A potential therapeutic strategy for inhibition of ocular neovascularization with a new endogenous protein: rhEDI-8t

Strategies to better treat glioblastoma: antiangiogenic agents and endothelial cell targeting agents

Glioblastoma multiforme (GBM) is the most prevalent and aggressive form of glioma, with poor prognosis and high mortality rates. As GBM is a highly vascularized cancer, antiangiogenic therapies to halt or minimize the rate of tumor growth are critical to improving treatment. In this review, antiangiogenic therapies, including small-molecule drugs, nucleic acids and proteins and peptides, are discussed. The authors further explore biomaterials that have been utilized to increase the bioavailability and bioactivity of antiangiogenic factors for better antitumor responses in GBM. Finally, the authors summarize the current status of biomaterial-based targeting moieties that target endothelial cells in GBM to more efficiently deliver therapeutics to these cells and avoid off-target cell or organ side effects.

Enhanced expression of Vastatin inhibits angiogenesis and prolongs survival in murine orthotopic glioblastoma model

Background

Antiangiogenic therapies are considered promising for the treatment of glioblastoma (GB). The non-collagenous C-terminal globular NC1 domain of type VIII collagen a1 chain, Vastatin, is an endogenous antiangiogenic polypeptide. Sustained enhanced expression of Vastatin was shown to inhibit tumour growth and metastasis in murine hepatocellular carcinoma models. In this study, we further explored the efficacy of Vastatin in the treatment of GB xenografts.

Method

Treatment of Vastatin was carried out using a nanopolymer gene vector PEI600-CyD-Folate (H1). Antiangiogenic effect of Vastatin was tested in vitro by using co-culture system and conditioned medium. An orthotopic GB murine model was established to examine the in vivo therapeutic effect of Vastatin alone treatment and its combination with temozolomide.

Results

Vastatin gene transfection mediated by H1 could target tumour cells specifically and suppress the proliferation of microvessel endothelial cells (MECs) through a paracrine inhibition manner. Enhancing Vastatin expression by intracerebral injection of H1-Vastatin significantly prolonged animal survival from 48 to 75 days in GB murine model, which was comparable to the effect of Endostatin, the most studied endogenous antiangiogenic polypeptide. The diminished presence of CD34 positive cells in the GB xenografts suggested that Vastatin induced significant antiangiogenesis. Moreover, a synergistic effect in extending survival was detected when H1-Vastatin was administered with temozolomide (TMZ) in GB chemoresistant murine models.

Conclusion

Our results suggest, for the first time, that Vastatin is an antiangiogenic polypeptide with significant potential therapeutic benefit for GB. H1-Vastatin gene therapy may have important implications in re-sensitizing recurrent GB to standard chemotherapeutic agents.

Vastatin, an Endogenous Antiangiogenesis Polypeptide That Is Lost in Hepatocellular Carcinoma, Effectively Inhibits Tumor Metastasis

Hepatocellular carcinoma (HCC) is a hypervascular cancer without effective treatment. Here we report that polypeptide of NC1 domain of type VIII collagen (Vastatin) is an endogenous polypeptide expressed in normal liver tissue but lost in the liver of most HCC patients (73.1%). Its expression level is negatively associated with tumor size (P = 0.035) and metastasis (P = 0.016) in HCC patients. To evaluate its potential use as a therapeutic, we constructed a recombinant adeno-associated virus carrying Vastatin (rAAV-Vastatin) to treat HCC in an orthotopic Buffalo rat model. rAAV-Vastatin treatment significantly prolonged the median survival, inhibited tumor growth, and completely prevented metastasis in HCC-bearing rats by decreasing microvessel density and increasing tumor necrosis. No detectable toxicity in nontumor-bearing mice was observed. To investigate its molecular mechanisms, we performed DNA microarray, western blotting assays, and bioinformatic analysis to determine its effect on global gene expression patterns and signal transduction pathways. Our results indicated that rAAV-Vastatin significantly reduced the expressions of Pck1, JAG2, and c-Fos, thus inhibiting the cellular metabolism, Notch and AP-1 signaling pathways, respectively. Hence, we demonstrated for the first time that Vastatin is a novel, safe, and effective antiangiogenic therapeutic and a potential biomarker for HCC.