ABSTRACT
Two independent regions within HNF1B are consistently identified in prostate and ovarian cancer genome-wide association studies (GWAS); their functional roles are unclear. We link prostate cancer (PC) risk SNPs rs11649743 and rs3760511 with elevated HNF1B gene expression and allele-specific epigenetic silencing, and outline a mechanism by which common risk variants could effect functional changes that increase disease risk: functional assays suggest that HNF1B is a pro-differentiation factor that suppresses epithelial-to-mesenchymal transition (EMT) in unmethylated, healthy tissues. This tumor-suppressor activity is lost when HNF1B is silenced by promoter methylation in the progression to PC. Epigenetic inactivation of HNF1B in ovarian cancer also associates with known risk SNPs, with a similar impact on EMT. This represents one of the first comprehensive studies into the pleiotropic role of a GWAS-associated transcription factor across distinct cancer types, and is the first to describe a conserved role for a multi-cancer genetic risk factor.
Subject(s)
DNA Methylation , Gene Expression Regulation, Neoplastic , Gene Regulatory Networks , Hepatocyte Nuclear Factor 1-beta/genetics , Ovarian Neoplasms/genetics , Promoter Regions, Genetic , Prostatic Neoplasms/genetics , Alleles , Cell Line, Tumor , Cell Movement , Cell Proliferation , Epithelial-Mesenchymal Transition , Female , Genetic Predisposition to Disease , Genetic Variation , Genome-Wide Association Study , Genotype , Humans , Linkage Disequilibrium , Male , Ovarian Neoplasms/pathology , Polymorphism, Single Nucleotide , Prostatic Neoplasms/pathology , RiskABSTRACT
PURPOSE: Available tools for prostate cancer diagnosis and prognosis are suboptimal and novel biomarkers are urgently needed. Here, we investigated the regulation and biomarker potential of the GABREâ¼miR-452â¼miR-224 genomic locus. EXPERIMENTAL DESIGN: GABRE/miR-452/miR-224 transcriptional expression was quantified in 80 nonmalignant and 281 prostate cancer tissue samples. GABREâ¼miR-452â¼miR-224 promoter methylation was determined by methylation-specific qPCR (MethyLight) in 35 nonmalignant, 293 prostate cancer [radical prostatectomy (RP) cohort 1] and 198 prostate cancer tissue samples (RP cohort 2). Diagnostic/prognostic biomarker potential of GABREâ¼miR-452â¼miR-224 methylation was evaluated by ROC, Kaplan-Meier, uni- and multivariate Cox regression analyses. Functional roles of miR-224 and miR-452 were investigated in PC3 and DU145 cells by viability, migration, and invasion assays and gene-set enrichment analysis (GSEA) of posttransfection transcriptional profiling data. RESULTS: GABREâ¼miR-452â¼miR-224 was significantly downregulated in prostate cancer compared with nonmalignant prostate tissue and had highly cancer-specific aberrant promoter hypermethylation (AUC = 0.98). Functional studies and GSEA suggested that miR-224 and miR-452 inhibit proliferation, migration, and invasion of PC3 and DU145 cells by direct/indirect regulation of pathways related to the cell cycle and cellular adhesion and motility. Finally, in uni- and multivariate analyses, high GABREâ¼miR-452â¼miR-224 promoter methylation was significantly associated with biochemical recurrence in RP cohort 1, which was successfully validated in RP cohort 2. CONCLUSION: The GABREâ¼miR-452â¼miR-224 locus is downregulated and hypermethylated in prostate cancer and is a new promising epigenetic candidate biomarker for prostate cancer diagnosis and prognosis. Tumor-suppressive functions of the intronic miR-224 and miR-452 were demonstrated in two prostate cancer cell lines, suggesting that epigenetic silencing of GABREâ¼miR-452â¼miR-224 may be selected for in prostate cancer.