Study on the Expression of CXCR4 Gene in Gastric Cancer and the Impact of Tumor Microenvironment Based on TCGA Database

Objective: To explore the expression of the CXCR4 gene in the tumor microenvironment of gastric cancer tissues and its clinical significance.Methods: The transcriptome data and clinical data of gastric cancer from the The Cancer Genome Atlas (TCGA) database were downloaded, and the expression difference of the CXCR4 gene was analyzed using the ESTIMATES algorithm and DESeq2, and the clinicopathological parameters of the patients were also analyzed. Surgical tissue specimens of patients diagnosed with gastric cancer by surgical treatment and pathological examination at Hefei First People's Hospital from August 2022 to August 2023 were retrospectively collected for reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry to verify its expression. The CIBERSORT algorithm was used to evaluate the correlation between CXCR4 and immune cell infiltration.Results: The immune score might be more suitable for indicating the prognosis of STAD patients. TCGA data showed that the expression level of the CXCR4 gene in gastric cancer tissues was significantly higher than that in adjacent tissues (P < 0.001), and the expression of CXCR4 had significant differences in tumor invasion depth and distant metastasis (all P < 0.05). The experimental results showed that the expression of CXCR4 was positively correlated with tumor distant metastasis and differentiation degree (all P < 0.05). Kaplan - Meier survival analysis of both TCGA data and clinical data showed that the survival time of gastric cancer patients in the high - expression group was significantly shortened (P = 0.003, P < 0.001). Immune cell infiltration analysis: two types of TICs, such as B cell memory and CD8 + T cells, were positively correlated with the expression of CXCR4; six types of TICs, such as resting CD4 memory T cells, activated dendritic cells, plasma cells, activated NK killer cells, macrophages M0, and activated mast cells, were negatively correlated with the expression of CXCR4.Conclusion: The high expression of CXCR4 in gastric cancer indicates a poor prognosis, which is closely related to the progression and metastasis of the tumor. And it is related to immune cell infiltration and may become a potential target for immunotherapy.