Poster No. 151 Novel Role of Tumor-Derived ExtracellularHsp90 as an Essential Mediator of Prostate Cancer Cell Migration and Stromal Cell Activation: Evidence for Autocrine and Paracrine Functions Venkatesababa Samanna1, Udhayakumar Gopal1, Jennifer Isaacs 1 1 Department of Cell and Molecular Pharmacology, Hollings

Cancer Center, Medical Uninversity of South Carolina (MUSC), Charleston, SC, USA Prostate cancer (PCa) is one of the most common and lethal diseases among men. Although early cancer is often curative, subsequent metastatic spread of tumor cells renders the disease untreatable. Treatment failure is also due to a poor understanding of the contribution of the tumor microenvironment to disease progression. We find that a number of PCa cells secrete heat shock protein 90 (Hsp90). This extracellular Hsp90 (eHsp90) acts in a manner distinct from the intracellular chaperone and has been implicated in regulating cell motility learn more in other models. Interestingly, we find that eHsp90 www.selleckchem.com/products/midostaurin-pkc412.html expression correlates with cancer aggressiveness.

Consistently, the more aggressive and metastatic PCa cells secreted several fold more eHsp90 relative to their weakly tumorigenic matched counterparts. Interference with this pathway by antibody or drug-mediated neutralization of native eHsp90 dramatically impaired tumor cell migration, thereby implicating eHsp90 in a constitutive pathway culminating in cell migration. Concomitant with inhibition of eHsp90, the activation of downstream mediators such as FAK, Src, and ERK were attenuated. The multifunctional receptor LRP1 (LDL-receptor Related Protein-1) has been proposed as the receptor for eHsp90. We find that silencing of LRP1 similarly reduced PCa signaling and migration, implicating an eHsp90-LRP1 signaling axis in PCa development. Addition of Hsp90 to prostate stromal cells, which lack Hsp90 secretion, potently stimulated ERK activation and cell motility, implicating paracrine effects. ERK activation

was inhibited by pretreatment with an inhibitor of MMP activity, Resveratrol suggesting that eHsp90 modulates ERK signaling and MMP activity to modulate cell migration. We propose that PCa aggressiveness may be due in part to increased secretion of eHsp90, which then activates the stroma to further support tumor growth. Poster No. 152 IL-6 Promotes Pancreatic Cancer Progression by Intractions of Fibroblasts Hidenobu Kamohara 1 , Takatoshi Ishiko1, Hiroshi Takamori1, Hideo Baba1 1 Department of Gastroenterological Surgery, Kumamoto University, Graduate School of Medical Sciences, Kumamoto, Kumamoto, Japan Introduction: IL-6 has pleiotropic function and are produced by various immunnocompetent cells, as well as cancer cells. Some studies have been demonstrated IL-6 play an important role in evading host immune surveillance in tumor microenvironment, but interactions of fibroblasts has not been fully understood. Therefore, the aim of this study is to reveal role of fibroblasts in pancreatic tumor microenvironment.