Effect Of TS Expression On Prognosis Of Gastric Cancer And Its Related Mechanism

Objective: TS is a key enzyme in thymidylate biosynthesis and DNA replication.Inhibition of TS expression can inhibit the abnormal proliferation of tumor cells.The purpose of this study was to explore the relationship between TS expression in gastric cancer tissues and clinicopathological factors and survival prognosis,as well as the related molecular mechanism of TS involvement in the occurrence and development of gastric cancer,and to further study the guiding significance of TS concentration changes in blood on the optimal time for intraperitoneal administration of raltitrexed in gastric cancer patients.Methods: The expression of TS in 80 gastric cancer tissues and adjacent normal tissues was detected by immunohistochemical method.The expression of TS mRNA in 20 cases of fresh frozen gastric cancer and corresponding adjacent tissues was detected by q-PCR.The concentration of TS in fresh gastric cancer and adjacent normal tissues was determined by ELISA.TS knockdown cell lines were established by culture of gastric cancer cell lines and si RNA transfection.The knockdown gastric cancer cell lines were used to further study the molecular mechanism of TS involved in the occurrence and development of gastric cancer.Blood TS concentration was detected by ELISA in 40 patients with raltitrexed before and after intraperitoneal administration.Results: Immunohistochemical results showed that the positive rate of TS in the wax block tissues of 80 gastric cancer patients(48.75%,39/80)was significantly higher than that in the adjacent tissues(23.75%,19/80)(P<0.001).Q-PCR results showed that the expression level of TS mRNA in 20 fresh gastric cancer tissues(3.08±1.70)was significantly higher than that in adjacent gastric cancer tissues(1.02±0.23)(P<0.001).ELSA showed that the mean TS concentration in 20 fresh gastric cancer tissues(1105.19±176.81)pmol/L was significantly higher than that in corresponding adjacent tissues(811.42±191.51)pmol/L(P<0.001).The results of clinicopathological analysis showed that the expression of TS in gastric cancer tissues was correlated with the degree of tumor differentiation(P<0.05).Results of survival analysis showed that the survival rate of TS negative gastric cancer patients was higher than that of TS positive patients(P<0.001).Cell experiment results showed that by establishing TS knockdown gastric cancer cell lines: The proliferation efficiency of gastric cancer cells knocked down by TS in CCK8 experiment was significantly lower than that in control group(P<0.01),and the migration and invasion efficiency of gastric cancer cells knocked down by TS in cell scratch and Transwell experiment were also significantly inhibited(P<0.05).The expressions of EMT-related N-cadherin and Vimentin were significantly decreased,while the expression of E-cadherin was significantly increased(P<0.05).The results of clinicopathological analysis showed that the expression of TS in blood was correlated with N stage and the degree of tumor differentiation(P<0.05).After intraperitoneal administration of raltitrexed,the blood TS concentration decreased to the lowest value on the second day,and the disease-free survival rate in the group given raltitrexed 2 days before surgery was significantly higher than that in the group given raltitrexed after surgery(P<0.05).Conclusions: The positive expression rate of TS in gastric cancer tissues was significantly increased,and the survival time of gastric cancer patients with low TS expression was longer.After TS knockdown,the proliferation,migration and invasion ability of gastric cancer cells were significantly reduced,and the EMT process was inhibited.The changes of TS concentration in the blood of patients with gastric cancer after intraperitoneal administration of raltitrexed can be used to guide the optimal time for intraperitoneal administration of raltitrexed,and the optimal time for intraperitoneal administration of raltitrexed is two days before surgery.