Association between promoter methylation and expression of thyroid hormone receptor beta (THRß) gene in patients with gastric cancer in an Iranian population.

BACKGROUND AND AIM: There is evidence that gastric cancer patients suffer from thyroid disorders. However, the relationship between thyroid receptor (TR) expression and gastric cancer remains unknown. The aim of this study was to evaluate the status of promoter methylation and expression of the thyroid hormone receptor beta (THRß) gene in gastric cancer patients in an Iranian population. METHODS: Analysis of THRß promoter methylation was performed on 85 pairs of formalin-fixed, paraffin-embedded (FFPE) tissue samples as cases and controls via methylation-specific polymerase chain reaction (PCR [MSP]). The samples were obtained from tumors and surrounding healthy tissues from resected gastric cancers. The expression assay was also performed with 25 FFPE tissue pairs (tumor and surrounding healthy tissues of the same individual) using real-time PCR. RESULTS: The results of the present study show that there is a statistically significant difference between tumor and adjacent normal tissues regarding promoter methylation status and THRß expression (P = 0.04 and P = 0.036, respectively). CONCLUSION: Therefore, promoter methylation of THRß may be involved in the development of gastric cancer.

Analysis of promoter methylation, polymorphism and expression profile of cytotoxic T-lymphocyte-associated antigen-4 in patients with gastric cancer.

BACKGROUND AND AIM: Cytotoxic T lymphocyte-associated antigen-4 (CTLA4) is a crucial immune-checkpoint receptor regulating T-cell activation. The current study was carried out to evaluate the function of CTLA4 gene in patients with gastric cancer. METHODS: The methylation of CTLA4 gene promoter was evaluated by methylation-specific polymerase chain reaction (MSP) technique using 85 paraffin-embedded gastric cancer tissue samples and normal tissue on the tumor margins as control tissue samples. Expression analysis was performed on paraffin-embedded tissue samples (25 each of cancerous and normal tissues) using Real-time PCR. RESULTS: Statistically significant differences were observed between the tumor and margin-cell areas with respect to promoter methylation status (OR = 4.829, 95% CI: 2.46-9.48, p < 0.001) and CTLA4 expression profile (mean +/- SD = 7.56 +/- 17.35, p = 0.04). CONCLUSION: To the best of our knowledge, the current study is the first one highlighting the association between promoter hypermethylation of CTLA4 gene, decreased CTLA4 expression, and increased risk of gastric cancer.