ASSESSMENT OF THE VALUE OF METHYLATION FEATURES IN DIFFERENT TISSUES FOR PREOPERATIVE IDENTIFICATION OF HIGH-RISK BREAST TUMORS.

Epigenetic changes in breast cancer patients have long been believed to be a promising marker for clinical management - early detection, prognostication, etc. Various approaches are available to test global DNA or target gene methylation status. We used some of them in different tissues of patients with breast cancer to analyze possible links between epigenetic parameters and their value for predicting clinicopathological characteristics (most importantly stage and lymph node status) of tumors. Patients with ductal and lobular invasive carcinoma were included in the study along with age-matched controls. Blood, tumor tissue and normal breast ductal epithelial cells were investigated using MS-HRM technique (for BRCA1 gene promoter methylation assessment), COBRA-PCR (for Alu element methylation quantification) and ELISA-based method (for global DNA methylation estimation). These parameters were analyzed in comparison to clinical, histologic and phenotypic characteristics of the tumors. BRCA1 promoter methylation was detected exclusively in tumor tissues and in only two cases, both of which had aggressive phenotype. Alu and global DNA methylation showed markedly low levels in all tissues of cancer patients compared to healthy controls, with extreme hypomethylation in tumor tissue. Changes in these two parameters were not always concordant. Methylation levels detected in blood showed rather weak relationship with clinicopathological characteristics of tumors. We could conclude that tested parameters are not useful for preoperative determination of tumor stage or lymph node status, neither any other clinicopathological characteristics of tumors. Epigenetics signatures of different tissues of the same patient are not homogenous. Given the uniform picture of DNA methylation in blood in some of investigated groups, additional data and very careful approach are required when considering using it as a diagnostic or predictive tool.

Immunohistochemical expression of BRCA1 protein in invasive ductal carcinoma of the breast.

Immunohistochemically detected BRCA1 positivity has been reported to indicate the presence of full-length functional protein, while immunohistochemical negativity may be a result of sporadic BRCA1 mutation. We set out to study the immunohistochemical expression of BRCA1 protein in breast cancer and assess associations with lymph node status, histologic grade and expression of other biomarkers. We examined 100 patients aged from 21 to 71 years diagnosed with invasive ductal carcinoma. Immunohistochemistry was performed using anti-BRCA1, ER, PR, HER2/neu, and Ki-67 (MIB-1) antibodies. Cytoplasmic or nuclear-cytoplasmic BRCA1 expression was identified in a total of 64 breast cancer patients. None of the breast cancer tissue samples showed solely nuclear BRCA1 immunoreactivity. BRCA1 expression was associated with higher histologic grade, and majority of BRCA1-positive patients were below 50 years of age. Most BRCA1-negative patients had intermediate grade tumors. BRCA1 expression was positively associated with ER and PR positivity, and negatively associated with HER2/neu overexpression. Although immunohistochemistry can be an inexpensive and valuable preliminary method for detecting the BRCA1 status, BRCA1 protein localization is a complex issue. Well designed studies are needed to further investigate the performance of various anti-BRCA1 antibodies in formalin- fixed paraffin-embedded tissue samples, assess their association with BRCA1 gene mutations and determine clinical usefulness of BRCA1 immunohistochemistry.