Anne-Renee Hartman

BRCA1 induces DNA damage recognition factors and enhances nucleotide excision repair

Inheritance of a mutation in the gene BRCA1 confers on women a 50–85% lifetime risk of developing breast cancer. Mutations in the TP53 tumor-suppressor gene are found in 70–80% of BRCA1-mutated breast cancer but only 30% of those with wildtype BRCA1 (ref. 3). The p53 protein regulates nucleotide excision repair (NER) through transcriptional regulation of genes involved in the recognition of adducts in genomic DNA. Loss of p53 function results in deficient global genomic repair (GGR), a subset of NER that targets and removes lesions from the whole genome. Here we show that BRCA1 specifically enhances the GGR pathway, independent of p53, and can induce p53-independent expression of the NER genes XPC, DDB2, and GADD45. Defects in the NER pathway in BRCA1-associated breast cancers may be causal in tumor development, suggesting a multistep model of carcinogenesis.

Frequency of mutations in individuals with breast cancer referred for BRCA1 and BRCA2 testing using next‐generation sequencing with a 25‐gene panel

Next‐generation sequencing (NGS) allows for simultaneous sequencing of multiple cancer susceptibility genes and, for an individual, may be more efficient and less expensive than sequential testing. The authors assessed the frequency of deleterious germline mutations among individuals with breast cancer who were referred for BRCA1 and BRCA2 (BRCA1/2) gene testing using a panel of 25 genes associated with inherited cancer predisposition.

Chemosensitization to cisplatin by inhibitors of the Fanconi anemia/BRCA pathway

Cisplatin resistance occurs, at least in part, through the function of the Fanconi anemia (FA)/BRCA pathway, a DNA-damage response pathway required for repair of cisplatin cross-links. In the current study, we designed a cell-based screening strategy to identify small-molecule inhibitors of the FA/BRCA pathway with the hypothesis that such molecules could restore sensitivity to platinum agents. We identified four inhibitors, including three protein kinase inhibitors (wortmannin, H-9, and alsterpaullone) and one natural compound (curcumin) that inhibit the FA/BRCA pathway. We show that curcumin, a compound that is generally regarded as safe, inhibits the monoubiquitination of the FANCD2 protein as predicted by the screen and consequently sensitizes ovarian and breast tumor cell lines to cisplatin through apoptotic cell death. We believe that this study shows an efficient, high-throughput method for identifying new compounds that may sensitize cancer cells to DNA-damaging chemotherapy. [Mol Cancer Ther 2006;5(4):952–61]

Prevalence of BRCA mutations in an unselected population of triple-negative breast cancer

This study assessed BRCA1 and BRCA2 mutation prevalence in an unselected cohort of patients with triple‐negative breast cancer (BC).

Homologous Recombination Deficiency (HRD) Score Predicts Response to Platinum-Containing Neoadjuvant Chemotherapy in Patients with Triple-Negative Breast Cancer

Purpose: BRCA1/2-mutated and some sporadic triple-negative breast cancers (TNBC) have DNA repair defects and are sensitive to DNA-damaging therapeutics. Recently, three independent DNA-based measures of genomic instability were developed on the basis of loss of heterozygosity (LOH), telomeric allelic imbalance (TAI), and large-scale state transitions (LST). Experimental Design: We assessed a combined homologous recombination deficiency (HRD) score, an unweighted sum of LOH, TAI, and LST scores, in three neoadjuvant TNBC trials of platinum-containing therapy. We then tested the association of HR deficiency, defined as HRD score ≥42 or BRCA1/2 mutation, with response to platinum-based therapy. Results: In a trial of neoadjuvant platinum, gemcitabine, and iniparib, HR deficiency predicted residual cancer burden score of 0 or I (RCB 0/I) and pathologic complete response (pCR; OR = 4.96, P = 0.0036; OR = 6.52, P = 0.0058). HR deficiency remained a significant predictor of RCB 0/I when adjusted for clinical variables (OR = 5.86, P = 0.012). In two other trials of neoadjuvant cisplatin therapy, HR deficiency predicted RCB 0/I and pCR (OR = 10.18, P = 0.0011; OR = 17.00, P = 0.0066). In a multivariable model of RCB 0/I, HR deficiency retained significance when clinical variables were included (OR = 12.08, P = 0.0017). When restricted to BRCA1/2 nonmutated tumors, response was higher in patients with high HRD scores: RCB 0/I P = 0.062, pCR P = 0.063 in the neoadjuvant platinum, gemcitabine, and iniparib trial; RCB 0/I P = 0.0039, pCR P = 0.018 in the neoadjuvant cisplatin trials. Conclusions: HR deficiency identifies TNBC tumors, including BRCA1/2 nonmutated tumors more likely to respond to platinum-containing therapy. Clin Cancer Res; 22(15); 3764–73. ©2016 AACR.

Frequency of Germline Mutations in 25 Cancer Susceptibility Genes in a Sequential Series of Patients With Breast Cancer

PURPOSE Testing for germline mutations in BRCA1/2 is standard for select patients with breast cancer to guide clinical management. Next-generation sequencing (NGS) allows testing for mutations in additional breast cancer predisposition genes. The frequency of germline mutations detected by using NGS has been reported in patients with breast cancer who were referred for BRCA1/2 testing or with triple-negative breast cancer. We assessed the frequency and predictors of mutations in 25 cancer predisposition genes, including BRCA1/2, in a sequential series of patients with breast cancer at an academic institution to examine the utility of genetic testing in this population. METHODS Patients with stages I to III breast cancer who were seen at a single cancer center between 2010 and 2012, and who agreed to participate in research DNA banking, were included (N = 488). Personal and family cancer histories were collected and germline DNA was sequenced with NGS to identify mutations. RESULTS Deleterious mutations were identified in 10.7% of women, including 6.1% in BRCA1/2 (5.1% in non-Ashkenazi Jewish patients) and 4.6% in other breast/ovarian cancer predisposition genes including CHEK2 (n = 10), ATM (n = 4), BRIP1 (n = 4), and one each in PALB2, PTEN, NBN, RAD51C, RAD51D, MSH6, and PMS2. Whereas young age (P < .01), Ashkenazi Jewish ancestry (P < .01), triple-negative breast cancer (P = .01), and family history of breast/ovarian cancer (P = .01) predicted for BRCA1/2 mutations, no factors predicted for mutations in other breast cancer predisposition genes. CONCLUSION Among sequential patients with breast cancer, 10.7% were found to have a germline mutation in a gene that predisposes women to breast or ovarian cancer, using a panel of 25 predisposition genes. Factors that predict for BRCA1/2 mutations do not predict for mutations in other breast/ovarian cancer susceptibility genes when these genes are analyzed as a single group. Additional cohorts will be helpful to define individuals at higher risk of carrying mutations in genes other than BRCA1/2.

Cancer Susceptibility Gene Mutations in Individuals With Colorectal Cancer

Purpose Hereditary factors play an important role in colorectal cancer (CRC) risk, yet the prevalence of germline cancer susceptibility gene mutations in patients with CRC unselected for high-risk features (eg, early age at diagnosis, personal/family history of cancer or polyps, tumor microsatellite instability [MSI], mismatch repair [MMR] deficiency) is unknown. Patients and Methods We recruited 1,058 participants who received CRC care in a clinic-based setting without preselection for age at diagnosis, personal/family history, or MSI/MMR results. All participants underwent germline testing for mutations in 25 genes associated with inherited cancer risk. Each gene was categorized as high penetrance or moderate penetrance on the basis of published estimates of the lifetime cancer risks conferred by pathogenic germline mutations in that gene. Results One hundred five (9.9%; 95% CI, 8.2% to 11.9%) of 1,058 participants carried one or more pathogenic mutations, including 33 (3.1%) with Lynch syndrome (LS). Twenty-eight (96.6%) of 29 available LS CRCs demonstrated abnormal MSI/MMR results. Seventy-four (7.0%) of 1,058 participants carried non-LS gene mutations, including 23 (2.2%) with mutations in high-penetrance genes (five APC, three biallelic MUTYH, 11 BRCA1/2, two PALB2, one CDKN2A, and one TP53), 15 of whom lacked clinical histories suggestive of their underlying mutation. Thirty-eight (3.6%) participants had moderate-penetrance CRC risk gene mutations (19 monoallelic MUTYH, 17 APC*I1307K, two CHEK2). Neither proband age at CRC diagnosis, family history of CRC, nor personal history of other cancers significantly predicted the presence of pathogenic mutations in non-LS genes. Conclusion Germline cancer susceptibility gene mutations are carried by 9.9% of patients with CRC. MSI/MMR testing reliably identifies LS probands, although 7.0% of patients with CRC carry non-LS mutations, including 1.0% with BRCA1/2 mutations.

BRCA1 and p53: compensatory roles in DNA repair

The BRCA1 breast cancer susceptibility gene has been implicated in many cellular processes, yet its specific mechanism of tumor suppression remains unclear. BRCA1 plays a role in several DNA repair pathways including nucleotide excision repair (NER). Loss of the p53 tumor suppressor gene, a key regulator of NER, is an important and necessary event in the pathogenesis of BRCA1-mutated tumors. Here we discuss the role of BRCA1 and NER in breast cancer and the interactions of BRCA1 with p53 in breast tumorigenesis and suggest approaches for risk assessment and chemotherapeutic management of BRCA1-related breast cancer.

Ductal Lavage of Fluid-Yielding and Non–Fluid-Yielding Ducts in BRCA1 and BRCA2 Mutation Carriers and Other Women at High Inherited Breast Cancer Risk

Objective: Nipple fluid production and atypical breast duct cells in women at high risk of breast cancer have been associated with further increased risk. Most publications on ductal lavage for cell collection report cannulating fluid-yielding ducts only. We report lavage of fluid-yielding and non–fluid-yielding ducts in women at high inherited breast cancer risk. Methods: A pilot breast cancer screening study including ductal lavage was conducted in 75 women at high inherited risk, 56 (74.7%) of whom had BRCA1/2 mutations. Ductal lavage was attempted in any duct identifiable with a catheter. Results: Ducts were successfully catheterized in 60 of 75 patients (80%). Successfully catheterized patients were younger (median age 41 versus 53 years, P = 0.0003) and more often premenopausal (51.7% versus 20%, P = 0.041). Thirty-one successfully catheterized patients [51.6%, 95% confidence interval (39.4-63.9%)] had non–fluid-yielding ducts only. Seventeen patients [28.3% (18.5-40.9%)] had atypical cells. Twelve of seventeen [70.6% (46.8-87.2%)] samples with atypia were from non–fluid-yielding ducts. Patients with non–fluid-yielding ducts (versus fluid-yielding ducts) were more likely to have had prior cancer (48.4% versus 17.2%, P = 0.014) or chemotherapy (45.2% versus 17.2%, P = 0.027); this was also true in patients with atypia from non–fluid-yielding ducts. Conclusion: Successfully lavaged women were younger and more often premenopausal. Atypical cells can be found in non–fluid-yielding ducts in patients at high inherited breast cancer risk. Non–fluid-yielding ducts, and atypia from non–fluid-yielding ducts, are more common in patients with prior cancer and chemotherapy. Larger studies are needed to identify risk factors and prognostic significance associated with atypia and non–fluid-yielding ducts in high-risk populations, and define their role as biomarkers.

Opinions of women with high inherited breast cancer risk about prophylactic mastectomy: an initial evaluation from a screening trial including magnetic resonance imaging and ductal lavage

Objective  Prophylactic mastectomy (PM) is often considered, but variably chosen by women at high inherited risk of breast cancer; few data exist on patient tolerance of intensive breast screening as an alternative to PM. We performed an evaluation of high‐risk womens tolerance of a breast screening protocol using clinical breast examination, mammography, breast magnetic resonance imaging (MRI) and ductal lavage (DL), and of change in attitudes toward PM after screening.