Androgens activate mitogen-activated protein kinase via epidermal growth factor receptor/insulin-like growth factor 1 receptor in the mouse PC-1 cell line (original) (raw)
Related papers
Journal of Molecular Endocrinology, 2007
In the male, androgens promote growth and differentiation of sex reproductive organs through ligand activation of the androgen receptor (AR). Here, we show that androgens are not major actors of the cell cycle arrest associated with the differentiation process, and that the epidermal growth factor (EGF)-mediated signalling interferes with AR activities to regulate androgen response when epithelial cells are differentiated. Higher AR expression and enhanced androgen responsiveness correlate with reduction of phosphorylated ERK1/2 over differentiation. These modifications are associated with recruitment of cells in phase G 0 /G 1 , up-regulation of p27 kip1 , down-regulation of p21 Cip1 and p53 proteins, and accumulation of hypo-phosphorylated Rb. Exposure to EGF reduces AR expression levels and blocks androgendependent transcription in differentiated cells. It also restores p53 and p21 Cip1 levels, Rb hyper-phosphorylation, ERK1/2 activation and promotes cell cycle re-entry as p27 kip1 protein levels are decreased. Treatment with a MEK inhibitor reverses the EGF-mediated AR down-regulation in differentiated cells, thus suggesting the existence of an inverse correlation between EGF and androgen signalling in non-tumoural epithelia. Interestingly, when androgen signalling is set in differentiated cells, dihydrotestosterone exerts an inhibitory effect on ERK activity but paradoxically does not modify EGFR (ErbB1) phosphorylation, indicating that androgens are able to disrupt the EGFR-ERK cascade. Overall, our data demonstrate the existence of a balance between AR and mitogen-activated protein kinase activities that favours either the maintenance of differentiated conditions or the enhancement of cell proliferation capacities.
Rapid signalling pathway activation by androgens in epithelial and stromal cells
Steroids, 2004
Estradiol rapidly activates Src as well as the Src-dependent pathway in human mammary cancer-derived MCF-7 cells, in human prostate cancer-derived LNCaP cells and in Cos cells transiently expressing hERs [EMBO J. 15 (1996) 1292; EMBO J. 17 (1998) 2008]. In addition, estradiol immediately stimulates, yes, an ubiquitous member of the Src kinase family, in human colon carcinoma-derived Caco-2 cells [Cancer Res. 56 (1996) 4516]. Progestins and androgens activate the same pathway in human mammary and prostate cancer-derived cells [EMBO J. 17 (1998) 2008; EMBO J. 19 (2000) 5406]. We observed that estradiol also stimulates the phosphatidylinositol-3-kinase (PI3K)/AKT pathway in MCF-7 cells [EMBO J. 20 (2001) 6050]. In these cells, activation of the Src- and the PI3 K-dependent pathways is simultaneous and mediated by direct interactions of the two kinases with ERalpha. The signalling pathway activation by sex-steroid hormones leads to DNA synthesis and cell growth in human mammary and pros...
PROTEOMICS, 2010
Anabolic androgenic steroids, a class of steroid hormones related to testosterone, are natural ligands of androgen receptor (AR), a member of the nuclear receptor superfamily of ligandactivated transcription factors. AR binds specific DNA elements, known as androgenresponse elements. Testosterone, the main male sexual hormone, binds AR directly and indirectly, through conversion into dihydrotestosterone (DHT), its more active metabolite. Anabolic androgenic steroids are frequently detected in the urine of doped athletes; their consumption is also growing among sport amateurs and adolescents. The effects of androgens can differ depending on the target cells and/or tissues. To gain insight into transcription activation mechanisms of AR, we investigated AR protein signaling in human peripheral blood lymphocytes treated with supraphysiological doses of DHT. We performed a comparative proteomic analysis and we identified about 30 differentially expressed proteins. At least five species contained a consensus androgen-response elements sequence in the promoter region of related coding genes. The analysis also revealed that high doses of DHT activate the drug detoxification process, could stimulate an increase in cell motility and exert a prosurvival effect rather than an apoptotic one.
Determinants of Receptor- and Tissue-Specific Actions in Androgen Signaling
Endocrine Reviews, 2015
The physiological androgens testosterone and 5α-dihydrotestosterone regulate the development and maintenance of primary and secondary male sexual characteristics through binding to the androgen receptor (AR), a ligand-dependent transcription factor. In addition, a number of nonreproductive tissues of both genders are subject to androgen regulation. AR is also a central target in the treatment of prostate cancer. A large number of studies over the last decade have characterized many regulatory aspects of the AR pathway, such as androgen-dependent transcription programs, AR cistromes, and coregulatory proteins, mostly in cultured cells of prostate cancer origin. Moreover, recent work has revealed the presence of pioneer/licensing factors and chromatin modifications that are important to guide receptor recruitment onto appropriate chromatin loci in cell lines and in tissues under physiological conditions. Despite these advances, current knowledge related to the mechanisms responsible f...
The Androgen Receptor Acetylation Site Regulates cAMP and AKT but Not ERK-induced Activity
Journal of Biological Chemistry, 2004
The androgen receptor (AR) regulates ligand-dependent gene transcription upon binding specific DNA sequences. The AR conveys both trans-activation and trans-repression functions, which together contribute to prostate cellular growth, differentiation, and apoptosis. Like histone H3, the AR is post-translationally modified by both acetylation and phosphorylation. The histone acetyltransferase p300 transactivates the AR and directly acetylates the AR in vitro at a conserved motif. Point mutations of the AR acetylation motif that abrogate acetylation reduce trans-activation by p300 without affecting the trans-repression function of the AR. The current studies assessed the functional relationship between acetylation and phosphorylation of the AR. Herein trans-activation of the AR acetylation site mutants were enhanced by the p42/ p44 MAPK pathway but were defective in regulation by protein kinase A (PKA) signaling. PKA inhibition augmented ARwt activity but not AR acetylation mutant gene reporter activity and association at an androgen response element in chromatin immunoprecipitation assays. Mutations of the lysine residues at the AR acetylation site reduced trichostatin A (TSA) responsiveness and ligand-induced phosphorylation of the AR. The AR acetylation site mutant formed ligandinduced phosphorylation-dependent isoforms with distinguishable characteristics from wild type AR as determined with two-dimensional electrophoresis. Conversely, point mutation of a subset of AR phosphorylation sites reduced trichostatin A responsiveness and trans-activation by histone acetyltransferases. Together these studies suggest that acetylation and phosphorylation of the AR are linked events and that the conserved AR lysine motif contributes to a select subset of pathways governing AR activity.
A physiological role for androgen actions in the absence of androgen receptor DNA binding activity
Molecular and Cellular Endocrinology, 2012
We tested the hypothesis that androgens have physiological actions via non-DNA binding-dependent androgen receptor (AR) signaling pathways in males, using our genetically modified mice that express a mutant AR with deletion of the 2nd zinc finger of the DNA binding domain (AR(ΔZF2)) that cannot bind DNA. In cultured genital skin fibroblasts, the mutant AR(ΔZF2) has normal ligand binding ability, phosphorylates ERK-1/2 in response to 1 min DHT treatment (blocked by the AR antagonist bicalutamide), but has reduced androgen-dependent nuclear localization compared to wildtype (WT). AR(ΔZF2) males have normal baseline ERK-1/2 phosphorylation, with a 1.5-fold increase in Akt phosphorylation in AR(ΔZF2) muscle vs WT. To identify physiological actions of non-DNA binding-dependent AR signaling, AR(ΔZF2) males were treated for 6 weeks with dihydrotestosterone (DHT). Cortical bone growth was suppressed by DHT in AR(ΔZF2) mice (6% decrease in periosteal and 7% decrease in medullary circumference vs untreated AR(ΔZF2) males). In conclusion, these data suggest that non-DNA binding dependent AR actions suppress cortical bone growth, which may provide a mechanism to fine-tune the response to androgens in bone.
Cancer research, 1995
Androgens are required for the optimal growth and development of both the normal prostate and steroid-sensitive prostate cancer. PC3 prostate cancer cell lines stably expressing the human androgen receptor (AR) and possessing an androgen-sensitive phenotype (PC3-hAR) were used to examine the role of the epidermal growth factor receptor (EGFR) in androgen-stimulated prostate cancer cell growth. Epidermal growth factor (EGF) and dihydrotestosterone (DHT) independently induced the growth of PC3-hAR cells. Moreover, EGF and DHT in combination exerted a synergistic effect on PC3-hAR cell growth. DHT-exposed PC3-hAR cells expressed a greater than 2-fold increase in EGFR mRNA and 50% more EGFR protein than controls. Time course radioligand-binding assays confirmed these findings by showing an elevation in EGF binding in the DHT-exposed PC3-hAR cells. In addition, radioligand competition-binding studies revealed a 2-fold increase in EGFR-EGF binding affinity in the PC3-hAR cells after DHT t...
Modulation of androgen-responsive gene expression by estrogen
Molecular and Cellular Endocrinology, 1992
Studies on hormonal action frequently focus on a single hormone. In intact animals, however, genes may respond to the balance of muhiple hormones. Therefore, we have studied the mutual influence of sex steroids on eight genes previously known to be testosterone-responsive in kidneys of mice. A variety of responses to estrogen were recorded. Effects occurred primarily at the transcriptional lever although in several cases there was also evidence of decreased mRNA stability. Estrogen did not affect the nuclear location of the androgen receptor. Apparently each gene interacts with both androgen-receptor complex and estrogen-receptor complex, and the ultimate outcome depends on each gene's detailed reguiato~ structure.
The Androgen Receptor as Mediator of Gene Expression and Signal Transduction Pathways
Trends in Endocrinology & Metabolism, 1998
The current model of action of androgens involves activation of a cytoplasmic receptor that migrates into the nucleus to regulate the expression of specific genes, either positively or negatively. While positive regulation requires direct binding of the receptor to DNA, negative regulation occurs mainly through protein-protein interactions of the receptor and other transcription factors. More recent findings have shown that the receptor also mediates non-conventional responses attributed hitherto only to activated growth factor receptors. These actions proceed principally through activation of cytoplasmic kinases and they suggest that in addition to its genomic functions, the androgen receptor also regulates non-genomic processes.
Endocrinology, 2010
To identify the initial response to androgens and estrogens in the orchidectomized, regressed epididymis, we determined the gene expression changes triggered by the administration of either of two metabolites of testosterone, 5␣-dihydrotestosterone (DHT) or 17-estradiol (E2), in the regressed rat epididymis. Adult rats were orchidectomized and 8 d later implanted with either empty implants (control), DHT-filled-, or E2-filled-polydioxanone implants. Rats were euthanized 12 h, 1 d, and 7 d later, and RNA was extracted and probed on Rat230-2.0 Affymetrix arrays. Probe sets that respond to DHT or E2 were identified at early time points; although the expression of some was repressed, the expression of many others was either transiently or chronically elevated. Nerve growth factor receptor (Ngfr) and S100 calcium binding protein G (S100g) were two E2 up-regulated genes detected at 12 h. Among the genes that showed a dramatic early response to DHT were endothelin 1 (Edn1), bone morphogenetic protein 4 (Bmp4), and IGF binding protein 3 (Igfbp3), which were suppressed, and IGF-I (Igf1), which was induced. Genes that were up-or down-regulated by DHT were classified based on biological function. Using PathwayStudio 4.0, we identified genes that were linked and directly influenced either the expression or regulation of one another. Epidermal growth factor and IGF-I play an important role in the pathway due to their function in regulation and expression of many other genes. These results provide novel insights into the impact of androgen action on the expression of genes that are important for epididymal function.