Utility of DNA Repair Protein Foci for the Detection of Putative BRCA1 Pathway Defects in Breast Cancer Biopsies

Willers, Henning; Taghian, Alphonse G.; Luo, Chenmei; Treszezamsky, Alejandro D.; Sgroi, Dennis; Powell, Simon N.

doi:10.1158/1541-7786.mcr-09-0149

Cited by 104 publications

(90 citation statements)

References 28 publications

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“…This percentage is lower than some estimates described in other publications, which report that up to 25% of sporadic breast cancers have a BRCAness phenotype and might be related to a possible HR deficiency (38). Other research groups report even higher percentages of primary breast tumors to have impaired HR based on a RAD51 focus formation assay (35,39,40). There are several explanations for these discrepancies.…”

Section: Discussioncontrasting

confidence: 55%

Functional Ex Vivo Assay to Select Homologous Recombination–Deficient Breast Tumors for PARP Inhibitor Treatment

Naipal

Verkaik

Ameziane

et al. 2014

Clinical Cancer Research

146

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Purpose: Poly(ADP-ribose) polymerase (PARP) inhibitors are promising targeted treatment options for hereditary breast tumors with a homologous recombination (HR) deficiency caused by BRCA1 or BRCA2 mutations. However, the functional consequence of BRCA gene mutations is not always known and tumors can be HR deficient for other reasons than BRCA gene mutations. Therefore, we aimed to develop a functional test to determine HR activity in tumor samples to facilitate selection of patients eligible for PARP inhibitor treatment.Experimental design: We obtained 54 fresh primary breast tumor samples from patients undergoing surgery. We determined their HR capacity by studying the formation of ionizing radiation induced foci (IRIF) of the HR protein RAD51 after ex vivo irradiation of these organotypic breast tumor samples. Tumors showing impaired RAD51 IRIF formation were subjected to genetic and epigenetic analysis.Results: Five of 45 primary breast tumors with sufficient numbers of proliferating tumor cells were RAD51 IRIF formation deficient (11%, 95% CI, 5%-24%). This HR defect was significantly associated with triple-negative breast cancer (OR, 57; 95% CI, 3.9-825; P ¼ 0.003). Two of five HR-deficient tumors were not caused by mutations in the BRCA genes, but by BRCA1 promoter hypermethylation.Conclusion: The functional RAD51 IRIF assay faithfully identifies HR-deficient tumors and has clear advantages over gene sequencing. It is a relatively easy assay that can be performed on biopsy material, making it a powerful tool to select patients with an HR-deficient cancer for PARP inhibitor treatment in the clinic. Clin Cancer Res; 20(18); 4816-26. Ó2014 AACR.

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Section: Discussioncontrasting

confidence: 55%

Functional Ex Vivo Assay to Select Homologous Recombination–Deficient Breast Tumors for PARP Inhibitor Treatment

Naipal

Verkaik

Ameziane

et al. 2014

Clinical Cancer Research

146

View full text Add to dashboard Cite

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“…Methods to functionally characterize HR deficiency in fresh tumor samples offer a 'gold standard' for assessing HR, but are technically difficult and at this time not feasible to scale in a clinical setting. Powell and colleagues demonstrated that lack of RAD51 foci after ex vivo ionizing radiation on fresh breast cancer samples was significantly associated with genomic scars (LOH, LST, TAI) and biallelic inactivation of DNA repair genes [40]. In a prospective series, 16/56 (29%) primary breast tumors revealed defective RAD51 recruitment following irradiation [41].…”

Section: Additional Potential Hr Deficiency Biomarkers: Expression Simentioning

confidence: 99%

Homologous recombination deficiency and host anti-tumor immunity in triple-negative breast cancer

Telli

Stover

Loi

et al. 2018

Breast Cancer Res Treat

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Purpose Triple-negative breast cancer (TNBC) is associated with worse outcomes relative to other breast cancer subtypes. Chemotherapy remains the standard-of-care systemic therapy for patients with localized or metastatic disease, with few biomarkers to guide benefit. Methods We will discuss recent advances in our understanding of two key biological processes in TNBC, homologous recombination (HR) DNA repair deficiency and host anti-tumor immunity, and their intersection. Results Recent advances in our understanding of homologous recombination (HR) deficiency, including FDA approval of PARP inhibitor olaparib for BRCA1 or BRCA2 mutation carriers, and host anti-tumor immunity in TNBC offer potential for new and biomarker-driven approaches to treat TNBC. Assays interrogating HR DNA repair capacity may guide treatment with agents inducing or targeting DNA damage repair. Tumor infiltrating lymphocytes (TILs) are associated with improved prognosis in TNBC and recent efforts to characterize infiltrating immune cell subsets and activate host anti-tumor immunity offer promise, yet challenges remain particularly in tumors lacking pre-existing immune infiltrates. Advances in these fields provide potential biomarkers to stratify patients with TNBC and guide therapy: induction of DNA damage in HR-deficient tumors and activation of existing or recruitment of host anti-tumor immune cells. Importantly, these advances provide an opportunity to guide use of existing therapies and development of novel therapies for TNBC. Efforts to combine therapies that exploit HR deficiency to enhance the activity of immune-directed therapies offer promise. Conclusions HR deficiency remains an important biomarker target and potentially effective adjunct to enhance immunogenicity of 'immune cold' TNBCs.

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“…In response to DNA damage, BRCA1 assembles into nuclear foci, and these structures appear to be a prerequisite for efficient HR. Monitoring the formation of BRCA1 foci is frequently used to estimate DNA repair/recombination in different situations, including in tumor cells (21)(22)(23)(24)(25)(26). Because Bcl-2 impacts HR, we investigated the effects of Bcl-2 on the formation of endogenous BRCA1 foci induced by ionizing radiation (IR).…”

Section: Bcl-2 Inhibits the Formation Of Brca1 Focimentioning

confidence: 99%

Bcl-2 Inhibits Nuclear Homologous Recombination by Localizing BRCA1 to the Endomembranes

et al. 2011

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Genetic stability requires coordination of a network of pathways including DNA repair/recombination and apoptosis. In addition to its canonical anti-apoptotic role, Bcl-2 negatively impacts genome stability. In this study, we identified the breast cancer tumor suppressor BRCA1, which plays an essential role in homologous recombination (HR), as a target for Bcl-2 in the repression of HR. Indeed, ionizing radiation-induced BRCA1 foci assembly was repressed when Bcl-2 was expressed ectopically, in human SV40 fibroblasts, or spontaneously, in lymphoma t(14:18) cells and in HeLa and H460 cancer cell lines. Moreover, we showed that the transmembrane (TM) domain of Bcl-2 was required for both inhibition of BRCA1 foci assembly and the inhibition of HR induced by a double-strand break targeted into an intrachromosomal HR substrate by the meganuclease I-SceI. Fluorescence confocal microscopy, proximity ligation assay, and electron microscopy analyses as well as Western blot analysis of subcellular fractions showed that Bcl-2 and BRCA1 colocalized to mitochondria and endoplasmic reticulum in a process requiring the TM domain of Bcl-2. Targeting BRCA1 to the endomembranes depletes BRCA1 from the nucleus and, thus, accounts for the inhibition of HR. Furthermore, our findings support an apoptosis-stimulatory role for the cytosolic form of BRCA1, suggesting a new tumor suppressor function of BRCA1. Together, our results reveal a new mode of BRCA1 regulation and for HR in the maintenance of genome stability. Cancer Res; 71(10); 3590-602. Ó2011 AACR.

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Utility of DNA Repair Protein Foci for the Detection of Putative BRCA1 Pathway Defects in Breast Cancer Biopsies

Cited by 104 publications

References 28 publications

Functional Ex Vivo Assay to Select Homologous Recombination–Deficient Breast Tumors for PARP Inhibitor Treatment

Functional Ex Vivo Assay to Select Homologous Recombination–Deficient Breast Tumors for PARP Inhibitor Treatment

Homologous recombination deficiency and host anti-tumor immunity in triple-negative breast cancer

Bcl-2 Inhibits Nuclear Homologous Recombination by Localizing BRCA1 to the Endomembranes

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