Abstract Prostate cancer is the most frequently diagnosed malignancy in men and although effective treatment is possible for early stage disease, advanced prostate cancer has a very poor prognosis. Thus, identification of biomarkers that can accurately and reliably diagnose prostate cancer in its early stages is urgently needed. MatLyLu and Dunning G are rat prostate cancer cell lines which have different metastatic capabilities. Using microarray analysis we previously identified a set of metastasis-associated genes that are over-expressed in MatLyLu. Genes found to be differentially expressed include several previously associated with the metastatic process, but not previously reported in prostate cancer. We also have found differential expression of genes that code for several proteoglycans involved in epithelial cell-extracellular matrix interaction, cell adhesion molecules, genes related to motility, growth factor receptors, and tumor suppressor genes. We are currently validating the expression of these candidate genes in human prostate cancer cell lines with different metastatic abilities (LNCaP, PC3, PWR-1E) and in clinical samples of prostate cancer at different disease stages using quantitative real time PCR (qRT-PCR) and immunohistochemistry. A better understanding of the molecular events leading to the metastatic prostate cancer phenotype will help to further identify genes or gene-products involved in this process, which may prove useful as biomarkers for diagnosis and/or prognosis of the disease. Project code: 110745921483. Supported by Colciencias Grant # RC No.462-2008 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5185. doi:10.1158/1538-7445.AM2011-5185