Abstract 5283: A role for mitochondrial derived reactive oxygen species in regulating pro-migratory signaling pathways via p130cas

Abstract

Abstract A cell's migratory and invasive potential depends on a multitude of signaling pathways, which present novel targets for anti-cancer therapies. We and others have shown that reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), are modulators of tumorigenicity and contribute to the migratory phenotype of cancer cells (Connor et al. 2008, Cancer Research). Intrinsic levels of ROS are elevated in numerous metastatic cancer types, which suggests that these cells have evolved to utilize sublethal increases in ROS levels as novel second messengers in regulating pro-metastatic signaling events. Here we present evidence to support this hypothesis and describe how ROS may act as second messengers in the Focal Adhesion Kinase (FAK) pathway. Cells displaying intrinsic picomolar changes in H2O2 levels, either endogenously (metastatic 253J-BV bladder cancer cell line, compared to its non-metastatic parental 253J-P line), or as a consequence of enforced mitochondrial manganese superoxide dismutase (Sod2) expression, display an enhanced migratory phenotype. This is accompanied by a loss of mature vinculin positive focal adhesions. Mechanistically, we show that the protein tyrosine phosphatases PTP-PEST and PTEN are oxidized and inactivated in cells displaying enhanced H2O2 levels and that this can be reversed by effective removal of H2O2 following expression of the H2O2 detoxifying enzyme catalase (CAT). A consequence of PTP-PEST oxidation and inactivation is a concomitant increase in phosphorylation of its primary substrate p130cas, an adaptor protein of the FAK signaling cascade. Further, increases in intracellular H2O2 levels shift the localization of p130cas to the cell surface, as assessed by membrane/cytoskeletal fractionation and immunofluorescent staining, indicative of localized activation of FAK pathway signaling at the leading edge. Again co-expression of CAT negates these effects, indicating that these mechanisms are H2O2 dependent. The data described support the hypothesis that elevated mitochondrial ROS levels can regulate the spatial activation of pro-migratory signaling pathways, enhancing the metastatic potential of cancer cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5283.