dentification of testosterone-/androgen receptor-regulated genes in mouse Sertoli cells

Androgen and androgen receptor （AR） play important roles in male spermatogenesis and fertility, yet detailed androgen/AR signals in Sertoli cells remain unclear. To identify AR target genes in Sertoli cells, we analyzed the gene expression profiles of testis between mice lacking AR in Sertoli cells （S-AR-/y） and their littermate wild-type （WT） mice. Digital gene expression analysis identified 2276 genes downregulated and 2865 genes upregulated in the S-AR-/y mice testis compared to WT ones. To further nail down the difference within Sertoli cells, we first constructed Sertoli cell line TM4 with stably transfected AR （named as TM4/AR） and found androgens failed to transactivate AR in Sertoli TM4 and TM4/AR cells. Interestingly, additional transient transfection of AR-cDNA resulted in significant androgen responsiveness with TM4/AR cells showing 10 times more androgen sensitivity than TM4 cells. In the condition where maximal androgen response was demonstrated, we then analyzed gene expression and found the expression levels of 2313 genes were changed more than twofold by transient transfection of AR-cDNA in the presence of testosterone. Among these genes, 603 androgen-/ AR-regulated genes, including 164 upregulated and 439 downregulated, were found in both S-AR-/y mice testis and TM4/AR cells. Using informatics analysis, the gene ontology was applied to analyze these androgen-/AR-regulated genes to predict the potential roles of androgen/AR in the process of spermatogenesis. Together, using gene analysis in both S-AR-/y mice testis and TM4/AR cells may help us to better understand the androeen/AR signals in Sertoli cells and their influences in spermatogenesis.

Expression of human AR cDNA driven by its own promoter results in mild promotion, but not suppression, of growth in human prostate cancer PC-3 cells

Aim： To examine the physiological role of the androgen receptor （AR） in the PC-3 cell line by transfecting full-length functional AR cDNA driven by its natural human AR promoter. Methods： We generated an AR-expressing PC-3（AR）9 stable clone that expresses AR under the control of the natural human AR promoter and compared its proliferation to that of the PC-3（AR）2 （stable clone that expresses AR under the control of the cytomegalovirus （CMV） promoter, established by Heisler et al.） after androgen treatment. Results： We found that dihydrotestosterone （DHT） from 0.001 nmol/L to 10 nmol/L induces cell cycle arrest or inhibits proliferation of PC-3（AR）2 compared with its vector control, PC-3（plRES）. In contrast, PC-3（AR）9 cell growth slightly increased or did not change when treated with physiological concentrations of 1 nmol/L DHT. Conclusion： These data suggest that intracellular control of AR expression levels through the natural AR promoter might be needed for determining AR function in androgen-independent prostate cancer （AIPC） PC-3 cells. Unlike previous publications that showed DHT mediated suppression of PC-3 growth after transfection of viral promoter-driven AR overexpression, we report here that DHT-mediated PC-3 proliferation is slightly induced or does not change compared with its baseline after reintroducing AR expression driven by its own natural promoter, as shown in PC-3（AR）9 prostate cancer cells.

The diverse and contrasting effects of using human prostate cancer cell lines to study androgen receptor roles in prostate cancer

The androgen receptor （AR） plays an important role in the development and progression of prostate cancer （PCa）. Androgen deprivation therapy is initially effective in blocking tumor growth, but it eventually leads to the hormonerefractory state. The detailed mechanisms of the conversion from androgen dependence to androgen independence remain unclear. Several PCa cell lines were established to study the role of AR in PCa, but the results were often inconsistent or contrasting in different cell lines, or in the same cell line grown under different conditions. The cellular and molecular alteration of epithelial cells and their microenvironments are complicated, and it is difficult to use a single cell line to address this important issue and also to study the pathophysiological effects of AR. In this paper, we summarize the different effects of AR on multiple cell lines and show the disadvantages of using a single human PCa cell line to study AR effects on PCa. We also discuss the advantages of widely used epithelium-stroma co-culture systems, xenograft mouse models, and genetically engineered PCa mouse models. The combination of in vitro cell line studies and in vivo mouse models might lead to more credible results and better strategies for the study of AR roles in PCa.

Androgen Receptor Is a Tumor Suppressor and Proliferator in Prostate Cancer

Targeting androgens via androgen deprivation therapy (ADT) to suppress androgens/androgen receptor (AR) functions remains the standard treatment for prostate cancer. However, most tumors eventually recur

Differential regulation of glutathione S-transferase Yb1mRNA levels in rat prostate, liver and brain by androgen

Northern blot analysis of glutathione S-transferase (GST) Yb1 mRNA in different tissues of male and female rats revealed that its tissue-specific transcription patterns were highly sex hormone related. Although the GST Yb1 mRNA could be detected in most of the tissues examined at various levels, the highest abundance was observed in the ventral prostate, uterus and liver, which were the main target tissue for androgen, estrogen and glucocorticoid respectively The effect of androgen on the transcription of GST Yb1 was also tissue-specific. Since androgen withdrawal by castration caused the up-regulation of GST Yb1 mRNA in the ventral prostate but down-regulation in the liver and no effect in the brain, evaluation of this system for studying the regulation mechanisms of gene expression by which androgen exerts its differential effects has been discussed.

Recent advances in the study of testicular nuclear receptor 4

Testicular nuclear receptor 4(TR4),also known as NR2C2(nuclear receptor subfamily 2,group C,member 2),is a transcriptional factor and a member of the nuclear receptor family.TR4 was initially cloned from human and rat hypothalamus,prostate,and testes libraries.For almost two decades,its specific tissue distribution,genomic organization,and chromosomal assignment have been well investigated in humans and animals.However,it has been very difficult to study TR4's physiological functions due to a lack of specific ligands.Gene knock-out animal techniques provide an alternative approach for defining the biological functions of TR4.In vivo studies of TR4 gene knockout mice(TR4-/-) found that they display severe spinal curvature,subfertility,premature aging,and prostate prostatic intraepithelial neoplasia(PIN) development.Upstream modulators,downstream target gene regulation,feedback mechanisms,and differential modulation mediated by the recruitment of other nuclear receptors and coregulators have been identified in studies using the TR4-/-phenotype.With the establishment of a tissue-specific TR4-/-mouse model,research on TR4 will be more convenient in the future.