title: Regulation of interferon pathway in 2-methoxyestradiol-treated osteosarcoma cells.
abstract: BACKGROUND
  Osteosarcoma is a bone tumor that often affects children and young adults. Although a combination of surgery and chemotherapy has improved the survival rate in the past decades, local recurrence and metastases still develop in 40% of patients. A definite therapy is yet to be determined for osteosarcoma. Anti- tumor compound and a metabolite of estrogen, 2-methoxyestradiol (2-ME) induces cell death in osteosarcoma cells. In this report, we have investigated whether interferon (IFN) pathway is involved in 2-ME-induced anti-tumor effects in osteosarcoma cells.
  
  
  METHODS
  2-ME effects on IFN mRNA levels were determined by Real time PCR analysis. Transient transfections followed by reporter assays were used for investigating 2-ME effects on IFN-pathway. Western blot analyses were used to measure protein and phosphorylation levels of IFN-regulated eukaryotic initiation factor-2 alpha (eIF-2α).
  
  
  RESULTS
  2-ME regulates IFN and IFN-mediated effects in osteosarcoma cells. 2 -ME induces IFN gene activity and expression in osteosarcoma cells. 2-ME treatment induced IFN-stimulated response element (ISRE) sequence-dependent transcription and gamma-activated sequence (GAS)-dependent transcription in several osteosarcoma cells. Whereas, 2-ME did not affect IFN gene and IFN pathways in normal primary human osteoblasts (HOB). 2-ME treatment increased the phosphorylation of eIF-2α in osteosarcoma cells. Furthermore, analysis of osteosarcoma tissues shows that the levels of phosphorylated form of eIF-2α are decreased in tumor compared to normal controls.
  
  
  CONCLUSIONS
  2-ME treatment triggers the induction and activity of IFN and IFN pathway genes in 2-ME-sensitive osteosarcoma tumor cells but not in 2-ME-resistant normal osteoblasts. In addition, IFN-signaling is inhibited in osteosarcoma patients. Thus, IFN pathways play a role in osteosarcoma and in 2-ME-mediated anti-proliferative effects, and therefore targeted induction of IFN signaling could lead to effective treatment strategies in the control of osteosarcoma.
authors.affiliation: Department of Orthopedics, College of Medicine, Mayo Clinic, Rochester, MN 55906, USA.
authors.forename: Fritz
authors.initials: F
authors.lastname: Wimbauer
authors.forename: Caihong
authors.initials: C
authors.lastname: Yang
authors.forename: Kristen L
authors.initials: KL
authors.lastname: Shogren
authors.forename: Minzhi
authors.initials: M
authors.lastname: Zhang
authors.forename: Ribu
authors.initials: R
authors.lastname: Goyal
authors.forename: Scott M
authors.initials: SM
authors.lastname: Riester
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Yaszemski
authors.forename: Avudaiappan
authors.initials: A
authors.lastname: Maran
mesh_terms: D000077584:2-Methoxyestradiol; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007372:Interferons / Q000235:genetics / Q000378:metabolism*; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D015852:Eukaryotic Initiation Factor-2; D004958:Estradiol; D000077584:2-Methoxyestradiol; D007372:Interferons