, Australia, 2 Biochemistry, School of Medicine, University of Melbourne, Melbourne, Vic., Australia, 3 Breast

Cancer Metastasis Laboratory, Peter MacCallum Cancer Centre, Melbourne, Vic., Australia, 4 Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA, 5 Department of Medicine, Harvard Medical School, Boston, MA, USA, 6 NICTA VRL Laboratory, Department of Electrical and Electronic Engineering, University of Melbourne, PXD101 mouse Melbourne, Vic., Australia Recent evidence on the genomic integrity of non-malignant cells surrounding carcinoma cells has reinvigorated the discussion about the origin of the altered phenotype exhibited by carcinoma associated fibroblasts (CAF). Many hypotheses have been proposed for the origin of these altered cells, including standard connective tissue acute phase and stress response, fibroblast senescence, reciprocal interactions with the cancer cells, fibroblast specific somatic mutations, differentiation

precursors and infiltrating mesenchymal stem cells. We have addressed each of those options experimentally and found evidence for reciprocal interaction between tumour associated macrophages and cancer associated fibroblasts are elevated in patients, with an associated poor outcome. This supports current understanding of cancer etiology, based on previous animal models, NVP-HSP990 chemical structure as well as offers novel avenues for therapy. O34 VEGI, an Endogenous Antiangiogenic Cytokine, Inhibits find more Hematopoietic Stem Cell Differentiation into Endothelial Progenitor Cell Lu-Yuan Li 1 1 College of Pharmacy, Nankai University, Tianjin, China Endothelial progenitor cells (EPC) play a critical role in post-natal and tumor vasculogenesis. Vascular endothelial growth inhibitor (VEGI; NCT-501 TNFSF15) has been shown to inhibit endothelial cell proliferation by inducing apoptosis. We report here that VEGI inhibits the differentiation of EPC from mouse bone marrow-derived Sca1+ mononuclear cells.

Analysis of EPC markers indicates a significant decline of the expression of endothelial cell markers, but not stem cell markers, on VEGI-treated cells. Consistently, the VEGI-treated cells exhibit a decreased capability to adhere, migrate and form capillary-like structures on Matrigel. In addition, VEGI induces apoptosis of differentiated EPC but not early stage EPC. When treated with VEGI, an increase of phospho-Erk and a decrease of phospho-Akt are detected in early stage EPC, while activation of NF-κB, JNK and caspase-3 are seen in differentiated EPC. Furthermore, VEGI induced apoptosis of differentiated EPC is, at least partly, mediated by death receptor-3 (DR3), which is detected on differentiated EPC only. VEGI induced apoptosis signals can be inhibited by neutralizing antibodies against DR3 or recombinant extracellular domain of DR3.