ABSTRACT
Objectives: To investigate the association between EBV viral infectious dose, infection with EBV and/or H. pylori and histologically different gastric diseases and cancer. Also, to study the association between EBV and/or H. pylori infection with DNA methylation patterns of human tumor suppressor genes p16 and CDH1 in progression of primary gastric diseases to neoplasia. Methods: The current prospective cross-section study included a total of 94 GTPs taken from patients suffering from gastro-duodenal manifestations recruited to Gastro-Endoscopy Department at Gastroenterology and Hepatology Teaching Hospital, Baghdad, Iraq, from November 2017 to October 2018. Two gastric tissue biopsies (GTBs) were collected from those patients. Genomic DNA was extracted from fresh GTPs. Direct molecular identification of H. pylori in extracted DNA was performed by amplification of species-specific urea. Identification of Epstein-Barr nuclear antigen 1(EBNA1) in extracted DNA was performed using nested PCR. DNA samples positive to EBNA1 were submitted for viral load estimation using quantitative real time PCR. Methylation patterns of p16 and CDH1 promoters were detected in modified DNA samples by sodium sulfate using MS-PCR. Results: Of total samples, 39 (41.5%) of DNA samples were positive for H. pylori and 18 (19.15%) DNA samples were positive for EBNA-1. Studying EBV load, 8/23DNA samples were showed infectious dose of EBV. Studying methylation patterns of p16 and CDH-1 promoters, 21/42 and 19/42 DNA samples were provide results for MSPPCR, respectively. Conclusion: Epstein-Barr virus and H. pylori infection may have a synergistic effect in developing different gastric diseases and that enable the clinician to choose the suitable treatment regime.
ABSTRACT
BACKGROUND: Inactivation of p16 has been associated with promoter region hypermethylation in different types of malignancies, including non-Hodgkin's lymphomas (NHLs). This loss of p16 was found frequently in cases of mucosa-associated lymphoid tissue (MALT) lymphomas. Recent studies indicate that promoter hypermethylation is often an early event in tumor progression in the follow-up of NHLs. METHODS: To investigate the usefulness of p16 methylation in the diagnosis and follow-up of gastric low-grade MALT lymphomas, we analyzed methylation status of p16 using methylation-specific polymerase chain reaction methods in the sequential biopsy specimens of 13 patients with gastric low-grade MALT lymphomas undergoing Helicobacter pylori eradication therapy. RESULTS: Five of thriteen cases showed p16 hypermethylation upon diagnosis. In four of five methylation positive cases, abnormal methylation was detected in the specimen even after the treatment, although there were no histologic evidence of disease. This methylation disappeared in the later samples of two of the cases, and they have remained in complete remission. Immunohistochemically, the loss of p16 protein expression was detected in one of three methylation-positive cases, and in none of the methylation-negative cases. CONCLUSIONS: These results suggest that p16 methylation is relatively fequent in low-grade gastric MALT lymphomas, and it may have clinical applications in the management and follow-up of low-grade gastric MALT lymphomas.
Subject(s)
Humans , Biopsy , Diagnosis , Follow-Up Studies , Helicobacter pylori , Helicobacter , Lymphoid Tissue , Lymphoma , Lymphoma, B-Cell, Marginal Zone , Lymphoma, Non-Hodgkin , Methylation , Polymerase Chain Reaction , Promoter Regions, GeneticABSTRACT
BACKGROUND: Loss of heterozygosity (LOH) and mutation of the p16 tumor suppressor gene have been detected in non-Hodgkin's lymphomas (NHLs). Recently, hypermethylation of the p16 gene has been reported. The role of p16 gene alterations in the genesis of NHLs and their high-grade transformations require explanation. METHODS: LOH of D9S171 and IFNA microsatellite markers, DNA hypermethylation, and mutation of exon 1 and 2A were assessed in 43 cases of NHLs. The genetic abnormalities were compared with the protein expression by immunohistochemistry, and they were evaluated according to the histologic subtypes, grades and immunophenotypes. RESULTS: DNA hypermethylation was the most common p16 gene abnormality and was found in 30 of 39 cases (76.9%). Eight cases (18.6%) showed LOH in one or both microsatellite markers, and five cases (11.6%) showed mutations in exon 1 or 2A. Loss of protein expression was seen in 17 cases (39.5%) and was associated with mutation and LOH. Loss of protein was more frequent in high-grade lymphomas than in low-grade lymphomas. CONCLUSION: These results suggest that the functional loss of the p16 gene contributes to the development of NHLs, especially to the development of high-grade lymphomas.