L‐kynurenine and quinolinic acid inhibited markers of cell survival in B16 F10 melanoma cells in vitro

Melanoma is an aggressive malignancy and remains a major cause of skin cancer mortality, highlighting the need for new treatment strategies. Recent findings revealed that L‐kynurenine and quinolinic acid induce cytotoxicity and morphological changes in B16 F10 melanoma cells in vitro. This paper highlights the effects of L‐kynurenine and quinolinic acid at previously determined half‐maximal inhibitory concentrations on cell cycle progression, cell death and extracellular signal‐regulated protein kinase inhibition. Melanoma, B16 F10 and murine macrophages, RAW 264.7 cells were used in this study, as both cell lines express all the enzymes associated with the kynurenine pathway. Post exposure to the compounds at half‐maximal inhibitory concentrations, transmission electron microscopy was used to assess intracellular morphological changes. Flow cytometry was used to analyse cell cycle progression and quantify apoptosis via the dual staining of Annexin V and propidium iodide and cell survival via extracellular signal‐regulated protein kinase. L‐kynurenine and quinolinic acid at half‐maximal inhibitory concentrations induced intracellular morphological changes representative of cell death. Flow cytometry revealed alterations in cell cycle distribution, increased apoptosis and significantly inhibition of cell survival. L‐kynurenine and quinolinic acid are exogenous kynurenine compounds which inhibited cell survival through extracellular signal‐regulated protein kinase inhibition, induced cell cycle alterations and induced apoptosis in B16 F10 melanoma cells. Significance statement Data obtained in the current study revealed information regarding the in vitro effects of L‐kynurenine and quinolinic acid on B16 F10 melanoma cell cycle progression, intracellular morphology, extracellular signal‐regulated kinase 1/2 inhibition and cell death. Evaluating the therapeutic effects of kynurenine metabolites against melanoma may potentially result in improved future cancer treatment options to manage the global melanoma burden.