Integrin β1 activation induces an anti-melanoma host response

PLoS One. 2017 Apr 27;12(4):e0175300. doi: 10.1371/journal.pone.0175300. eCollection 2017.

Abstract

TGF-β is a cytokine thought to function as a tumor promoter in advanced malignancies. In this setting, TGF-β increases cancer cell proliferation, survival, and migration, and orchestrates complex, pro-tumorigenic changes in the tumor microenvironment. Here, we find that in melanoma, integrin β1-mediated TGF-β activation may also produce tumor suppression via an altered host response. In the A375 human melanoma cell nu/nu xenograft model, we demonstrate that cell surface integrin β1-activation increases TGF-β activity, resulting in stromal activation, neo-angiogenesis and, unexpectedly for this nude mouse model, increase in the number of intra-tumoral CD8+ T lymphocytes within the tumor microenvironment. This is associated with attenuation of tumor growth and long-term survival benefit. Correspondingly, in human melanomas, TGF-β1 correlates with integrin β1/TGF-β1 activation and the expression of markers for vasculature and stromal activation. Surprisingly, this integrin β1/TGF-β1 transcriptional footprint also correlates with the expression of markers for tumor-infiltrating lymphocytes, multiple immune checkpoints and regulatory pathways, and, importantly, better long-term survival of patients. These correlations are unique to melanoma, in that we do not observe similar associations between β1 integrin/TGF-β1 activation and better long-term survival in other human tumor types. These results suggest that activation of TGF-β1 in melanoma may be associated with the generation of an anti-tumor host response that warrants further study.

MeSH terms

  • Animals
  • Antibodies / immunology*
  • Cell Line, Tumor
  • Cell Proliferation
  • Cell Transformation, Neoplastic
  • Extracellular Space / metabolism
  • Female
  • Integrin beta1 / immunology*
  • Integrin beta1 / metabolism*
  • Melanoma / blood supply
  • Melanoma / immunology*
  • Melanoma / metabolism*
  • Melanoma / pathology
  • Mice
  • Mice, Nude
  • Neovascularization, Pathologic / immunology
  • Signal Transduction / immunology
  • Survival Analysis
  • T-Lymphocytes / cytology
  • T-Lymphocytes / immunology
  • Transforming Growth Factor beta / metabolism
  • Tumor Microenvironment / immunology

Substances

  • Antibodies
  • Integrin beta1
  • Transforming Growth Factor beta