| Objective: To investigate the DNA methylation status of the promoter region within the coding gene hsa-miR-124a in human gastric cancer tissue, and examine its association with the expression of Rb and CDK6 protein and clinicopathological factors. Methods. : 1, Extract total DNA of gastric carcinoma and corresponding adjacent tissues from 30 patients with surgical resection, treat the extracted DNA with bisulfite modification and purification, use methylation-specific PCR (MS-PCR) method to detect the DNA methylation status of the promoter region within the coding gene hsa-miR-124a and analyze the data ; 2, Detect CDK6 and Rb protein expression with immunohistochemistry methods in these gastric cancer samples, analyze the correlation between these two with the methylation status of the promoter region within the coding gene hsa-miR-124a we extrcted; 3, Study the medical records of gastric cancer invasion, tumor stage, pathological type and the clinical calculations with these 30 patients, and analyze the correlation among these clinical pathological factors with the DNA methylation status of the promoter region within the coding gene hsa-miR-124a we detected. Results: 1, Among the methylation status of the promoter region within the coding gene hsa-miR-124a of these 30 cases, 8 cases were not detected of methylation (26.7%), and 22 patients (73.3%) showed significant methylation. In 22 cases, 18 cases were detected hsa-miR-124a-1 positive, 20 cases of hsa-miR-124a-2 positive, and 15 cases of hsa-miR-124a-3 positive. The overall methylation rate was 60.0% (18/30), 66.7% (20/30) and 50.0% (15/30).The overall methylation in gastric cancer was 73.3% (22/30), significantly higher than the methylation rate of 10.0% (3 / 30) (p <0.05) in adjacent normal tissue. The difference between the two was statistically significant (p <0.05).But the differences between total methylated and unmethylated rates within the three pairs of genes were not statistically significant (P>0.05). 2, Detect with immunohistochemistry in 30 cases gastric cancer of paraffin embedded sections of the Rb protein and CDk6 protein expression, in the detection of Rb protein, apparently strongly positive samples of 18 cases accounted for 60.0% (+++), 5 accounted for 16.7% of all samples were positive (++); 3 weak positive (+) were detected accounting for 10.0%. So the overall positive rate was 86.7% (26/30).As cases of CDk6 protein expression, in the samples of all 30 patients, the overall positive rate was 80.0% (24/30), between Rb and CDk6 no significant difference was detected of the overall positive rate (P> 0.05). The three R values among the DNA methylation status of the promoter region within the coding gene hsa-miR-124a, CDK6 and Rb expression status were: 0.43,0.45 and 0.54. So a positive correlation (P <0.025) was detected among the three groups of data. 3, There is no correlation between DNA methylation of the promoter region within the coding gene hsa-miR-124a with gender, age, tumor location, pathologic type of these cases(p> 0.05), but with tumor size (<5cm and 5cm), differentiation (differentiated and poorly differentiated), lymph node metastasis (with or without) and depth of invasion (T1, T2, T3, T4) are closely related. Conclusion Hypermethylation of hsa-miR-124a is present in gastric cancer tissues, and is associated with increased expression of CDK6 and Rb protein. These may be related to the proliferation and development of malignancy in the stomach. |
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