Effects of repetitive pretreatment with isothiocyanates on the stress resistance capacity of RGM1 cells.

In this study, we investigated the effects of repeated isothiocyanate (ITC) pretreatment on cytotoxicity, cytoprotective gene expression, and chromatin accessibility in rat gastric epithelial RGM1 cells. Cells were pretreated with ITCs at low concentrations (0-2 µM) four times at 48 h intervals, followed by exposure to higher concentrations of ITCs. Repeated benzyl isothiocyanate (BITC) pretreatment significantly attenuated BITC-induced cytotoxicity compared with untreated controls. Moreover, repeated BITC pretreatment (2 µM) markedly increased the mRNA expression levels of cytoprotective genes, including glutathione S-transferase π and heat shock protein 27. Repeated BITC pretreatment also conferred cross-tolerance to low-pH and heat stress conditions. In addition, BITC treatment significantly upregulated the expression of several carbonic anhydrase isoforms associated with intracellular pH homeostasis. A DNase I-based chromatin accessibility assay revealed that repeated BITC pretreatment promoted euchromatin formation at the HO-1 gene locus. Furthermore, euchromatin formation in cytoprotective gene regions was also induced under various stress conditions. These findings suggest that repeated exposure to BITC enhances cellular stress tolerance through the induction of cytoprotective genes and stress-dependent chromatin remodeling.