title: Role of metallothioneins in irradiated human rectal carcinoma.
abstract: BACKGROUND
  Metallothioneins (MT) are low-molecular weight, metal-binding proteins that play a role in cellular proliferation and differentiation, as well as in cellular defense mechanisms. They act as scavengers of free radicals produced by irradiation. A number of in vitro and in vivo studies have linked overexpression of cellular MT with tumor cell resistance to radiation. This is the first study that investigates whether MT expression is involved in the radioresistance of rectal carcinoma.
  
  
  METHODS
  Using a mouse monoclonal antibody, MT expression was analyzed by immunohistochemistry on surgical samples (n = 85) from 85 patients with locally advanced rectal carcinoma who were treated preoperatively with a hyperfractionated and accelerated radiotherapy schedule and on tumor biopsies (n = 13) obtained before treatment. The potential correlations between MT expression and pathologic variables and survival were examined.
  
  
  RESULTS
  MT were expressed strongly in both the cytoplasm and nucleus of tumor cells in 7 biopsy and 42 surgical samples. A comparison of MT expression in biopsy and surgical specimens showed that MT expression did not change after irradiation in most cases. Against all expectations, MT were expressed more frequently in tumors from responders than in those from the nonresponders (P = 0.02). There was no correlation between MT expression and tumor stage, histology after radiotherapy, or survival.
  
  
  CONCLUSIONS
  These findings do not Cansupport the hypothesis that MT overexpression at the end of radiotherapy is a marker for radiation resistance.
authors.affiliation: Institute of Pathology, Lausanne, Switzerland. hanifa.bouzourene@chuv.hospvd.ch
authors.forename: Hanifa
authors.initials: H
authors.lastname: Bouzourene
authors.forename: Pascal
authors.initials: P
authors.lastname: Chaubert
authors.forename: Sandra
authors.initials: S
authors.lastname: Gebhard
authors.forename: Fred T
authors.initials: FT
authors.lastname: Bosman
authors.forename: Philippe
authors.initials: P
authors.lastname: Coucke
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor / Q000032:analysis*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008668:Metallothionein / Q000096:biosynthesis* / Q000494:pharmacology; D051379:Mice; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D012004:Rectal Neoplasms / Q000503:physiopathology* / Q000532:radiotherapy*
chemical_list: D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D008668:Metallothionein