Activation of P-TEFb by Androgen Receptor-Regulated Enhancer RNAs in Castration-Resistant Prostate Cancer

Area of Science:

• Molecular Biology
• Cancer Research
• RNA Biology

Background:

• Androgen receptor (AR) signaling is crucial for castration-resistant prostate cancer (CRPC) progression.
• The specific roles of AR-bound enhancers in CRPC remain largely undefined.

Purpose of the Study:

• To investigate the function and disease relevance of AR-regulated enhancers in CRPC.
• To elucidate the mechanism by which enhancer RNAs (eRNAs) contribute to CRPC progression.

Main Methods:

• Identification and characterization of AR-regulated eRNAs in CRPC models.
• Biochemical assays to determine interactions between PSA eRNA, CYCLIN T1, and P-TEFb.
• Gene editing (TALEN) to assess the functional importance of the TAR-L motif in eRNA.
• Analysis of RNA polymerase II phosphorylation (Pol II-Ser2p) and cell growth.

Main Results:

• A subset of AR-regulated eRNAs, exemplified by PSA eRNA, are upregulated in CRPC cells, xenografts, and patient tissues.
• PSA eRNA binds CYCLIN T1, activating P-TEFb and enhancing transcription of target genes via Pol II-Ser2p.
• A specific HIV-1 TAR RNA-like (TAR-L) motif within PSA eRNA is essential for CYCLIN T1 binding.
• Disruption of the TAR-L motif impairs Pol II-Ser2p levels and CRPC cell proliferation.

Conclusions:

• A novel mechanism of P-TEFb activation mediated by eRNAs in CRPC has been uncovered.
• Altered eRNA expression, linked to aberrant AR function, represents a potential therapeutic avenue for CRPC.