The Effect Of Enterogastric Reflux And Protease Activated Receptor-2 On The Initiation Of Gastric Stump Cancer

GSC is a rare disease, which accounts for 1.1% to 3.3% of all stomach cancer. However, the incidence of GSC has not reduced in recent years. Many factors are related to GSC, such as enterogastric reflux, lack of hydrochloric acid in gastric juice, bacteria breeding and genetic factors. Chronic gastritis caused by enterogastric reflux has drawn increasing attention among researchers. Due to the long-term effects of enterogastric reflux, chronic inflammation of gastric mucosa evolved into dysplasia and gastric carcinoma. However, the molecular mechanism underlying gastric inflammation-carcinoma transition is still unclear. PAR-2 belongs to the G protein coupled receptor family, which is extensively expressed in the digestive tract. PAR-2 is involved in inflammation regulation and the pathological process of tumor formation. The reflux juice is rich in trypsin, which can increase PAR-2 expression in gastric mucosa and activate a variety of signaling pathways. However, whether PAR2 is involved in the occurrence of inflammation-associated cancer is still unknown.The objective of this research is to establish a mouse model of GSC and to evaluate the role of PAR-2 in the initiation of GSC. The mouse model of enterogastric reflux was established by gastrojejunostomy(side to side anastomosis). Gastrojejunostomy results in reflux similar to Billroth Ⅱ reconstruction, after which intestinal juice, bile and pancreatic juice in the proximal jejunum can regurgitate into stomach. Besides gastrojejunostomy group (n=12), We also set up two control groups, sham operation group (n=9) which underwent an operation of gastric incision and suture, and blank control group (n=6) without any operation. Mice were killed at 1,3 and 6 months after gastrojejunostomy and mice gastric tissues were collected. Paraffin-imbedding section with HE staining were used for pathological diagnosis at each stage. Expression levels of inflammatory mediators and PAR-2 in mouse gastric tissue were evaluated with Western Blotting, real-time quantitative PCR and immunohistochemical staining. In addition, we also collected 36 cases of human GSC specimens and PAR-2 expression was evaluated in residual stomach tissue with immunohistochemical staining.The mouse model of enterogastric reflux was established successfully. The concentration of total bile acid (TBA) in mouse gastric juice increased significantly after gastroenterostomy. Pathological examination found chronic inflammation in gastric mucosa in the gastroenterostomy group. Chronic inflammation was also graded. At the 3rd、6th months after gastroenterostomy, chronic inflammation in gastric mucosa got the highest score, comparing with the sham operation group and the blank control group(P< 0.05). At the 3rd、6th months after gastroenterostomy, intestinal metaplasia and atypical hyperplasia were found in several mouse stomach tissues of the gastroenterostomy group. The mRNA levels of IL-6、IL-8、TNF-α、COX-2、iNOS、PAR-2 in mouse gastric tissue in the gastroenterostomy group increased significantly(P<0.05). The protein level of PAR-2 in mouse gastric tissue of the gastroenterostomy group increased significantly comparing with the sham operation group and the blank control group(P< 0.05). The protein level of PAR-2 in Human GSC was connected with initial operation method, percent PAR-2 positive cases for GSC following Billroth Ⅱ reconstruction was higher than GSC following Billroth Ⅰ and Roux-en-Y reconstruction. Intestinal type GSC had a higher percentage of PAR-2 positive cases than diffuse type GSC.The mouse model of enterogastric reflux can successfully simulate the pathological process of gastric reflux in patients with distal gastrectomy. Long-term enterogastric reflux can cause chronic inflammation in gastric mucosa, which was accompanied by precancerous lesions (intestinal metaplasia, atypical hyperplasia). Enterogastric reflux increased the expression of PAR-2, cox-2 and iNOS. The mouse model of enterogastric reflux can be used to study mechanism underlying GSC. Our data suggests that PAR-2 may play an important role in the transformation from gastric chronic inflammation into gastric carcinoma The expression of PAR-2 in Human GSC was connected with enterogastric reflux.The GSC is a rare disease, but the incidence of GSC has not reduced in recent years. The prevention and treatment of GSC is a challenge for doctors and patients. It is significant to know the characteristics of GSC and the prognosis of the patients with GSCo The GSC following Proximal gastrectomy is more rare, literature about this disease is very little. The objective of this subject research is to evaluate the clinicopathological features and prognosis of GSC following radical operations, and to evaluate the clinicopathological features of GSC following Proximal gastrectomy.The clinicopathological features and long-term survival rate of 63 patients who had underwent curative gastrectomy for gastric stump carcinoma from November 1999 to December 2014 were analyzed retrospectively. The clinicopathological features of 16 patients with gastric stump carcinoma following proximate gastrectomy from 1999 to 2014 were analyzed retrospectively camparing with the patients with GSC following distal gastrectomy.To group according to the initial benign or malignance gastric diseases, The initial benign diseases group has a longer interval between initial gastrectomy and diagnosis of GSC than The initial malignance diseases group (benign vs malignance:24.8 vs 8.9 years, P<0.05); The initial benign diseases group has a bigger tumor size than the initial malignant diseases group(6.9 vs 4.3 cm, P<0.05); The GSC were more frequently located in anastomosis in the initial benign diseases group than the initial malignant diseases group(50% vs 26.3%, P<0.05); To group according to the reconstructed way following initial gastrectomy, the Billroth Ⅱ group has a longer interval than Billroth I group(22.8 vs 12.3 years, P<0.05); The Billroth Ⅱ group has a bigger tumor size than the Billroth 1 group(6.73 vs 3.75 cm, P<0.05). The GSC were more frequently located in anastomosis in the Billroth Ⅱ group than the Billroth I group(52.4% vs 21%, P<0.05). The results of survival analysis display that The 80-month survival rate of stage Ⅰ-Ⅱ group were significantly higher than the stage Ⅲ group (64.7% vs 18.5%, P<0.05); There’s no statistically significant difference in 100-month survival rate by camparing the initial benign group with the initial malignant group(37.1% vs 40%, P>0.05); There’s no statistically significant difference in 80-month survival rate between the Billroth II group and the Billroth I group(43.1% vs 27.3%, P>0.05). There’s no statistically significant difference in age, gender, interval time, histological type, tumor size, depth of tumor, lymph nodes metastasis, surgical method, hospital stay by camparing the GSC following proximate gastrectomy with the GSC following distal gastrectomy. The GSC following proximate gastrectomy has a higher proportion of TNM stage IV(50%) than the GSC following distal gastrectomy(13.8%).The patients with GSC had different clinicopathological features according to the initial diseases and the reconstruction methods. For patients with resectable GSC, long-term survival was associated with TNM staging, rather than the initial diseases and the reconstruction methods. The patients with GSC following proximate gastrectomy has a higher proportion of TNM stage Ⅳ and has lower resection rate than the patients with GSC following distal gastrectomy.