A combined approach identifies three mRNAs that are down-regulated by microRNA-29b and promote invasion ability in the breast cancer cell line MCF-7

Background and aims MicroRNAs (miRNAs) are short noncoding RNAs that regulate gene expression by targeting mRNAs. Our previous study found that miR-29b strongly regulates the migration and invasion of breast cancer cells. Here, we aimed to identify the mRNAs targeted by miR-29b. Methods We used microarray experiments in conjunction with computational methods to identify the mRNAs that were most susceptible to miR-29b-mediated repression. We further confirmed the activities of three target genes, C1QTNF6, SPARC, and COL4A2, by luciferase reporter analyses and invasion assays. Results We evaluated the impact of miR-29b on global mRNA expression in MCF-7 human breast cancer cells through microarray analysis and further analyzed four genes that were at least twofold down-regulated and predicted as miR-29b targets by at least two of the four widely used miRNA target prediction algorithms. We also analyzed one mRNA that was down-regulated by 1.8-fold but was predicted to have significant interactions with miR-29b in pathway analysis and was predicted as a miR-29b target by all four algorithms. Luciferase reporter and invasion assays revealed that C1QTNF6, SPARC, and COL4A2 were targeted by miR-29b and that the degradation of any one of these mRNAs could promote invasion in MCF-7 cells. Conclusions C1QTNF6, SPARC, and COL4A2 are targeted by miR-29b, and the down-regulation of these three mRNAs can contribute to the invasion ability of MCF-7 cells.