The p63 Protein Isoform ΔNp63α 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, Delta Np63 alpha, promotes miR-205 transcription and controls EMT in human bladder cancer cells. Delta Np63 alpha, E-cadherin and miR-205 were coexpressed in a panel of bladder cancer cell lines (n = 28) and a cohort of primary bladder tumors (n = 98). Stable knockdown of Delta Np63 alpha 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 Delta Np63 alpha in the mesenchymal bladder cancer cell line UM-UC3 induced miR-205 and suppressed ZEB1/2. Delta Np63 alpha knockdown 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 Delta Np63 alpha-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.