Interactions of tumor cells with endothelium in a microvasculature of distant organs determine the outcome of metastasis. Previously, we could show that L-selectin deficiency reduced the

recruitment of myeloid cells, and attenuated metastasis. Here we provide evidence for the molecular mechanism involved in the tumor cell-mediated activation of endothelial cells leading to formation of a metastatic niche. Selectin-mediated cell-cell interactions of tumor cells with platelets and leukocytes induce endothelial activation associated with a production of inflammatory chemokines. Enhanced expression BIBW2992 of the key chemoattractant for monocytic cells is associated with metastatic progression. DAPT Inhibition of

monocyte recruitment strongly reduced survival of tumor cell and metastasis. Our findings demonstrate that the selectin-dependent endothelial expression of chemokines contributes to the formation of a permissive metastatic microenvironment. Poster No. 197 Anti-Tumor Activity of an Apoptosis-Targeting Peptide-Conjugated Heparin Derivative in Breast Cancer Xenografts Sang-Moon Bae1, Hyeri Shin1, Jong-Ho Kim1, Byung-Heon Lee1, In-San Kim1, Youngro Byun2, Rang-Woon Park 1 1 Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu, Korea Republic, 2 College of Pharmacy, Seoul National University, Seoul, Korea Republic HT10, a taurocholic acid-conjugated low molecular weight heparin derivative is a novel angiogenesis inhibitor. We aimed for designing a new angiogenesis inhibitor with tumor homing capability by introducing the active targeting moiety to previously developed HT10.

The end-amine low molecular heparin was conjugated to Apopep-1, the apoptosis-targeting peptide, mediated by succinimidyl-4-[N-maleimidomethyl]cyclohexane-1-carboxylate and then HT-Apopep was completed by adding taurocholic acid. Plasmin The intravenous administration of HT-Apopep in MDA-MB231 human breast cancer-bearing mice for 14 days resulted in significantly reduced tumor size compared to vehicle-treated control. The antitumor effect of HT-Apopep was dose-dependent and superior to unmodified HT10 and moreover, to bevacizumab, a humanized anti-VEGF monoclonal neutralizing antibody. Immunohistochemical analysis of tumor tissues demonstrated that HT-Apopep decreased the number of CD34-positive erythrocyte-filled blood vessels and Ki67-positive proliferating cells in tumor. These results suggest that combining the angiogenesis inhibitor with active targeting moiety improves antitumor efficacy and HT-Apopep is a promising candidate for cancer therapeutics with tumor homing antiangiogenic activity. Poster No.