The p63 Protein Isoform Np63 Inhibits Epithelial-Mesenchymal Transition in Human Bladder Cancer Cells: ROLE OF MIR-205

ArticleinJournal of Biological Chemistry 288(5) · December 2012with24 Reads
DOI: 10.1074/jbc.M112.408104 · Source: PubMed
Abstract
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.
    • "MiR-205 is repressed by both TAp63 and ∆Np63 and, in the presence of prostate cancer metastases, loss of both p63 and miR-205 were observed [53]. Also, TAp63 isoform is capable to inhibit the expression of Dicer, responsible for pre-microRNA cleavage, demonstrating great importance in metastasis suppression through global microRNA expression [49, 54]. Our data demonstrated that the expressions of p63–at both protein and mRNA levels–were significantly reduced by miR-223-5p in SW962 cells. "
    [Show abstract] [Hide abstract] ABSTRACT: MiR-223-5p has been previously mentioned to be associated with tumor metastasis in HPV negative vulvar carcinomas, such as in several other tumor types. In the present study, we hypothesized that this microRNA would be important in vulvar cancer carcinogenesis and progression. To investigate this, we artificially mimicked miR-223-5p expression in a cell line derived from lymph node metastasis of vulvar carcinoma (SW962) and performed in vitro assays. As results, lower cell proliferation (p < 0.01) and migration (p < 0.001) were observed when miR-223-5p was overexpressed. In contrast, increased invasive potential of these cells was verified (p < 0.004). In silico search indicated that miR-223-5p targets TP63, member of the TP53 family of proteins, largely described with importance in vulvar cancer. We experimentally demonstrated that this microRNA is capable to decrease levels of p63 at both mRNA and protein levels (p < 0.001, and p < 0.0001; respectively). Also, a significant inverse correlation was observed between miR-223-5p and p63 expressions in tumors from patients (p = 0.0365). Furthermore, low p63 protein expression was correlated with deeper tumor invasion (p = 0.0491) and lower patient overall survival (p = 0.0494). Our study points out miR-223-5p overexpression as a putative pathological mechanism of tumor invasion and a promising therapeutic target and highlights the importance of both miR-223-5p and p63 as prognostic factors in vulvar cancer. Also, it is plausible that the evaluation of p63 expression in vulvar cancer at the biopsy level may bring important contribution on prognostic establishment and in elaborating better surgical approaches for vulvar cancer patients.
    Full-text · Article · Jun 2016
    • "Our results have demonstrated that ΔNp63α promotes the migration of hybrid BLBC cells and lung squamous cancer cells. Conversely ΔNp63α can suppress mesenchymal-like cancer migration through the miR205 dependent suppression of ZEB1/2 [27, 28, 71], and the silencing of FAK [72]. Mesenchymal-like cells express low to undetectable levels of ΔNp63α [17], and thus have adopted a ΔNp63α-independent migratory mechanism. "
    [Show abstract] [Hide abstract] ABSTRACT: Tumor invasion can be induced by changes in gene expression that alter cell phenotype. The transcription factor ΔNp63α promotes basal-like breast cancer (BLBC) migration by inducing the expression of the mesenchymal genes Slug and Axl, which confers cells with a hybrid epithelial/mesenchymal state. However, the extent of the ΔNp63α regulated genes that support invasive behavior is not known. Here, using gene expression analysis, ChIP-seq, and functional testing, we find that ΔNp63α promotes BLBC motility by inducing the expression of the atypical cadherin FAT2, the vesicular binding protein SNCA, the carbonic anhydrase CA12, the lipid binding protein CPNE8 and the kinase NEK1, along with Slug and Axl. Notably, lung squamous cell carcinoma migration also required ΔNp63α dependent FAT2 and Slug expression, demonstrating that ΔNp63α promotes migration in multiple tumor types by inducing mesenchymal and non-mesenchymal genes. ΔNp63α activation of FAT2 and Slug influenced E-cadherin localization to cell-cell contacts, which can restrict spontaneous cell movement. Moreover, live-imaging of spheroids in organotypic culture demonstrated that ΔNp63α, FAT2 and Slug were essential for the extension of cellular protrusions that initiate collective invasion. Importantly, ΔNp63α is co-expressed with FAT2 and Slug in patient tumors and the elevated expression of ΔNp63α, FAT2 and Slug correlated with poor patient outcome. Together, these results reveal how ΔNp63α promotes cell migration by directly inducing the expression of a cohort of genes with distinct cellular functions and suggest that FAT2 is a new regulator of collective invasion that may influence patient outcome.
    Article · Apr 2016
    • "This is accomplished by an intricate network of transcription factor activation, including TWIST, SNAIL, SLUG, ZEB1 and ZEB2 which are also under epigenetic regulation through various miRNAs [38, 40, 41]. Importantly, recent evidences also support a role for ΔNp63 modulating EMT [18, 19]. Here we report that spontaneous tumors arising in Trp53 ΔEpi mice display early repression of ΔNp63 expression. "
    [Show abstract] [Hide abstract] ABSTRACT: The TP63 gene codes for two major isoform types, TAp63 and ΔNp63, with probable opposite roles in tumorigenesis. The ΔNp63α protein is frequently amplified and overexpressed in different epithelial tumors. Accordingly, it has been considered a potential oncogene. Nonetheless, a possible metastatic suppressor activity has also been suggested based on the experimental observation that its expression is reduced or even absent in advanced invasive tumors. Such metastatic suppressor activities are often related to tumors bearing point mutated TP53 gene. However, its potential roles in TP53-deficient tumors are poorly characterized. Here we show that in spontaneous tumors, induced by the epidermal-specific Trp53 ablation, the reduction of ΔNp63 expression is an early event, whereas it is re-expressed in the lung metastatic lesions. Using knock down and ectopic expression approaches, we show that ΔNp63 expression opposes the epithelial-mesenchymal transition and reduces the metastatic potential of the cells. This process occurs through the modulation of ΔNp63-dependent downstream targets (including transcription factors and microRNAs) likely to play metastatic roles. Further, ΔNp63 also favors the expression of factors involved in iPS reprogramming, thus suggesting that it can also modulate specific stem cell traits in mouse epidermal tumor cells. Overall, our data assign antimetastatic roles to ΔNp63 in the context of p53 deficiency and epidermis.
    Full-text · Article · Jul 2015
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