Alternol-Induced Oxidative Modification of SQSTM1/p62 Is Associated with Nrf2 Signaling and Autophagy-Related Responses in Prostate Cancer Cells

SQSTM1/p62 is a multifunctional scaffold protein that plays important roles in selective autophagy and cellular redox homeostasis. While phosphorylation-dependent regulation of p62 has been extensively studied, the functional significance of oxidative modification remains incompletely understood. Our previous studies showed that the natural small compound Alternol induces cancer cell-specific killing via a xanthine oxidase-mediated strong oxidative stress. In this study, we investigated p62-associated oxidative responses under Alternol-induced oxidative stress conditions in prostate cancer cells. Using biochemical assays and cell-based models, we found that Alternol treatment was associated with the accumulation of oxidized and high-molecular-weight p62 species, accompanied by altered KEAP1 association and increased Nrf2-associated signaling. Furthermore, Alternol-induced p62 oxidative modification was associated with autophagy-related responses and adaptive cellular survival under oxidative stress conditions. Disruption of the Cys105/113-dependent oxidative modification response attenuated Nrf2-associated transcriptional activity and increased cellular sensitivity to Alternol treatment. Collectively, our findings support an association between p62 oxidative modification and redox-responsive autophagy- and antioxidant-associated signaling pathways under Alternol-induced oxidative stress conditions, providing new insight into adaptive stress responses in prostate cancer cells.