Role of metallothioneins in irradiated @entity1 XXXX .

@entity5 @entity1 @entity189
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 @entity5 cell resistance to radiation. This is the first study that investigates whether MT expression is involved in the radioresistance of @entity189 . METHODS: Using a mouse monoclonal antibody, MT expression was analyzed by immunohistochemistry on surgical samples (n = 85) from 85 @entity1 with locally advanced @entity189 who were treated preoperatively with a hyperfractionated and accelerated radiotherapy schedule and on @entity5 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 @entity5 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 @entity5 from responders than in those from the nonresponders (P = 0.02). There was no correlation between MT expression and @entity5 stage, histology after radiotherapy, or survival. CONCLUSION: These findings do not Cansupport the hypothesis that MT overexpression at the end of radiotherapy is a marker for radiation resistance.
