miR-1470 mediates lapatinib induced p27 upregulation by targeting c-jun.

Our previous study indicated that lapatinib induces p27-dependent G(1) arrest through both transcriptional and post-translational mechanisms. Using miRNA microarray technology and quantitative RT-PCR, we further investigated the potential miRNAs that involved in p27 upregulation and Her-2 signaling pathway alteration with lapatinib treatment. A subset of 7 miRNAs was significantly affected in both 0.5 µM and 2.0 µM and 24 h and 48 h lapatinib treatment. Among them, only miR-1470, miR-126, and miR-1208 were identified in the Her-2 pathway after KEGG pathway analysis. However, luciferase reporter assay confirmed that miR-1470 directly recognized the 3'-untranslated region of c-jun transcripts, which was consistent with TargetScan analysis. miR-1470 significantly decreased c-jun expression, thus miR-1470 may repressc-jun activation of cyclinD1 expression, and consequently promoted the upregulation of p27, a key molecule in the cell cycle arrest. Taken together, the present study provided the first evidences that miR-1470 mediated lapatinib induced p27 upregulation by targeting c-jun.