metribolone and Disease-Models--Animal

We demonstrate that the androgen receptor (AR) regulates a transcriptional program of DNA repair genes that promotes prostate cancer radioresistance, providing a potential mechanism by which androgen deprivation therapy synergizes with ionizing radiation. Using a model of castration-resistant prostate cancer, we show that second-generation antiandrogen therapy results in downregulation of DNA repair genes. Next, we demonstrate that primary prostate cancers display a significant spectrum of AR transcriptional output, which correlates with expression of a set of DNA repair genes. Using RNA-seq and ChIP-seq, we define which of these DNA repair genes are both induced by androgen and represent direct AR targets. We establish that prostate cancer cells treated with ionizing radiation plus androgen demonstrate enhanced DNA repair and decreased DNA damage and furthermore that antiandrogen treatment causes increased DNA damage and decreased clonogenic survival. Finally, we demonstrate that antiandrogen treatment results in decreased classical nonhomologous end-joining.. We demonstrate that the AR regulates a network of DNA repair genes, providing a potential mechanism by which androgen deprivation synergizes with radiotherapy for prostate cancer.

Topics: Androgen Antagonists; Animals; Antineoplastic Agents, Hormonal; Cell Line, Tumor; Disease Models, Animal; DNA Damage; DNA Repair; Gene Expression Regulation, Neoplastic; Humans; Male; Metribolone; Mice; Prostatic Neoplasms; Prostatic Neoplasms, Castration-Resistant; Radiation, Ionizing; Receptors, Androgen; Signal Transduction; Xenograft Model Antitumor Assays

We have shown previously that the ras and myc oncogenes can induce poorly differentiated mouse prostate carcinomas in vivo with high frequency (greater than 90%) using inbred C57BL/6 mice in the mouse prostate reconstitution model system. To study the androgen sensitivity of these carcinomas, we have developed an in vitro model system which includes a cell line from normal urogenital sinus epithelium (CUGE) and cell lines from three ras + myc transformed mouse prostate carcinomas (RM-9, RM-1, and RM-2). CUGE cells, as well as all prostate carcinoma cell lines, were positive for cytokeratin 18 mRNA and immunoreactive to cytokeratin-specific antiserum. Two out of three of the early passage carcinoma cell lines were clonal with respect to Zipras/myc 9 retrovirus integration as determined by Southern blot analysis. Whereas significant mitogenic effects of testosterone (10 nM) were not seen in CUGE cells grown in serum-free medium, under similar conditions approx. 2-fold increases in cell number were seen in all low passage prostate carcinoma cell lines. Also, in the presence of growth inhibitory levels of suramin (50 micrograms/ml), testosterone was capable of significant growth stimulation in the carcinoma cell lines. With further propagation from low passage [20-25 population doublings (PD)] to high passage (75-100 PD), all carcinoma cell lines demonstrated increased and similar growth rate in the presence and absence of testosterone. These cell lines maintained stable androgen receptor numbers and binding kinetics during the transition from testosterone-responsive growth to reduced responsivity over multiple passages in culture (> 150 PD). Overall, our studies indicate that the capacity to bind testosterone is stably maintained through the transition of the androgen-sensitive to insensitive phenotype and raise the possibility that androgen sensitivity can persist throughout progression but is masked by the acquisition of autocrine pathways.

Topics: Androgens; Animals; Blotting, Southern; Cell Division; Cell Transformation, Neoplastic; Disease Models, Animal; DNA Probes; Drug Tolerance; Female; Genes, myc; Genes, ras; Keratins; Kinetics; Male; Metribolone; Mice; Mice, Inbred C57BL; Receptors, Androgen; RNA, Messenger; Testosterone; Tumor Cells, Cultured

During the course of another investigation, three dogs had been castrated 3 months previously. Upon completion of the experiment, it was discovered that one dog presented a spontaneous prostatic adenocarcinoma of intraalveolar proliferative type at histology. Prostate weight of this dog before castration was estimated to be 22 g by tridimensional measurement at laparotomy and remained relatively constant (19 g) 3 months after castration. These results indicate that if regression had occurred in some cell populations (androgen-dependent) it was only partial and masked by growth of androgen-independent cells. Analysis of 12 individual steroids in peripheral blood and in prostatic tissue attested of a normal adrenal secretory activity. A series of 15 hydrolytic enzymes along with receptors for androgen, estrogen, and progesterone, were determined in prostatic tissue obtained at sacrifice. Enzymatic activities were those of typical epithelial cells, and most of them remained relatively high despite low levels of circulating testosterone. However, two markers of androgen action in dog prostate, acid phosphatase and arginine esterase, were significantly reduced. Receptor levels were similar to those of castrated animals. Thus, cancer cells had probably retained some androgen sensitivity.

Topics: Adenocarcinoma; Animals; Castration; Cell Nucleus; Cytosol; Disease Models, Animal; Dogs; Estradiol; Estrenes; Male; Metribolone; Promegestone; Prostate; Prostatic Hyperplasia; Prostatic Neoplasms; Receptors, Steroid; Testosterone Congeners; Time Factors