Poster No. 20 Apigenin: A Phytochemical that Modulates the Cell-Surface Expression of the Multifunctional Protein CD26 on Human Colorectal Carcinoma Cells Emilie Lefort 1 , Jonathan Blay2 1 Department of Pathology, Dalhousie University, Halifax, NS, Canada, 2 Departments of Pathology, Pharmacology and Biology, Dalhousie University, Halifax, NS, Canada Background: CD26, also known as dipeptidyl

peptidase IV (DPPIV), is present at the cell surface of a variety of tissues, including the epithelial lining of the normal human colon. CD26 expression is decreased in a number of malignancies and in the instance of colon cancer this decrease in level is believed to facilitate the process of metastasis to distant organs including lymph nodes and liver. CD26 itself is a multifunctional I-BET-762 order anchor protein that serves as the major cellular

binding protein for the ecto-enzyme adenosine deaminase (ADA) and also interacts with proteins of the extracellular matrix, principally collagen and fibronectin. CD26 also possesses an intrinsic dipeptidyl peptidase enzymatic activity, allowing it to cleave and inactivate peptides like CXCL12, the ligand for the chemokine receptor CXCR4. To further explore the potential anticancer properties of the AMN-107 order bioflavonoid compound apigenin, we investigated its effects on the cellular expression of CD26 on human colorectal carcinoma cells. Methods: Cell-surface expression of functional CD26 protein on HT-29 colorectal

carcinoma was quantified using a cell-based radio-immunoassay. The multiple functions of the CD26 molecule were explored through measurements of DPPIV enzymatic activity, binding of exogenous ADA and adhesion to cellular fibronectin. Cell viability was assessed through MTT assay and by trypan blue exclusion. Results: Apigenin significantly up-regulated CD26 cell-surface expression and functions. This would be predicted to act to oppose the metastatic process. When 4-Aminobutyrate aminotransferase apigenin was combined with chemotherapeutic agents utilized in the treatment of colorectal cancer, the increase in CD26 expression was further enhanced. Conclusion: By increasing the expression of CD26 and its functions to normal levels, apigenin could be of benefit in restraining the tendency of colon cancer cells to metastasize, and enhancing the action of chemotherapeutic agents. Supported by NSERC of Canada and by studentship award from Dalhousie CRTP. Poster No. 21 Modulation Of Angiopoietin Expression By Platelet-Derived Endothelial Cell Growth Factor/Thymidine Phosphorylase In Human Glioblastoma Cells Sandra Liekens 1 , Annelies Bronckaers1, Cindy Schiepers1, Jan Balzarini1 1 Department of Microbiology and Immunology, Rega Institute for Medical Research, Leuven, Belgium Thymidine phosphorylase (TP), also known as platelet-derived endothelial cell growth factor (PD-ECGF), catalyzes the conversion of thymidine to thymine and 2-deoxy-D-ribose-1-phosphate.