Regulation of programmed death ligand 1 expression by interferon-γ and tumour necrosis factor-α in canine tumour cell lines

Vet Comp Oncol. 2023 Jun;21(2):279-290. doi: 10.1111/vco.12886. Epub 2023 Mar 8.

Abstract

Expression of programmed death ligand 1 (PD-L1) on tumour cells provides an immune evasion mechanism by inducing suppression of cytotoxic T cells. Various regulatory mechanisms of PD-L1 expression have been described in human tumours, however, little is known in canine tumours. To investigate whether inflammatory signalling is involved in PD-L1 regulation in canine tumours, the effects of interferon (IFN)-γ and tumour necrosis factor (TNF)-α treatment were examined in canine malignant melanoma cell lines (CMeC and LMeC) and an osteosarcoma cell line (HMPOS). The protein level of PD-L1 expression was upregulated by IFN-γ and TNF-α stimulation. Upon IFN-γ stimulation, all cell lines showed an increase in expression of PD-L1, signal transducer and activator of transcription (STAT)1, STAT3 and genes regulated by STAT activation. Upregulated expression of these genes was suppressed by the addition of a JAK inhibitor, oclacitinib. Contrastingly, upon TNF-α stimulation, all cell lines exhibited higher gene expression of the nuclear factor kappa B (NF-κB) gene RELA and genes regulated by NF-κB activation, whereas expression of PD-L1 was upregulated in LMeC only. Upregulated expression of these genes was suppressed by the addition of an NF-κB inhibitor, BAY 11-7082. The expression level of cell surface PD-L1 induced by IFN-γ and TNF-α treatment was reduced by oclacitinib and BAY 11-7082, respectively, indicating that upregulation of PD-L1 expression by IFN-γ and TNF-α stimulation is regulated via the JAK-STAT and NF-κB signalling pathways, respectively. These results provide insights into the role of inflammatory signalling in PD-L1 regulation in canine tumours.

Keywords: cell signalling; immunology; in vitro models; oncology; small animal.

MeSH terms

  • Animals
  • B7-H1 Antigen / genetics
  • B7-H1 Antigen / metabolism
  • Cell Line, Tumor
  • Dog Diseases* / drug therapy
  • Dogs
  • Humans
  • Interferon-gamma / metabolism
  • Interferon-gamma / pharmacology
  • NF-kappa B / metabolism
  • Tumor Necrosis Factor-alpha* / metabolism

Substances

  • Tumor Necrosis Factor-alpha
  • CD274 protein, human
  • B7-H1 Antigen
  • NF-kappa B
  • Interferon-gamma
  • oclacitinib
  • 3-(4-methylphenylsulfonyl)-2-propenenitrile