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Updated: Feb 4, 2026
Analysis of DNA Double-strand Break DSB Repair in Mammalian Cells
Published on: September 8, 2010
Pyruvate kinase M2 regulates homologous recombination-mediated DNA double-strand break repair
Steven T Sizemore1, Manchao Zhang2, Ju Hwan Cho1
1Department of Radiation Oncology, Arthur G James Comprehensive Cancer Center and Richard L. Solove Research Institute, The Ohio State University Medical Center, Columbus, OH, 43210, USA.
Abstract:
Resistance to genotoxic therapies is a primary cause of treatment failure and tumor recurrence. The underlying mechanisms that activate the DNA damage response (DDR) and allow cancer cells to escape the lethal effects of genotoxic therapies remain unclear. Here, we uncover an unexpected mechanism through which pyruvate kinase M2 (PKM2), the highly expressed PK isoform in cancer cells and a master regulator of cancer metabolic reprogramming, integrates with the DDR to directly promote DNA double-strand break (DSB) repair. In response to ionizing radiation and oxidative stress, ATM phosphorylates PKM2 at T328 resulting in its nuclear accumulation. pT328-PKM2 is required and sufficient to promote homologous recombination (HR)-mediated DNA DSB repair through phosphorylation of CtBP-interacting protein (CtIP) on T126 to increase CtIP's recruitment at DSBs and resection of DNA ends. Disruption of the ATM-PKM2-CtIP axis sensitizes cancer cells to a variety of DNA-damaging agents and PARP1 inhibition. Furthermore, increased nuclear pT328-PKM2 level is associated with significantly worse survival in glioblastoma patients. Combined, these data advocate the use of PKM2-targeting strategies as a means to not only disrupt cancer metabolism but also inhibit an important mechanism of resistance to genotoxic therapies.
Insights
Pyruvate kinase M2 (PKM2) directly aids cancer cells in repairing DNA damage, promoting resistance to genotoxic therapies. Targeting PKM2 could overcome this resistance and improve cancer treatment outcomes.
Area of Science:
- Molecular Biology
- Cancer Research
- Genetics
Background:
- Resistance to genotoxic therapies is a major challenge in cancer treatment, leading to treatment failure and recurrence.
- The mechanisms by which cancer cells activate the DNA damage response (DDR) and evade lethal effects of genotoxic therapies are not fully understood.
Purpose of the Study:
- To investigate the role of pyruvate kinase M2 (PKM2) in the DNA damage response and its contribution to therapeutic resistance.
- To elucidate the molecular mechanism by which PKM2 promotes DNA double-strand break (DSB) repair.
Main Methods:
- Investigated the interaction between PKM2 and the DDR pathway using cell culture models exposed to ionizing radiation and oxidative stress.
- Utilized phosphorylation site analysis (T328 on PKM2, T126 on CtIP) and assessed the recruitment of proteins to DSBs.
- Examined the impact of disrupting the ATM-PKM2-CtIP axis on cancer cell sensitivity to DNA-damaging agents and PARP1 inhibition.
- Correlated nuclear PKM2 levels with patient survival data in glioblastoma.
Main Results:
- PKM2 is phosphorylated by ATM at T328 in response to DNA damage, leading to its nuclear accumulation.
- Nuclear pT328-PKM2 directly promotes homologous recombination (HR)-mediated DSB repair by phosphorylating CtIP, enhancing its recruitment to DSBs and DNA end resection.
- Disrupting the ATM-PKM2-CtIP pathway sensitizes cancer cells to genotoxic agents and PARP1 inhibitors.
- Elevated nuclear pT328-PKM2 levels correlate with poorer survival in glioblastoma patients.
Conclusions:
- PKM2 acts as a critical mediator integrating metabolic reprogramming with the DNA damage response to promote cancer cell survival.
- The ATM-PKM2-CtIP axis represents a novel mechanism of resistance to genotoxic therapies.
- Targeting PKM2 offers a potential therapeutic strategy to overcome resistance to DNA-damaging agents and improve glioblastoma treatment.
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