Overexpression of peroxiredoxin I and thioredoxin1 in human breast carcinoma

BACKGROUND: Peroxiredoxins (Prxs) are a novel group of peroxidases containing high antioxidant efficiency. The mammalian Prx family has six distinct members (Prx I-VI) in various subcellular locations, including peroxisomes and mitochondria, places where oxidative stress is most evident. The function of Prx I in particular has been implicated in regulating cell proliferation, differentiation, and apoptosis. Since thioredoxin1 (Trx1) as an electron donor is functionally associated with Prx I, we investigated levels of expression of both Prx I and Trx1. METHODS: We investigated levels of expression of both Prx I and Trx1 in breast cancer by real-time polymerase chain reaction (RT-PCR) and Western blot. RESULTS: Levels of messenger RNA (mRNA) for both Prx I and Trx1 in normal human breast tissue were very low compared to other major human tissues, whereas their levels in breast cancer exceeded that in other solid cancers (colon, kidney, liver, lung, ovary, prostate, and thyroid). Among members of the Prx family (Prx I-VI) and Trx family (Trx1, Trx2), Prx I and Trx1 were preferentially induced in breast cancer. Moreover, the expression of each was associated with progress of breast cancer and correlated with each other. Western blot analysis of different and paired breast tissues revealed consistent and preferential expression of Prx I and Trx1 protein in breast cancer tissue. CONCLUSION: Prx I and Trx1 are overexpressed in human breast carcinoma and the expression levels are associated with tumor grade. The striking induction of Prx I and Trx1 in breast cancer may enable their use as breast cancer markers.