Abstract: Background and purpose: RNA helicase DEAD-box helicase 19A (DDX19A), a member of the DDX protein superfamily, is mainly involved in the RNA transport process. Many members of this family are involved in the genesis and progression of tumors, however, the role of DDX19A in gastric cancer has not been reported. Combined with bioinformatics analysis, the expression of DDX19A in gastric cancer tissues and its clinical significance were investigated. Methods: The UALCAN database was used to analyze the expression difference of DDX19A in gastric cancer tissues and adjacent gastric tissues at the transcriptional level, and the relationship between its expression in gastric cancer and clinical stage was further analyzed. Kaplan-Meier Plotter database was used to analyze the correlation between DDX19A expression level and overall survival (OS) and disease-free survival (DFS) of gastric cancer patients. Western blot assay was used to detect the expression of DDX19A protein in 16 pairs of frozen fresh gastric cancer tissues and adjacent gastric mucosa. A total of 109 paraffin specimens of gastric cancer and 30 paracancerous gastric mucosa specimens were collected from Department of Pathology, Affiliated Hospital of Chengde Medical College from 2011 to 2015, and clinicopathological data of all patients were complete. Immunohistochemical S-P four-step method was used to detect the expression of DDX19A protein in 109 cases of gastric cancer and 30 cases of adjacent gastric mucosa. The relationship between the overexpression of DDX19A protein and the clinicopathological characteristics and prognosis of gastric cancer was statistically analyzed. Results: UALCAN and Kaplan-Meier Plotter database search results showed that DDX19A mRNA expression was significantly higher in gastric cancer tissues than in adjacent gastric tissues (P<0.01), and its high expression was positively correlated with clinical stage and poor prognosis of gastric cancer patients (P<0.05). Western blot results showed that DDX19A protein was significantly overexpressed in gastric cancer tissues (P<0.01). Immunohistochemical experiments showed that the positive expression rate of DDX19A in gastric cancer tissues was 68.8% (75/109), which was significantly higher than that in paracancerous gastric mucosa (33.3%, 10/30) (P<0.01). The high expression of DDX19A was closely related to the differentiation degree, infiltration depth and TNM stage of gastric cancer (P<0.05), but not to gender, age, tumor size or lymph node metastasis (P>0.05). In 69 cases with complete follow-up data, the OS of patients with high DDX19A expression was significantly lower compared with those with low DDX19A expression (P<0.05). Conclusion: DDX19A is highly expressed in gastric cancer tissues, and is associated with clinical staging, invasiveness and poor prognosis of patients. It is expected to be a potential biomarker and a new therapeutic target related to the prognosis of gastric cancer.

Key words: Gastric cancer, DDX19A, Prognosis, UALCAN, Kaplan-Meier Plotter