Superoxide dismutases and p53 protein levels in blood cells of breast cancer patients.

OBJECTIVE

Radiation treatment of breast cancer (BC) often results in post-therapy complications. The undesired sequelae could be avoided by the diagnostic screening of biomarkers for prediction of ionizing radiation (IR)-linked injury of healthy tissues.

METHODS

The expression of antioxidative defence enzymes CuZn- and Mn-superoxide dismutase (CuZnSOD, MnSOD) and tumor suppressor protein p53 was measured in blood cells of 19 women with BC (age groups 30-45 and 46-60 years) and respective controls. The proteins were detected by specific immunostaining and quantified by laser-scanning densitometry.

RESULTS

Constitutive expression of CuZnSOD was significantly elevated in the group of BC patients (up to 254 arbitrary units, AU/mL) relative to the control group (105-130 AU/mL). The constitutive expression of MnSOD was elevated (up to 94 AU/mL) in the group of BC patients relative to the controls (53-56 AU/mL). p53 was also constitutively more expressed in BC patients (35-42 AU/mL) than in controls (32-33 AU/mL). Both MnSOD and p53 were inducible by (60)Co gamma-ray IR (up to 170 AU/mL and 51 AU/mL, respectively) in the BC patient group. The levels of IR-induced p53 correlated inversely with MnSOD levels.

CONCLUSIONS

The constitutive expression of all 3 proteins could be a useful biomarker for the presence of BC, but only MnSOD overexpression may be the predictive biomarker for selection of BC patients that would be less susceptible to IR-linked complications.