Potent CTLs can be induced against tumor cells in an environment of lower levels of systemic MFG-E8

Cancer Sci. 2024 Apr;115(4):1114-1128. doi: 10.1111/cas.16099. Epub 2024 Feb 8.

Abstract

The direction and magnitude of immune responses are critically affected when dead cells are disposed of. Milk fat globule-epidermal growth factor-factor 8 (MFG-E8) promotes the engulfment of apoptotic normal and cancerous cells without inducing inflammation. We have previously reported that a certain proportion of the cancer cells express abundant MFG-E8, and that such expression is associated with the shorter survival of patients with esophageal cancer who had received chemotherapy before surgery. However, the influence of tumor-derived and systemically existing MFG-E8 on antitumor immune responses has not yet been fully investigated. Herein, we showed that CTL-dependent antitumor immune responses were observed in mice with no or decreased levels of systemic MFG-E8, and that such responses were enhanced further with the administration of anti-PD-1 antibody. In mice with decreased levels of systemic MFG-E8, the dominance of regulatory T cells in tumor-infiltrating lymphocytes was inverted to CD8+ T cell dominance. MFG-E8 expression by tumor cells appears to affect antitumor immune responses only when the level of systemic MFG-E8 is lower than the physiological status. We have also demonstrated in the clinical setting that lower levels of plasma MFG-E8, but not MFG-E8 expression in tumor cells, before the treatment was associated with objective responses to anti-PD-1 therapy in patients with non-small cell lung cancer. These results suggest that systemic MFG-E8 plays a critical role during the immunological initiation process of antigen-presenting cells to increase tumor-specific CTLs. Regulation of the systemic level of MFG-E8 might induce efficient antitumor immune responses and enhance the potency of anti-PD-1 therapy.

Keywords: antitumor immune response; biomarker; efferocytosis; priming; tumor microenvironment.

MeSH terms

  • Animals
  • Antigens, Surface / metabolism
  • Carcinoma, Non-Small-Cell Lung* / drug therapy
  • Esophageal Neoplasms* / drug therapy
  • Humans
  • Inflammation / pathology
  • Lung Neoplasms* / drug therapy
  • Mice
  • Milk Proteins / metabolism
  • T-Lymphocytes, Cytotoxic / metabolism

Substances

  • Antigens, Surface
  • Milk Proteins
  • MFGE8 protein, human
  • Mfge8 protein, mouse