| Backgroubd:Gastric cancer ranks second in the global cancer mortality rate,and the vast majority of cases were diagnosed at an advanced stage,Less than 20%of patients can survive for more than five years after various comprehensive treatments a[1-2].At present,the main means of treating malignant tumors are radical surgery and postoperative adjuvant chemotherapy.However,during the application of traditional chemotherapy drugs to inhibit or kill tumor cells,most patients will have serious side effects such as infection,anorexia,organ toxicity,etc.[3].Therefore,the search for new chemotherapeutic drugs with strong efficacy and mild side effects is of great significance for tumor treatment.The harmine?HM?is a natural?-carboline alkaloid found in several plants,such as Peganum harmala seeds,Ayahuasca,etc.It has anti-anxiety and anti-depression,inhibits tumor cell growth and proliferation,and anti-leukemia and other pharmacological effects[4-5].Studies have shown that the mechanism of HM inhibiting the proliferation,migration and invasion of gastric cancer cells is mainly related to the down-regulated expression of the COX-2[6-7].However,the signal pathway of HM inhibiting COX-2 expression is not yet clear.Aims:The purpose of this study is to further analyze the effects of PTEN/Akt/MDM2signaling pathway in the harmine?HM?-mediated inhibition of COX-2 expression in gastric cancer cells.Methods:SGC-7901 and MKN-45 were routinely cultured in culture medium.AKT-siRNA,PTEN-siRNA and MDM2-siRNA were constructed and respectively transfected into SGC-7901 and MKN-45,and then added or not added HM for 24 h.The expression of PTEN,Akt and phosphorylated Akt?p-Akt?,MDM2 and phosphorylated MDM2?p-MDM2?,as well as COX-2 expression was detected by Western blot analysis.Sub-confluent cell cultures were treated with different concentrations of HM(4,8,16,32?mol·L-1)for 24 or 48h,then apply MTT colorimetric assay to detect cell proliferation and Hochest/PI staining was used to observe the changes of apoptosis.Results:HM dose-dependently inhibited proliferation and induced apoptosis of SGC-7901 and MKN-45 cells and increased its PTEN expression,inhibited its p-AKT,p-MDM2 and COX-2 expression.Slicencing PTEN expression by siRNA reversed the effect of HM on inhibiting p-AKT,P-MDM2 and COX-2expression.Slicencing AKT expression by siRNA coordinated with HM in inhibiting p-MDM2 and COX-2 expression.Slicencing MDM2 expression by siRNA coordinated with HM in inhibiting COX-2 expression.Conclusion:HM inhibits proliferation of gastraic cancer cells by down-regulation of COX-2 expression through PTEN/AKT/MDM2/COX-2 signaling pathway. |
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