ERBB2 overexpression occurs in numerous types of primary human tumors and alterations in microRNA (miRNA) expression have been associated with tumor suppression OF tumorigenesis in human cancer, nevertheless, little is known about natural miRNAs acting on ERBB2. In this study, bioinformatical analysis of the 3'-UTRs of ERBB2 revealed the target elernents for miR-548d-3p and miR-559. Moreover, a predicted miRNA/mRNA interaction experimental validation showed that both miR-548d-3p and miR-559 can interact: specifically with the 3'-UTR of the ERBB2 mRNA. And miR-548d-3p plus miR-559 transfection showed a cooperative regulation of translationally repressing ERBB2 mRNA rather than by either miR-548d-3p or miR-559 alone. These results not only Support the idea that different miRNAs can simultaneously and cooperatively repress a given target mRNA but also preliminarily validate the role of miR-548d-3p and miR-559 in regulating the ERBB2 expression. These data provide molecular basis for the application of miRNAs in ERBB2-targeted therapy. (c) 2009 Published by Elsevier Inc.