Global Genome Methylation Status in Gastritis Lesion in Comparison with Normal Adjacent Tissue and its Relationship with Clinicopathologic Findings

Abstract

Objective: To determine the role of global genome methylation in gastritis lesionand its relation with clinicopathologic finding.Materials and Methods: The study was conducted on 44 gastritis and normaladjacent specimens using a technique composed of restriction enzyme digestionand pyrosequencing known as LUMA (LUminometric Methylation Assay). Atfirst, DNA extracted from gastritis lesion and normal tissue was digested withHpaII (sensitive to methylation in recognition site) and MspI (insensitive). Theseenzymes leave an overhang after cutting which are then filled in a polymerase extensionassay with stepwise addition of dNTPs using pyrosequencing. The comparisonof the height of picks obtained form both enzymes provides the possibilityto evaluate and compare global genome methylation level of normal and gastritistissues. If the target site is fully methylated, the HpaII /MspI will approach towardzero .If not, this ratio will go around one. In the other conditions the ratio variesbetween 0-1.Results: According to our findings, gastritis tissue was significantly more hypomethylated(p=0.04) than the nornal tissue and Global genome methylation had nocorrelation with sex, age, microsatellite instability (MSI) and gastritis severity.Conclusion: Global DNA hypomethylation occurs in the gastritis lesion. Presumablythe process of hypomethylation keeps falling in the next steps leading togastric cancer.

Keywords

• Hypomethylation
• DNA Methylation
• Gastritis
• Gastric Cancer
• Sequencing