Overexpression of peroxiredoxin in human breast cancer.

The peroxiredoxins (Prx) are a family of 25 kDa peroxidases that can reduce H2O2 using an electron from thioredoxin (Trx) or other substances. The mammalian Prx family is divided into six groups (Prx I-VI) on the basis of homology of amino acid sequences. They are located in the cytosol and play a role in the cell signaling system. Previous reports have shown that Prx II has proliferative and anti-apoptotic properties and thus may induce carcinogenic changes. We conducted this study to reveal the change in expression of Prx in human breast cancer in comparison to normal tissues. Western immunoblotting using Prx type I, II and III antibodies was undertaken on 24 human breast cancer tissues and normal counterparts. We used antibodies against purified recombinant NKEF-A/PAG, NKEF-B and MER 5 which are the Prx isoforms. Type I Prx was overexpressed in the cancer tissues of 21 patients (87.5%), type II in 18 patients (75%) and type III in 19 patients (79.2%) in relation to normal tissue. However, no significant relationship was found between Prx overexpression and clinicopathological parameters of breast cancer such as tumor size, lymphatic invasiveness, hormone receptor status or nuclear and histologic grade. In conclusion, Prx is overexpressed in breast cancer tissues to a great extent suggesting that Prx has a proliferative effect and may be related to cancer development or progression.