The p63 Protein Isoform Np63 Inhibits Epithelial-Mesenchymal Transition in Human Bladder Cancer Cells: ROLE OF MIR-205
Epithelial-mesenchymal transition (EMT) is a physiological process that plays important roles in tumor metastasis, stemness, and drug resistance. EMT is typically characterized by the loss of the epithelial marker E-cadherin and increased expression of EMT-associated transcriptional repressors, including ZEB1 and ZEB2. The miR-200 family and miR-205 prevent EMT through suppression of ZEB1/2. p53 has been implicated in the regulation of miR-200c, but the mechanisms controlling miR-205 expression remain elusive. Here we report that the p53 family member and p63 isoform, Np63α, promotes miR-205 transcription and controls EMT in human bladder cancer cells. Np63α, E-cadherin and miR-205 were co-expressed in a panel of bladder cancer cell lines (n=28) and a cohort of primary bladder tumors (n=98). Stable knockdown (KD) of Np63α in the epithelial bladder cancer cell line UM-UC6 decreased the expression of miR-205 and induced the expression of ZEB1/2, effects that were reversed by expression of exogenous miR-205. Conversely, overexpression of Np63α in the mesenchymal bladder cancer cell line UM-UC3 induced miR-205 and suppressed ZEB1/2. Np63α KD reduced the expression of the primary and mature forms of miR-205 and the miR-205 host gene (miR-205HG) and decreased binding of RNA Pol II to the miR-205HG promoter, inhibiting miR-205HG transcription. Finally, high miR-205 expression was associated with adverse clinical outcomes in bladder cancer patients. Together, our data demonstrate that Np63α-mediated expression of miR-205 contributes to the regulation of EMT in bladder cancer cells and identify miR-205 as a molecular marker of the lethal subset of human bladder cancers.