Prostate cancer is the most common cancer and the second leading cause of cancer death in men. Most of the prostate cancers are slow-growing and latent, posing little danger to men who carry them. Only a small portion of these cancers (23%) will become clinically significant, i.e., they will grow faster and will eventually kill the patients if left untreated. Unfortunately, it is difficult at present to accurately predict which cancer will stay silent and which will become clinically significant. Based on the available scientific knowledge, one of the most promising methods to predict the behavior of a tumor is to analyze the presence or absence of gene products for a specific set of genes. To use this method, we have to first identify all the genes whose presence or absence is important for cancer formation and progression. However, only a small number of such genes are known and most of them are yet to be discovered. With the development of new techniques, it is becoming possible to isolate all the genes from a specific cell population. In this proposed study, we will use the powerful method of mRNA differential display to identify all the genes whose presence or absence is different in a normal prostate cell compared with tumor cell. The following objectives will be pursued: (1) To isolate and determine the DNA structure of the terminal portions of genes whose presence or absence is related to the development and progression of prostate cancer by the method of mRNA differential display; (2) To quantitatively determine the amounts of these genes identified in aim #1 in human normal prostate tissues and prostate cancers of various grades using Northern blot analysis and/or RT-PCR assay; (3) To identify the complete DNA structure for the genes identified in aim #2 in collaboration with scientists at Human Genome Sciences, Inc.