American Association for Cancer Research
cd-23-0486_supplementary_figure_s5_suppsf5.pdf (517.68 kB)

Supplementary Figure S5 from Targeting DHX9 Triggers Tumor-Intrinsic Interferon Response and Replication Stress in Small Cell Lung Cancer

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journal contribution
posted on 2024-03-01, 12:00 authored by Takahiko Murayama, Jun Nakayama, Xinpei Jiang, Kenichi Miyata, Alexander D. Morris, Kathy Q. Cai, Rahul M. Prasad, Xueying Ma, Andrey Efimov, Neel Belani, Emily R. Gerstein, Yinfei Tan, Yan Zhou, William Kim, Reo Maruyama, Kerry S. Campbell, Lu Chen, Yibin Yang, Siddharth Balachandran, Israel Cañadas

CDK9 inhibition rescues the DHX9 depletion effect on cell survival by reducing replication stress


G. Harold and Leila Y. Mathers Foundation (Mathers Foundation)

National Institute of General Medical Sciences (NIGMS)

United States Department of Health and Human Services

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Lung Cancer Research Foundation (LCRF)

W. W. Smith Charitable Trust (The W. W. Smith Charitable Trust)



Activating innate immunity in cancer cells through cytoplasmic nucleic acid sensing pathways, a phenomenon known as “viral mimicry,” has emerged as an effective strategy to convert immunologically “cold” tumors into “hot.” Through a curated CRISPR-based screen of RNA helicases, we identified DExD/H-box helicase 9 (DHX9) as a potent repressor of double-stranded RNA (dsRNA) in small cell lung cancers (SCLC). Depletion of DHX9 induced accumulation of cytoplasmic dsRNA and triggered tumor-intrinsic innate immunity. Intriguingly, ablating DHX9 also induced aberrant accumulation of R-loops, which resulted in an increase of DNA damage–derived cytoplasmic DNA and replication stress in SCLCs. In vivo, DHX9 deletion promoted a decrease in tumor growth while inducing a more immunogenic tumor microenvironment, invigorating responsiveness to immune-checkpoint blockade. These findings suggest that DHX9 is a crucial repressor of tumor-intrinsic innate immunity and replication stress, representing a promising target for SCLC and other “cold” tumors in which genomic instability contributes to pathology. One promising strategy to trigger an immune response within tumors and enhance immunotherapy efficacy is by inducing endogenous “virus-mimetic” nucleic acid accumulation. Here, we identify DHX9 as a viral-mimicry-inducing factor involved in the suppression of double-stranded RNAs and R-loops and propose DHX9 as a novel target to enhance antitumor immunity.See related commentary by Chiappinelli, p. 389.This article is featured in Selected Articles from This Issue, p. 384

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