BackgroundLung cancer is a major threat to public health and remains difficult to treat. Repositioning of existing drugs has emerged as a therapeutic strategy in lung cancer. Clinically, low-dose montelukast has been used to treat asthma.ObjectiveWe evaluated the potential of using montelukast to treat lung cancer.MethodsMigration was detected using wound-healing and Transwell assays, the expression of CysLT1 using western blotting, and subcellular localization of CysLT1 using immunofluorescence. CRISPR/Cas9 technology was used to further investigate the function of CysLT1.ResultsSubcellular localization staining showed that the CysLT1 distribution varied in murine and human lung cancer cell lines. Furthermore, montelukast suppressed CysLT1 expression in lung cancer cells. The treated cells also showed weaker migration ability compared with control cells. Knockout ofCysLT1using CRISPR/Cas9 editing in A549 cells further impaired the cell migration ability.ConclusionMontelukast inhibits the migration of lung cancer cells by suppressing CysLT1 expression, demonstrating the potential of using CysLT1 as a therapeutic target in lung cancer.