Comprehensive analysis of the associations of LOXL1-4 with prognosis and immune infiltration in breast cancer

Objective: Invasive breast carcinoma (BRCA) is the most common cancer in women, and the prognosis of BRCA patients is poor. Lysine oxidase-like (LOXL) family genes have been demonstrated to be dysregulated in some malignancies and play crucial roles in tumor progression. However, the exact expression patterns and prognostic value of LOXL1-4 in BRCA remain unclear. Methods: : Here, we investigated the expression levels, genetic variation, gene–gene interaction network, and prognostic value of LOXL1-4 in patients with BRCA using R and existing public bioinformatics databases. Gene ontology (GO) and KEGG pathway enrichment analyses were performed to explore biological functions via DAVID 6.8 and R. Moreover, GDSC and CTRP drug sensitivity data were analyzed to reveal that LOXL1-4 were correlated with the drug response across cancers. The relationship between LOXL1-4 expression and tumor immune infiltration was studied in the TIMER database. Results: : The results revealed that LOXL1/2/4 were aberrantly expressed in BRCA. Moreover, LOXL1/2/4 expression was significantly associated with relapse-free survival (RFS), and LOXL4 expression was significantly associated with overall survival (OS). LOXL2 expression was associated with distant metastasis-free survival (DMFS). Immune score analysis showed that LOXL1-4 were significantly related to the tumor immune microenvironment and markedly correlated with immune cell infiltration. Further analysis demonstrated that copy number variations (CNVs) of LOXL1-4 were obviously associated with immune infiltration in BRCA and that CNV of LOXL2 was markedly associated with the OS and PFS of patients with BRCA. Conclusion: Our study reveals that LOXL1-4 expression is correlated with prognosis and immune infiltration levels, possibly providing new insights into immunotherapy for patients with breast cancer.