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

Abstract

Summary The androgen receptor (AR) is required for castration resistant prostate cancer (CRPC) progression, but the function and disease relevance of AR-bound enhancers remain unclear. Here, we identify a group of AR-regulated enhancer RNAs (e.g. PSA eRNA) that are upregulated in CRPC cells, patient-derived xenografts (PDX) and patient tissues. PSA eRNA binds to CYCLIN T1, activates P-TEFb and promotes cis and trans target gene transcription by increasing serine-2 phosphorylation of RNA polymerase II (Pol II-Ser2p). We define an HIV-1 TAR RNA-like (TAR-L) motif in PSA eRNA that is required for CYCLIN T1 binding. Using TALEN-mediated gene editing we further demonstrate that this motif is essential for increased Pol II-Ser2p occupancy levels and CRPC cell growth. We have uncovered a P-TEFb activation mechanism and reveal altered eRNA expression that is related to abnormal AR function and may potentially be a therapeutic target in CRPC.

JMJD6 Licenses ERα-Dependent Enhancer and Coding Gene Activation by Modulating the Recruitment of the CARM1/MED12 Co-activator Complex

“…Several studies reported recently that enhancer RNAs (eRNAs) are involved in transcriptional regulation of nearby coding genes (Lam et al, 2013, Kim et al, 2010, Melo et al, Lai et al, 2013, Mousavi et al, 2013, Hsieh et al, 2014, Schaukowitch et al, 2014, Pnueli et al, 2015, Zhao et al, 2016, Li et al, 2013). For instance, estrogen-induced eRNAs from ERα-bound active enhancers were critical for the transcriptional activation of cognate estrogen-induced coding genes (Li et al, 2013).…”

“…eRNAs have been defined as short transcripts (50–2000 nucleotides) that are transcribed bi-directionally, or sometimes uni-directionally, from enhancer regions (Kim et al, 2010). Although whether eRNAs themselves are functional remains to be unequivocally proven, many studies have clearly demonstrated that enhancer transcription occurs before coding gene activation and may help to create an open chromatin environment, facilitate promoter and enhancer looping, and contribute to coding gene transcriptional regulation (Hsieh et al, 2014, Lai et al, 2013, Lam et al, 2013, Melo et al, 2013, Mousavi et al, 2013, Schaukowitch et al, 2014, Pnueli et al, 2015, Zhao et al, 2016, Li et al, 2013). In addition, enhancer transcription has been suggested to play an essential role in enhancer marker (H3K4me1/2) deposition at de novo enhancers (Kaikkonen et al, 2013).…”

Alterations of androgen receptor-regulated enhancer RNAs (eRNAs) contribute to enzalutamide resistance in castration-resistant prostate cancer

“…ChIP was performed as described previously [51] using anti-AR antibody (N20, Santa Cruz Biotechnology). LNCaP and C4-2 cells were treated with mibolerone, a synthetic androgen (1 nM) or ethanol for 3 days.…”

BRD4 localization to lineage-specific enhancers is associated with a distinct transcription factor repertoire

“…Application of chromosomal conformation capture analyses suggests that long-range chromosomal interactions facilitate the expression of target genes, for example by bridging distal enhancer regions with the transcriptional start site (TSS) via specific TFs and cofactors (12,13). In addition, recent findings uncovered non-coding transcripts produced from enhancer regions (eRNA) that might also promote enhancer-mediated long-range chromosomal interactions and/or P-TEFb activation (14–18). Notably, BRD4 also occupies intergenic regions containing putative enhancers and facilitates eRNA transcription (10,19–22).…”