A p21-ZEB1 Complex Inhibits Epithelial-Mesenchymal Transition through the MicroRNA 183-96-182 Cluster

Abstract

The tumor suppressor p21 acts as a cell cycle inhibitor and has also been shown to regulate gene expression by functioning as a transcription co-repressor. Here, we identified p21-regulated microRNAs (miRNAs) by sequencing small RNAs from isogenic p21+/+ and p21-/- cells. Three abundant miRNA clusters, miR-200b-200a-429, miR-200c-141 and miR-183-96-182 were down-regulated in p21-deficient cells. Consistent with the known function of the miR-200 family and p21 in inhibition of epithelial-mesenchymal transition (EMT) we observed EMT upon loss of p21 in multiple model systems. To explore a role of the miR-183-96-182 cluster in EMT, we identified its genome-wide targets and found that miR-183 and miR-96 repressed common targets, including SLUG, ZEB1, ITGB1 and KLF4. Re-introduction of miR-200, miR-183 or miR-96 in p21-/- cells inhibited EMT, cell migration and invasion. Conversely, antagonizing miR-200 and miR-183-96-182 cluster miRNAs in p21+/+ cells increased invasion and elevated the levels of VIM, ZEB1 and SLUG mRNAs. Furthermore, we found that p21 forms a complex with ZEB1 at the miR-183-96-182 cluster promoter to inhibit transcriptional repression of this cluster by ZEB1 suggesting a reciprocal feedback loop.