Lu C, Brown LC, Antonarakis ES, Armstrong AJ, Luo J. Androgen receptor variant-driven prostate cancer II: advances in laboratory investigations.
Prostate Cancer Prostatic Dis 2020;
23:381-397. [PMID:
32139878 PMCID:
PMC7725416 DOI:
10.1038/s41391-020-0217-3]
[Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 02/17/2020] [Accepted: 02/19/2020] [Indexed: 02/07/2023]
Abstract
Background:
The androgen receptor (AR) is a key prostate cancer drug target.
Suppression of AR signaling mediated by the full-length AR (AR-FL) is the
therapeutic goal of all existing AR-directed therapies. AR-targeting agents
impart therapeutic benefit, but lead to AR aberrations that underlie disease
progression and therapeutic resistance. Among the AR aberrations specific to
castration-resistant prostate cancer (CRPC), AR variants (AR-Vs) have
emerged as important indicators of disease progression and therapeutic
resistance.
Methods:
We conducted a systemic review of the literature focusing on recent
laboratory studies on AR-Vs following our last review article published in
2016. Topics ranged from measurement and detection, molecular origin,
regulation, genomic function, and preclinical therapeutic targeting of
AR-Vs. We provide expert opinions and perspectives on these topics.
Results:
Transcript sequences for 22 AR-Vs have been reported in the
literature. Different AR-Vs may arise through different mechanisms, and can
be regulated by splicing factors and dictated by genomic rearrangements, but
a low-androgen environment is a prerequisite for generation of AR-Vs. The
unique transcript structures allowed development of in-situ and in-solution
measurement and detection methods, including mRNA and protein detection, in
both tissue and blood specimens. AR variant-7 (AR-V7) remains the main
measurement target and the most extensively characterized AR-V. Although
AR-V7 co-exists with AR-FL, genomic functions mediated by AR-V7 do not
require the presence of AR-FL. The distinct cistromes and transcriptional
programs directed by AR-V7 and their co-regulators are consistent with
genomic features of progressive disease in a low-androgen environment.
Preclinical development of AR-V-directed agents currently focuses on
suppression of mRNA expression and protein degradation as well as targeting
of the amino-terminal domain.
Conclusions:
Current literature continues to support AR-Vs as biomarkers and
therapeutic targets in prostate cancer. Laboratory investigations reveal
both challenges and opportunities in targeting AR-Vs to overcome resistance
to current AR-directed therapies.
Collapse