Attenuated adenosine-to-inosine editing of microRNA-376a* promotes invasiveness of glioblastoma cells
Yukti Choudhury, … , Beng-Ti Ang, Shu Wang
Yukti Choudhury, … , Beng-Ti Ang, Shu Wang
Published October 24, 2012
Citation Information: J Clin Invest. 2012;122(11):4059-4076. https://doi.org/10.1172/JCI62925.
View: Text | PDF
Research Article

Attenuated adenosine-to-inosine editing of microRNA-376a* promotes invasiveness of glioblastoma cells

Abstract

In the human brain, microRNAs (miRNAs) from the microRNA-376 (miR-376) cluster undergo programmed “seed” sequence modifications by adenosine-to-inosine (A-to-I) editing. Emerging evidence suggests a link between impaired A-to-I editing and cancer, particularly in high-grade gliomas. We hypothesized that disruption of A-to-I editing alters expression of genes regulating glioma tumor phenotypes. By sequencing the miR-376 cluster, we show that the overall miRNA editing frequencies were reduced in human gliomas. Specifically in high-grade gliomas, miR-376a* accumulated entirely in an unedited form. Clinically, a significant correlation was found between accumulation of unedited miR-376a* and the extent of invasive tumor spread as measured by magnetic resonance imaging of patient brains. Using both in vitro and orthotopic xenograft mouse models, we demonstrated that the unedited miR-376a* promoted glioma cell migration and invasion, while the edited miR-376a* suppressed these features. The effects of the unedited miR-376a* were mediated by its sequence-dependent ability to target RAP2A and concomitant inability to target AMFR. Thus, the tumor-dependent introduction of a single base difference in the miR-376a* sequence dramatically alters the selection of its target genes and redirects its function from inhibiting to promoting glioma cell invasion. These findings uncover a new mechanism of miRNA deregulation and identify unedited miR-376a* as a potential therapeutic target in glioblastoma cells.

Authors

Yukti Choudhury, Felix Chang Tay, Dang Hoang Lam, Edwin Sandanaraj, Carol Tang, Beng-Ti Ang, Shu Wang

×

Figure 10

Expression of RAP2A and AMFR mRNAs in clinical specimens and animal tumor models.

Options: View larger image (or click on image) Download as PowerPoint
Expression of RAP2A and AMFR mRNAs in clinical specimens and animal tumo...
(A) Correlation of RAP2A mRNA and unedited miR-376a* levels in primary tumors (n = 22). (B) Correlation of AMFR mRNA and unedited miR-376a* levels in primary tumors (n = 21). For A and B, expression of miR-376a*A was determined by factoring the editing frequency with expression of total miR-376a* measured by qRT-PCR. Pearson’s correlation coefficient is indicated. (C) Expression of AMFR and RAP2A mRNA in xenograft tumors formed by U87 cells stably expressing miR-376a* (see Figure 6A). Values are relative to gene expression in U87/376a*G. (D) Relative expression of AMFR and RAP2A mRNA in U87 and ELM-selected 2M1 cells (n = 3). For C and D, error bars indicate SD. *P < 0.05, **P < 0.01 by t test. (E) Immunoblotting of RAP2A and AMFR in U87 and ELM 2M1 cells. β-Actin was used as loading control. (F) RAP2A expression in GBMs is significantly lower compared with normal brain tissue (NB), astrocytomas (AA), oligodendrogliomas (OAG), and mixed tumor types (MIX) in the REMBRANDT database. Data represent median expression. ***P < 0.001 compared with NB by t test. (G) Kaplan-Meier survival curves for RAP2A expression from REMBRANDT (n = 142 for high and n = 148 for low) and Gravendeel (n = 134 for high and n = 138 for low) glioma patient data. Two Affymetrix probesets corresponding to RAP2A were analyzed, and P value was determined by log-rank test.