Nucleophosmin 1 Cooperates with BRD4 to Facilitate C-Myc Transcription to Promote Prostate Cancer Progression

Nucleophosmin 1 (NPM1) is a multifunctional protein that promotes tumor progression in various cancers and is associated with a poor prognosis of prostate cancer (PCa). However, the mechanism by which NPM1 exerts its malignant potential in PCa remains elusive. Here, we showed that NPM1 is overexpressed in PCa cell lines and tissues and that the dysregulation of NPM1 promotes PCa proliferation. We also demonstrated that NPM1 transcriptionally upregulates c-Myc expression in PCa cells that is diminished by blockade of bromodomain-containing protein 4 (BRD4). Furthermore, we detected a correlation between NPM1 and c-Myc in patient PCa specimens. Mechanistically, NPM1 influences and cooperates with BRD4 to facilitate c-Myc transcription to promote PCa progression. In addition, JQ1, a bromodomain and extra-terminal domain (BET) inhibitor, in combination with NPM1 inhibition suppresses PCa progression in vitro and in vivo. These results indicate that NPM1 promotes PCa progression through a c-Myc -mediated pathway via BRD4, and blockade of the NPM1-c-Myc oncogenic pathway may be a therapeutic strategy for PCa.