Study On The Mechanism Of Tristetraprolin Expression In PTX Sensitive Gastric Cancer Cells During The Course Of Taxol Induced Senescence

Background: Gastric carcinoma is the most common digestive system malignant tumor in China.Neoadjuvant / adjuvant chemotherapy is an important clinical tool in the treatment of gastric cancer.However,drug resistance is still a difficult problem that can not be solved in clinical work.Cancer cell overproduce of senescence associated secretory phenotype(SASPs)during chemotherapy is proved to be the main cause of drug resistance.Tristetraprolin(ZFP36,TTP,TIS11 or Nup475)is a new type of tumor suppressor which combines with SASPs related cytokines' mRNAs,makes these mRNAs degradation though transported the mRNA to P-Body and mediated deadenylation.TTP can thus inhibit excessive secretion of SASPs and enhance the sensitivity of tumor cells to chemotherapeutic drugs.However,whether and how TTP expression changes in the course of chemotherapy induced cell senescence are not yet clear.Meanwhile,whether the expression change of TTP is related to the sensitivity of chemotherapeutic drugs is still unknown.To develop effective therapeutics to treat gastric cancer,the molecular mechanisms of TTP expression should be identified.Therefore,the present study intends to study the change and the specific molecular mechanism of TTP expression in Taxol relative sensitivity and relative resistant cell's senescence model.Methods: The four common gastric cancer cell lines(SGC-7901,BGC-823,HGC-27 and NCL-N87)were screened by paclitaxel,and the relative sensitivity and the relative resistance to Taxol cell lines were identified.In order to construction of gastric cancer cell senescence model,relative sensitivity and relative resistance gastric cancer cells were treated with paclitaxel.The senescence models were validated using senescence associated ?-galactose glucoside enzyme staining assay.The difference of TTP expression between relative sensitive and resistant senescence model was identified by Western-Blot.The expression difference of IL-1a,IL-1?,IL-6 and IL-8 between relative sensitivity cell and its senescence model were measured by qRT-PCR and ELISA.IL-1a,IL-1?,IL-6,IL-8 were used to treat with paclitaxel sensitive gastric cancer cells,and the key cytokine stimulate expression of TTP can thus be screened out.The short hairpin RNA(Sh-RNA)of screened key cytokine was used for construct the Sh-gastric cancer cell senescence model.TTP expression level in Sh-gastric cancer cells senescence model was detected by Western-Blot,so as to determine the stimulatory effect on TTP expression and screened key cytokine in the aging process.Finlly,the key signal pathway mediate TTP expression during senescence was identified using the blocking agent of the NF-?B.Results: In the current study,we found that SGC-7901 was the relative resistance to PTX gastric cancer cell line and the BGC-823 cell line was relative sensitivity to PTX.As the results of Western-Blot,TTP expression level in PTX induced BGC-823 cell senescence model was significant higher than in PTX induced SGC-7901 cell senescence model.As the results of qRT-PCR and ELISA,the expression level of IL-1a,IL-1?,IL-6 and IL-8 in senescence model group were higher than in control group.By IL-1a,IL-1?,IL-6,IL-8 stimulate assay as well as the Sh-IL-1? assay,we found that,IL-1? was the key cytokine stimulate expression of TTP during PTX induced cell senescence.And the stimulate effect of IL-1? on TTP expression in PTX induced BGC-823 cell senescence model was mainly mediated by NF-kB non-classical signal pathway and NF-kB classical signal pathway.Conclusions: Firstly,this study successfully constructed a PTX induced gastric cancer cell senescence model.Secondly,the results showed that IL-1? was the main stimulating factor for TTP expression in the process of PTX induced gastric cancer cell senescence.Finally,we found that,NF-?B non-classical signal pathway and NF-?B classical signal pathway are the mainly signal pathway mediate TTP expression in the process of PTX induced gastric cancer cell senescence.