Manganese superoxide dismutase expression correlates with p53 status and local recurrence of cervical carcinoma treated with radiation therapy.

Manganese superoxide dismutase (Mn-SOD) inactivates the radiation effect by removal of radiation-induced toxic superoxide radicals. The purpose of this study was to assess the correlation among Mn-SOD, radiation sensitivity, and prognosis following radiation therapy. The Mn-SOD, p53 oncoprotein, and c-erbB-2 oncoprotein expressions in 52 specimens from patients with cervical cancer treated with radiation therapy were investigated immunohistochemically. The frozen sections were stained using antihuman Mn-SOD, anti-p53 monoclonal antibodies, and anti-c-erbB-2 oncoprotein polyclonal antibody followed by the avidin-biotin peroxidase complex method. Correlations among Mn-SOD expression, prognosis, and failure patterns were analyzed. Additionally, correlations between p53 and c-erbB-2 oncoproteins and Mn-SOD expression were investigated. Positive expression of Mn-SOD in cervical carcinoma was 48.1%. No significant difference in positivity of Mn-SOD expression was noted according to stage and histological subtypes. The 5-year survival rate of Mn-SOD-positive patients was 42.5 %, significantly poorer than the 77.0% of Mn-SOD-negative patients (P < 0.05). Analysis of the failure patterns revealed that patients with Mn-SOD expression showed a significantly higher incidence of local recurrence than those without. However, there was no difference in distant metastasis between them. Although both p53 and c-erbB-2 oncoprotein expressions were significantly associated with the prognosis of the same patients, Mn-SOD expression was associated with p53 oncoprotein expression but not with that of c-erbB-2 oncoprotein. Our results demonstrate that the Mn-SOD level of cancer cells is correlated with local control and is an important prognostic factor in radiation therapy for cervical cancer. The Mn-SOD level may help explain the intrinsic radiosensitivity of cervical cancer cells.