Abstract 2090: Investigating peroxiredoxin expression, activity, and potential downstream signaling in cancerous MCF7 and normal MCF10A breast epithelial cells

Abstract

Abstract Peroxiredoxins are thiol-specific antioxidant proteins that protect cells from oxidative stress. They have been implicated in cell signaling, proliferation and apoptosis, and studies have found elevated levels in many types of cancer, suggesting a protective role for these proteins in cancer cells. We previously showed that Prdx1 is overexpressed in the MCF7 breast cancer line as compared to the normal MCF10A line, and that suppression of Prdx1 and/or Prdx6 increases susceptibility to oxidative stress-induced apoptosis, with a more profound effect in MCF10A cells. In the present study, we sought to investigate other differences in peroxiredoxin expression and activity between these lines, as well as potential downstream targets. We found that mRNA levels of Prdxs1-5 were significantly elevated in MCF7 cells, while comparable levels of Prdx6 mRNA were found. A Prdx6 antibody, however, detects two bands by western blot: an upper 30-32 kDa species expressed at equal levels in both lines, and a 24-26 kDa species significantly overexpressed in MCF7 cells. An antibody specific for oxidized Prdx6 detected both products, demonstrating elevated levels in the cancer cells. Interestingly, the two species were differentially affected by siRNA-mediated Prdx1 and/or Prdx6 suppression. We further examined potential downstream targets of peroxiredoxin-regulated signaling. The two lines showed relatively comparable levels of p38, JNK1, ERK2, and c-Abl1b mRNA. In contrast, ERK1 mRNA levels were higher in MCF7 cells, while c-Abl1a was expressed only in the normal line. Peroxiredoxin suppression by siRNA transfection had no significant effect on p38, ERK1, or ERK2 in either cell type, but did lead to a decrease in c-Abl and JNK1 expression differentially in the two lines. Together, these data suggest different roles for Prdx1 and Prdx6 in normal vs. cancerous breast epithelial cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2090. doi:10.1158/1538-7445.AM2011-2090