title: ALDH1A1 is a novel EZH2 target gene in epithelial ovarian cancer identified by genome-wide approaches.
abstract: Epithelial ovarian cancer (EOC) remains the most lethal gynecologic malignancy in the United States. EZH2 silences gene expression through trimethylating lysine 27 on histone H3 (H3K27Me3). EZH2 is often overexpressed in EOC and has been suggested as a target for EOC intervention. However, EZH2 target genes in EOC remain poorly understood. Here, we mapped the genomic loci occupied by EZH2/H3K27Me3 using chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) and globally profiled gene expression in EZH2-knockdown EOC cells. Cross-examination of gene expression and ChIP-seq revealed a list of 60 EZH2 direct target genes whose expression was upregulated more than 1.5-fold upon EZH2 knockdown. For three selected genes (ALDH1A1, SSTR1, and DACT3), we validated their upregulation upon EZH2 knockdown and confirmed the binding of EZH2/H3K27Me3 to their genomic loci. Furthermore, the presence of H3K27Me3 at the genomic loci of these EZH2 target genes was dependent upon EZH2. Interestingly, expression of ALDH1A1, a putative marker for EOC stem cells, was significantly downregulated in high-grade serous EOC (n = 53) compared with ovarian surface epithelial cells (n = 10, P < 0.001). Notably, expression of ALDH1A1 negatively correlated with expression of EZH2 (n = 63, Spearman r = -0.41, P < 0.001). Thus, we identified a list of 60 EZH2 target genes and established that ALDH1A1 is a novel EZH2 target gene in EOC cells. Our results suggest a role for EZH2 in regulating EOC stem cell equilibrium via regulation of ALDH1A1 expression.
authors.affiliation: Women's Cancer Program and Epigenetics and Progenitor Cell Keystone Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.forename: Benjamin G
authors.initials: BG
authors.lastname: Bitler
authors.forename: Vinod
authors.initials: V
authors.lastname: Vathipadiekal
authors.forename: Marie E
authors.initials: ME
authors.lastname: Maradeo
authors.forename: Michael
authors.initials: M
authors.lastname: Slifker
authors.forename: Caretha L
authors.initials: CL
authors.lastname: Creasy
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Tummino
authors.forename: Paul
authors.initials: P
authors.lastname: Cairns
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Birrer
authors.forename: Rugang
authors.initials: R
authors.lastname: Zhang
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D000080924:Aldehyde Dehydrogenase 1 Family; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D000071221:Enhancer of Zeste Homolog 2 Protein; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism; D063151:Polycomb Repressive Complex 2; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D050697:Retinal Dehydrogenase; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D014157:Transcription Factors; D000080924:Aldehyde Dehydrogenase 1 Family; D000444:Aldehyde Dehydrogenase; C510223:ALDH1A1 protein, human; D050697:Retinal Dehydrogenase; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2