RESUMO
Objective:To investigate the effects of Cordyceps sinensis (CS) on cellular apoptosis and Sirt1 expression in HK2 cells followed by ischemia-reperfusion (I/R).Methods:HK2 cells were incubated with different concentrations of CS (10,20,40,80,160,320 mg/L) for 24 hours,and the optimal concentration of CS was selected by measuring cell proliferation.The confluent HK2 cells were incubated with 0.01 μmol/L antimycin A for 2 hours to induce ischemia in vitro,and then the reperfusion was achieved by incubating cells with glucose-replete complete growth medium for 24 hours.HK2 cells were divided into 4 groups:a control group,an I/R group,an I/R+CS (160 mg/L) group,and an I/R+CS (160 mg/L)+Sirtinol (25 μtmol/L) group.Twenty-four hours later,total RNA and protein were collected.The cell proliferation was evaluated by MTT assay;the mRNA and protein expression of Sirtl and the cleaved caspase-3 were measured by qRT-PCR and Western blot,respectively.The cellular apoptosis rate was determined by Annexin V-FITC/PI double staining and flow cytometry.Results:Certain concentrations (10-160 mg/L) of CS did not show effect on the proliferation of HK2 cells (P＞0.05),while 320 mg/L of CS inhibited cell proliferation significantly (P＜0.01);compared with the control group,the mRNA and protein expressions of Sirtl and the cleaved caspase-3 in the I/R group were up-regulated (P＜0.01) and the apoptosis rate was extremely high;compared with the I/R group,CS significantly up-regulated Sirt1 mRNA and protein expression (P＜0.01) while down-regulated cleaved caspase-3 mRNA and protein levels (P＜0.01),and reduced apoptosis rate (P＜0.05).The effects of CS were blocked in the presence of sirtinol,an inhibitor of CS.Conclusion:CS protects HK2 cells from I/R injury through activation of Sirt 1 pathway.