Expression Of MiRNA-449 In Gastric Cancer And Its Mechanism

Objective:In order to provide the basis for the early diagnosis,effective treatment and prognosis assessments of gastric cancer,we explore the mechanism of miRNA-449 in the occurrence of gastric cancer through the expression of miRNA-449 gene and E2F1 protein.Methods:The specimen together with adjacent tissues was obtained in 31 patients of gastric carcinoma.Total RNA was extracted from these tissues,and reversely transcribed into cDNA by stem-loop technique.Then the expression of miRNA-449 was determined by real-time quantitative PCR.The method of Western Blot was taken to detect the expression of E2F1.Results:1. The expression of miRNA-449:Compared with adjacent normal tissue, expression of miRNA-449a was down-regulated in 23 cases (74.19%) and up-regulated in 8 cases (25.81%).The relative expression of miRNA-449a was 3.85±2.45 in gastric cancer tissue and 4.66±2.41 in adjacent normal tissue,so the expression level was generally lower than that of the adjacent tissues(t=2.516, P=0.017, P<0.05).In consistent with miRNA-449a,expression of miRNA-449b was down-regulated in 24 cases (77.42%) and up-regulated in 7 cases (22.58%).The relative expression of miRNA-449b was 3.66±2.54 in gastric cancer tissue and 4.27±2.33 in adjacent normal tissue,so the expression level was generally lower than that of the adjacent tissues (t=2.525, P=0.017, P<0.05).The expression of miRNA-449a and miRNA-449b had 21 cases with consistent downward and 6 cases with consistent increased in gastric cancer. But,the expression of miRNA-449c was down-regulated in 18 cases (58.06%) and up- regulated in 13 cases (41.94%).The relative expression of miRNA-449c was 2.82±1.98 in gastric cancer tissue and 3.05±2.05 in adjacent normal tissue,so the expression level had no statistically significant difference (t=0.607, P=0.503, P>0.05). The expression of miRNA-449a/b/c is down-regulated in BGC-823 compared with GES-1 (P=0.003/0.017/0.005, P<0.05)2. The relationship of the expression of miRNA-449a/b and clinical data:The changes of the expression of miRNA-449a/b was significantly associated with lymph node metastasis.There were 17 cases which had lymph node metastasis that the expression of miRNA-449 a/b was down-regulated in 18 (94.45%),and this expression respectively occurred in 6(46.15%) and 7(53.85%) of 13 cases which didn’t have lymph node metastasis.The percentages of down-regulated were compared in lymph and non-lymph node metastasis groups showed that,the difference was statistically significant based on the Fisher exact test(P=0.004/0.012, P<0.05).But the changes had no correlation with the patient’s age,sex,diameter,depth of invasion and differentiation of tumors in gastric cancer.3. The expression of E2F1 protein:Compared with adjacent normal tissue, the expression of E2F1 in gastric cancer was higher in 13 cases (76.47%) and lower in 4 cases (23.53%).The relative expression of E2F1 was 1.14±0.49 in gastric cancer tissue and 0.97±0.41 in adjacent normal tissue,so the expression level was higher in average which had statistically significant(t=2.138, P=0.048, P<0.05). Conclusion:1. The results showed that miRNA-449a/b was downregulated and E2F1 was upregulated in gastric cancer. It suggested that miRNA-449a/b participated in the occurrence of gastric cancer.2. The changes of the expression of miRNA-449a/b was associated with lymph node metastasis in gastric cancer.It suggested that miRNA-449a/b may serve as a marker for the prognosis of gastric cancer.