Fibrinogen-Like Protein 2 (FGL2) is a Novel Biomarker for Clinical Prediction of Human Breast Cancer

BACKGROUND: Fibrinogen-like protein 2 (FGL2) is a member of the fibrinogen-like protein family and possesses important regulatory functions in both innate and adaptive immune responses. FGL2 is overexpressed in glioma, and its expression level is negatively associated with the prognosis of glioma patients. However, the diagnostic value of FGL2 is unknown in breast carcinoma. MATERIAL/METHODS: We comprehensively analyzed the expression pattern of FGL2 in breast cancer. Several online databases – TCGA, Oncomine, GEPIA, Kaplan-Meier plotter, and PrognoScan – were used in this study. RESULTS: Based on the TCGA dataset and Oncomine database, we found that the expression level of FGL2 was remarkably lower in breast cancer compared with adjacent normal tissues. Clinical data showed that the expression level of FGL2 was significantly associated with radiation therapy, PR status, and tumor stage. Bioinformatics analysis of the GEPIA, Kaplan-Meier plotter, and PrognoScan databases showed that lower FGL2 expression levels were associated with a worse prognosis in breast cancer patients. Furthermore, the expression level of FGL2 was positively correlated with the immune cell infiltrations in breast cancer, especially those cells with high antitumor activities. GO, KEGG, and GSEA analyses also validated that FGL2 was closely related to genes involved in the immune response, signal transduction, and T cell receptor signaling pathway in breast cancer. CONCLUSIONS: The results demonstrated that high expression of FGL2 is a useful marker for breast cancer treatment and appears to be correlated with enhanced antitumor activities in breast cancer patients.