As a member group in the Cooperative Network for Molecular Genetic and Cytogenetic Studies of Prostate Cancer we propose to investigate the role of mutant transcriptional regulators in the genesis of prostate cancer and its progression from clinically silent to clinically evident disease. Our studies together with those of other participating groups will examine the hypothesis that progression of prostatic cancer is determined by the acquisition of multiple genetic changes that enable prostate cells to escape the normal constraints on their proliferation. Initial aims will focus on identification of somatic mutations in the p53, retinoblastoma (RB), and androgen receptor (AR) genes. A combination of molecular genetic and immunochemical methods will be utilized in the detection and characterization of the expression of mutant regulatory proteins. p53 and RB genes are negative regulators of cell proliferation and mutational inactivation of these gene products could represent early events in the natural history of prostatic cancer. AR is a positive regulator of proliferation and may be mutated as a later event or as an early event later amplified by clonal selection. A variety of AR mutants could be capable of androgen independent stimulation of growth and functional analyses will evaluate the oncogenic potential of the mutant ARs. p53 and androgen receptor gene cooing regions will be amplified by the polymerase chain reaction (PCR) from genomic DNA and from mRNA using reverse transcription and PCR. Codon DNA sequences will be screened by denaturing gradient gel electrophoresis. Because of the large size of the RB gene, reverse transcription and PCR analysis of mRNA will be combined with immunochemical analysis using a variety of antibody probes. Detailed immunohistochemical analyses of expression of mutant and wild type genes will be performed with both conventional and confocal laser scanning microscopy. Studies are designed to utilize mutant genes as markers for investigation of the lineage of cancer cells to determine whether androgen insensitive cells arise from androgen sensitive cells or from pre-existing clones of insensitive cells. An existing tumor bank and large clinic population of both blacks and whites in different age groups will permit detailed racial and age comparisons in an attempt to explain the increased incidence of clinically evident prostatic cancer in blacks and the increase in general with aging.
