| Background:Gastric cancer is a malignant tumor that seriously endangers human health.Natural plant polyphenol curcumin,because of it9s safety,effectiveness,cheap and low toxicity,and anti-Helicobacter pylori,anti-inflammatory,anti-oxidation,anti-tumor and other effects has been concerned by researchers.The high expression of miR-21 in almost all solid tumors,including gastric cancer,has been recognized as an oncogenic factor.MiR-21 can be used for regulating the occurrence and development of gastric cancer by various target sites.Whether curcumin can prevent the occurrence and progression of gastric cancer by regulating miR-21 and its target pathway PTEN/PI3K/Akt is worth exploring.There are many problems in the chemical prevention and treatment of gastric cancer,such as drug resistance,side effects of chemotherapy,intolerability and so on.Whether curcumin combined with PD98059,a MAPK pathway specific inhibitor,can play a synergistic role in anti gastric cancer has not been studied.In this study,it is also discussed.Objection:1.Preliminary detection of whether curcumin has effective effects on prevention and treatment of occurrence and development of stomach cancer.2.Whether miR-21/PTEN/PI3K/Akt pathway is one of the major regulatory mechanisms in curcumin anti-gastric cancer,and a preliminary verification of the mechanism is carried out.3.To find out whether curcumin and PD98059 can play a role on synergistic anti-gastric cancer,and to explore the mechanism of such action.Methods:1.The anti-gastric cancer effect of curcumin and its combination with PD98059 or VO-Ohpic trihydrate(a highly potent inhibitor of PTEN)was observed in vitro.2.QRT-PCR and western blotting were used to observe the effects of curcumin alone or in combination with PD98059 on the expression of miR-21 and miR-21/PTEN/Akt pathway.3.The relationship between miR-21 and the expression of target gene PTEN was verified in vitro.4.Effect of curcumin on malignant transformation of gastric epithelial cells induced by MNNG.Results:1.(1)Curcumin induced proliferation inhibition of gastric cancer MGC-803 cells in concentration-and time-dependent form,and could effectively induce apoptosis of gastric cancer cells.(2)PD98059 has a significant synergistic effect on the apoptosis of the gastric cancer cells induced by curcumin.(3)Curcumin can inhibit the migration of MGC-803 cells,and VO-Ohpic trihydrate is helpful to restore the migration ability of MGC-803 cells inhibited by curcumin.2.(1)After MGC-803 cells were treated with different concentrations of curcumin,the level of miR-21 decreased gradually with the increase of curcumin concentration,and there was a negative correlation between them.(2)The expression of miR-21 in MGC-803 cells treated by PD98059 combined with curcumin of different concentrations showed an increasing trend compared with that of curcumin of corresponding concentrations alone,suggesting that there may be other mechanisms involved in the effect of PD98059 combined with curcumin on miR-21 level.3.(1)Curcumin alone(0?40 ?M)could effectively inhibit the expression of p-Akt and induce the up-regulation of PTEN protein expression in a certain concentration range(0-40 ?M).The expression of PTEN was negatively correlated with the expression of p-Akt,and the up-regulation of PTEN expression was negatively correlated with the down-regulation of miR-21 expression induced by curcumin.Curcumin may induce apoptosis and inhibit cell proliferation and migration of gastric cancer MGC-803 cells through miR-21/PTEN/Akt pathway.(2)The combination of PD98059 and curcumin can reduce the expression of p-Akt of MGC-803 cells to PD98059 or curcumin.In the combination of PD98059 and curcumin,the expression of PTEN in MGC-803 cells is lower than that of PD98059 alone or curcumin alone.4.Through cell experiments in vitro and Real-time PCR,Western blot,double luciferase test,we verified that miR-21 can target PTEN gene.5.(1)Curcumin can inhibit the malignant transformation of GES-1 cells induced by MNNG.(2)Curcumin can play an obvious protective role in MNNG-induced chromosome damage in GES-1 cells.Conclusion:1·Curcumin may induce apoptosis and inhibit cell proliferation and migration of gastric cancer MGC-803 cells through miR-21/PTEN/Akt pathway.2.Curcumin can inhibit the malignant transformation of gastric epithelial cells induced by MNNG.3.Curcumin and PD98059 can play a synergistic anti-gastric cancer effect,in addition to miR-21/PTEN/Akt pathway may be involved in this synergistic effect,there may be other important mechanisms involved. |
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