BRCA1 promoter hypermethylation, 53BP1 protein expression and PARP-1 activity as biomarkers of DNA repair deficit in breast cancer.

BACKGROUND: Poly(adenosine diphosphate-ribose) polymerase 1 (PARP-1) and the balance between BRCA1 and 53BP1 play a key role in the DNA repair and cell stress response. PARP inhibitors show promising clinical activity in metastatic triple negative (TN) or BRCA-mutated breast cancer. However, a comprehensive analysis of PARP-1 activity, BRCA1 promoter methylation and 53BP1 expression in tumours without known BRCA1 mutation has not yet been carried out. METHODS: We investigated cytosolic PARP-1 activity, 53BP1 protein levels and BRCA1 promoter methylation in 155 surgical breast tumour samples from patients without familial breast cancer history or known BRCA1 mutations who were treated between January 2006 and November 2009 and evaluated their statistical association with classical predictive and prognostic factors. RESULTS: The mitotic count score was the only parameter clearly associated with PARP-1 activity. BRCA1 promoter hypermethylation (15.4% of all cancers) was significantly associated with uPA and PAI-1 levels, tumour grade, mitotic count score, hormone receptor and HER2 negative status and TN profile (29% of TN tumours showed BRCA1 promoter hypermethylation compared to 5% of grade II-III hormone receptor-positive/HER2-negative and 2% of HER2-positive tumours). No statistical association was found between BRCA1 promoter hypermethylation and PARP-1 activity. High 53BP1 protein levels correlated with lymph node positivity, hormone receptor positivity, molecular grouping, unmethylated BRCA1 promoter and PARP-1 activity. In TN tumours, BRCA1 promoter methylation was only marginally associated with age, PARP-1 activity was not associated with any of the tested clinico-pathological factors and high 53BP1 protein levels were significantly associated with lymph node positivity. Only 3 of the 14 TN tumours with BRCA1 promoter hypermethylation presented high 53BP1 protein levels. CONCLUSIONS: Breast cancers that harbour simultaneously high 53BP1 protein level and BRCA1 promoter hypermethylation and are the putative target population of drugs targeting DNA repair appear to be restricted to a small subgroup of TN tumours.

[HE4, a novel marker for epithelial ovarian cancer: evaluation of analytical performances]. / HE4, un nouveau marqueur des cancers épithéliaux ovariens: évaluation des performances analytiques.

Human epididymis protein 4 (HE4) is a novel marker for ovarian cancer. HE4 exhibits a high sensitivity to detect ovarian cancer and can be used with CA125 as a predictor of malignancy. Additional uses of HE4 are as an aid of monitoring response to therapy for patients with invasive ovarian cancer and as a marker to detect recurrences in the follow-up after treatment of the primary tumor. The HE4 EIA, an enzyme immunoassay for the quantitative determination of HE4 in human serum developed by Fujirebio Diagnostic Inc. (Tokyo, Japan), is now available with a CE-IVD label in Europe (Diasource, Nivelles, Belgium). The aim of the study was to evaluate according to the COFRAC LAB GTA 04 guide, the analytical performance of the test, using 4 standardized samples (target values: 49.8, 140.4, 167.6 and 415.2 pmol/L) and serum samples from patients with ovarian cancer treated in our institution. Intra- and inter-assay precisions showed coefficients of variation less than 10%. The low limit of detection (4 pmol/L) and the limit of quantitation (8 pmol/L) are suitable for clinical samples assessment. The assay mean dilution linearity is 100 +/- 10% (90 to 107% of recovery). Globally, the uncertainty varied from 13.1% (low values) to 28.1% (elevated values). We conclude that the HE4 EIA from Fujirebio Diagnostic Inc. displayed convenient analytical performances that allows its use it clinical practice.