Long Noncoding RNA DRAIC Inhibits Prostate Cancer Progression by Interacting with IKK to Inhibit NF-κB Activation.

DRAIC is a 1.7 kb spliced long noncoding RNA downregulated in castration-resistant advanced prostate cancer. Decreased DRAIC expression predicts poor patient outcome in prostate and seven other cancers, while increased DRAIC represses growth of xenografted tumors. Here, we show that cancers with decreased DRAIC expression have increased NF-κB target gene expression. DRAIC downregulation increased cell invasion and soft agar colony formation; this was dependent on NF-κB activation. DRAIC interacted with subunits of the IκB kinase (IKK) complex to inhibit their interaction with each other, the phosphorylation of IκBα, and the activation of NF-κB. These functions of DRAIC mapped to the same fragment containing bases 701-905. Thus, DRAIC lncRNA inhibits prostate cancer progression through suppression of NF-κB activation by interfering with IKK activity. SIGNIFICANCE: A cytoplasmic tumor-suppressive lncRNA interacts with and inhibits a major kinase that activates an oncogenic transcription factor in prostate cancer. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/5/950/F1.large.jpg.