| IntroductionGastric cancer is one of the leading malignancies in many countries of the world and its mortality is at the first place in our country. The gastric radical resection is the main treatment of gastric cancer at present and the postoperative 5-year survival rate after surgery is only about 40% mostly because of the recurrence and metastasis. So it is becoming the key point in gastric cancer study that researching on the correlation between the expression of some new molecular markers and the behavior of invasion and metastasis.During the invasion and metastasis of gastric tumor, it is an essential procedure that the tumor cells excrete many proteinases enzymes to degrade extracellular matrix(ECM)and basement membrane(BM). As the most important gene of matrix metalloproteinases(MMPs) and tissue inhibitor of metalloproteinases(TIMPs), MMP-7 and TIMP-1 are well known as proteinases that considered to play significant roles in gastric cancer invasion and metastasis.ObjectiveTo investigate the expression of MMP-7 and TIMP-1 mRNA and its clinical significance in advanced distal gastric cancer. To investigate the molecular mechanism of barrier effect of resisting cancer invasion in pyloric ring.Methods1. Patients and tissue collection 52 samples of gastric tumor tissues and pyloric ring tissues,23 samples of duodenum tissue and 52 samples of corresponding para-cancerous normal tissues as contrast were collected after surgical resection performed in the Department of Surgical Oncology in the First Affiliated Hospital of China Medical University during 2008-2009. None of the patients received the chemical therapy or radiotherapy before resection.2. MethodWe put paraffin block HE dyeing of pyloric ring tissues and duodenum tissues and definite the invasion in pylorus and duodenum. Then total RNA of each sample was extracted by using Trizol reagent and reverse-transcribed by using a SuperScript Preamplification System for First Strand cDNA Synthesis Kit. After that Real-time PCR was carried out by using primers designed and the product of PCR was analyzed using Rotor-Gene 6000 system. The results ofΔCT were expressed as mean士SD, Statistic software SPSS 16.0 for Windows was used to analyze The results using Student t test and X2test. The accepted level of significance was p<0.05(two-tailed).Results1,The expression level of MMP-7 in gastric tumor tissues was 2.23 times higher than in corresponding para-cancerous tissues in average(P<0.05). The expression level of MMP-7 in pyloric ring and duodenum was separately 0.47 times and 0.29 times lower than in corresponding para-cancerous tissues in average(P<0.05, P＜0.01).2,The expression level of TIMP-1 in gastric tumor tissues was 0.5 times lower than in corresponding para-cancerous tissues in average(P＜0.01).3,The expression level of MMP-7,TIMP-1 in gastric tumor tissues was correlated with the depth of invasion(P<0.05, P<0.01),lymphonode metastasis(P<0.05, P<0.05),histodifferentiation (P＜0.01, P＜0.01),distal invasion(P<0.05, P＜0.05) but nothing with macroscopic type(P> 0.05),growth type(P> 0.05)and Bormann's classification (P> 0.05). 4,The expression level of MMP-7 in gastric pyloric ring tissues was correlated with pyloric ring invasion(P<0.01), however, the expression level of TIMP-1 in gastric pyloric ring tissues had no relation to pyloric ring invasion(P> 0.05).Conclusions1,The expression level of MMP-7 in gastric tumor tissues was higher than in corresponding para-cancerous tissues and the expression level of MMP-7 in pyloric ring and duodenum was lower than in corresponding para-cancerous tissues. The expression level of MMP-7 was correlated with lymphonode metastasis,depth of invasion,histodifferentiation,distal invasion. We can conclude that MMP-7 has an important role in gastric occurrence, development, invasion and metastasis.2,The expression level of TIMP-1 in gastric tumor tissues was lower than in corresponding para-cancerous tissues and the expression level of TIMP-1 was correlated with lymphonode metastasis,depth of invasion,histodifferentiation and distal invasion. We can conclude that TIMP-1 has an important role in gastric occurrence, development, invasion and metastasis.3,The high expression of MMP-7 and the low expression of TIMP-1 in gastric tumor tissues are related to the aggressiveness of the gastric cancer and might serve as malign factors for prognosis and have important instruction value for later clinical treatment.4,The lower expression of MMP-7 in pyloric ring and duodenum might be related to the molecular mechanism of barrier effect of resisting cancer invasion in pyloric ring.
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