2008 Annual Meeting Abstracts

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Introduction: A murine model utilizing subcutaneous injection of spontaneously transformed endothelial (EOMA) cells results in development of hemangioendothelioma (HE) tumors with 100% efficiency. Affected mice die from Kassabach-Merritt syndrome. We have previously shown that blueberry extract (BBE) treatment of EOMA cells prior to injection can significantly inhibit the incidence and size of HE. The mechanism for BBE inhibition and the use of BBE as an oral treatment regimen for HE was investigated.

Methods: For in vitro mechanistic studies BBE was added to EOMA cells in culture at 150 mg/ml. Lack of toxicity was confirmed by LDH assay. BBE was evaluated for its effects on both the c-Jun N-terminal kinase (JNK) and NF-kB signaling pathways that culminate in monocyte chemoattractant protein-1 (MCP-1) expression, which is required for HE development (Gordillo et al, Amer J Physiol. 287(4):C866-873). Anti-angiogenic effects of BBE on EOMA cells were assessed using Matrigel and transwell migration assays. For in vivo studies HE were generated by injecting EOMA cells subcutaneously. Mice received daily gavage feedings of BBE. Serum samples were obtained for toxicity and biomarker studies. One set of mice were observed for survival another set of mice had tumors harvested at 7 days to evaluate tumor size.
Results: BBE treatment of EOMA cells significantly inhibited NF-kB activation and the entire JNK signaling pathway including JNK, c-Jun and AP-1 activation as well as MCP-1 protein expression. BBE also inhibited EOMA cell proliferation as detected by BrdU incorporation. BBE inhibited angiogenic EOMA cell sprouting on Matrigel and migration in transwell assays. Oral feeding of BBE resulted in a significant decrease in tumor volume compared to vehicle treated controls and provided a significant survival advantage based on Kaplan-Meier survival curve. Oral BBE also caused a decrease in the host antioxidant status in both the lipid and aqueous phases in the serum of treated mice. No BBE toxicites were observed in histologic and serologic studies done on mice gavage fed BBE at doses 25 times greater than effective treatment levels.

Conclusions:.BBE can inhibit NF-kB and JNK signaling pathways, which are both known to be redox sensitive signaling pathways with tumor promoting properties. Oral BBE dosing can alter host antioxidant status and inhibit HE growth and development in vivo. BBE represents a potential therapeutic anti-angiogenic strategy for treating vascular tumors. [GMG Supported by K08 GM066964 NIGMS]

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