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Published on: January 31, 2018
LKB1 is a DNA damage response protein that regulates cellular sensitivity to PARP inhibitors
Yi-Shu Wang1, Jianfeng Chen2, Fengmei Cui2
1Key Laboratory of Pathobiology, Ministry of Education, Norman Bethune College of Medicine, Jilin University, Changchun, Jilin 130021, China.
Abstract:
Liver kinase B1 (LKB1) functions as a tumor suppressor encoded by STK11, a gene that mutated in Peutz-Jeghers syndrome and in sporadic cancers. Previous studies showed that LKB1 participates in IR- and ROS-induced DNA damage response (DDR). However, the impact of LKB1 mutations on targeted cancer therapy remains unknown. Herein, we demonstrated that LKB1 formed DNA damage-induced nuclear foci and co-localized with ataxia telangiectasia mutated kinase (ATM), γ-H2AX, and breast cancer susceptibility 1 (BRCA1). ATM mediated LKB1 phosphorylation at Thr 363 following the exposure of cells to ionizing radiation (IR). LKB1 interacted with BRCA1, a downstream effector in DDR that is recruited to sites of DNA damage and functions directly in homologous recombination (HR) DNA repair. LKB1 deficient cells exhibited delayed DNA repair due to insufficient HR. Notably, LKB1 deficiency sensitized cells to poly (ADP-ribose) polymerase (PARP) inhibitors. Thus, we have demonstrated a novel function of LKB1 in DNA damage response. Cancer cells lacking LKB1 are more susceptible to DNA damage-based therapy and, in particular, to drugs that further impair DNA repair, such as PARP inhibitors.
Insights
Liver kinase B1 (LKB1) is crucial for DNA damage repair. LKB1 deficiency delays DNA repair, making cancer cells more vulnerable to PARP inhibitors and other DNA-damaging therapies.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Liver kinase B1 (LKB1), encoded by STK11, is a known tumor suppressor.
- LKB1 plays a role in DNA damage response (DDR) pathways, including responses to ionizing radiation (IR) and reactive oxygen species (ROS).
- The specific impact of LKB1 mutations on cancer cells' response to targeted therapies is not well understood.
Purpose of the Study:
- To investigate the role of LKB1 in DNA damage response and its implications for cancer therapy.
- To determine how LKB1 mutations affect DNA repair mechanisms, particularly homologous recombination (HR).
- To assess the sensitivity of LKB1-deficient cancer cells to DNA-damaging agents, including PARP inhibitors.
Main Methods:
- Immunofluorescence to detect LKB1 foci formation and co-localization with DDR markers (ATM, γ-H2AX, BRCA1).
- Western blotting to analyze LKB1 phosphorylation.
- Cellular assays to assess DNA repair kinetics and homologous recombination efficiency in LKB1-deficient cells.
- Treatment of cancer cells with PARP inhibitors to evaluate drug sensitivity.
Main Results:
- LKB1 forms DNA damage-induced nuclear foci and co-localizes with key DDR proteins ATM, γ-H2AX, and BRCA1.
- ATM-mediated phosphorylation of LKB1 at Thr 363 occurs after IR exposure.
- LKB1 interacts with BRCA1, a critical protein in homologous recombination (HR) DNA repair.
- LKB1-deficient cells exhibit impaired DNA repair due to insufficient HR, leading to delayed repair.
- LKB1 deficiency significantly sensitizes cancer cells to poly (ADP-ribose) polymerase (PARP) inhibitors.
Conclusions:
- LKB1 has a novel and critical function in the DNA damage response, particularly in facilitating homologous recombination repair.
- LKB1 deficiency compromises DNA repair, rendering cancer cells more susceptible to DNA damage-based therapies.
- Targeting LKB1-deficient cancers with PARP inhibitors represents a promising therapeutic strategy due to enhanced sensitivity.
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