Broad and Conserved Immune Regulation by Genetically Heterogeneous Melanoma Cells

• Published in: Cancer research (Chicago, Ill.) Vol. 77; no. 7; pp. 1623 - 1636
• Main Authors: Neubert, Natalie J, Tillé, Laure, Barras, David, Soneson, Charlotte, Baumgaertner, Petra, Rimoldi, Donata, Gfeller, David, Delorenzi, Mauro, Fuertes Marraco, Silvia A, Speiser, Daniel E
• Format: Journal Article
• Language: English
• Published: United States American Association for Cancer Research, Inc 01-04-2017
• Subjects: Benign; Cancer; CD8 antigen; Cell Line, Tumor; Cytotoxicity; Flow cytometry; Gene expression; Gene flow; Gene regulation; Genetic Heterogeneity; GTP Phosphohydrolases - genetics; Humans; Immunoregulation; Immunotherapy; Interferon-gamma - pharmacology; Lymphocyte Activation; Lymphocytes; Lymphocytes T; Melanoma; Melanoma - immunology; Melanoma - therapy; Membrane Proteins - genetics; Mutation; Proto-Oncogene Proteins B-raf - genetics; T-Lymphocytes, Cytotoxic - immunology; Tumor Escape; Tumor Microenvironment; Tumor Necrosis Factor-alpha - pharmacology; Tumor necrosis factor-α; γ-Interferon
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.CAN-16-2680

Although mutations drive cancer, it is less clear to what extent genetic defects control immune mechanisms and confer resistance to T-cell-based immunotherapy. Here, we studied the reactions of malignant and benign melanocyte lines to cytotoxic CD8
T cells (CTL) using flow cytometry and gene expression analyses. We found rapid and broad upregulation of immune-regulatory genes, essentially triggered by CTL-derived IFNγ and augmented by TNFα. These reactions were predominantly homogenous, independent of oncogenic driver mutations, and similar in benign and malignant cells. The reactions exhibited both pro- and antitumorigenic potential and primarily corresponded to mechanisms that were conserved, rather than acquired, by mutations. Similar results were obtained from direct
analysis of the tumor microenvironment. Thus, immune regulation in the tumor landscape may often be driven by conserved mechanisms, which may explain why T-cell-based immunotherapy can provide durable benefits with relatively infrequent escape.
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