title: E2F8 as a Novel Therapeutic Target for Lung Cancer.
abstract: BACKGROUND
  The E2F members have been divided into transcription activators (E2F1-E2F3) and repressors (E2F4-E2F8). E2F8 with E2F7 has been known to play an important physiologic role in embryonic development and cell cycle regulation by repressing E2F1. However, the function of E2F8 in cancer cells is unknown.
  
  
  METHODS
  E2F8 expression was assessed by immunoblotting or immunofluorescence staining in human lung cancer (LC) cells and tissues from LC patients (n = 45). Cell proliferation, colony formation, and invasion analysis were performed to evaluate the role of E2F8 in LC. Microarray analysis was used to determine the target genes of E2F8. The regulation of E2F8 on the expression of ubiquitin-like PHD and RING domain-containing 1 (UHRF1), one of E2F8 target genes, was determined using chromatin immunoprecipitation and promoter activity assays. Human LC xenograft models were used to determine the effects of inhibiting E2F8 by siRNAs (n = 7 per group) or antisense morpholino (n = 8 per group) on tumor growth. Survival was analyzed using the Kaplan-Meier method and group differences by the Student's t test. All statistical tests were two-sided.
  
  
  RESULTS
  LC tumors overexpressed E2F8 compared with normal lung tissues. Depletion of E2F8 inhibited cell proliferation and tumor growth. E2F8 knockdown statistically significantly reduced the expression of UHRF1 (~60%-70%, P < .001), and the direct binding of E2F8 on the promoter of UHRF1 was identified. Kaplan-Meier analysis with a public database showed prognostic significance of aberrant E2F8 expression in LC (HR = 1.91 95% CI = 1.21 to 3.01 in chemo-naïve patients, P = .0047).
  
  
  CONCLUSIONS
  We demonstrated that E2F8 is overexpressed in LC and is required for the growth of LC cells. These findings implicate E2F8 as a novel therapeutic target for LC treatment.
authors.affiliation: Section of Medical Oncology, Department of Internal Medicine (SAP, JWL, RSH, JSK) and Translational Research Program (RSH, JSK), Yale Comprehensive Cancer Center, Departments of Pathology and Medical Oncology (JP), Yale School of Medicine, New Haven, CT; Yale Center for Genome Analysis, Yale University, Orange, CT (FLG).
authors.forename: Sin-Aye
authors.initials: SA
authors.lastname: Park
authors.affiliation: Section of Medical Oncology, Department of Internal Medicine (SAP, JWL, RSH, JSK) and Translational Research Program (RSH, JSK), Yale Comprehensive Cancer Center, Departments of Pathology and Medical Oncology (JP), Yale School of Medicine, New Haven, CT; Yale Center for Genome Analysis, Yale University, Orange, CT (FLG).
authors.forename: James
authors.initials: J
authors.lastname: Platt
authors.affiliation: Section of Medical Oncology, Department of Internal Medicine (SAP, JWL, RSH, JSK) and Translational Research Program (RSH, JSK), Yale Comprehensive Cancer Center, Departments of Pathology and Medical Oncology (JP), Yale School of Medicine, New Haven, CT; Yale Center for Genome Analysis, Yale University, Orange, CT (FLG).
authors.forename: Jong Woo
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Section of Medical Oncology, Department of Internal Medicine (SAP, JWL, RSH, JSK) and Translational Research Program (RSH, JSK), Yale Comprehensive Cancer Center, Departments of Pathology and Medical Oncology (JP), Yale School of Medicine, New Haven, CT; Yale Center for Genome Analysis, Yale University, Orange, CT (FLG).
authors.forename: Francesc
authors.initials: F
authors.lastname: López-Giráldez
authors.affiliation: Section of Medical Oncology, Department of Internal Medicine (SAP, JWL, RSH, JSK) and Translational Research Program (RSH, JSK), Yale Comprehensive Cancer Center, Departments of Pathology and Medical Oncology (JP), Yale School of Medicine, New Haven, CT; Yale Center for Genome Analysis, Yale University, Orange, CT (FLG).
authors.forename: Roy S
authors.initials: RS
authors.lastname: Herbst
authors.affiliation: Section of Medical Oncology, Department of Internal Medicine (SAP, JWL, RSH, JSK) and Translational Research Program (RSH, JSK), Yale Comprehensive Cancer Center, Departments of Pathology and Medical Oncology (JP), Yale School of Medicine, New Haven, CT; Yale Center for Genome Analysis, Yale University, Orange, CT (FLG). jpeter.koo@yale.edu.
authors.forename: Ja Seok
authors.initials: JS
authors.lastname: Koo
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D022762:CCAAT-Enhancer-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D047369:Chromatin Immunoprecipitation; D005455:Fluorescent Antibody Technique; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D015151:Immunoblotting; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D051379:Mice; D058990:Molecular Targeted Therapy; D014411:Neoplastic Stem Cells; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D046888:Tissue Array Analysis; D044767:Ubiquitin-Protein Ligases; D015854:Up-Regulation; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D022762:CCAAT-Enhancer-Binding Proteins; C504723:E2F8 protein, human; D012097:Repressor Proteins; C406364:UHRF1 protein, human; D044767:Ubiquitin-Protein Ligases