To detect the methylation status of the promoter region of cytokine signal transduction inhibitor 1 (SOCS-1) in gastric cancer tissues and to explore the relationship between the methylation status and Helicobacter pylori (Hp) infection in gastric cancer.

From September 2016 to September 2018, sixty-three patients undergoing gastric cancer surgery (gastric cancer group) and sixty-seven patients undergoing gastric mucosal biopsy for gastric mucosal polyps (control group) were selected. The methylation status of SOCS-1 gene was detected in gastric mucosa tissues of the two groups. The expression of SOCS-1 gene and protein in pathological tissues were detected by RT-PCR and Western blotting. Rapid urease test was used to detect Hp infection and the correlation between SOCS-1methylation and Hp infection in gastric cancer was analyzed.

Compared with the control group, the positive rate of Hp infection in gastric cancer patients increased (74.60% vs 11.94%, χ²=52.234, P<0.001). Compared with the control group, the abnormal methylation rate of CpG island in the promoter region of SOCS-1 in gastric cancer group increased (80.95% vs 5.97%, χ²=74.491, P<0.001). Compared with negative Hp infection, the proportion of SOCS-1 methylation in Hp-positive gastric cancer patients increased significantly (95.74% vs 4.26%, χ²=26.261, P<0.001). Positive Hp infection was a risk factor for SOCS-1 methylation (OR=1.576, 95% CI: 1.126-2.205, P=0.035). SOCS-1 methylation was associated with low differentiation of gastric cancer and lymph node metastasis in TNM stage (χ²=11.530, 9.380, 11.581, all P<0.01). Compared with the negative Hp infection group, the expressions of SOCS-1 mRNA and protein in the positive group decreased significantly (P<0.05).

Hp infection may be closely related to SOCS-1 methylation and promote the occurrence and development of gastric cancer by influencing SOCS-1 methylation.