ABSTRACT: The cAMP-induced intestinal chloride secretion plays a significant role in the pathogenesis of secretory diarrheas. This study aimed to investigate the anti-secretory effects of α,β-dehydromonacolin K, a derivative of lovastatin from Aspergillus sclerotiorum, on cAMP-induced chloride and fluid secretion in human T84 cells and human colonoids. In T84 cells, α,β-dehydromonacolin K inhibited cAMP-induced chloride secretion with an IC50 of ~ 6.32 μM. Apical chloride current analyses in T84 cells demonstrated that α,β-dehydromonacolin K inhibits CFTR chloride channels, stimulated by cAMP agonists, with IC50 of ~ 1 μM. Interestingly, potency of α,β-dehydromonacolin K on CFTR inhibition was decreased in the presence of AMP-activated protein kinase inhibitor or when genistein, a direct CFTR activator, was as a stimulator. Basolateral potassium current analyses indicated that α,β-dehydromonacolin K did not affect basolateral potassium channel activities. In a three-dimensional (3D) model of human colonoids, α,β-dehydromonacolin K significantly suppressed both cAMP-induced and calcium-induced fluid secretion. Proteomic analysis in human clonoids revealed that α,β-dehydromonacolin K interacted with 33 proteins, including those associated with nonsense-mediated mRNA decay. Notably, inhibitory effects of α,β-dehydromonacolin K on cAMP-induced chloride secretion in T84 cells and cAMP-induced fluid secretion in human colonoids were significantly diminished in the presence of a nonsense-mediated mRNA decay inhibitor SMG 1i, suggesting that α,β-dehydromonacolin K inhibited the cAMP-induced fluid secretion in human intestinal epithelial cells by mechanisms involving the nonsense-mediated mRNA decay pathways. In summary, α,β-dehydromonacolin K represents a promising class of natural compounds that exerts an anti-secretory effect in human intestinal epithelia via a novel mechanism of action.
