Dysregulated expression of androgen-responsive and nonresponsive genes in the androgen-independent prostate cancer xenograft model, CWR22-R

Abstract

9needed; these are often laborious and not practical for high-throughput screening. In order to develop a rapid automated mutation detection method, we have evaluated denaturing high-performance liquid chromatography for detection of TP53 mutations in tumor tissue. The specificity and sensitivity of the method were compared to those of denaturing gradient gel electrophoresis through testing on standard-quality DNA preparations as well as on DNA extracted from formalin-fixed, paraffin-embedded tissue sections. Amler, Lukas[8]Functional dissection of transcriptional profiles in androgen-dependent andindependent prostate cancer Using microarray analysis, we have measured changes in gene expression that occurred during the evolution of a primary prostate cancer xenograft, CWR22, from normalcy to relapsed, androgen-independent growth following androgen deprivation therapy. Rather than relying on simple pairwise comparison of the data between successive biological states (for example, normal versus tumor), we clustered the expression data on the basis of behavior in multiple biological states, representative of the entire process of prostate cancer progression. By examining the data in the context of different proliferative conditions, before and after hormonal manipulation in the xenograft model, we could identify groups of genes associated with proliferation, metabolism, hormone responsiveness and malignant transformation, as well as a small number of genes directly associated with androgen-independent growth. Our results imply that the evolution to androgen independence is due, in part, to reactivation of the androgen-response pathway in the absence of androgens, but that this reactivation is probably incomplete. Amler, Lukas [9]Dysregulated expression of androgenresponsive and nonresponsive genes in the androgen-independent prostate cancer xenograft model, CWR22-R Treatment of metastatic prostate cancer with androgen ablation often elicits dramatic tumor regressions, but the response is rarely complete, making clinical recurrence inevitable with time. To gain insight into therapy-related progression, we used microarray analysis to monitor changes in gene expression that occurred following androgen starvation of an androgen-dependent prostate tumor xenograft, CWR22, and the emergence of an androgen-independent tumor, CWR22-R. Androgen deprivation arrested the growth of CWR22 cells, as evidenced by decreased expression of genes encoding cell cycle components and basal cell metabolism, respiration and transcription, as well as the induced expression of putative negative regulatory genes that may act to sustain cells in a nonproliferative state. Evolution of androgen-independent growth and proliferation, represented by CWR22-R, was associated with a re-entry into the active cell cycle and the upregulation of several genes that were expressed at low levels or absent in the androgen-dependent tumor. Restoration of androgen to mice bearing androgenindependent CWR22-R tumors induced, augmented or repressed the expression ...

Failure of hormone therapy in prostate cancer involves systematic restoration of androgen responsive genes and activation of rapamycin sensitive signaling

“…For example, the FKBP5 gene, which encodes for a steroid receptor interacting immunophilin (Nair et al, 1997), was one of the most strongly repressed (ratio 50.2) genes during therapy (Figures 2c and 3c). In contrast, FKBP5 expression in the recurrent tumors was twofold higher than in the primary tumors (Figures 2c and 3c), as also suggested by another study (Amler et al, 2000). The restoration of androgen-responsive genes was validated in duplicate experiments on an independent cDNA microarray containing 8152 genes.…”

Androgen-induced expression of endoplasmic reticulum (ER) stress response genes in prostate cancer cells

“…Growth factors commonly involved in cell proliferation and tumorigenesis, e.g., IGF I, EGF and KGF have been shown to activate the transcription transactivation functions of the AR (Culig et al, 1994). Recent studies analysing expression of ARGs in hormone sensitive and refractory CWR22 nude mice xenograft model have also shown sustained expression of some ARGs in AR positive recurrent tumors following castration suggesting constitutive activation of AR signaling in these tumors (Nagabhushan et al, Amler et al, 2000;Mousses et al, 2002). Thus androgen regulation of critical target genes may play a role in normal prostate growth and prostate tumorigenesis.…”

“…These reporters may serve as potential biomarkers for predisposition/initiation/ progression of prostate cancers (Xu et al, 2001;Vaarala et al, 2000;Amler et al, 2000). Towards this aim, we are analysing the ARG repertoire in prostate cancer cells using high-throughput approaches and evaluating their significance in human CaP (Xu et al, 2000a(Xu et al, , 2001.…”

Biomarkers of Selenium Action in Prostate Cancer

“…With progression to androgen resistance, AR signaling remains intact, and virtually all tumors continue to express AR and PSA, despite absent ligand, possibly due to increased sensitivity to androgen or activation of signaling pathways downstream of AR [22][23][24][25]. In vitro, AS cell lines show expression of many androgen regulated genes, as well as many other genes not affected by androgen that are distinct from AI cell lines.…”