This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Although an immunochemical test for prostate specific antigen (PSA) test has proved valuable for early diagnosis of prostate adenocarcinoma (PCa), elevated PSA levels are also seen in a number of other prostatic conditions that have distinct therapeutic requirements, such as benign prostate hyperplasia (BPH). Biomarkers other than PSA that can be assessed in biopsy specimens, in serum or in urine will be valuable in determining the appropriate strategy for intervention. Monoclonal antibodies (MAbs) provide a rapid and specific means of detecting the presence of biomarkers, independent of whether they result from changes in gene and protein expression, or from biological modification of proteins or other macromolecules. We propose to isolate antibodies that recognize novel biomarkers associated with tumorigenic potential of prostate cells. The underlying hypothesis of this work is that detectable antigens are differentially expressed in prostate cells as they become oncogenically transformed. Identification of these antigens, some of which are likely to be present on the surfaces of cells, may be performed using paired cell lines that differ in tumorigenic potential. Although MAbs can be easily used to distinguish antigens on cells, isolation of MAbs by traditional, hybridoma methods is difficult in the absence of purified antigen. Antibody phage display permits the use of affinity subtraction and purification techniques for selection of MAbs (Aim 1) binding to antigens that differ between closely related cell types, even without prior knowledge of the nature of the antigens involved. Lineage-related human prostate cell lines, RWPE-1 and RWPE-2, which differ in the absence/presence of a Ki-Ras gene, are an ideal platform for identification of tumorigenicity-associated antigens. Antibody phage display libraries will be subtracted on RWPE-1 and selected on RWPE-2 cell lines. MAbs identified in this manner will be verified for their specificity (Aim 3) for tumorigenic cultured cells, and their cognate antigens characterized (Aim 2). Archived serum, radical prostatectomy and biopsy specimens from localized and metastatic PCa will be probed with the novel MAbs to determine the scope of expression of the antigens in cancer patients. The primary outcome of this study will be novel antibodies against biomarkers associated with tumorigenic prostate disease. This will have an impact on diagnosis and treatment of prostatic cancer in that they will permit the development of diagnostic assays that can predict the tumorous potential of abnormal prostatic growth. Antibodies or other molecules directed against these antigens may also prove novel therapeutic targets and thus have the potential to dramatically reduce mortality.
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