RESUMO
Intratumoral heterogeneity in bladder cancer is a barrier to accurate molecular sub-classification and treatment efficacy. However, individual cellular and mechanistic contributions to tumor heterogeneity are controversial. We examined potential mechanisms of FOXA1 and PTEN inactivation in bladder cancer and their contribution to tumor heterogeneity. These analyses were complemented with inactivation of FOXA1 and PTEN in intermediate and luminal mouse urothelium. We show inactivation and reduced expression of FOXA1 and PTEN is prevalent in human disease, where PTEN and FOXA1 are downregulated by allelic loss and site-specific DNA hypermethylation, respectively. Conditional inactivation of both Foxa1 and Pten in intermediate/luminal cells in mice results in development of bladder cancer exhibiting squamous features as well as enhanced sensitivity to a bladder-specific carcinogen. In addition, FOXA1 is hypermethylated in basal bladder cancer cell lines, and this is reversed by treatment with DNA methyltransferase inhibitors. By integrating human correlative and in vivo studies, we define a critical role for PTEN loss and epigenetic silencing of FOXA1 in heterogeneous human disease and show genetic targeting of luminal/intermediate cells in mice drives squamous differentiation.
Assuntos
Carcinoma de Células Escamosas/patologia , Diferenciação Celular , Metilação de DNA , Fator 3-alfa Nuclear de Hepatócito/genética , Perda de Heterozigosidade , PTEN Fosfo-Hidrolase/genética , Neoplasias da Bexiga Urinária/patologia , Animais , Apoptose , Biomarcadores Tumorais , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/metabolismo , Proliferação de Células , Feminino , Regulação Neoplásica da Expressão Gênica , Fator 3-alfa Nuclear de Hepatócito/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neoplasias Musculares/genética , Neoplasias Musculares/metabolismo , Neoplasias Musculares/patologia , PTEN Fosfo-Hidrolase/metabolismo , Prognóstico , Células Tumorais Cultivadas , Neoplasias da Bexiga Urinária/genética , Neoplasias da Bexiga Urinária/metabolismoRESUMO
Epigenetic aberrations are prominent in bladder cancer (BC) and contribute to disease pathogenesis. We characterized histone deacetylase (HDAC) expression, a family of deacetylation enzymes, in both in vitro and in vivo BC model systems and analyzed expression data from The Cancer Genome Atlas (TCGA). Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting analysis was used to determine the expression status of Class I and II HDACs in ten human BC cell lines, while qRT-PCR was used to determine HDAC expression in 24 human tumor specimens. The TCGA cohort consists of 408 muscle invasive BC (MIBC) clinical samples and analysis of this data set identified expression of HDAC4 and -9 as being associated with basal-squamous disease. These findings agree with qRT-PCR results identifying increased expression of HDAC4, -7, and -9 in basal BC cell lines (p < 0.05; Kruskal-Wallis test) and in clinical specimens with invasive bladder cancer (not statistically significant). We also observed increased expression in Hdac4, -7, and -9 in commonly used BC mouse models. Here, we identify suitable preclinical model systems for the study of HDACs, and show increased expression of Class IIa HDACs, specifically HDAC4 and HDAC9, in basal BC cell lines and in invasive clinical specimens. These results suggest this class of HDACs may be best suited for targeted inhibition in patients with basal BC.