Mechanism of antiandrogen action: Conformational changes of the receptor

Kuil, Cor W.; Mulder, E.

doi:10.1016/0303-7207(94)90112-0

Cited by 53 publications

(42 citation statements)

References 18 publications

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“…As expected, BIC-occupied AR remained unaffected by the T877A mutation, and showed no change in response to N-CoR. This is in accordance with the previous finding that the BIC-induced AR conformation is not changed by the T877A mutation [9], and with the ability of T877A-AR from LNCaP cells to recruit N-CoR to the PSA promoter [25] and subsequently inhibit PSA production in the presence of BIC [43].…”

Section: Discussionsupporting

confidence: 92%

“…The underlying molecular mechanism for the change in response to OHF and CPA is not fully understood. Some clue is given by the observation that, after binding of OHF and CPA, the T877A mutation allows the AR to adopt an active conformation, similar to that found with the agonists R1881 and DHT [9,17].…”

Section: Introductionmentioning

confidence: 96%

“…The change in AR protein structure is dependent on the type of ligand that occupies the LBD. In this respect, antiandrogens induce a conformational change in the AR protein different from that induced by androgens [9].…”

Section: Introductionmentioning

confidence: 99%

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Differential modulation of androgen receptor transcriptional activity by the nuclear receptor co-repressor (N-CoR)

Berrevoets

Umar

Trapman

et al. 2004

Biochemical Journal

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Antiandrogens are widely used agents in the treatment of prostate cancer, as inhibitors of AR (androgen receptor) action. Although the precise mechanism of antiandrogen action is not yet elucidated, recent studies indicate the involvement of nuclear receptor co-repressors. In the present study, the regulation of AR transcriptional activity by N-CoR (nuclear receptor co-repressor), in the presence of different ligands, has been investigated. Increasing levels of N-CoR differentially affected the transcriptional activity of AR occupied with either agonistic or antagonistic ligands. Small amounts of co-transfected N-CoR repressed CPA (cyproterone acetate)-and mifepristone (RU486)-mediated AR activity, but did not affect agonist (R1881)-induced AR activity. Larger amounts of co-transfected N-CoR repressed AR activity for all ligands, and converted the partial agonists CPA and RU486 into strong AR antagonists. In the presence of the agonist R1881, co-expression of the p160 co-activator TIF2 (transcriptional intermediary factor 2) relieved N-CoR repression up to control levels. However, in the presence of RU486 and CPA, TIF2 did not functionally compete with N-CoR, suggesting that antagonistbound AR has a preference for N-CoR. The AR mutation T877A (Thr 877 → Ala), which is frequently found in prostate cancer and affects the ligand-induced conformational change of the AR, considerably reduced the repressive action of NCoR. The agonistic activities of CPA-and hydroxyflutamideoccupied T877A-AR were hardly affected by N-CoR, whereas TIF2 strongly enhanced their activities. These results indicate that lack of N-CoR action allows these antiandrogens to act as strong agonists on the mutant AR.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 96%

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Differential modulation of androgen receptor transcriptional activity by the nuclear receptor co-repressor (N-CoR)

Berrevoets

Umar

Trapman

et al. 2004

Biochemical Journal

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“…Functional characterization showed that the mutant receptor induced transcription upon addition of RU486 (14). These results led to the hypothesis that the activity of antagonists is based on the induction of a non-functional conformation at the C terminus of steroid hormone receptors (4 -6, 11).Androgen binding to the androgen receptor (AR) 1 changed the receptor structure in such a way that the entire ligand binding domain resisted proteolytic degradation (10,16,17). However, for the antiandrogen-bound receptor, the outcome of preliminary studies on resistance against proteolytic degradation varied in different investigations.…”

mentioning

confidence: 99%

“…Androgen binding to the androgen receptor (AR) 1 changed the receptor structure in such a way that the entire ligand binding domain resisted proteolytic degradation (10,16,17). However, for the antiandrogen-bound receptor, the outcome of preliminary studies on resistance against proteolytic degradation varied in different investigations.…”

mentioning

confidence: 99%

Ligand-induced Conformational Alterations of the Androgen Receptor Analyzed by Limited Trypsinization

Kuil

Berrevoets

Mulder

1995

Journal of Biological Chemistry

131

103

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Limited proteolysis of in vitro produced human androgen receptor was used to probe the different conformations of the receptor after binding of androgens and several antiandrogens. The results provide evidence for five different conformations of the receptor, as detected by the formation of proteolysis resisting fragments: 1) an initial conformation of the unoccupied receptor not resisting proteolytic attack; and receptor conformations characterized by 2) a 35-kDa proteolysis resisting fragment spanning the ligand binding domain and part of the hinge region, obtained with most antagonists, and in an initial step after agonist binding; 3) a 29-kDa proteolysis resisting fragment spanning the ligand binding domain, obtained in the presence of agonists after an activation process; 4 and 5) 30-and 25-kDa fragments, derived from 2 and 3, but missing part of the C terminus, obtained with RU486 (RU486 has antiandrogenic properties, besides its effects as an antiprogestagen/antiglucocorticoid). Concomitantly with the change from 2 to 3 (and of 4 to 5 for RU486), dissociation of the 8 S complex of receptor with associated proteins occurred. With a mutant receptor (LNCaP cell mutation in C-terminal region), some antagonists activated transcription analogous to agonists, and induced the activated receptor conformation 3. A mutant lacking the C-terminal 12 amino acids bound RU486 but not androgens, and formed with RU486 conformation 5. These data imply that, after the initial rapid binding of ligand, androgens induce a conformational change of the receptor, a process that also involves release of associated proteins. RU486 induces an inappropriate conformation of the C-terminal end, similar as found for its effect on the progesterone receptor. In contrast, the other antiandrogens act at a different step in the mechanism of action: they do not induce an abnormal conformation, but act earlier and prevent a conformation change by stabilizing a complex with associated proteins.The biological effects of androgens and other steroid hormones are mediated through intracellular receptors, belonging to the steroid and thyroid hormone receptor superfamily (1). Upon activation by the hormone, steroid receptors interact with specific DNA sequences, located in the flanking regions of target genes, resulting in modulation of the expression of these genes (2-4). Steroid hormone receptor antagonists inhibit the biological effects of agonists, and are frequently used in the treatment of hormone-based dysfunctions in human. Furthermore, the synthetic antagonists are important tools to define the molecular mechanism of transactivation by steroid hormones (5, 6).Agonists and antagonists may change the spatial structure of the receptor in distinct ways, as was first indicated by gel retardation experiments: antagonist-and agonist-receptor-DNA complexes showed slightly different mobilities (7-10). Recently, limited proteolysis of progesterone, estrogen, and glucocorticoid receptors pinpointed the distinction in conformation between hormone-and ant...

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A multi‐parameter imaging assay identifies different stages of ligand‐induced androgen receptor activation

et al. 2013

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Androgens exert their key function in development and maintenance of the male phenotype via the androgen receptor (AR). Ligand-activated ARs also play a role in prostate cancer. Despite initial success of treatment by testosterone depletion or blocking of androgen binding to the AR using antiandrogens, eventually all tumors escape to a therapy resistant stage. Development of novel therapies by other antagonistic ligands or compounds that target events subsequent to ligand binding is very important. Here, we validate a fluorescence resonance energy transfer (FRET) based imaging assay for ligand-induced AR activity, based on the conformational change in the AR caused by interaction between the FQNLF motif in the N-terminal domain and the cofactor binding groove in the ligand-binding domain (N/C-interaction). We test the assay using known agonistic and antagonistic ligands on wild type AR and specific AR mutants. Our data show a strong correlation between the ligand-induced AR N/C-interaction and transcriptional activity in wild type AR, but also in AR mutants with broadened ligand responsiveness. Moreover, we explore additional readouts of this assay that contribute to the understanding of the working mechanism of the ligands. Together, we present a sensitive assay that can be used to quantitatively assess the activity of agonistic and antagonistic AR ligands. ' 2013 International Society for Advancement of Cytometry Key terms androgen receptor; recurrent prostate cancer; ligand; N/C-interaction; quantitative live cell imaging; FRET

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Mechanism of antiandrogen action: Conformational changes of the receptor

Cited by 53 publications

References 18 publications

Differential modulation of androgen receptor transcriptional activity by the nuclear receptor co-repressor (N-CoR)

Differential modulation of androgen receptor transcriptional activity by the nuclear receptor co-repressor (N-CoR)

Ligand-induced Conformational Alterations of the Androgen Receptor Analyzed by Limited Trypsinization

A multi‐parameter imaging assay identifies different stages of ligand‐induced androgen receptor activation

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