Non-small cell lung cancer (NSCLC) patients harboring a KRAS mutation have unfa-vorable therapeutic outcomes with chemotherapies, and the mutation also renders tolerance to immunotherapies. There is an unmet need for a new strategy for overcoming immunosuppression in KRAS-mutant NSCLC. The recently discovered role of melatonin demonstrates a wide spectrum of anticancer impacts; however, the effect of melatonin on modulating tumor immunity is largely unknown. In the present study, melatonin treatment significantly reduced cell viability accompanied by inducing cell apoptosis in KRAS-mutant NSCLC cell lines including A549, H460, and LLC1 cells. Mechanistically, we found that lung cancer cells harboring the KRAS mutation exhibited a higher level of programmed death ligand 1 (PD-L1). However, treatment with melatonin substantially downregulated PD-L1 expressions in both the presence and absence of interferon (IFN)-γ stimu-lation. Moreover, KRAS-mutant lung cancer cells exhibited higher Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) levels, and PD-L1 expression was positively correlated with YAP and TAZ in lung cancer cells. Treatment with melatonin effectively suppressed YAP and TAZ, which was accompanied by downregulation of YAP/TAZ downstream gene expressions. The combination of melatonin and an inhibitor of YAP/TAZ robustly decreased YAP and PD-L1 expressions. Clinical analysis using public databases revealed that PD-L1 expression was positively correlated with YAP and TAZ in patients with lung cancer, and PD-L1 overexpression suggested poor survival probability. An animal study further revealed that administration of mela-tonin significantly inhibited tumor growth and modulated tumor immunity in a syngeneic mouse model. Together, our data revealed a novel antitumor mechanism of melatonin in modulating the immunosuppressive tumor microenvironment by suppressing the YAP/PD-L1 axis and suggest the therapeutic potential of melatonin for treating NSCLC.

Original languageEnglish
Article number5649
JournalInternational journal of molecular sciences
Issue number11
Publication statusPublished - Jun 1 2021


  • Hippo pathway
  • Lung cancer
  • Melatonin
  • PD-L1
  • Tumor immunity

ASJC Scopus subject areas

  • Catalysis
  • Molecular Biology
  • Spectroscopy
  • Computer Science Applications
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry


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