CXCL2 as a Prognostic Marker in Breast Cancer is Associated with Immune Infiltration and Regulated by miR-215

Background: CXCL2 is a part of chemokine superfamily, which encodes secretory proteins involved in immune regulation and inflammation. The correlation between CXCL2 and prognosis of different cancers, tumor infiltrating lymphocytes are not clear. Methods: We analyzed the expression of CXCL2 and its effect on clinical prognosis through Oncomine database, Tumor Immune Estimation Resource (TIMER) website, Kaplan-Meier plotter, PrognoScan database and Gene Expression Profiling Interactive Analysis (GEPIA). TIMER and GEPIA were used to analyze the correlation between CXCL2 and the gene marker of immune infiltration. StarBase was used to predict the miRNA that may regulate CXCL2. The relationship between miR-532-5p and CXCL2 was detected by qRT-PCR. Kaplan-Meier plotter was used to evaluate the impact of miR-532-5p on clinical prognosis. Results: PrognoScan, Kaplan-Meier plotter and GEPIA database analysis showed that low expression of CXCL2 was associated with poor disease-specific survival time (DSS), relapse-free survival time (RFS) and overall disease survival (OS) in breast cancer patients. In addition, low expression of CXCL2 was associated with poor OS and RFS in patients with lymph node positive breast cancer. CXCL2 expression was positively correlated with the infiltration of B cells, CD4+T and CD8+T cells, neutrophils and dendritic cells (DCs) in BRCA, mainly in Luminal breast cancer. MiR-532-5p can directly regulate CXCL2 expression. High miR-532-5p expression is significantly correlated with HER2 negative, grade 2 and 3 and poor OS in patients with HER+ER- breast cancer. Conclusion: CXCL2 is closely related to the prognosis and immune infiltration level of breast cancer patients, it can be regulated by miR-532-5p.