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Updated: Aug 14, 2025

Characterizing DNA Repair Processes at Transient and Long-lasting Double-strand DNA Breaks by Immunofluorescence Microscopy
Published on: June 8, 2018
Cancer Cell Resistance to IFNγ Can Occur via Enhanced Double-Strand Break Repair Pathway Activity
Tong Han1, Xujun Wang2, Sailing Shi1
1Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration, Ministry of Education, Department of Orthopedics, Tongji Hospital, Frontier Science Center for Stem Cells, School of Life Science and Technology, Tongji University, China.
Abstract:
The pleiotropic cytokine interferon-gamma (IFNγ) is associated with cytostatic, antiproliferation, and proapoptotic functions in cancer cells. However, resistance to IFNγ occurs in many cancer cells, and the underlying mechanism is not fully understood. To investigate potential IFNγ-resistance mechanisms, we performed IFNγ-sensitivity screens in more than 40 cancer cell lines and characterized the sensitive and resistant cell lines. By applying CRISPR screening and transcriptomic profiling in both IFNγ-sensitive and IFNγ-resistant cells, we discovered that activation of double-strand break (DSB) repair genes could result in IFNγ resistance in cancer cells. Suppression of single-strand break (SSB) repair genes increased the dependency on DSB repair genes after IFNγ treatment. Furthermore, inhibition of the DSB repair pathway exhibited a synergistic effect with IFNγ treatment both in vitro and in vivo. The relationship between the activation of DSB repair genes and IFNγ resistance was further confirmed in clinical tumor profiles from The Cancer Genome Atlas (TCGA) and immune checkpoint blockade (ICB) cohorts. Our study provides comprehensive resources and evidence to elucidate a mechanism of IFNγ resistance in cancer and has the potential to inform combination therapies to overcome immunotherapy resistance.
Insights
Cancer cells can resist interferon-gamma (IFNγ) therapy by activating double-strand break (DSB) repair genes. Inhibiting DSB repair enhances IFNγ effectiveness, offering new combination therapy strategies for cancer treatment.
Area of Science:
- Oncology
- Molecular Biology
- Immunotherapy
Background:
- Interferon-gamma (IFNγ) exhibits anti-cancer properties, including cytostatic and proapoptotic effects.
- However, many cancer cells develop resistance to IFNγ, limiting its therapeutic efficacy.
- The molecular mechanisms underlying IFNγ resistance remain incompletely understood.
Purpose of the Study:
- To investigate the mechanisms of IFNγ resistance in cancer cells.
- To identify potential therapeutic strategies to overcome IFNγ resistance.
Main Methods:
- Conducted IFNγ-sensitivity screens across over 40 cancer cell lines.
- Utilized CRISPR screening and transcriptomic profiling to compare sensitive and resistant cells.
- Validated findings in The Cancer Genome Atlas (TCGA) and immune checkpoint blockade (ICB) cohorts.
Main Results:
- Activation of double-strand break (DSB) repair genes was identified as a mechanism conferring IFNγ resistance.
- Suppression of single-strand break (SSB) repair genes increased reliance on DSB repair pathways post-IFNγ treatment.
- Inhibition of DSB repair pathways synergized with IFNγ treatment in vitro and in vivo.
Conclusions:
- DSB repair gene activation is a key driver of IFNγ resistance in cancer.
- Targeting DSB repair pathways in combination with IFNγ holds promise for overcoming immunotherapy resistance.
- This study provides evidence for novel combination therapies against cancer.
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