The Screening And Investigation Of Multidrugresistance Related Gene Profile In Gastric Cancer

The gastric cancer is the most common malignant carcinoma and characteristic of low dignosis rate and hige mortality in China.Nowdays the gastric cancer patients have obtained more survival and life quantity advantage by using new chemodrugs.However, the multidrug resistance predominantly block the therapy effect.So it is important to investigate the novel multidrug resistance genes and the mechanism of them involved in MDR.This study firstly established a resistant cell line SGC7901/DDP by increasingly dose of cisplatin from 0.02 to 1.0 ug/ml and test the MDR phenotype by detecting cell morphology using electron microscopy, drug sensitivity using MTT array, cell cycle using flow cytometry(FCM) and P-glycoprotein expression using RT-PCR and Westren blot.We identified distinct genes between SGC7901 and SGC7901/DDP cell lines using Affymetrix gene chip. Notch1,which play a key role in cell signal pathway,was found up-regulated in drug resistant cell and verified by RT-PCR and Westren blot.After the Notch1 expression was inhibited by drug inhibitor,the MDR phenotype was significantly reduced in SGC7901/DDP cell line detected by MTT array and P-gp expression was down-regulated in gene and protein levels.The apoptosis of both cell lines increased detected by flow cytometry after the depression of Notch1.The expression of Notch1, NF-κB and P-gp was detected in a tissue microarray containing 168 spots of cancer tissue and 27 spots normal gastric tissue by immunohistochemistry. We investigated that the expression of Notch-1, NF-κB and P-gp proteins, was significantly up-regulated in gastric cancer as compared with common gastric tissue. The positive expression of Notch1 was closely related with tumor size, histology grade, depth of invasion and vessel invasion. The expression of NF-κB in cancer tissue was remarkably higher than that in control group,which was significantly associated with tumor size, differentiation grade,depth of invasion,metastasis and vessel invasion.The expression of Notch1, NF-κB and P-gp had a significant positive relationship. Kaplan-Meier analysis revealed a significant impact on survival by Notch1, NF-κB and P-gp.COX Regression showed that Notch1 was one of the independent factors effecting the the prognosis of gastric cancer.In conclusion,we identified a large amount of meaningful differential genes which involed in MDR by utilizing gene array.Among them, Notch1,which acted as an important signal pathway protein,may involed in gastric cancer MDR phenotype mediated by NF-κB pathway and could be a promising therapy target in future.