Expression and clinical significance methylation modification of Sfrp5 gene in gastric cancer tissues and adjacent normal tissues

doi:10.3969/j.issn.1002-7386.2018.14.002

Abstract：Objective To investigate the expression and clinical significance methylation modification of Sfrp5 gene in gastric cancer tissues and adjacent normal tissues, and to explore its correlation with clinical pathological parameters. Methods Ninety specimens of gastric cancer tissues which were confirmed by pathological examination and 90 cases of normal tissues adjacent to carcinoma were enrolled in the study. Among the patients with gastric cancer tissues,there were 73 males,17 females,with age arrang being 46~76 yr, and the average age being 64 yr. In the aspect of histological type, there were 35 cases of high and moderately differentiated adenocarcinoma, 55 cases of poorly differentiated and undifferentiated adenocarcioma. Moreover 33 cases had lymph node metastasis and 57 cases had no lymph node metastasis. All the specimens were taken from primary tumor and normal tissues adjacent to carcinoma ( more than 5 cm away from the cut edge). The specimens were frozened in liquid nitrogen immediately after obtained. The specimens were treated by routine method for pathological examination. Moreover all the patients were not treated by chemotherapy and radiotherapy before surgery,with complete clinical and pathological data. The methylation status of Sfrp5 gene in cancer tissues and in adjacent normal tissues was detected by methylation specific PCR methylation, and the expression levels of Sfrp5 were detected by immunohistochemistry. Results The positive expression rate of Sfrp5 protein in gastric cancer tissues and in normal tissues adjacent to carcinoma was 20% (18/90) and 90% (81/90),respectively, there was significant difference between the two groups (P<0. 05). The methylation rate of Sfrp5 gene in gastric cancer tissues and normal tissues adjacent to carcinoma was 82. 2% (74/90) and 18. 9% (17/90),respectively, there was significant difference between the two groups (P<0. 05). Moreover the methylation rate of Sfrp5 gene in tissues without lymph node metastasis was 66. 7% (22/33),which was significantly lower than that [86. 0% (49/57)] in the tissues with lymph node metastasis (P<0. 05). The methylation rate of Sfrp5 gene in high differentiation group was 71. 4% (25/35),which was lower than that [81. 8% (45/55)] in poor differentiation group,however, there was no significant difference between the two groups (P >0. 05). In addition the methylation rate of Sfrp5 gene was 84. 5% (71/84) in ≥50 years group,which was 100% (6/6) in≤50 years group,but there was no significant difference between the two groups (P>0. 05). The methylation rate of Sfrp5 gene was 76. 4% (13/17) in female group,which was lower than that [76. 7% (56/73)] in male group,but there was no significant difference between the two groups (P>0. 05). Conclusion The high levels of Sfrp5 gene methylation frequency are the main reason of the decrease of its protein in gastric cancer tissues, which may be correlated with the pathogenesis and development of gastric cancer.