Expression Of KLf5and KLf6in Human Gastric Carcinoma And Premalignant Tissues

Background and ObjectivesGastric carcinoma is the most common cancer in digestive system. Each year the newly diagnosed gastric carcinoma accounts for10%of all cancer cases detected. The five-year survival rate for early gastric carcinoma is about90%, but only10-15%for advanced gastric cancer. Currently, up to80%cases of the patients were diagnosed at their advanced stage. So far, the molecular carcinogenesis of gastric carcinoma is unclear. KLF5and KLF6, belonging to the KLF family, were recognized as tumor suppressor genes in many kinds of human cancers, but their roles in gastric pathogenesis is not known. The aim of this project is to detect the expressions of KLF5and KLF6in human gastric carcinoma and premalignant gastric lesions, to investigate the relationship between the expression profiles of the proteins and clinicopathological characteristics of patients, so as to elucidate the roles of KLF5and KLF6in the occurrence and development of gastric carcinoma, and evaluate whether the detection of the two biomarkers could be helpful for the surveillance of gastric precancerous lesions and the early detection of gastric carcinoma.Materials and methods1、 Tissues:Fresh frozen gastric carcinoma tissues and matched tumor-adjacent normal gastric mucosa tissues were collected from30patients with gastric carcinoma in the general surgery and thoracic surgery department of the Second Affiliated Hospital of Zhengzhou University. The tissues were immediately preserved in the tube with RNA-waiter solution and stored in the refrigerator of-80℃. RT-PCR was used to analyze the expression level of KLF5and KLF6mRNA in these tissue samples. Meanwhile, the expressions of KLF5and KLF6protein were detected by immunohistochemistry in111formalin-fixed paraffin-embedded samples, including20cases of normal gastric mucosa,45cases of intestinal metaplasia,16cases of dysplasia, and30cases of gastric carcinoma. The association of KLF6expression with clinicopathological characteristics was analyzed.2、 Methods:HID-AB-PAS staining, Immunohistochemical staining and RT-PCR were used to detect the expression of KLF5and KLF6in gastric carcinoma and premalignant gastric tissues.3、 Analyses:Statistical analysis was performed using the SPSS version17.0. The correlation between the expression levels of KLF5and KLF6proteins with different clinicopathological characteristics parameters was measured by Chi-square test, Correction chi-square test or Fisher’s chi-square test. After ANOVA, we used t-test, Kruskal-Wallis test or Mann-Whitney U rank-sum test. The data was expressed as the x±S. P<0.05was considered as statistical significance.Results1、After HID-AB-PAS staining, the intestinal metaplasia (IM) can be divided into three types:type III IM secretes brownish black sulfuric acid mucus, type II IM secretes red neutral mucus, and type I IM secretes blue sialic acid mucus.2、 The expression of KLF5in normal gastric mucosa and IM tissues were located in cell membrane, cytoplasm and nucleus, but in nucleus of dysplasia and gastric carcinoma with yellow or brown. The positive rate of KLF5protein expression in normal gastric mucosa, type I and II IM, type III IM, dysplasia and gastric carcinoma were95%(19/20),83%(25/30),60%(9/15),56%(9/16),37%(11/30), respectively. There were significant differences between normal gastric mucosa and type III IM, dysplasia and gastric carcinoma (χ2=4.557,5.643,17.014, P=0.033,0.018,0.000). There was clear correlation between the positive expression with the clinicopathological characteristics, such as depth of invasion, differentiated degree and the size of the tumor (χ2=3.961,8.623,6.904, P=0.046,0.003,0.009).3、 The expression of KLF6in normal gastric mucosa and IM tissues were located in cytoplasm and nucleus, but in nucleus of dysplasia and gastric carcinoma with yellow or brown. The positive rate of KLF6protein expression in normal gastric mucosa, type Ⅰ and Ⅲ IM, type Ⅲ IM, dysplasia and gastric carcinoma were90%(18/20),73%(22/30),53%(8/15),50%(8/16),33%(13/30), respectively. There were significant differences between normal gastric mucosa and type III IM, dysplasia and gastric carcinoma (χ2=4.266,5.236,11.092,P=0.039,0.022,0.001). There were clear correlations between the positive expression with the clinicopathological characteristics, such as differentiation and the size of the tumor (χ2=8.438,4.617, P=0.004,0.032).4、There was obvious correlation between the protein expressions of KLF5and KLF6in normal gastric mucosa (χ2=9.497, P value=0.002, r=0.688).5、There was obvious correlation between the protein expressions of KLF5and KLF6in gastric carcinoma (χ2=10.476, P value=0.001, r=0.591).6、 There was no significant difference of the expression of KLF5mRNA between normal gastric mucosa and gastric carcinoma (Mann-Whitney U value=402.0, P value=0.478).7、 There was no significant difference of the expression of KLF6mRNA between normal gastric mucosa and gastric carcinoma (Mann-Whitney U value=426.0, P value=0.723).Conclusions1、 Compared to that in normal gastric mucosa, the expressions of KLF5and KLF6have decreased in gastric carcinoma, especially in the poorly differentiated group and big size group, indicating that the abnormal expression of KLF5and KLF6may take roles in development and progression of the gastric carcinoma.2、Compared to that in normal gastric mucosa, the expressions of KLF5and KLF6were much lower in the premalignant gastric lesions and gastric carcinoma which might be useful for surveillance of gastric premalignant lesions and early detection of gastric carcinoma.3、 There was a positive correlation between the expressions of KLF5and KLF 6in gastric carcinoma. They may have promoting effect with each other.