Intracellular redox status controls membrane localization of pro- and anti-migratory signaling molecules

Abstract

Shifts in intracellular Reactive Oxygen Species (ROS) have been shown to contribute to carcinogenesis and to tumor progression. In addition to DNA and cell damage by surges in ROS, sub-lethal increases in ROS are implicated in regulating cellular signaling that enhances pro-metastatic behavior. We previously showed that subtle increases in endogenous H2O2 regulate migratory and invasive behavior of metastatic bladder cancer cells through phosphatase inhibition and consequential phosphorylation of p130cas, an adapter of the FAK signaling pathway. We further showed that enhanced redox status contributed to enhanced localization of p130cas to the membrane of metastatic cells. Here we show that this signaling complex can similarly be induced in a redox-engineered cell culture model that enables regulation of intracellular steady state H2O2 level by enforced expression of superoxide dismutase 2 (Sod2) and catalase. Expression of Sod2 leads to enhanced p130cas phosphorylation in HT-1080 fibrosarcoma and UM-UC-6 bladder cancer cells. These changes are mediated by H2O2, as co-expression of Catalase abrogates p130cas phosphorylation and its interaction with the adapter protein Crk. Importantly, we establish that the redox environment influence the localization of the tumor suppressor and phosphatase PTEN, in both redox-engineered and metastatic bladder cancer cells that display endogenous increases in H2O2. Importantly, PTEN oxidation leads to its dissociation from the plasma membrane. This indicates that oxidation of PTEN not only influences its activity, but also regulates its cellular localization, effectively removing it from its primary site of lipid phosphatase activity. These data introduce hitherto unappreciated paradigms whereby ROS can reciprocally regulate the cellular localization of pro- and anti-migratory signaling molecules, p130cas and PTEN, respectively. These data further confirm that altering antioxidant status and the intracellular ROS environment can have profound effects on pro-metastatic signaling pathways.

Mitochondrial Superoxide Dismutase Has a Protumorigenic Role in Ovarian Clear Cell Carcinoma

“…These were chosen based on previous observations of their redox regulation and involvement in tumor cell migration (8,9,18,19). shRNA-Sod2 cells exhibited a 50% decrease in phospho-Akt levels compared to scramble control cells, while there was no appreciable change observed in phosphorylation of FAK or the focal adhesion adapter protein p130cas (Fig.…”

“…It has been previously shown that high expression of Sod2 is associated with metastatic progression (8,10,17,20–23), and that dependence of cancer cell migration is related to cellular H 2 O 2 production (9,19,24,25). For example, we have shown that steady-state increases in H 2 O 2 can lead to induction of the focal adhesion kinase pathway and migration of metastatic bladder cancer cells and cells with enforced Sod2 expression (9,19). This was mediated by oxidation-dependent inhibition of the phosphatase PTPN12, leading to enhanced phosphorylation of p130cas and Rac1 activation.…”

Crosstalk between calcium and reactive oxygen species signaling in cancer

“…PTEN is a known tumor suppressor commonly lost in a number of cancer types and re-expression of PTEN has been shown to restore IP 3 R mediated apoptosis [315]. Interestingly, PTEN is a direct target for redox mediated signaling, as cysteine oxidation leads to decreased PTEN activity, and redox mediated inactivation has been observed in cancer cells with higher redox status [98, 316, 317]. Whether PTEN oxidation and a concomitant decrease in IP 3 R mediated Ca 2+ release into mitochondria are involved in apoptosis resistance of tumor cells, remains to be elucidated.…”

Expanding roles of superoxide dismutases in cell regulation and cancer

“…Mitochondria have important roles in human cancer [46] and SOD2 has been shown to be required for maintaining mitochondrial integrity and functions [44,47]. Because SOD2 is exclusively localized in the MM where mtDNA resides, it has been presumed that a main function of SOD2 is to protect mtDNA against oxidative damage.…”