Increased ACSL6 Expression Predicts a Favorable Prognosis in Triple-negative Breast Cancer

Background: Long-chain acyl-coenzyme A synthases (ACSLs) are responsible for the catalysis of fatty acids into their corresponding fatty acyl-CoAs. The dysregulation of ACSLs has been increasingly recognized in cancer patients. However, the function of ACSL6 in triple-negative breast cancer (TNBC) is still completely unknown. Methods: In this study, immunohistochemistry was applied to detect ACSL6 protein expression using a TNBC tissue microarray. Additionally, the mRNA levels of ACSL6 in human normal tissues and pancancer tissues were analyzed using Genotype Tissue Expression (GTEx) datasets and The Cancer Genome Atlas (TCGA) database. The correlations between the levels of ACSL6 expression and clinical characteristics were analyzed. The survival analysis of ACSL6 in TNBC was carried out using the Kaplan‒Meier Plotter online tool. Associations of ACSL6 with immune infiltration analyses were conducted using the ESTIMATE, CIBERSORT, and TISIDB databases. The relationship between ACSL6 and sensitivity to drugs was analyzed from Genomics of Drug Sensitivity in Cancer (GDSC). Results: The results indicated a significant increase in ACSL6 expression in TNBC tissues compared to adjacent normal tissues. However, high ACSL6 expression was significantly associated with favorable survival outcomes in TNBC patients. Enrichment analysis revealed that coexpressed genes of ACSL6 were significantly enriched in various immunity processes. ACSL6 was positively correlated with the infiltration of memory CD4 T cells, while a negative correlation was found between ACSL6 and M2 macrophages and resting dendritic cells. Further analysis revealed that high levels of ACSL6 correlated with increased survival outcomes in cancer patients who received immunotherapy. Conclusion: Altogether, the current findings highlight the potential value of ACSL6 as a diagnostic and prognostic marker in the treatment of TNBC.