title: Androgen receptor antagonism by divalent ethisterone conjugates in castrate-resistant prostate cancer cells.
abstract: Sustained treatment of prostate cancer with androgen receptor (AR) antagonists can evoke drug resistance, leading to castrate-resistant disease. Elevated activity of the AR is often associated with this highly aggressive disease state. Therefore, new therapeutic regimens that target and modulate AR activity could prove beneficial. We previously introduced a versatile chemical platform to generate competitive and non-competitive multivalent peptoid oligomer conjugates that modulate AR activity. In particular, we identified a linear and a cyclic divalent ethisterone conjugate that exhibit potent anti-proliferative properties in LNCaP-abl cells, a model of castrate-resistant prostate cancer. Here, we characterize the mechanism of action of these compounds utilizing confocal microscopy, time-resolved fluorescence resonance energy transfer, chromatin immunoprecipitation, flow cytometry, and microarray analysis. The linear conjugate competitively blocks AR action by inhibiting DNA binding. In addition, the linear conjugate does not promote AR nuclear localization or co-activator binding. In contrast, the cyclic conjugate promotes AR nuclear localization and induces cell-cycle arrest, despite its inability to compete against endogenous ligand for binding to AR in vitro. Genome-wide expression analysis reveals that gene transcripts are differentially affected by treatment with the linear or cyclic conjugate. Although the divalent ethisterone conjugates share extensive chemical similarities, we illustrate that they can antagonize the AR via distinct mechanisms of action, establishing new therapeutic strategies for potential applications in AR pharmacology.
authors.affiliation: Department of Chemistry, New York University, New York, New York 10003, United States.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Levine
authors.forename: Eugine
authors.initials: E
authors.lastname: Lee
authors.forename: Alex
authors.initials: A
authors.lastname: Greenfield
authors.forename: Richard
authors.initials: R
authors.lastname: Bonneau
authors.forename: Susan K
authors.initials: SK
authors.lastname: Logan
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Garabedian
authors.forename: Kent
authors.initials: K
authors.lastname: Kirshenbaum
mesh_terms: D059002:Androgen Receptor Antagonists / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D005003:Ethisterone / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D046228:Microarray Analysis; D064129:Prostatic Neoplasms, Castration-Resistant / Q000378:metabolism*
chemical_list: D059002:Androgen Receptor Antagonists; D005003:Ethisterone