Correlation between Chemokine CXCL-12 and its Receptor CXCR4 Expression is Associated with Clinical Prognosis of Gastric Cancer

Background: To analyze the differences in gene expression levels of chemokine CXCL-12 and its receptor CXCR4 in gastric cancer and the relationship between their correlations with the clinical prognosis of gastric cancer. Methods: The information on gastric cancer in the TCGA (The Cancer Genome Atlas) database was downloaded from the Broad GDAC FIREHOSE, including CXCL-12 and CXCR4 gene expression data of 415 gastric cancer tissues and 35 normal gastric tissues; clinical information of 392 gastric cancer cases. All patients were divided into either a correlated (significantly higher or lower correlation between CXCL12 and CXCR4 expression) or uncorrelated groups. Wilcoxon rank sum test was used to analyze the differential gene expressions of CXCL-12 and CXCR4 between gastric cancer tissues and normal gastric tissues. Furthermore, one-way analysis of variance and Kaplan-Meier survival analysis were used to analyze the differential gene expressions of CXCL-12 and CXCR4 and the prognosis in patients with different stages of gastric cancer. Gastric cancer patients were divided into two groups according to whether CXCL-12 and CXCR4 gene expressions were correlated or not. Kaplan-Meier survival analysis was used to analyze the three-year survival of the two groups. Results: There were differences between CXCL-12 and CXCR4 expression in 415 gastric cancer tissues and 35 normal gastric tissues. No statistically significant difference between CXCL-12 and CXCR4 was detected in different stages of gastric cancer. There were differences of the five-year survival in different stages of gastric cancer. Further analysis showed that the three-year survival in the correlated group was superior compared to the uncorrelated one. Conclusions: The gene expression of CXCL-12 and CXCR4 was significantly different between gastric cancer tissues and normal gastric tissues. Moreover, the correlation between CXCL-12 and CXCR4 gene expression may be used as a predictor of clinical prognosis in patients with gastric cancer.