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Author Spotlight: Tracing the Ferroptotic Signatures and Cell Death Dynamics in Medulloblastoma for Advanced Therapeutics
Published on: March 15, 2024
Targeting GPX4-mediated ferroptosis protection sensitizes BRCA1-deficient cancer cells to PARP inhibitors
Xuexia Xie1, Congcong Chen2, Cong Wang3
1School of Biopharmacy, China Pharmaceutical University, Nanjing, 211198, China; Department of Anesthesiology and General Surgery, The First Affiliated Hospital of Jinan University, 510632, Guangzhou, China.
Abstract:
BRCA1 is one of the most frequently-mutated tumor suppressor genes in ovarian and breast cancers. Loss of BRCA1 triggers homologous recombination (HR) repair deficiency, consequently leading to genomic instability and PARP inhibitors (PARPi)-associated synthetic lethality. Although, the roles of BRCA1 in DNA repair and replication have been extensively investigated, its tumor suppressive functions beyond genome safeguard remain poorly understood. Here, we report that BRCA1 promotes ferroptosis susceptibility through catalyzing K6-linked polyubiquitination of GPX4 and subsequently accelerating GPX4 degradation. Depletion of BRCA1 induces ferroptosis resistance in ovarian cancer cells due to elevated GPX4 protein, and silence of GPX4 significantly suppresses the growth of BRCA1-deficient ovarian cancer xenografts. Importantly, we found that PARPi triggers ferroptosis in ovarian cancer cells, inhibition of GPX4 markedly increase PARPi-induced ferroptosis in BRCA1-deficient ovarian cancer cells. Combined treatment of GPX4 inhibitor and PARPi produces synergistic anti-tumor efficacy in BRCA1-deficient ovarian cancer cells, patient derived organoid (PDO) and xenografts. Thus, our study uncovers a novel mechanism via which BRCA1 exerts tumor suppressive function through regulating ferroptosis, and demonstrates the potential of GPX4 as a therapeutic target for BRCA1-mutant cancers.
Insights
BRCA1 loss in ovarian cancer increases resistance to ferroptosis by elevating GPX4 protein. Targeting GPX4 with inhibitors synergizes with PARP inhibitors (PARPi) to treat BRCA1-mutant cancers.
Area of Science:
- Molecular Oncology
- Cancer Therapeutics
- DNA Repair Mechanisms
Background:
- BRCA1 mutations are common in ovarian and breast cancers, leading to homologous recombination (HR) deficiency and genomic instability.
- While BRCA1's role in DNA repair is established, its broader tumor suppressive functions, particularly in regulating cell death pathways, are less understood.
- Understanding novel BRCA1 functions is crucial for developing effective therapeutic strategies against BRCA1-mutant cancers.
Purpose of the Study:
- To investigate the role of BRCA1 in regulating ferroptosis, a form of programmed cell death.
- To explore the therapeutic potential of targeting ferroptosis in BRCA1-deficient ovarian cancers.
- To identify novel mechanisms underlying BRCA1's tumor suppressive activity beyond genome maintenance.
Main Methods:
- Investigated BRCA1's role in ferroptosis by examining its effect on GPX4 protein levels and degradation.
- Utilized genetic manipulation (depletion/silencing) of BRCA1 and GPX4 in ovarian cancer cell lines and xenograft models.
- Assessed the impact of ferroptosis regulators and PARP inhibitors (PARPi) on cancer cell viability and tumor growth, including combination therapies.
Main Results:
- BRCA1 loss confers resistance to ferroptosis by increasing GPX4 protein levels, which protects cells from ferroptosis.
- GPX4 silencing significantly inhibited the growth of BRCA1-deficient ovarian cancer xenografts.
- PARPi treatment induced ferroptosis in ovarian cancer cells, and inhibiting GPX4 enhanced this effect, leading to synergistic anti-tumor activity with PARPi.
Conclusions:
- BRCA1 promotes ferroptosis susceptibility by catalyzing GPX4 ubiquitination and degradation, thus acting as a tumor suppressor through ferroptosis regulation.
- GPX4 is a critical mediator of ferroptosis resistance in BRCA1-deficient ovarian cancers.
- Combined inhibition of GPX4 and PARPi represents a promising therapeutic strategy for BRCA1-mutant ovarian cancers.
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