RAI14 Is a Prognostic Biomarker and Correlated With Immune Cell Infiltrates in Gastric Cancer

OBJECTIVE: To analyze the expression and clinical significance of retinoic acid-induced protein 14 (RAI14) in gastric cancer and its relationship with immune cell infiltration by mining databases such as Oncomine, TIMER, UALCAN, and Kaplan Meier Plotter. METHODS: RAI14 expression in various cancer types was analyzed using the Oncomine and TIMER databases. We used the Kaplan-Meier Plotter and UALCAN databases to evaluate the impact of RAI14 on clinicopathological parameters in gastric cancer. The correlation between RAI14 expression and immune cell invasion was studied using TIMER. TIMER was also used to analyze the correlation between RAI14 expression and marker levels of tumor-infiltrating immune cells. RESULTS: High RAI14 expression in gastric cancer was significantly associated with poor overall survival (OS; hazard ratio [HR] = 1.82, 95% confidence interval [CI] = 1.53–2.15, P < 0.001) and poor progression-free survival (PFS; HR = 2.16, 95% CI = 1.77–2.65, P < 0.001). Furthermore, high RAI14 expression was significantly associated with poor prognosis of patients with stage 2–4 gastric cancer, but not with OS and PFS of stage 1 patients (OS P = 0.17; PFS P = 0.09), and patients with stage N0 PFS had nothing to do (PFS P = 0.238). RAI14 expression was positively correlated with the infiltration levels of monocytes, tumor-associated macrophages, macrophages, neutrophils, and Treg cells in gastric cancer. Besides, RAI14 expression was closely related to various marker genes in immune cells. CONCLUSION: RAI14 is highly expressed in gastric cancer, and its expression level is correlated with the prognosis of patients with gastric cancer. RAI14 plays also an important role in the recruitment and regulation of infiltrating immune cells and is, thus, expected to become a target for the optimal treatment of gastric cancer.