Androgen receptor and MYC transcriptomes are equilibrated in multilayer regulatory circuitries in prostate cancer

Abstract

Background: The discovery of androgen receptor (AR) having transrepression effects completes the circle of its functionalities as a typical transcription factor, which intrinsically bears dual functions of activation and repression linked to co-factor competition and redistribution. Indeed, AR dual functions are exemplified by locus-wide regulation of the oncogenic 8q24-MYC region.

Methods: RT-qPCR assay and public RNA-profiling datasets were used to assess MYC transcription in androgen-sensitive cell lines. Public ChIP-seq and RNA-Seq datasets were computed to evaluate AR-MYC direct and indirect signatures. Gene sets in typical MYC and AR pathways were monitored to validate their cross-talks. Bio-informatics and chromosome conformation capture (3C) assay were performed in the AR gene locus to examine androgen-elicited distal regulation. Finally, co-factor re-distribution were globally tracked between AR and MYC binding sites.

Results: In this report, we found MYC responded negatively to androgen with hypersensitivity, rivaling AR natural functions as an innate androgen effector. Furthermore, both direct and indirect AR and MYC transcriptional programs were actively in equilibration. With established androgen-mediated versus MYC-mediated gene subsets, we validated AR and MYC pathways were both bidirectional and extensively entangled. In addition, we determined that the AR gene locus resembled the MYC gene region and both loci were androgen-repressed via epigenetics and chromatin architectural alterations. Significantly, transcriptional factor profiling along the prostate cancer (PCa) genome exposed that PCa transcriptomes were dynamically equilibrated between AR-binding site and MYC-binding site.

Conclusion: Together, our findings stratified AR-MYC interactions that are extensively wired and intricately organized to compensate for essential PCa transcriptional programs and neutralize excessive signaling.

Keywords: MYC; androgen receptor; dual functions; equilibration; prostate cancer; transcriptional circuitry.