Development and Characterization of an \u3cem\u3eIn vitro\u3c/em\u3e Model of Prostate Cancer Progression

Establishing and characterizing models of prostate cancer are necessary to analysis, the models can be used to identify cancer-specific proteins, as well as potential therapeutic compounds. The C3(l)/Tag transgenic mouse system is a unique model of prostate cancer that has yielded cell lines representing different stages of cancer progression. These cell lines represent an in vitro model of prostate cancer development and have been used to analyze characteristic aspects of cancer. Recently, two cell lines, Pr-111 and Pr-117, derived from prostatic intraepithelial neoplasia (PIN) lesions were established in culture and molecularly and morphologically characterized (Soares C.R., Shibata M.-A., Green J.E., Jorcyk C.L., 2002). Pr-111 cells have a reduced growth rate, exhibit androgen-dependent growth, and develop small tumors in nude mice only after several months. In contrast, Pr-117 cells show a high proliferation rate and androgen-independent growth in vitro and form large tumors by 6 weeks leading to numerous metastases in vivo. These cell lines in addition to the previously described Pr-142 cell line (Jorcyk et al., 1998) and a cell line isolated from a lung metastasis, Pr-14C1 (Soares, in preparation) combine to form a complete model of prostate tumor progression. The characterization of the PIN cell line, Pr-111, adds an important component for the study of prostate cancer development. Most studies of prostate cancer prevention have been limited to advanced disease; however, the Pr-111 cell line adds a new dimension for studying early stage prostate cancer. Here, the Pr-111 cells were analyzed as an in vitro model for chemoprevention by using two commonly prescribed therapies, flutamide and etoposide. Using a cytotoxicity assay, PIN cells were inhibited from proliferation with both therapies in a concentration-dependent manner. Morphological and DNA fragmentation studies suggest that after 24 hours of treatment, cells demonstrated characteristic signs of apoptosis. These findings indicate that Pr-111 cells may provide a new model for studying early stages of prostate cancer progression for traditional chemotherapy intervention. Early treatment of prostate cancer ensures a more successful outcome for most patients. Currently, invasive procedures including needle biopsy ensures an accurate diagnosis for prostate disease; therefore, research has focused on novel proteins that may be detected in serum, like prostate specific antigen (PSA), as diagnostic tools. The technique of choice has been to use the new technology of array analysis. The C3(1)/Tag derived cell line model of prostate cancer progression was analyzed by two different types of arrays to detect differentially expressed genes among the cell lines. Comparison analyses identified hundreds of sequences of known genes. In addition, unknown sequences (ESTs) were identified that will help to elucidate various novel proteins involved in the progression of prostate cancer. RT-PCR, Northern and western blot analyses were used to validate the array data, in addition to characterizing the transcriptomes of the prostate cancer cell lines. The data collected and presented here add two new cell lines, Pr-111 (PIN) and Pr-117 (adenocarcinoma), to the C3(1)/Tag in vitro model of prostate cancer. This model is a unique animal model that has yielded cell lines from both diagnostic and significant stages of disease that can in turn be used to study novel proteins and therapies for the early detection and treatment of prostate cancer