Abstract 2262: Elevated peroxiredoxin expression in breast cancer and its protective role in doxorubicin-resistance

Peroxiredoxin (Prdx) proteins are thiol-specific antioxidants that protect cells from oxidative stress in various normal and disease states. There are six different Prdx proteins expressed in mammals, each possessing a characteristic tissue and subcellular distribution. Recent studies have revealed elevated Prdx levels in many cancers, suggesting a protective role for these proteins in cancer cell survival. In the present study we analyzed Prdx levels in several human breast tumor samples, and also investigated the function of Prdx proteins in the MCF-7 breast cancer cell line. Analysis of breast tumor and adjacent normal breast tissue from almost 20 patients showed elevated levels of most Prdx proteins in tumor tissue from the majority of patients. To address the role of Prdxs in breast cancer, we used transient siRNA transfections of MCF-7 cells and examined resulting cell viability in the absence and presence of doxorubicin treatment. Our data show that individual suppression of four of six of the Prdx proteins leads to increased cell death, as well as increased sensitivity to doxorubicin-induced toxicity. Finally, we show that clonal selection of doxorubicin-resistant MCF-7 cells by two-week culture in 0.1uM doxorubicin resulted in a marked elevation in the expression of several Prdx proteins. Similar studies are currently underway in the highly metastatic MDA cell line, and possible upstream regulators of Prdx overexpression in these lines are being investigated. Together, these data show a strong protective role for Peroxiredoxins in breast cancer cell survival, and suggest that Prdx overexpression in breast cancer may play a role in chemotherapy-resistance. Citation Format: Jillian Muhlbauer, Gregg Perlmutter, Caitlin McDonald, Harry Cintineo, Caterina Aiello, Shelley A. Phelan. Elevated peroxiredoxin expression in breast cancer and its protective role in doxorubicin-resistance. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2262. doi:10.1158/1538-7445.AM2014-2262