Improving function of cytotoxic T-lymphocytes by transforming growth factor-β inhibitor in oral squamous cell carcinoma

Cancer Sci. 2021 Oct;112(10):4037-4049. doi: 10.1111/cas.15081. Epub 2021 Aug 2.

Abstract

Immunotherapy with immune-checkpoint therapy has recently been used to treat oral squamous cell carcinomas (OSCCs). However, improvements in current immunotherapy are expected because response rates are limited. Transforming growth factor-β (TGF-β) creates an immunosuppressive tumor microenvironment (TME) by inducing the production of regulatory T-cells (Tregs) and cancer-associated fibroblasts and inhibiting the function of cytotoxic T-lymphocytes (CTLs) and natural killer cells. TGF-β may be an important target in the development of novel cancer immunotherapies. In this study, we investigated the suppressive effect of TGF-β on CTL function in vitro using OSCC cell lines and their specific CTLs. Moreover, TGFB1 mRNA expression and T-cell infiltration in 25 OSCC tissues were examined by in situ hybridization and multifluorescence immunohistochemistry. We found that TGF-β suppressed the function of antigen-specific CTLs in the priming and effector phases in vitro. Additionally, TGF-β inhibitor effectively restored the CTL function, and TGFB1 mRNA was primarily expressed in the tumor invasive front. Interestingly, we found a significant negative correlation between TGFB1 mRNA expression and the CD8+ T-cell/Treg ratio and between TGFB1 mRNA expression and the Ki-67 expression in CD8+ T-cells, indicating that TGF-β also suppressed the function of CTLs in situ. Our findings suggest that the regulation of TGF-β function restores the immunosuppressive TME to active status and is important for developing new immunotherapeutic strategies, such as a combination of immune-checkpoint inhibitors and TGF-β inhibitors, for OSCCs.

Keywords: TGF-β; cytotoxic T-cells; immunotherapy; oral squamous cell carcinoma; regulatory T-cells.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • CD8-Positive T-Lymphocytes / cytology
  • CD8-Positive T-Lymphocytes / immunology
  • Cancer-Associated Fibroblasts / cytology
  • Cancer-Associated Fibroblasts / immunology
  • Cell Line, Tumor
  • Cell Proliferation
  • Female
  • Humans
  • Immune Checkpoint Inhibitors / therapeutic use*
  • Immunotherapy, Adoptive / methods*
  • Interferon-gamma / analysis
  • Interferon-gamma / metabolism
  • Ki-67 Antigen / metabolism
  • Killer Cells, Natural / cytology
  • Killer Cells, Natural / immunology
  • Lymphocytes, Tumor-Infiltrating / cytology
  • Lymphocytes, Tumor-Infiltrating / immunology
  • Male
  • Middle Aged
  • Mouth Neoplasms / metabolism
  • Mouth Neoplasms / therapy*
  • RNA, Messenger / metabolism
  • Smad2 Protein / metabolism
  • Smad3 Protein / metabolism
  • Squamous Cell Carcinoma of Head and Neck / metabolism
  • Squamous Cell Carcinoma of Head and Neck / therapy*
  • T-Lymphocytes, Cytotoxic / cytology
  • T-Lymphocytes, Cytotoxic / drug effects*
  • T-Lymphocytes, Cytotoxic / immunology
  • T-Lymphocytes, Cytotoxic / metabolism
  • T-Lymphocytes, Regulatory / cytology
  • T-Lymphocytes, Regulatory / immunology
  • Tetrazolium Salts / pharmacology
  • Transforming Growth Factor beta / antagonists & inhibitors
  • Transforming Growth Factor beta / immunology
  • Transforming Growth Factor beta1 / analysis
  • Transforming Growth Factor beta1 / antagonists & inhibitors*
  • Transforming Growth Factor beta1 / genetics
  • Transforming Growth Factor beta1 / metabolism
  • Tumor Microenvironment / immunology*
  • Tumor Necrosis Factor-alpha / analysis
  • Tumor Necrosis Factor-alpha / metabolism
  • Young Adult

Substances

  • 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium
  • Immune Checkpoint Inhibitors
  • Ki-67 Antigen
  • RNA, Messenger
  • SMAD2 protein, human
  • SMAD3 protein, human
  • Smad2 Protein
  • Smad3 Protein
  • Tetrazolium Salts
  • Transforming Growth Factor beta
  • Transforming Growth Factor beta1
  • Tumor Necrosis Factor-alpha
  • Interferon-gamma