Principle findings: We utilized structure prediction server (http://​www.​robetta.​org) to predict the three dimensional structure of active heparanase. The structure obtained clearly delineates a TIM-barrel fold previously anticipated for the enzyme. Interestingly, the model also revealed the existence of a C-terminal domain (C-domain) apparently not being an integral part of the TIM-barrel fold. We provide evidence that the C-domain is critical for heparanase enzymatic activity and secretion. Moreover, the C-domain Omipalisib concentration was found to mediate non-enzymatic functions of

heparanase, facilitating Akt phosphorylation, cell proliferation, and tumor xenografts progression. Binding experiments indicate the existence of high affinity, low abundant cell surface receptor, and cross-linking experiments revealed the existence of two major cell surface binding protein(s)/receptor(s) complexes, exhibiting molecular weights of ~ 130 and ~ 170 kDa that interact with heparanase

C-domain. Conclusions: These findings support the notion that heparanase exert enzymatic activity-independent function, selleck inhibitor and identifies, for the first time, protein domains responsible for heparanase-mediated signaling. Inhibitors directed against the C-domain, combined with inhibitors of heparanase enzymatic activity, are expected to neutralize heparanase function and to profoundly affect tumor progression and metastasis. Poster No. 74 Polarization of Macrophages in Lung Metastasis Formation Annamaria Gal 1 , Thomas Tapmeier1, Ruth J. Muschel1 1 Gray Institute for Radiation Oncology & Biology, University of Oxford, Oxford, UK Tumor associated macrophages have been described in primary tumors. They polarize towards the alternatively activated phenotype (M2) with a distinct receptor and cytokine pattern and support tumor

growth. Less is known however about macrophage polarization and the pro-tumoral macrophages in metastasis formation. In a mouse model of experimental metastasis, we i.v. injected B16F10 melanoma cells into Y-27632 2HCl C57BL/6 syngeneic mice and monitored lung colony formation. In a time course of tumor cell challenge, we analysed immune cell infiltration and cytokine expression in order to characterize the metastatic lung environment. Shortly after tumor cell injection (30 min), we found an inflammatory response, involving Gr-1+, CD11b+, Ly6C+neutrophil and monocyte infiltration that ceased within 24 h. After 24 h, we observed CD68+, CD11b+monocyte/macrophage recruitment that lasted no longer than up to 48 h of tumor cell challenge. The recruited macrophages displayed a cytokine pattern resembling the M1 macrophage subpopulation predominantly with IL-12 expression.