Downregulation of androgen receptor transcription by promoter g-quadruplex stabilization as a potential alternative treatment for castrate-resistant prostate cancer.
Androgen receptor (AR) signaling remains an important regulatory pathway in castrate-resistant prostate cancer, and its transcriptional downregulation could provide a new line of therapy. A number of small-molecule ligands have previously demonstrated the ability to stabilize G-quadruplex structures and affect gene transcription for those genes whose promoters contain a quadruplex-forming sequence. Herein, we report the probable formation of new G-quadruplex structure present in the AR promoter in a transcriptionally important location. NMR spectroscopy, circular dichroism, UV spectroscopy, and UV thermal melting experiments for this sequence are consistent with G-quadruplex formation. Fluorescence resonance energy transfer (FRET) melting studies have identified a novel compound, MM45, which appears to stabilize this G-quadruplex at submicromolar concentrations. The effects of MM45 have been investigated in prostate cancer cell lines where it has been shown to inhibit cell growth. A reporter assay intended to isolate the effect of MM45 on the G-quadruplex sequence showed dose-dependent transcriptional repression only when the AR promoter G-quadruplex sequence is present. Dose-dependent transcriptional repression of the AR by MM45 has been demonstrated at both a protein and mRNA level. This proof of concept study paves the route toward a potential alternative treatment pathway in castrate-resistant prostate cancer.
CRUK Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, U.K. tommitchell@doctors.org.uk
Tom
T
Mitchell
Antonio
A
Ramos-Montoya
Marco
M
Di Antonio
Pierre
P
Murat
Stephan
S
Ohnmacht
Marialuisa
M
Micco
Sarah
S
Jurmeister
Lee
L
Fryer
Shankar
S
Balasubramanian
Stephen
S
Neidle
David E
DE
Neal
D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002942:Circular Dichroism; D015536:Down-Regulation / Q000187:drug effects*; D031541:Fluorescence Resonance Energy Transfer; D054856:G-Quadruplexes / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007094:Imides / Q000494:pharmacology*; D008297:Male; D009281:Naphthalenes / Q000494:pharmacology*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011467:Prostate / Q000187:drug effects / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000235:genetics; D011944:Receptors, Androgen / Q000235:genetics*; D013056:Spectrophotometry, Ultraviolet; D015533:Transcriptional Activation / Q000187:drug effects
D000970:Antineoplastic Agents; D007094:Imides; D009281:Naphthalenes; D011944:Receptors, Androgen; C542131:naphthalenediimide