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Updated: May 9, 2026
Silencing of BRCA2 to Identify Novel BRCA2-regulated Biological Functions in Cultured Human Cells
Published on: August 12, 2015
In vivo genetic circuit drives systemic PARP1 siRNA assembly into small extracellular vesicles for BRCA2-deficient
Ayesha Javed1, Uzair Ur-Rehman2, Ronglu Yuan1
1Nanjing Drum Tower Hospital Center of Molecular Diagnostic and Therapy, Chinese Academy of Medical Sciences Research Unit of Extracellular RNA, State Key Laboratory of Pharmaceutical Biotechnology, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, NJU Advanced Institute of Life Sciences (NAILS), Institute of Artificial Intelligence Biomedicine, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China.
Rationale:
BRCA2-mutant breast cancer is a major clinical challenge, with current poly ADP-ribose polymerase inhibitor (PARPi) therapies limited by systemic toxicity and acquired resistance. This study aimed to develop a RNA interference (RNAi) strategy to selectively inhibit PARP1 in breast tumors via a systemic, non-viral delivery platform.
Methods:
We designed a genetic circuit as a naked DNA plasmid, encoding a PARP1-specific siRNA embedded within a pre-miR-155 backbone under the control of a cytomegalovirus (CMV) promoter. Its therapeutic potential was assessed following intravenous injection in two orthotopic breast cancer models: an immunocompetent BRCA2-deficient model (E0771) and an immunodeficient BRCA2-mutant xenograft model (HCC1599).
Results:
The plasmid was predominantly taken up by the liver, where it reprogrammed hepatocytes to produce and package the PARP1 siRNA into endogenous small extracellular vesicles (sEVs) for systemic circulation. These sEVs demonstrated intrinsic tumor-homing capabilities, leading to efficient delivery and significant PARP1 gene silencing within breast tumors. This resulted in potent inhibition of tumor growth, accompanied by increased apoptosis and reduced proliferation in both preclinical models. The platform showed enhanced tumor specificity and a reduction in off-target effects compared to conventional small-molecule PARPi.
Conclusion:
We present a novel synthetic biology approach that leverages hepatic sEV production for the systemic delivery of siRNA to breast cancer. This strategy effectively suppresses tumor growth in BRCA2-deficient mice models and offers a promising therapeutic alternative with potential to overcome the limitations of current PARP inhibitor treatments for breast cancer.
Insights
A novel RNA interference (RNAi) strategy uses engineered liver cells to produce extracellular vesicles carrying PARP1 siRNA. This approach effectively targets BRCA2-mutant breast tumors, inhibiting growth and offering a promising alternative to current therapies.
Area of Science:
- Synthetic biology
- RNA interference (RNAi) therapeutics
- Extracellular vesicle (EV) biology
Background:
- BRCA2-mutant breast cancer presents significant clinical challenges.
- Current poly ADP-ribose polymerase inhibitor (PARPi) therapies face limitations due to toxicity and resistance.
- A need exists for targeted therapies with improved specificity and reduced side effects.
Purpose of the Study:
- To develop a novel RNA interference (RNAi) strategy for selective PARP1 inhibition in breast tumors.
- To create a systemic, non-viral delivery platform for RNAi therapeutics.
- To evaluate the therapeutic potential in preclinical models of BRCA2-mutant breast cancer.
Main Methods:
- Designed a genetic circuit encoding a PARP1-specific siRNA within a pre-miR-155 backbone.
- Utilized a cytomegalovirus (CMV) promoter for controlled gene expression.
- Assessed therapeutic efficacy via intravenous injection in orthotopic BRCA2-deficient and BRCA2-mutant breast cancer models.
Main Results:
- Engineered liver cells produced and packaged PARP1 siRNA into endogenous small extracellular vesicles (sEVs).
- These sEVs exhibited intrinsic tumor-homing capabilities, enabling efficient delivery and PARP1 gene silencing in breast tumors.
- Demonstrated potent tumor growth inhibition, increased apoptosis, and reduced proliferation with enhanced tumor specificity and fewer off-target effects.
Conclusions:
- A novel synthetic biology approach leverages hepatic sEV production for systemic siRNA delivery to breast cancer.
- This strategy effectively suppresses tumor growth in BRCA2-deficient models.
- Presents a promising therapeutic alternative to overcome limitations of current PARP inhibitor treatments.
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