The Diagnostic Value of ACSL1, ACSL4, and ACSL5 and the Clinical Potential of an ACSL Inhibitor in Non-Small-Cell Lung Cancer

Simple Summary Long-chain Acyl-CoA synthetase (ACSL) family members are involved in long-chain fatty acid activation, a crucial step for cells to utilize fatty acids (FAs) in the regulation of FA homeostasis. Cancer cells utilize the limited environmental FAs via the dysregulation of ACSL isoforms to adapt to an altered lipid metabolism. Dysregulated ACSLs are associated with either cancer promotion or inhibition, dependent on the cellular context. The role of ACSLs in different cancer types has not yet been fully elucidated, and, particularly, their role in lung cancer is unclear. In this study, we analyzed the expression pattern of ACSLs, evaluated their diagnostic values, and explored the therapeutic potential of the ACSL inhibitor Triacsin C in human lung cancer cells. Abstract Abnormal expression of ACSL members 1, 3, 4, 5, and 6 is frequently seen in human cancer; however, their clinical relevance is unclear. In this study, we analyzed the expression of ACSLs and investigated the effects of the ACSL inhibitor Triacsin C (TC) in lung cancer. We found that, compared to normal human bronchial epithelial (NHBE) cells, ACSL1, ACSL4, and ACSL6 were highly expressed, while ACSL3 and ACSL5 were lost in the majority of lung cancer cell lines. ACSL activity was associated with the expression levels of the ACSLs. In primary lung tumors, a higher expression of ACSL1, ACSL4, and ACSL5 was significantly correlated with adenocarcinoma (ADC). Moreover, ACSL5 was significantly reversely related to the proliferation marker Ki67 in low-grade tumors, while ACSL3 was positively associated with Ki67 in high-grade tumors. Combination therapy with TC and Gemcitabine enhanced the growth-inhibitory effect in EGFR wild-type cells, while TC combined with EGFR-TKIs sensitized the EGFR-mutant cells to EGFR-TKI treatment. Taken together, the data suggest that ACSL1 may be a biomarker for lung ADC, and ACSL1, ACSL4, and ACSL5 may be involved in lung cancer differentiation, and TC, in combination with chemotherapy or EGFR-TKIs, may help patients overcome drug resistance.