MALDI-TOF analysis was performed on sera taken from control and carcinogen-treated at each necropsy time point. The peak 4253 m/z revealed a monotone change in the intensity difference that was statistically significant between the treated and untreated rats over weeks 2, 3, 4, and 5. The corresponding band was excised from a gel and possible identifications were determined via electrospray ionization (ESI). One biologically plausible candidate for this band was Dermcidin, a protein previously linked to breast cancer. We have found Dermcidin levels to increase mTOR inhibitor in serum during disease progression, gaining

significance as tumor size increases. We are currently characterizing the role that Dermcidin plays in rat mammary carcinogenesis and investigating a potential correlation with human breast carcinogenesis. Poster No. 59 Role of CD24 in Gene Regulation and Cancer Invasion Niko Bretz 1 , Mina buy BIBW2992 Fogel2, Steffen Runz1, Peter Altevogt1 1 Department of Translational Immunology D015, German Cancer Research Center, Heidelberg, Germany, 2 Institute of Pathology, Kaplan Medical Center, Rehovot, Israel CD24 is a mucin-like, highly O- and N-glycosylated, glycosyl-phosphatidylinositol (GPI-) anchored membrane protein. It is expressed in maturing

B-cells, neutrophils, epithelial cells and neuronal tissue. CD24 is also overexpressed in various types of human cancers such as lung, stomach, colorectal, prostate, breast and ovarian. In tumors, CD24 has been shown to affect cell proliferation and migration, tumor growth and invasion. However, the cellular downstream events of CD24

remain completely unclear. Here, we investigated CD24-dependent gene regulation in RNAi and overexpression systems in vitro. RNA-microarray based chip-analysis verified by quantitative real-time PCR, identified a small number of genes that Anacetrapib were regulated by CD24 expression. One of the most promising target genes is tissue factor pathway inhibitor-2 (TFPI-2). This member of the Kunitz-type serin proteinase inhibitor family functions in the maintenance and the stability of the tumor microenvironment. TFPI-2 is secreted into the extracellular matrix (ECM) and acts as an inhibitor of matrix metalloproteases (MMP) or plasmin-mediated ECM proteolysis. Downregulation of TFPI-2 protein enhances cancer cell ability to degrade ECM due to the lack of this potent inhibitor function. Using ovarian carcinoma cells and CD24-transfected cell lines, we provide evidence that CD24 promoted effects on tumor cell invasion and Gilteritinib datasheet MMP-activity could be mediated by TFPI-2 levels. Poster No.