Inhibitory effect and molecular mechanism of 3,3′-diindolelmethane on the proliferation of gastric cancer cells
Objective To investigate the role and molecular mechanism of 3,3′-diindolelmethane(DIM),a natural plant compound in cruciferous vegetables,in the prevention and treatment of gastric cancer,and then provide experimental evidence for the application of dietary plant nutrition in the prevention of gastric cancer.Methods After human gastric cancer cell line BGC-823 was treated with dif-ferent concentrations of DIM,including 0,20,40,60,80,100,and 120 μmol/L,for 24 hours,the cell survival rate was determined by the tetramethylazolium blue(MTT)method.Western blot was used to detect the expression levels of Calpain,activating transcrip-tion factor 4(ATF4)and CAAT/enhancer-binding protein homologous protein(CHOP).The changes of intracellular calcium ion con-centration were detected by a calcium ion fluorescent probe.After ATF4 in BGC-823 cells was specifically knocked down using the small interfering RNA(siRNA)of ATF4,the expression levels of ATF4 and CHOP were detected by Western blot and the cell survival rate was determined by the MTT method.After the BGC-823 cells were pretreated with the calcium ion chelator BAPTA-AM,the ex-pression levels of calpain,ATF4 and CHOP proteins were measured by Western blot and the changes in cell proliferation activity were determined by the MTT method.Results The detection results of the MTT,Western blot,and calcium ion fluorescent probe methods showed that with the increase of DIM concentration,the proliferation ability of BGC-823 cells significantly decreased(P<0.05).Mean-while,the expressions of Calpain,ATF4,and CHOP proteins were up-regulated(P<0.05)and the fluorescence intensity of intracellu-lar calcium ion increased.After transfection with the siRNA of ATF4,the expression level of ATF4 in BGC-823 cells was decreased(F=16.17,P<0.05).Compared with the DIM+si-NC group,the cell survival rate in the DIM+si-ATF4 group was increased(F=74.46,P<0.05).After the intracellular calcium ions were chelated by BAPTA-AM,the expression levels of Calpain,ATF4,and CHOP proteins in the DIM+BAPTA-AM group were significantly lower than that in the DIM group(F=24.58,34.93,and 24.45,re-spectively,P<0.05),while the cell survival rate was the opposite(F=31.13,P<0.05).Conclusion DIM can increase the concen-tration of intracellular calcium ions and up-regulate the expressions of Calpain,ATF4 and CHOP proteins,thereby inducing the endo-plasmic reticulum stress in gastric cancer cells and inhibiting their proliferation.
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