title: Cytochrome P450 CYP3A4/5 expression as a biomarker of outcome in osteosarcoma.
abstract: OBJECTIVE
  Osteosarcoma, the most common pediatric primary bone tumor, is an aggressive malignancy with a tendency for early pulmonary metastasis. A reliable biomarker to predict clinical outcome at diagnosis has not yet been identified. To date, pathological review of neoadjuvant chemotherapy-induced necrosis is the most useful determinant of which patients are likely to develop metastatic disease. There is a clinical need to identify patients who will benefit from more aggressive preoperative therapy or perhaps require less aggressive chemotherapy. More than 30 human P450 isoenzymes have been characterized, with at least nine possessing some clinical relevance. One of these, CYP3A4/5 is involved in metabolic activation and detoxification of a wide number of carcinogens and chemotherapeutic agents, including many drugs that are useful in the treatment of osteosarcomas.
  
  
  METHODS
  Osteosarcoma tissue microarray blocks containing biopsies from 18 primary tumors were used to analyze the expression of P450s 1A1/2, 1B1, 2B6, 2D6, and 3A4/5 by enzyme-linked avidin-biotin complexed immunohistochemistry. The frequencies of expression were 83%, 67%, and 83% for P450s 1A1/2, 1B1, and 3A4/5, respectively. P450s 2B6 and 2D6 were not detectable.
  
  
  RESULTS
  These results were extended by developing a fluorescent-based quantitative immunocytochemistry technique to assess the levels of CYP3A4/5 in 18 paraffin-embedded primary biopsy sections. Expression of CYP3A4/5 was found to be significantly higher in primary biopsies of patients who developed distant metastatic disease compared with biopsies from patients with nonmetastatic disease (P = 0.0004).
  
  
  CONCLUSIONS
  High cytochrome P450 CYP3A4/5 expression may predict metastasis and poor prognosis in osteosarcomas. Its use as a biomarker of therapeutic response will have implications for the treatment of these tumors.
authors.affiliation: Department of Environmental Health Sciences, Toxicology Program, University of Michigan, Ann Arbor 48109, USA.
authors.forename: Hassan R
authors.initials: HR
authors.lastname: Dhaini
authors.forename: Dafydd G
authors.initials: DG
authors.lastname: Thomas
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Giordano
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Johnson
authors.forename: J Sybil
authors.initials: JS
authors.lastname: Biermann
authors.forename: Kirsten
authors.initials: K
authors.lastname: Leu
authors.forename: Paul F
authors.initials: PF
authors.lastname: Hollenberg
authors.forename: Laurence H
authors.initials: LH
authors.lastname: Baker
mesh_terms: D000293:Adolescent; D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis*; D001706:Biopsy; D002648:Child; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009362:Neoplasm Metastasis; D012516:Osteosarcoma / Q000473:pathology* / Q000628:therapy*; D011237:Predictive Value of Tests; D011379:Prognosis; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C473667:cytochrome P-450 CYP3A45; C510163:CYP3A4 protein, human