OP01 Prion-like protein doppel as a novel marker for tumoral angiogenesis and tumor targeting

[摘要] Background: Approved angiogenesis inhibitors generally target certain growth factorsor their receptors, which exist in both normal and cancerous cells; this results insuppression of cell-signaling pathways throughout the body and causes adverse effects. For this reason, there is a need for a new angiogenesis inhibitor that canspecifically target the tumor vasculature. In our previous study, we revealed thatdoppel, a prion-like protein, was overexpressed specifically in the tumor vasculatures,but not in normal endothelium, and its expression enhanced blood vessel formation.Methods: Doppel monoclonal antibodies were produced through 2-track methods.We evaluated whether the doppel antibody inhibits angiogenesis by spheroid assaysand immunoblotting. Using the hanging drop method, the human colonic tumorassociated endothelial cells (HCTECs) spheroids were embedded and incubated withgrowth factor and doppel antibodies. Further, we conducted immunoblot andmicroarray for investigating the underlying mechanisms. In addition, we injectedfluorescent dye-conjugated doppel antibody into xenograft mouse models and visualized the tumor-targeting efficacy using in vivo imaging system (IVIS). Also, the tumor-targeting effect and internalization into tumoral cells were evaluated usingconfocal microscopy.Results: In spheroid assays, we found that doppel antibody inhibits spheroidsprouting. In anti- phosphorylation assays, the amount of phosphorylated VEGFR2was decreased in antibody-treated groups. When antibody-treated lysate was addedto the microarray kit, STAT5A and beta-catenin were inhibited. Inhibition of STAT5Amay promote apoptosis and increase sensitivity to anticancer drugs, and inhibition ofbeta-catenin may further increase suppression of angiogenesis. In addition, doppelantibody specifically accumulates in the tumor. Also, in both cancer cells and tumorendothelial cells, doppel antibody targets tumoral cells and then internalizationoccurs.Conclusions: Doppel antibodies in development have been screened and selected fortheir anti-angiogenic efficacy. We have validated our hypothesis by showing thatdoppel antibody can inhibit angiogenesis-related factors, which in turn brings antiangiogenic efficacy. We also confirmed that our novel target, doppel, could be themarker for tumor targeting. We hope that doppel antibody is expected to be a newand superior tumor vasculature-specific angiogenesis inhibitor that can overcome thelimitations of existing anti-angiogenic agents.

[学科分类] 社会科学、人文和艺术（综合）

[关键词] Angiogenesis;Tumor Targeting;Antibody