Frontiers in Immunology (Sep 2024)

Cytosolic nucleic acid sensors and interferon beta-1 activation drive radiation-induced anti-tumour immune effects in human pancreatic cancer cells

  • Sylvia Kerschbaum-Gruber,
  • Sylvia Kerschbaum-Gruber,
  • Sylvia Kerschbaum-Gruber,
  • Ava Kleinwächter,
  • Ava Kleinwächter,
  • Ava Kleinwächter,
  • Ava Kleinwächter,
  • Ava Kleinwächter,
  • Katerina Popova,
  • Katerina Popova,
  • Katerina Popova,
  • Alexandra Kneringer,
  • Alexandra Kneringer,
  • Alexandra Kneringer,
  • Lisa-Marie Appel,
  • Lisa-Marie Appel,
  • Lisa-Marie Appel,
  • Lisa-Marie Appel,
  • Katharina Stasny,
  • Anna Röhrer,
  • Anna Röhrer,
  • Anna Röhrer,
  • Ana Beatriz Dias,
  • Ana Beatriz Dias,
  • Ana Beatriz Dias,
  • Ana Beatriz Dias,
  • Johannes Benedum,
  • Johannes Benedum,
  • Johannes Benedum,
  • Johannes Benedum,
  • Johannes Benedum,
  • Lena Walch,
  • Lena Walch,
  • Andreas Postl,
  • Andreas Postl,
  • Andreas Postl,
  • Sandra Barna,
  • Sandra Barna,
  • Sandra Barna,
  • Bernhard Kratzer,
  • Winfried F. Pickl,
  • Winfried F. Pickl,
  • Altuna Akalin,
  • Filip Horvat,
  • Filip Horvat,
  • Vedran Franke,
  • Joachim Widder,
  • Joachim Widder,
  • Dietmar Georg,
  • Dietmar Georg,
  • Dietmar Georg,
  • Dea Slade,
  • Dea Slade,
  • Dea Slade,
  • Dea Slade,
  • Dea Slade

DOI
https://doi.org/10.3389/fimmu.2024.1286942
Journal volume & issue
Vol. 15

Abstract

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IntroductionPancreatic ductal adenocarcinoma (PDAC) remains a leading cause of cancer-related deaths worldwide with limited treatment options due to extensive radiation and chemotherapy resistance. Monotherapy with immune checkpoint blockade showed no survival benefit. A combination of immunomodulation and radiotherapy may offer new treatment strategies, as demonstrated for non-small cell lung cancer. Radiation-induced anti-tumour immunity is mediated through cytosolic nucleic acid sensing pathways that drive the expression of interferon beta-1 (IFNB1) and proinflammatory cytokines.MethodsHuman PDAC cell lines (PANC-1, MIA PaCa-2, BxPC-3) were treated with X-rays and protons. Immunogenic cell death was measured based on HMGB1 release. Cytosolic dsDNA and dsRNA were analysed by immunofluorescence microscopy. Cell cycle progression, MHC-I and PD-L1 expression were determined by flow cytometry. Galectin-1 and IFNB1 were measured by ELISA. The expression levels and the phosphorylation status of the cGAS/STING and RIG-I/MAVS signalling pathways were analysed by western blotting, the expression of IFNB1 and proinflammatory cytokines was determined by RT-qPCR and genome-wide by RNA-seq. CRISPR-Cas9 knock-outs and inhibitors were used to elucidate the relevance of STING, MAVS and NF-κB for radiation-induced IFNB1 activation.ResultsWe demonstrate that a clinically relevant X-ray hypofractionation regimen (3x8 Gy) induces immunogenic cell death and activates IFNB1 and proinflammatory cytokines. Fractionated radiation induces G2/M arrest and accumulation of cytosolic DNA in PDAC cells, which partly originates from mitochondria. RNA-seq analysis shows a global upregulation of type I interferon response and NF-κB signalling in PDAC cells following 3x8 Gy. Radiation-induced immunogenic response is regulated by STING, MAVS and NF-κB. In addition to immunostimulation, radiation also induces immunosuppressive galectin-1. No significant changes in MHC-I or PD-L1 expression were observed. Moreover, PDAC cell lines show similar radiation-induced immune effects when exposed to single-dose protons or photons.ConclusionOur findings provide a rationale for combinatorial radiation-immunomodulatory treatment approaches in PDAC using conventional photon-based or proton beam radiotherapy.

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