PARP inhibition enhances tumor cell–intrinsic immunity in ERCC1-deficient non–small cell lung cancer
Roman M. Chabanon, … , Christopher J. Lord, Sophie Postel-Vinay
Roman M. Chabanon, … , Christopher J. Lord, Sophie Postel-Vinay
Published December 27, 2018
Citation Information: J Clin Invest. 2019;129(3):1211-1228. https://doi.org/10.1172/JCI123319.
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Research Article Oncology

PARP inhibition enhances tumor cell–intrinsic immunity in ERCC1-deficient non–small cell lung cancer

Abstract

The cyclic GMP-AMP synthase/stimulator of IFN genes (cGAS/STING) pathway detects cytosolic DNA to activate innate immune responses. Poly(ADP-ribose) polymerase inhibitors (PARPi) selectively target cancer cells with DNA repair deficiencies such as those caused by BRCA1 mutations or ERCC1 defects. Using isogenic cell lines and patient-derived samples, we showed that ERCC1-defective non–small cell lung cancer (NSCLC) cells exhibit an enhanced type I IFN transcriptomic signature and that low ERCC1 expression correlates with increased lymphocytic infiltration. We demonstrated that clinical PARPi, including olaparib and rucaparib, have cell-autonomous immunomodulatory properties in ERCC1-defective NSCLC and BRCA1-defective triple-negative breast cancer (TNBC) cells. Mechanistically, PARPi generated cytoplasmic chromatin fragments with characteristics of micronuclei; these were found to activate cGAS/STING, downstream type I IFN signaling, and CCL5 secretion. Importantly, these effects were suppressed in PARP1-null TNBC cells, suggesting that this phenotype resulted from an on-target effect of PARPi on PARP1. PARPi also potentiated IFN-γ–induced PD-L1 expression in NSCLC cell lines and in fresh patient tumor cells; this effect was enhanced in ERCC1-deficient contexts. Our data provide a preclinical rationale for using PARPi as immunomodulatory agents in appropriately molecularly selected populations.

Authors

Roman M. Chabanon, Gareth Muirhead, Dragomir B. Krastev, Julien Adam, Daphné Morel, Marlène Garrido, Andrew Lamb, Clémence Hénon, Nicolas Dorvault, Mathieu Rouanne, Rebecca Marlow, Ilirjana Bajrami, Marta Llorca Cardeñosa, Asha Konde, Benjamin Besse, Alan Ashworth, Stephen J. Pettitt, Syed Haider, Aurélien Marabelle, Andrew N.J. Tutt, Jean-Charles Soria, Christopher J. Lord, Sophie Postel-Vinay

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Figure 4

PARPi generate CCFs in a DNA repair defect– and cell cycle-dependent manner.

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PARPi generate CCFs in a DNA repair defect– and cell cycle-dependent man...
(A) Schematic of the generation of BRCA1-revertant and PARP1-knockout cell lines from the parental BRCA1-mutant SUM149 TNBC cell line. (B) Representative immunofluorescence images of DMSO-, Ruca-, and Ola-exposed SUM149-BRCA1mut and SUM149-PARP1–/– cells. Cells were exposed to 6 μM Ruca, 10 μM Ola, or DMSO (vehicle) during 72 hours. White arrows, CCFs; yellow arrows, micronuclei. Scale bars: 20 μm. (C) Automated quantification of CCFs in SUM149-BRCA1mut, SUM149-BRCA1rev, and SUM149-PARP1–/– cells exposed to increasing doses of Ruca or Ola (μM). Shown is CCF number per cell normalized to DMSO. Mean ± SD, n = 3, Kruskal-Wallis test and post hoc Dunn’s test, relative to DMSO control. Results shown are representative of 2 experiments performed with similar results. (D) Western blot of histone H3 in the nuclear and cytoplasmic fractions of SUM149-BRCA1mut and SUM149-PARP1–/– cells exposed to PARPi during 48 hours. β-Tubulin and lamin B1 were used as fraction purity controls. (E and F) Automated quantification of CCFs in A549-ERCC1WT/WT (E) and SUM149-BRCA1mut (F) cells exposed to increasing doses of Ruca or Ola (μM) in the presence or absence of the cell cycle blocker CDK1i RO-3306. Shown is CCF number per cell normalized to DMSO. Mean ± SD, n = 3, Kruskal-Wallis test and post hoc Dunn’s test, relative to DMSO control. *P < 0.05, **P < 0.01, ***P < 0.001.