Frequent Loss of IRF2 in Cancers Leads to Immune Evasion through Decreased MHC Class I Antigen Presentation and Increased PD-L1 Expression
Autor: | Kenneth L. Rock, Benjamin J Chen, Pranitha Vangala, Paul Meraner, Manuel Garber, Abraham L. Brass, Barry A. Kriegsman |
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Rok vydání: | 2019 |
Předmět: |
medicine.medical_treatment
Immunology Antigen presentation Down-Regulation CD8-Positive T-Lymphocytes Major histocompatibility complex B7-H1 Antigen Article 03 medical and health sciences 0302 clinical medicine Immune system Neoplasms MHC class I medicine Immunology and Allergy Humans Antigen Presentation biology MHC class I antigen Histocompatibility Antigens Class I Immunotherapy Neoplasm Proteins Gene Expression Regulation Neoplastic HEK293 Cells Peptide transport biology.protein Cancer research Tumor Escape CD8 Interferon Regulatory Factor-2 030215 immunology HeLa Cells |
Zdroj: | J Immunol |
ISSN: | 1550-6606 |
Popis: | To arise and progress, cancers need to evade immune elimination. Consequently, progressing tumors are often MHC class I (MHC-I) low and express immune inhibitory molecules, such as PD-L1, which allows them to avoid the main antitumor host defense, CD8+ T cells. The molecular mechanisms that led to these alterations were incompletely understood. In this study, we identify loss of the transcription factor IRF2 as a frequent underlying mechanism that leads to a tumor immune evasion phenotype in both humans and mice. We identified IRF2 in a CRISPR-based forward genetic screen for genes that controlled MHC-I Ag presentation in HeLa cells. We then found that many primary human cancers, including lung, colon, breast, prostate, and others, frequently downregulated IRF2. Although IRF2 is generally known as a transcriptional repressor, we found that it was a transcriptional activator of many key components of the MHC-I pathway, including immunoproteasomes, TAP, and ERAP1, whose transcriptional control was previously poorly understood. Upon loss of IRF2, cytosol-to–endoplasmic reticulum peptide transport and N-terminal peptide trimming become rate limiting for Ag presentation. In addition, we found that IRF2 is a repressor of PD-L1. Thus, by downregulating a single nonessential gene, tumors become harder to see (reduced Ag presentation), more inhibitory (increased checkpoint inhibitor), and less susceptible to being killed by CD8+ T cells. Importantly, we found that the loss of Ag presentation caused by IRF2 downregulation could be reversed by IFN-stimulated induction of the transcription factor IRF1. The implication of these findings for tumor progression and immunotherapy are discussed. |
Databáze: | OpenAIRE |
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