title: Differentiation-inducing factor-1 enhances 5-fluorouracil action on oral cancer cells inhibiting E2F1 and thymidylate synthase mRNAs accumulation.
abstract: OBJECTIVE
  Differentiation-inducing factor-1 (DIF-1) is a morphogen originally identified in the amoebozoan Dictyostelium discoideum. In mammalian cells, it has been shown to activate GSK3β, which in turn is expected to reduce levels of β-catenin and cyclin D1, thus mediating DIF-1 antiproliferative properties. Since this could alter the expression and activity of E2F1 transcription factor and consequently those of the prognostic marker/chemotherapy target thymidylate synthase (TS), we evaluated (1) whether DIF-1 could effectively regulate these genes, (2) whether it could interfere with cell viability, and (3) whether DIF-1 activity could enhance the efficacy of the TS inhibitor 5-fluorouracil (5-FU).
  
  
  METHODS
  We investigated the effects of DIF-1 in continuous human cell lines derived from two oral tumor histotypes (corresponding to an adenosquamous and a squamous carcinoma) and a gingival epithelium. We evaluated mRNA accumulation by means of quantitative real-time PCR and efficacy of drugs on cell viability by means of MTT assay.
  
  
  RESULTS
  DIF-1 inhibited the accumulation of E2F1 mRNA and reduces TS mRNA levels in tumor cell lines, but did not alter mRNA levels in the gingival counterpart. As a result, it inhibited proliferation preferentially of tumor cell in time- and concentration-dependent manner. Moreover, it enhanced cytotoxic effects of 5-FU only in tumor cell, whereas reduced them in the gingival counterpart.
  
  
  CONCLUSIONS
  These findings suggest a tumor-specific action of DIF-1 on oral carcinoma cells. Thus, interfering with E2F1 and TS transcription, DIF-1 potentiates TS enzymatic inhibitors.
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Ospedale San Luigi Gonzaga, 10043 Orbassano, Italy.
authors.forename: Andrea Elio
authors.initials: AE
authors.lastname: Sprio
authors.forename: Federica
authors.initials: F
authors.lastname: Di Scipio
authors.forename: Paolo
authors.initials: P
authors.lastname: Ceppi
authors.forename: Paolina
authors.initials: P
authors.lastname: Salamone
authors.forename: Francesco
authors.initials: F
authors.lastname: Di Carlo
authors.forename: Giorgio Vittorio
authors.initials: GV
authors.lastname: Scagliotti
authors.forename: Mauro
authors.initials: M
authors.lastname: Papotti
authors.forename: Adriano
authors.initials: A
authors.lastname: Ceccarelli
authors.forename: Giovanni Nicolao
authors.initials: GN
authors.lastname: Berta
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004357:Drug Synergism; D050687:E2F1 Transcription Factor / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D005472:Fluorouracil / Q000008:administration & dosage / Q000494:pharmacology*; D015870:Gene Expression; D006588:Hexanones / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D009062:Mouth Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics
chemical_list: D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D006588:Hexanones; D012333:RNA, Messenger; C053433:1-((3,5-dichloro)-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone; D013940:Thymidylate Synthase; D005472:Fluorouracil