title: Differential Effects of Hepatocyte Nuclear Factor 4α Isoforms on Tumor Growth and T-Cell Factor 4/AP-1 Interactions in Human Colorectal Cancer Cells.
abstract: The nuclear receptor hepatocyte nuclear factor 4α (HNF4α) is tumor suppressive in the liver but amplified in colon cancer, suggesting that it also might be oncogenic. To investigate whether this discrepancy is due to different HNF4α isoforms derived from its two promoters (P1 and P2), we generated Tet-On-inducible human colon cancer (HCT116) cell lines that express either the P1-driven (HNF4α2) or P2-driven (HNF4α8) isoform and analyzed them for tumor growth and global changes in gene expression (transcriptome sequencing [RNA-seq] and chromatin immunoprecipitation sequencing [ChIP-seq]). The results show that while HNF4α2 acts as a tumor suppressor in the HCT116 tumor xenograft model, HNF4α8 does not. Each isoform regulates the expression of distinct sets of genes and recruits, colocalizes, and competes in a distinct fashion with the Wnt/β-catenin mediator T-cell factor 4 (TCF4) at CTTTG motifs as well as at AP-1 motifs (TGAXTCA). Protein binding microarrays (PBMs) show that HNF4α and TCF4 share some but not all binding motifs and that single nucleotide polymorphisms (SNPs) in sites bound by both HNF4α and TCF4 can alter binding affinity in vitro, suggesting that they could play a role in cancer susceptibility in vivo. Thus, the HNF4α isoforms play distinct roles in colon cancer, which could be due to differential interactions with the Wnt/β-catenin/TCF4 and AP-1 pathways.
authors.affiliation: Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, California, USA.
authors.forename: Linh M
authors.initials: LM
authors.lastname: Vuong
authors.affiliation: Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, California, USA.
authors.forename: Karthikeyani
authors.initials: K
authors.lastname: Chellappa
authors.affiliation: Department of Biochemistry, University of California, Riverside, Riverside, California, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Dhahbi
authors.affiliation: Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, California, USA.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Deans
authors.affiliation: Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, California, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Fang
authors.affiliation: Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, California, USA.
authors.forename: Eugene
authors.initials: E
authors.lastname: Bolotin
authors.affiliation: Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, California, USA.
authors.forename: Nina V
authors.initials: NV
authors.lastname: Titova
authors.affiliation: Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, California, USA.
authors.forename: Nate P
authors.initials: NP
authors.lastname: Hoverter
authors.affiliation: Department of Biochemistry, University of California, Riverside, Riverside, California, USA.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Spindler
authors.affiliation: Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, California, USA.
authors.forename: Marian L
authors.initials: ML
authors.lastname: Waterman
authors.affiliation: Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, California, USA frances.sladek@ucr.edu.
authors.forename: Frances M
authors.initials: FM
authors.lastname: Sladek
mesh_terms: D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016384:Consensus Sequence; D015972:Gene Expression Regulation, Neoplastic; D063990:Gene Ontology; D045325:HCT116 Cells; D051538:Hepatocyte Nuclear Factor 1-alpha / Q000378:metabolism*; D051557:Hepatocyte Nuclear Factor 4 / Q000502:physiology*; D006801:Humans; D008297:Male; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D020641:Polymorphism, Single Nucleotide; D011485:Protein Binding; D020033:Protein Isoforms / Q000502:physiology; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D059467:Transcriptome; D047368:Tumor Burden
chemical_list: C496487:HNF1A protein, human; C496592:HNF4A protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; D051557:Hepatocyte Nuclear Factor 4; D020033:Protein Isoforms; D018808:Transcription Factor AP-1