An Experimental Study On Interference EZH2 Gene Expression To Enhance The Sensitivity Of Gastric Cancer SGC7901 Cell Line Cells To Oxaliplatin

Gastric cancer is one of the most common gastrointestinal cancers threatening human health at present.It is also a malignant tumor with high mortality in China.Although surgery is the first treatment choice of gastric cancer,patients with gastric cancer in China often have a low rate of early consultation due to non-specific digestive tract symptoms.Most of the patients were diagnosed at the time of disease progression and lost the chance of radical surgery.For the patients with advanced gastric cancer,combined adjuvant therapy on the basis of surgery can improve the surgical resection rate and the patient's quality of life.Chemotherapy is the main adjuvant therapy.Combination chemotherapy with platinum drugs is the first line of chemotherapy for advanced gastric cancer,but platinum resistance is one of its main failure modes.Therefore,it is very important to evaluate the sensitivity of chemotherapy for gastric cancer before chemotherapy.The enhancer of zeste homolog 2?EZH2?is a catalytic subunit of the PRC2complex,which is homologous to the Drosophila gene and is the core member of the PcG gene family.Recent studies have found that EZH2 is overexpressed in many tumors,including hepatocellular carcinoma,breast cancer,bladder cancer and melanoma,and is related to the biological behavior of the tumor.Studies have shown that the overexpression of EZH2 is related to the histological grade,the level of infiltration,lymph node metastasis,distant metastasis and malignancy of the tumor.It is an independent biomarker for cancer patients with poor prognosis.This makes it possible to become an important molecular marker for early diagnosis and prognosis,and is more likely to become a new target for tumor targeted therapy.In this study,the expression level of EZH2 gene in gastric cancer SGC7901 cells was down-regulated by transfection of siRNA technique.CCK-8 assay was used to detect the proliferation ability of gastric cancer SGC7901 cells over time after down-regulation of EZH2 expression,and detect the changes in the proliferation inhibition rate of cells treated with different concentrations of oxaliplatin.To analyze the relationship between the expression of EZH2 gene and platinum drug sensitivity in gastric cancer cells,and to provide a theoretical basis for finding EZH2 targeting drugs that can reverse platinum resistance.Objective:The expression of EZH2 gene was downregulated by liposomes transfected with siRNA,and to study the proliferation of EZH2 gene on the SGC7901 cell line of gastric cancer and the role of EZH2 gene in the sensitivity of gastric cancer to oxaliplatin.Methods:The SGC7901 cell line of gastric cancer was cultured.According to the EZH2 gene sequence provided by Gene bank?ID:2146?,three specific EZH2 siRNA sequences and a nonspecific siRNA sequence were synthesized,and the four siRNA fragments were transfected into the gastric cancer SGC7901 cells respectively by liposome transfection.Transfected with the specific EZH2 siRNA sequence fragments?EZH2 siRNA-1,EZH2 siRNA-2,EZH2 siRNA-3?were used as the experimental group,and the transfected invalid sequence fragment was used as the negative control group,and the untransfected fragment was used as the blank control group.Fluorescence quantity realtime-PCR was used to detect the mRNA expression of EZH2gene in the above groups,and according to the results,the best interfering siRNA fragments were selected.The EZH2 siRNA fragment with the best transfection interference effect was taken as the experimental group,and the negative control group and blank control group were also given.The expression of EZH2 gene protein in each group was detected by Western blotting method.CCK-8 assay was used to detect the proliferation of cells in 24h,48h,72h and 96h,as well as the proliferation inhibition rate and half inhibitory concentration of the cells after treatment with different concentrations of oxaliplatin.The data were processed by SPSS19.0 software,and the relationship between EZH2 expression and the sensitivity of SGC7901 cells to oxaliplatin was analyzed by statistical methods.Results:1.Successful transfection of EZH2 siRNA fragments reduced the expression of EZH2 gene m RNA and protein levels in gastric cancer SGC7901 cells,and EZH2siRNA-2 had the best interference effect.2.In the experimental group,the expression of EZH2 gene was significantly down,and the cell proliferation ability of the experimental group was significantly lower than that in the blank control group and the negative control group,and the difference was statistically significant?P<0.05?.3.When the gastric cancer SGC7901 cells were treated with oxaliplatin with a concentration of 2?g/ml,4?g/ml,8?g/ml and 16?g/ml,the cell proliferation inhibition rate of the experimental group was significantly higher than that of the negative control group and blank control group,and the difference was statistically significant?P<0.01?.But there was no statistical difference?P=0.326?when the concentration of oxaliplatin was 32?g/ml.The half inhibitory concentration(IC₅₀)of oxaliplatin in the experimental group,the negative control group and the blank control group were 5.178,12.643 and13.601?g/ml,respectively.Conclusions:Down-regulating the expression of EZH2 gene could significantly inhibit the proliferation of gastric cancer cells and enhance the sensitivity of gastric cancer cells to platinum drugs.It is suggested that EZH2 gene is of great significance in the chemotherapy of gastric cancer,which provides a theoretical basis for further study on gene therapy of gastric cancer.