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Updated: Jul 12, 2025
Identifying the Effects of BRCA1 Mutations on Homologous Recombination using Cells that Express Endogenous Wild-type BRCA1
Published on: February 17, 2011
An activity-based functional test for identifying homologous recombination deficiencies across cancer types in real
Chih-Ying Lee1, Wen-Fang Cheng2, Po-Han Lin3
1Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.
Abstract:
Homologous recombination (HR)-mediated DNA repair is a prerequisite for maintaining genome stability. Cancer cells displaying HR deficiency (HRD) are selectively eliminated by poly(ADP-ribose) polymerase inhibitors (PARPis). To date, sequencing of HR-associated genes and analyzing genome instability have been used as clinical predictions for PARPi therapy. However, these genetic tests cannot reflect dynamic changes in the HR status. Here, we have developed a virus- and activity-based functional assay to quantify real-time HR activity directly. Instead of focusing on a few HR-associated genes, our functional assay detects endpoint HR activity and establishes an activity threshold for identifying HRD across cancer types, validated by PARPi sensitivity and BRCA status. Notably, this fluorescence-based assay can be applied to primary ovarian cancer cells from patients to reflect their level of HRD, which is associated with survival benefits. Thus, our work provides a functional test to predict the response of primary cancer cells to PARPis.
Insights
A new functional assay quantifies real-time homologous recombination (HR) activity, identifying HR deficiency (HRD) for predicting cancer treatment response. This method offers a dynamic alternative to genetic tests for PARPi therapy selection.
Area of Science:
- Molecular Biology
- Genetics
- Oncology
Background:
- Homologous recombination (HR) is crucial for genome stability.
- HR deficiency (HRD) makes cancer cells sensitive to poly(ADP-ribose) polymerase inhibitors (PARPis).
- Current genetic tests for HRD lack dynamic assessment of HR status.
Purpose of the Study:
- To develop a functional assay for real-time quantification of HR activity.
- To establish a method for identifying HRD across cancer types.
- To predict patient response to PARPi therapy.
Main Methods:
- Developed a virus- and activity-based functional assay.
- Quantified real-time HR activity using fluorescence.
- Established an HR activity threshold for HRD identification.
- Validated the assay with PARPi sensitivity and BRCA status in primary ovarian cancer cells.
Main Results:
- The functional assay directly quantifies HR activity.
- An activity threshold effectively identifies HRD across various cancer types.
- The assay's results correlate with PARPi sensitivity and BRCA status.
- Applied to primary ovarian cancer cells, the assay reflects patient HRD levels and predicts survival benefits.
Conclusions:
- The developed functional assay provides a direct measure of HR activity.
- This assay serves as a valuable tool for identifying HRD and predicting PARPi therapy response.
- The method is applicable to primary cancer cells, offering personalized treatment prediction.
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