| Gastric cancer is a disease of high mortality and poor prognosis. Most ofthese patients are in an advanced stage when they come to hospital and themajority will experience a relapse and metastasis soon after radical gastriccancer operation. So combined therapy which include operation,chemotherapy after operation and neoadjuvant chemotherapy may becomemore and more important for the treatment of gastric cancer. However, theeffect of chemotherapy is frequently hampered by cancer cell chemoresistance.Cisplatin, one of the most common anti-cancer drugs, is widely used forchemotherapy and neoadjuvant chemotherapy. Unfortunately, significantlevels of resistance in cancer cells emerge rapidly following cisplatin treatment.Survivin is a new inhibitor of apoptosis gene. Its increased expression intumors is related to relapse, chemotherapy resistance, poor prognosis and lowsurvival rate. Although the chemoprevention of non-steroid anti-inflammatorydrugs (NSAIDs) plays a very important role in cancer therapy, the precisemechanism of its effect is still unclear. Indomethacin, which is one of theNSAIDs, was found to decrease the expression of Survivin in the gastricmucosa. It suggests that using NSAIDs may associate with the change ofSurvivin expression.Therefore, we suppose that Survivin may be one of the key factors for chemoresistance of gastric cancer cell. Furthermore, it may have an effect onthe chemoprevention mechanism of NSAID. Combination with Aspirin whichis one of the classic NSAID may increase the effect of Cisplatin on theSGC7901/CDDP and improve the prognosis of advanced gastric cancer.Published articles have identified that gastric cancer is associated withpolymorphisms in many genes. Myeloperoxidase (MPO) is an oxidative stressrelated enzyme. MPO G-463A polymorphism has been found to be relatedwith many malignant tumors. But its association with the risk of gastric cancerhas not been reported. Moreover, only Yong Xu reported that mutation ofSurvivin may have relationship with the high expression of several tumors, butno research has been conducted to assess the relationship between Survivin andthe risk of gastric cancer. The identification of the relationship betweenpolymorphism of gastric cancer-related gene and the risk of gastric cancerdeeply will not only contribute to the understanding of the function of themolecules involved in gastric carcinogenesis but also offer novel moleculartools for diagnosis and reveal potential targets for therapeutic intervention.1. The effect and mechanism of Aspirin on SGC7901SGC7901 were cultured in vitro, stained by Trypan Blue. After that wedetected the growth inhibition, apoptosis and Survivin expression of SGC7901with 1, 3 and 10mM Aspirin separately at 24 hours by MTT, FCM, RT-PCRand Western-blot methods. We also detected the growth inhibition, apoptosis and expression of Survivin of SGC7901 with 3mM Aspirin at 24, 48 and 72hours respectively to investigate the effect and mechanism of Aspirin onSGC7901.Results: 1. Aspirin at certain concentration may inhibit the proliferation ofSGC7901, and the effect is in a concentration-and time-dependent manner; 2.The inhibition on SGC7901 proliferation of Aspirin may be related to theinduction of apoptosis, and the apoptosis is also concentration-and time-dependent; 3. The mRNA and protein expression of Survivin in SGC7901were suppressed by Aspirin in a time-dependent and concentration-dependentmanner. The results suggest that the decrease of Survivin expression to Aspirinmay be a pivotal factor to promote apoptosis and inhibit proliferation ofSGC7901.2. The establishment of SGC7901/CDDP and the role of Survivin inCisplatin resistanceWe established Cisplatin resistant cell line, which is SGC7901/CDDP bycell culture in vitro and gradually increasing the concentration of Cisplatin.We observed the morphology change, detected the Survivin expression changeof the two cell lines by RT-PCR and western-blot methods to investigate themechanism on SGC7901 resistant to low dose Cisplatin.Results: 1. There were morphology differences between SGC7901 andSGC7901/CDDP. 2. The level of Survivin expression in SGC7901/CDDP is higher than in SGC7901. The results suggest that SGC7901 resistant to lowdose Cisplatin may have association with the increased expression level ofSurvivin in SGC7901/CDDP.3. The effect of Aspirin combined with Cisplatin on SGC7901/CDDPWe detected the growth inhibition, apoptosis and Survivin expression ofSGC7901/CDDP with Aspirin separately, Cisplatin separately andcombination of Aspirin with Cisplatin at 24 hours by MTT, FCM, RT-PCRand Western-blot methods. We also investigated the mechanism of the effect.Results: 1. The survival rate is significantly lower in group of combinationof Aspirin with Cisplatin than in other groups (p＜0.05); 2. The apoptosis rateis significantly higher in group of combination of Aspirin with Cisplatin thanin other groups; 3. The Survivin expression level is significantly lower ingroup of combination of Aspirin with Cisplatin than in other groups (p＜0.05).The results suggest that Aspirin may exert inhibitory effect onSGC7901/CDDP and significantly enhanced its sensitivity to Cisplatin. Themechanism may have relationship with the increased Survivin expression levelin SGC7901/CDDP induced by Aspirin.4. Myeloperoxidase G-463A polymorphism and the risk of gastric cancer: acase-control studyIn this hospital-based, case-control study, we used polymerase chain reaction-restriction fragment length polymorphism protocols to examine theprevalence of MPO G-463A polymorphism in gastric cancer.Results: A significantly different distribution of the MPO-463G/A genotypewas demonstrated among the cases and controls (x~2=7.42, P=0.03). Subjectswith the variant genotypes (the sum of GA and AA) had a 44% reduced risk ofgastric cancer relative to those with GG (adjusted OR=0.56; 95% CI:0.32-0.97). Stratified analyses revealed that the protective effect of A allelewas significant in male (adjusted OR=0.51; 95% CI: 0.26-0.98) or younger(age＜58 years) (adjusted OR=0.42; 95% CI: 0.18-0.94) subjects, but not infemale or older subjects. In addition, there was also a significantly reduced riskin subjects residing in rural areas (adjusted OR=0.41; 95% CI: 0.18-0.95) butnot in urban areas. The interaction between the MPO G-463A polymorphismand smoking status was not observed in this study. Tumor differentiation wasnot found to be associated with the MPO genotype. In conclusion, our resultsshowed that the MPO-463 G to A variant may be associated with thedecreased risk of gastric cancer in Chinese population.5. The association between the Survivin C-31G polymorphism and gastriccancer risk in Chinese populationSurvivin is a bifunctional protein that inhibits apoptosis and regulates celldivision. It is involved in occurrence and development of gastric cancerousinvasion and/or metastasis. The C-31G polymorphism in the Survivin promoter could derepresse the cell cycle-dependent transcription of the human Survivingene, resulting in over-expression of Survivin at both mRNA and proteinlevels. In this hospital-based, case-control study, we investigated theassociation between the Survivin C-31G polymorphism and risk of gastriccancer in Chinese people using PCR-RFLP protocols.Results: The distribution of Survivin-31 genotype was similar between casesand controls (P=0.35). No statistically significant association was observedbetween gastric cancer risk and the variant genotype (GG+GC) (adjustedOR=0.70; 95% CI: 0.45-1.08). However, the variant genotype (GG+GC) wasassociated with risk of distal gastric cancer (adjusted OR=0.50; 95% CI:0.30-0.83), well differentiation tumor (adjusted OR=0.46; 95% CI: 0.22-0.97)and absence of lymph node metastasis (adjusted OR=0.53; 95% CI: 0.29-0.96).Our results suggested that the Survivin C-31G polymorphism may beassociated with distal gastric carcinogenesis, tumor differentiation andprogression in Chinese population.
|
PDF Full Text Request