title: Clinical impact of the methotrexate resistance-associated genes C-MYC and dihydrofolate reductase (DHFR) in high-grade osteosarcoma.
abstract: BACKGROUND
  Aims of this study were the validation of C-MYC involvement in methotrexate (MTX) resistance and the assessment of clinical impact of C-MYC and dihydrofolate reductase (DHFR) in osteosarcoma (OS).
  
  
  METHODS
  The involvement of C-MYC in MTX resistance was validated with an antisense approach. C-MYC and DHFR protein levels at diagnosis were assessed by immunohistochemistry on series of patients treated with either a MTX-based protocol (IOR/OS-1; 72 patients) or with a standard four-drug regimen (ISG/SSG 1; 61 patients).
  
  
  RESULTS
  Down-regulation of C-MYC significantly decreased the MTX resistance level of OS cells, demonstrating its causal involvement in this phenomenon. In clinical samples, a worse outcome was associated with increased levels of DHFR and C-MYC at diagnosis in the IOR/OS-1 patients and of C-MYC in the ISG/SSG 1 patients.
  
  
  CONCLUSIONS
  Meanwhile the adverse clinical impact of DHFR overexpression appeared to be closely related to the relevance of MTX in the chemotherapeutic protocol, that of C-MYC overexpression was more general and not strictly MTX related. The assessment of C-MYC and DHFR at diagnosis, together with that of other known prognostic markers, can be considered for an early identification of subgroups of OS patients with higher risk of adverse outcome.
authors.affiliation: Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Scionti
authors.affiliation: Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Michelacci
authors.affiliation: Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Pasello
authors.affiliation: Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: C M
authors.initials: CM
authors.lastname: Hattinger
authors.affiliation: Servizio di Anatomia Patologica, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Alberghini
authors.affiliation: Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: M C
authors.initials: MC
authors.lastname: Manara
authors.affiliation: Sezione di Chemioterapia, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Bacci
authors.affiliation: Sezione di Chemioterapia, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Ferrari
authors.affiliation: Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: K
authors.initials: K
authors.lastname: Scotlandi
authors.affiliation: Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Picci
authors.affiliation: Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy. Electronic address: massimo.serra@ior.it.
authors.forename: Massimo
authors.initials: M
authors.lastname: Serra
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis; D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D015870:Gene Expression / Q000187:drug effects; D016259:Genes, myc; D006801:Humans; D007150:Immunohistochemistry; D008727:Methotrexate / Q000494:pharmacology* / Q000627:therapeutic use; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000494:pharmacology; D012516:Osteosarcoma / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D016271:Proto-Oncogene Proteins c-myc / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D013762:Tetrahydrofolate Dehydrogenase / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; C489427:MYC protein, human; D016376:Oligonucleotides, Antisense; D016271:Proto-Oncogene Proteins c-myc; D013762:Tetrahydrofolate Dehydrogenase; D008727:Methotrexate