with IFN-alpha-expressing 9L cells tripled, and was still significantly increased when these constituted only 1% of transplanted tumor cells. A similar effect was seen when 50% of the transplanted cells were replaced by IFN-alpha-expressing bone marrow stromal cells. These data point to the local delivery of IFN-alpha(1) using cell vectors as a potent tool for the inhibition of tumor-induced angiogenesis.

Antiangiogenic and anti-invasive effects of sunitinib on experimental human glioblastoma

“…29 In addition, we used six fresh human specimens obtained from malignant glioma resection. After surgery, samples were immediately transferred to glioma-cell medium and prepared for implantation into brain slices obtained from young mice (see below).…”

“…Alternatively, this failure of anti-invasive effect may be due to a parallel increase in glioma invasion during antiangiogenic therapy. 29,42,43 Instead, it has been recently suggested that antiangiogenic therapy, which increases tumor hypoxia, may increase cell invasion by activating proinvasive signaling pathways. 44 The ability of sunitinib to exert antiangiogenic effects in an intracranial GBM model is a new and important finding.…”

Identification of Genes Selectively Regulated by IFNs in Endothelial Cells

“…This activity has been mainly attributed to indirect effects, including inhibition of basic fibroblast growth factor production by tumor cells (5) or down-regulation of IL-8 and vascular endothelial growth factor gene expression (6,7). In contrast, other data indicate that IFN-␣ also has direct effects on endothelial cells (EC), 4 including impairment of EC proliferation and migration (3,4,8). In addition, IFN-␥ may exert antiangiogenic activity both directly through cytostatic effects on proliferating EC (9) and indirectly through the induction of angiostatic chemokine expression in vivo (10,11).…”

Novel technologies for antiangiogenic drug delivery in the brain

“…Endogenous inhibitors such as interferon-α, angiostatin and endostatin were successfully formulated for use in brain tumor models. [59][60][61][62] Sengupta et al 63 developed a multi-drug delivery system composed of a copolymer PLGA and Phosphatidylcholine:cholesterol (PEG-DSPE) named nanocell, which enables the release of two drugs at different kinetics. The outer PEG-DSPE shell first releases an antiangiogenic agent, combretastatin, which regresses blood vessel growth, while the inner core of the nanoparticle composed of a polymer PLGA-doxorubicin, is trapped inside the tumor and slowly releases the chemotherapy drug.…”