miRNAs are key regulators of gene expression. By binding to many genes, they create a complex network of gene co-regulation.
We present here a target-based miRNA network construction and its analysis. Using different network-based approaches, they first identified two miRNA hub groups in the network, by their close connections and common targets. In one cluster containing three miRNAs, miR-612, miR-661 and miR-940, the annotated functions of the co-regulated genes suggested a role in small GTPase signalling. While confirming this hypothesis and although the three members of this cluster targeted same subsets of predicted genes, researchers showed that their overexpression still impacted cell fate differently. Indeed, miR-661 demonstrated enhanced phosphorylation of myosin II and an increase in cell invasion, indicating a potential oncogenic function. On the contrary, miR-612 and miR-940 inhibited phosphorylation of myosin II and cell invasion suggesting a potential tumour suppressor role.
Confirming these results, miR-940 was further found consistently downregulated in breast cancer tissues.
