Upregulation effect of glycyrrhizin on secretory component expression in Caco-2 cells

The aim of this study was to investigate whether glycyrrhizin, with steroid hormone-like effects, can upregulate expression of secretory component (SC) in human colonic epithelial Caco-2 and to explore its underlying mechanism. Cultures of Caco-2 were exposed to glycyrrhizin. Free SC in culture supernatants, SC protein, and SC mRNA expression were measured by enzyme-linked immunosorbent assay (ELISA), western blot, real-time PCR, respectively. Cultures of Caco-2 were exposed to RU486, a glucocorticoid receptor (GR) antagonist, combined with glycyrrhizin or dexamethasone (DEX), SC protein and SC mRNA expression were examined. Glycyrrhizin dose-dependently upregulated free SC in culture supernatants, SC mRNA and protein expression of SC (p<0.05). RU486 could inhibit DEX effects on SC expression (p<0.05), but did not inhibit glycyrrhizin effects on SC expression (p>0.05). The present study indicates that glycyrrhizin has a glucocorticoid-like upregulated effect on SC production in Caco-2 cells. It is likely that this effect is different from the mechanism of glucocorticoids.   Key words: Licorice, glucocorticoid, polymeric Ig receptor, glucocorticoid receptor.