Androgen receptor gene mutations in human prostate cancer.

Abstract

We screened human prostate cancer tissues for the presence of somatic mutations in the hormone binding domain of the androgen receptor (AR) gene. Exons E-H were amplified from genomic DNA using the polymerase chain reaction and analyzed by denaturing gradient gel electrophoresis (DGGE), which separates DNA fragments that differ by only a single base. We detected a mutation in exon E of the hormone binding domain in 1 of 26 specimens of untreated organ-confined stage B prostate cancer. The mutation was not detectable in peripheral blood lymphocyte DNA. Lymphocyte DNA (wild-type AR) migrated in DGGE as a single band. The tumor DNA migrated in DGGE as four bands, consistent with the presence of cells with mutant AR plus cells with wild-type AR and indicating that the tumor contained a somatic mutation. To our knowledge, a somatic AR gene mutation has not been reported previously. Sequencing revealed a G --A substitution in codon 730, changing valine to methionine. Codon 730 is in a region highly conserved among all steroid receptors. The abundance of the mutated fragment (about 50% of the DNA in the specimen) indicates its presence in cells with a growth advantage. A somatic mutation could be detected by DGGE if it represented at least 10% of the sample. Failure to detect mutations in other specimens analyzed may be due to this limit of sensitivity, the presence of mutations in other parts of the AR, or a low frequency of mutations in early stage disease.Prostate cancer is the most frequently diagnosed cancer and the second leading cause of cancer deaths in men in the U.S.(1). Recognition that androgen is required for the development of prostate cancer (2) and its growth (3) has been the basis for continuing interest in the role of the androgen receptor (AR) in prostate cancer (1,(4)(5)(6). The AR is a member of the superfamily of genes that code for the steroid and thyroid hormone receptor family of ligand-dependent nuclear transcription factors, all of which have an N-terminal domain that affects transcription efficiency, a central DNA

Expression of Structurally Unaltered Androgen Receptor in Extramammary Paget's Disease

“…Finally, we studied the integrity of the androgen receptor gene in 10 tumors excised from 8 advancedstage cases of EMPD, because mutations of the androgen receptor gene may confer a growth advantage in prostate cancer (Gaddipati et al, 1994;Newmark et al, 1992;Taplin et al, 1995;Tilley et al, 1996) as well as in male breast cancer (Lobaccaro et al, 1993). Exons 2 to 8 of the androgen receptor gene were directly sequenced.…”

“…Furthermore, androgen receptor gene mutations have also been found in localized or latent prostate cancer before hormonal therapy (Newmark et al, 1992;Takahashi et al, 1995;Tilley et al, 1996), suggesting that mutant androgen receptor might provide a growth advantage even in the presence of a normal androgen level. Thus, we examined exons 2 to 8 encoding DNAand hormone-binding domains of the androgen receptor gene by direct sequencing in 10 advanced EMPD tumors.…”

Epidermal Growth Factor Increases Coactivation of the Androgen Receptor in Recurrent Prostate Cancer

“…Tran 35 S-label (100 Ci/dish) (PerkinElmer Life Sciences) was added to the cells with or without DHT or EGF treatment and incubated for 1.5 h. Cells were washed, fresh culture medium with or without hormone was added, and cells were incubated for 0, 8, and 24 h. Lysates were prepared from labeled cells using RIPA buffer containing protease inhibitors. 35 S-Labeled AR protein was immunoprecipitated using AR52 IgG (73) and Pansorbin cells (Calbiochem) and analyzed by SDS gel electrophoresis. Autoradiographic signals were quantitated by densitometric scanning using an AlphaImager 3400 densitometer and AlphaEaseFC software (AlphaInnotech, San Leandro, CA).…”

“…AR mutations identified in prostate cancer include shorter than average CAG repeat lengths (33) associated with increased AR levels (34). The overall frequency of AR mutations in early stage disease is Ͻ5% (35), indicating that AR mutations do not account for prostate cancer initiation in most patients. The frequency of AR mutations increases in late stage recurrent prostate cancer (4,35,36) and may reflect adaptive changes to low androgen levels or anti-androgen treatment (37) or is in-dicative of the inherent genetic instability that characterizes advanced cancer cells.…”

The Transcriptional Co-Activator cAMP Response Element-Binding Protein-Binding Protein Is Expressed in Prostate Cancer and Enhances Androgen- and Anti-Androgen-Induced Androgen Receptor Function

“…28,29 The studies in DU-145 cells were continued with the mutated AR 730 val3met, which was discovered in a specimen of clinically localized prostate cancer. 30 Functional characterization of that mutated AR revealed increased activation by metabolic products of dihydrotestosterone and hydroxyflutamide. 31 The aim of those experiments was to assess a contribution of CBP to the enhanced activation.…”