Growth inhibition by microRNAs that target the insulin receptor substrate-1

We have examined several microRNAs (miRs) indicated by the databases as targeting the signaling pathway of the type-1 insulin-like growth factor receptor (IGF-IR). Most of the miRs tested had multiple targets, as expected, leading to cell death. However, miR145 seemed to affect its tumor suppressor activity largely by down-regulating the docking protein of the IGF-IR, the insulin receptor substrate-1 (IRS-1). These results suggest that, despite the many targets provided by the databases, in some cases a single target can be predominant in determining the end results.