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Updated: Jan 2, 2026
Silencing of BRCA2 to Identify Novel BRCA2-regulated Biological Functions in Cultured Human Cells
Published on: August 12, 2015
Significance of BRCA2 and RB1 Co-loss in Aggressive Prostate Cancer Progression
Goutam Chakraborty1, Joshua Armenia2, Ying Z Mazzu1
1Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York.
Purpose:
Previous sequencing studies revealed that alterations of genes associated with DNA damage response (DDR) are enriched in men with metastatic castration-resistant prostate cancer (mCRPC). BRCA2, a DDR and cancer susceptibility gene, is frequently deleted (homozygous and heterozygous) in men with aggressive prostate cancer. Here we show that patients with prostate cancer who have lost a copy of BRCA2 frequently lose a copy of tumor suppressor gene RB1; importantly, for the first time, we demonstrate that co-loss of both genes in early prostate cancer is sufficient to induce a distinct biology that is likely associated with worse prognosis.
Experimental Design:
We prospectively investigated underlying molecular mechanisms and genomic consequences of co-loss of BRCA2 and RB1 in prostate cancer. We used CRISPR-Cas9 and RNAi-based methods to eliminate these two genes in prostate cancer cell lines and subjected them to in vitro studies and transcriptomic analyses. We developed a 3-color FISH assay to detect genomic deletions of BRCA2 and RB1 in prostate cancer cells and patient-derived mCRPC organoids.
Results:
In human prostate cancer cell lines (LNCaP and LAPC4), loss of BRCA2 leads to the castration-resistant phenotype. Co-loss of BRCA2-RB1 in human prostate cancer cells induces an epithelial-to-mesenchymal transition, which is associated with invasiveness and a more aggressive disease phenotype. Importantly, PARP inhibitors attenuate cell growth in human mCRPC-derived organoids and human CRPC cells harboring single-copy loss of both genes.
Conclusions:
Our findings suggest that early identification of this aggressive form of prostate cancer offers potential for improved outcomes with early introduction of PARP inhibitor-based therapy.See related commentary by Mandigo and Knudsen, p. 1784.
Insights
Loss of BRCA2 and RB1 genes in early prostate cancer drives aggressive disease. Co-loss promotes invasiveness and suggests early PARP inhibitor therapy for improved outcomes in metastatic castration-resistant prostate cancer.
Area of Science:
- Oncology
- Genetics
- Molecular Biology
Background:
- Alterations in DNA damage response (DDR) genes are common in metastatic castration-resistant prostate cancer (mCRPC).
- BRCA2, a DDR gene, is frequently deleted in aggressive prostate cancer.
- Co-deletion of BRCA2 and the tumor suppressor gene RB1 is observed in prostate cancer patients.
Purpose of the Study:
- To investigate the molecular mechanisms and genomic consequences of BRCA2 and RB1 co-deletion in prostate cancer.
- To determine if co-loss of BRCA2 and RB1 is sufficient to induce a distinct, aggressive biology.
- To evaluate the therapeutic potential of PARP inhibitors in prostate cancer with BRCA2 and RB1 co-deletion.
Main Methods:
- Utilized CRISPR-Cas9 and RNAi to eliminate BRCA2 and RB1 in prostate cancer cell lines.
- Performed in vitro studies and transcriptomic analyses.
- Developed a 3-color FISH assay to detect genomic deletions in cell lines and patient-derived organoids.
Main Results:
- Loss of BRCA2 in prostate cancer cells induced a castration-resistant phenotype.
- Co-loss of BRCA2 and RB1 triggered an epithelial-to-mesenchymal transition, increasing invasiveness and aggressiveness.
- PARP inhibitors reduced cell growth in mCRPC organoids and cells with single-copy loss of both genes.
Conclusions:
- Co-loss of BRCA2 and RB1 in early prostate cancer creates a distinct biology associated with worse prognosis.
- Early identification of this genetic alteration may allow for timely intervention with PARP inhibitor therapy.
- This suggests a potential for improved outcomes in mCRPC through targeted therapy based on genetic profiling.
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