title: An investigation into CAG repeat length variation and N/C terminal interactions in the T877A mutant androgen receptor found in prostate cancer.
abstract: Prostate cancer may progress by circumventing ablation therapy due to mutations in the androgen receptor (AR) gene. The most intensively studied is the T877A mutation in the ligand binding domain (LBD), which causes the AR to become promiscuous, i.e., respond to a number of different ligands. Our investigations have shown that the T877A mutation alters the inverse relationship between CAG repeat length and transactivation in a noticeable albeit minor manner, while increasing N/C terminal interactions. In the presence of beta-catenin, a coactivator over-expressed in prostate cancer, the inverse relationship between CAG repeat length and transactivation is reversed for the wild type (wt) AR as well. We have also used molecular modeling with the AR and FXXLF and LXXLL peptides to investigate N/C terminal and coactivator interactions. In T877A, this approach revealed an increase in the flexibility of amino acid residues in the activation function 2 (AF-2) domain in the LBD, and a larger solvent accessible surface in T877A compared to the wt AR AF-2 domain. Thus, the improved induced fit of the AR N-terminal domain FXXLF-containing peptide into the T877A LBD could be due to the increased flexibility and solvent accessibility of the AF-2 domain. These new observations suggest that the AR CAG effect can be overridden by prostate cancer mutations, and also further our understanding of hormone-refractory prostate cancer by helping to explain the promiscuity of the T877A mutation.
authors.affiliation: Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada.
authors.forename: Jason
authors.initials: J
authors.lastname: Southwell
authors.forename: Shafinaz F
authors.initials: SF
authors.lastname: Chowdhury
authors.forename: Bruce
authors.initials: B
authors.lastname: Gottlieb
authors.forename: Lenore K
authors.initials: LK
authors.lastname: Beitel
authors.forename: Rose
authors.initials: R
authors.lastname: Lumbroso
authors.forename: Enrico O
authors.initials: EO
authors.lastname: Purisima
authors.forename: Mark
authors.initials: M
authors.lastname: Trifiro
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D017930:Genes, Reporter; D014644:Genetic Variation; D000882:Haplorhini; D007668:Kidney / Q000166:cytology; D008156:Luciferases / Q000378:metabolism; D008297:Male; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011471:Prostatic Neoplasms / Q000235:genetics*; D011485:Protein Binding; D011487:Protein Conformation; D011944:Receptors, Androgen / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D011944:Receptors, Androgen; D008156:Luciferases