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Updated: Sep 10, 2025
Serum and Plasma Copy Number Detection Using Real-time PCR
Published on: December 15, 2017
Molecular analysis of androgen receptor splice variant AR-V3 reveals eminent ambiguity regarding activity and
Neele Wüstmann1, Verena Humberg1, Julia Vieler1
1Department of Urology, University Hospital Muenster, Albert-Schweitzer Campus 1 A1, 48149, Muenster, Germany.
Background:
Androgen receptor (AR) splice variants (AR-Vs) have emerged as potential resistance mechanisms to AR-targeted agents (ARTAs) in prostate cancer (PC), particularly in the context of castration-resistant disease. Among them, AR-V3 has been frequently detected, yet its biological function remains unclear due to conflicting results from initial studies. This study aimed to comprehensively investigate the molecular structure, activity, and clinical relevance of AR-V3.
Methods:
We constructed plasmids encoding two AR-V3 isoforms-one newly identified isoform matching the human reference genome (AR-V3ref) and the other based on the 22Rv1 cell line sequence (AR-V322Rv1)-and transfected them into AR-negative PC-3 cells alone or co-expressed with AR full-length (AR-FL). Localization, transcriptional activity (via luciferase assays), and RNA sequencing were performed. Protein structure modeling was conducted using AlphaFold2. Nonsense-mediated decay (NMD) was assessed through pharmacological inhibition. Clinically, AR-V3 expression in circulating tumor cells (CTCs) from 65 patients starting ARTA treatment was analyzed in relation to progression-free survival (PFS) and overall survival (OS).
Results:
RNA-seq of AR-FL + AR-V3 vs. AR-FL alone showed no AR-V3-specific gene expression. Structure modeling revealed poor overall prediction confidence, particularly in the N-terminal domain, with no consistent structural features differentiating AR-V3ref and AR-V322Rv1. Both isoforms localized mainly to the cytoplasm, regardless of hormonal stimulation or AR-FL co-expression. Neither isoform showed androgen receptor element (ARE) binding activity unless co-expressed with AR-FL. NMD analysis indicated neither isoform was degraded by this pathway. Clinically, AR-V3 + patients had significantly shorter OS (median 13 vs. 23 months; p = 0.02) among CTC + patients but showed no difference in PSA response or PFS under ARTA treatment.
Conclusions:
Our data demonstrate that both AR-V3 isoforms are functionally inactive, lacking autonomous nuclear translocation or transcriptional activity. AR-V3 is not a substrate for NMD, and its protein structure remains poorly defined. While associated with worse overall survival, AR-V3 lacks predictive value for ARTA response, underscoring its limited utility as a biomarker. These findings emphasize the need for functional validation before integrating putative biomarkers into clinical practice.
Insights
Androgen receptor variant 3 (AR-V3) shows no independent activity in prostate cancer cells and is not a reliable biomarker for predicting response to AR-targeted agents, despite an association with shorter overall survival.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Androgen receptor (AR) splice variants (AR-Vs) are implicated in prostate cancer (PC) treatment resistance.
- AR-V3 is frequently detected, but its function and clinical relevance are debated.
Purpose of the Study:
- To comprehensively investigate the molecular structure, activity, and clinical relevance of AR-V3.
- To determine if AR-V3 isoforms possess autonomous function or serve as predictive biomarkers for AR-targeted agents (ARTAs).
Main Methods:
- Constructed and transfected AR-V3 isoforms (AR-V3ref, AR-V322Rv1) into AR-negative PC cells.
- Assessed localization, transcriptional activity (luciferase assays), RNA sequencing, and protein structure (AlphaFold2).
- Evaluated nonsense-mediated decay (NMD) and analyzed AR-V3 expression in circulating tumor cells (CTCs) from patients undergoing ARTA treatment.
Main Results:
- AR-V3 isoforms lacked specific gene expression, autonomous nuclear translocation, and transcriptional activity without AR full-length (AR-FL).
- Protein structure modeling showed poor confidence, particularly in the N-terminal domain.
- AR-V3 expression in CTCs correlated with shorter overall survival (OS) but not progression-free survival (PFS) or PSA response to ARTAs.
Conclusions:
- AR-V3 isoforms are functionally inactive and not substrates for NMD.
- AR-V3 lacks predictive value for ARTA response, indicating limited utility as a biomarker.
- Functional validation is crucial before clinical application of potential biomarkers.
