Possible association of thioredoxin and p53 in breast cancer

Expression of thioredoxin (TRX), a dithiol-reducing enzyme, and mutations o f p53 have been detected in various cancer tissues. We recently reported th at TRX-dependent redox regulation prays a crucial role in DNA binding activ ity of p53. In this study, we investigated the possibility of functional as sociation between TRX and p53 in breast cancer. First, we examined the expr ession of TRX and mutated p53 in 100 primary breast cancer tissues by immun ohistochemistry. Expression of TRX was detected in cases of 84/100 (84%) an d expression of p53, which means existence of mutated p53, in cases of 63/1 00 (63%). TRX positive cases was 89% (56/63) in mutant p53 positive cases. Next, we examined the expression of TRX and p53 in breast cancer cell line MCF-7 cells after CDDP treatment or irradiation. CDDP treatment or irradiat ion augmented expression of TRX and p53 in MCF-7 cells by western blotting. Immunofluorescence cell analysis by confocal microscopy showed that CDDP t reatment induced translocation of TRX into nuclei. These results suggest th e possible association of TRX with p53-dependent function including DNA rep air in breast cancer. (C) 2000 Elsevier Science B.V. All rights reserved.