miR‐574‐5p as RNA decoy for CUGBP1 stimulates human lung tumor growth by mPGES‐1 induction

Abstract

MicroRNAs (miRs) are important posttranscriptional regulators of gene expression. Besides their well‐characterized inhibitory effects on mRNA stability and translation, miRs can also activate gene expression. In this study, we identified a novel noncanonical function of miR‐574‐5p. We found that miR‐574‐5p acts as an RNA decoy to CUG RNA‐binding protein 1 (CUGBP1) and antagonizes its function. MiR‐574‐5p induces microsomal prostaglandin E synthase‐1 (mPGES‐1) expression by preventing CUGBP1 binding to its 3′UTR, leading to an enhanced alternative splicing and generation of an mPGES‐1 3′UTR isoform, increased mPGES‐1 protein expression, PGE2 formation, and tumor growth in vivo. miR‐574‐5p–induced tumor growth in mice could be completely inhibited with the mPGES‐1 inhibitor OIL Moreover, miR‐574‐5p is induced by IL‐1β and is strongly overexpressed in human nonsmall cell lung cancer where high mPGES‐1 expression correlates with a low survival rate. The discovered function of miR‐574‐5p as a CUGBP1 decoy opens up new therapeutic opportunities. It might serve as a stratification marker to select lung tumor patients who respond to the pharmacological inhibition of PGE2 formation.—Saul, M. J., Baumann, I., Bruno, A., Emmerich, A. C., Wellstein, J., Ottinger, S. M., Contursi, A., Dovizio, M., Donnini, S., Tacconelli, S., Raouf, J., Idborg, H., Stein, S., Korotkova, M., Savai, R., Terzuoli, E., Sala, G., Seeger, W., Jakobsson, P.‐J., Patrignani, P., Suess, B., Steinhilber, D. miR‐574‐5p as RNA decoy for CUGBP1 stimulates human lung tumor growth by mPGES‐1 induction. FASEB J. 33, 6933–6947 (2019). http://www.fasebj.org

Proteomics-Based Characterization of miR-574-5p Decoy to CUGBP1 Suggests Specificity for mPGES-1 Regulation in Human Lung Cancer Cells

“…As control, a scramble siRNA with an unspecific sequence (5 -UCUCUCACAACGGGCAUUU-3 ) was used. 24 h after transfection, A549 cells were incubated with 5 ng/ml of Interleukin (IL)-1β (Sigma-Aldrich) for further 24 h. The efficiency of the knockdown was determined by Western blot analysis as described in Saul et al (2019a).…”

“…RNA immunoprecipitation was performed as previously described (Saul et al, 2019a). In short, 6 × 10 6 A549 cells per RIP were resuspended in lysis buffer containing 10 mM Tris-HCl (Carl Roth) pH 7.5, 10 mM KCl (Sigma-Aldrich), 1.5 mM MgCl 2 , 0.5 mM DTT (Sigma-Aldrich), 0.9% Nonidet P-40 (Sigma-Aldrich), 20 µl ribonuclease inhibitor and protease inhibitor EDTA-free (Roche).…”

“…Recently, a new miR/RBP interaction was discovered. MiR-574-5p reveals a binding site for CUG-RNA binding protein 1 (CUGBP1) in its mature form (Saul et al, 2019a). Therefore, it can directly interact with CUGBP1 and promotes lung tumor growth in vivo by inducing microsomal prostaglandin E-synthase-1 (mPGES-1) expression, the terminal synthase responsible for the production of the pro-tumorigenic lipid mediator prostaglandin E 2 (PGE 2 ) (Nakanishi and Rosenberg, 2013).…”

“…Therefore, it can directly interact with CUGBP1 and promotes lung tumor growth in vivo by inducing microsomal prostaglandin E-synthase-1 (mPGES-1) expression, the terminal synthase responsible for the production of the pro-tumorigenic lipid mediator prostaglandin E 2 (PGE 2 ) (Nakanishi and Rosenberg, 2013). In human lung tumor and under inflammatory circumstances, miR-574-5p is strongly upregulated and increases mPGES-1 expression by preventing CUGBP1 binding to the mPGES-1 3 UTR which leads to an enhanced alternative splicing and the generation of a novel 3 UTR isoform (Saul et al, 2019a). The newly discovered link between miR-574-5p overexpression and PGE 2 -mediated tumor growth in vivo suggests that pharmacological inhibition of PGE 2 formation might be a potential therapeutic approach in combination with standard therapies for lung cancer patients with high miR-574-5p levels (Saul et al, 2019a).…”

“…In human lung tumor and under inflammatory circumstances, miR-574-5p is strongly upregulated and increases mPGES-1 expression by preventing CUGBP1 binding to the mPGES-1 3 UTR which leads to an enhanced alternative splicing and the generation of a novel 3 UTR isoform (Saul et al, 2019a). The newly discovered link between miR-574-5p overexpression and PGE 2 -mediated tumor growth in vivo suggests that pharmacological inhibition of PGE 2 formation might be a potential therapeutic approach in combination with standard therapies for lung cancer patients with high miR-574-5p levels (Saul et al, 2019a). Thereby, miR-574-5p could serve as a stratification and biomarker to identify suitable candidates, an approach which is also supported by earlier studies (Foss et al, 2011;Del Vescovo et al, 2014).…”