Abstract
MAPK/p38 is an important mammalian signaling cascade that responds to a variety of intracellular or extracellular stimuli, such as reactive oxygen species (ROS), and participates in numerous physiological and pathological processes. However, the biological function of p38 in different tumors, and even at different stages of the same tumor, remains elusive. To further understand the regulatory mechanism of p38 and oxidative stress in the occurrence and development of gastric cancer, we report SUMOylation as a novel post-translational modification occurring on lysine 152 of MAPK14/p38α through immunoprecipitation and series of pull-down assays in vitro and in vivo. Importantly, we determine that p38α-SUMOylation functions as an authentic sensor and accelerator of reactive oxygen species generation via interaction with and activation of MK2 in the nucleus, and the ROS accumulation, in turn, promotes the SUMOylation of p38α by stabilizing the PIASxα protein. This precise regulatory mechanism is exploited by gastric cancer cells to create an internal environment for survival and, ultimately, metastasis. This study reveals novel insights into p38α-SUMOylation and its association with the intracellular oxidative stress response, which is closely related to the processes of gastric cancer. Furthermore, the PIASxα/p38α-SUMOylation/MK2 cis-axis may serve as a desirable therapeutic target in gastric cancer as targeting PIASxα, MK2, or a specific peptide region of p38α may reconcile the aberrant oxidative stress response in gastric cancer cells.