Acidic stress induces protective autophagy in SGC7901 cells

OBJECTIVE: To investigate the effect of acidity on gastric cancer SGC7901 cells in terms of autophagy and provide a new strategy for therapeutically targeting gastric cancer autophagy in an acidic environment. METHODS: Transmission electron microscopy (TEM) and confocal laser scanning microscopy were used to examine the effect of an acidic environment on autophagosome formation. Light chain 3 (LC3) and p62 levels in SGC7901 cells exposed to acidic conditions were measured using Western blot analysis. To explore changes in autophagy flux, the cells were treated with an inhibitor of autophagy bafilomycin A1. The CCK-8 assay was performed to determine if inhibiting acid-induced autophagy affected cell proliferation. RESULTS: Increased autophagosome formation was observed by TEM. Punctate LC3 structures were observed in cells cultured under acidic conditions, whereas untreated cells exhibited diffuse and weak staining for punctate LC3 structures. Cytoplasmic LC3-I translocated to the autophagic membrane (LC3-II) levels increased under acidic conditions, whereas p62 levels decreased. The bafilomycin A1-induced inhibition of autophagy caused by the acidic environment inhibited cell proliferation. CONCLUSION: The acidic environment upregulates autophagy in SGC7901 cells. In long-term culture, a stable and high level of autophagy is maintained in an acidic environment, which has a protective effect on cells.