Eriodictyol accelerates glucocorticoid-induced apoptosis by promoting osteoblast autophagy

Ma Yunfeng; Han Xiaofei

doi:10.12307/2024.459

Abstract：BACKGROUND:Glucocorticoid-induced osteoporosis is a common complication of systemic glucocorticoid therapy,which is mainly characterized by its inhibitory effect on osteoblasts.Eriodictyol inhibits osteoclast differentiation and osteoporosis-induced by ovariectomy.However,it is unclear whether eriodictyol regulates glucocorticoid-induced osteoblasts. OBJECTIVE:To explore whether eriodictyol plays a role in glucocorticoid-induced osteoblast apoptosis and its potential regulatory mechanisms. METHODS:Dexamethasone-pretreated osteoblasts MC3T3-E1 were treated with the different concentrations(0,0.5,1,2.5,5,10 μmol/L)of eriodictyol or 5 μmol/L 3-methyladenine,an autophagy inhibitor,and then transfected with heme oxygenase 1 overexpression vector(pcDNA-HMOX1)and empty vector(pcDNA vector).Cell proliferation and apoptosis were assessed by using cell counting kit-8 assay and flow cytometry,respectively.The activity of caspase-3 was detected with ELISA.Western blot assay was used to detect the protein expression of autophagy-related proteins LC3-Ⅱ/LC3-Ⅰ,p62,Atg5 and Atg12,the expression of apoptotic related proteins Bax and Bcl-2,as well as the protein expression of AMPK and p-AMPK. RESULTS AND CONCLUSION:Low concentrations of eriodictyol were non-toxic to MC3T3-E1 cells and promoted cell proliferation,as well as increased the expression of autophagy related proteins LC3-Ⅱ/LC3-Ⅰ,p62,Atg5 and Atg12,decreased caspase-3 enzyme activity,inhibited Bax protein expression,promoted Bcl-2 protein expression and reduced dexamethasone-induced apoptosis in MC3T3-E1 cells in a dose-dependent manner.Moreover,eriodictyol significantly promoted heme oxygenase 1 expression in osteoblasts,whereas overexpression of heme oxygenase 1 promoted AMPK phosphorylation,activated autophagy,and inhibited dexamethasone-induced osteoblast apoptosis.While 3-methyladenine treatment counteracted the effects of heme oxygenase 1 overexpression on MC3T3-E1 cells.To conclude,low concentration of Eriodictyol is non-toxic to osteoblasts and activates AMPK signaling pathway by upregulating the expression of heme oxygenase 1,thereby promoting autophagy and inhibiting dexamethasone-induced osteoblast apoptosis.Eriodictyol has great potential for the treatment of glucocorticoid-induced osteoporosis.