Phenotypic characterization of BRCA1 and BRCA2 tumors based in a tissue microarray study with 37 immunohistochemical markers

Abstract

Familial breast cancers that are associated with BRCA1 or BRCA2 germline mutations differ in both their morphological and immunohistochemical characteristics. To further characterize the molecular difference between genotypes, the authors evaluated the expression of 37 immunohistochemical markers in a tissue microarray (TMA) containing cores from 20 BRCA1, 14 BRCA2, and 59 sporadic age-matched breast carcinomas. Markers analyzed included, amog others, common markers in breast cancer, such as hormone receptors, p53 and HER2, along with 15 molecules involved in cell cycle regulation, such as cyclins, cyclin dependent kinases (CDK) and CDK inhibitors (CDKI), apoptosis markers, such as BCL2 and active caspase 3, and two basal/myoepithelial markers (CK 5/6 and P-cadherin). In addition, we analyzed the amplification of CCND1, CCNE, HER2 and MYC by FISH. Unsupervised cluster data analysis of both hereditary and sporadic cases using the complete set of immunohistochemical markers demonstrated that most BRCA1-associated carcinomas grouped in a branch of ER-, HER2-negative tumors that expressed basal cell markers and/or p53 and had higher expression of activated caspase 3. The cell cycle proteins associated with these tumors were E2F6, cyclins A, B1 and E, SKP2 and Topo IIalpha. In contrast, most BRCA2-associated carcinomas grouped in a branch composed by ER/PR/BCL2-positive tumors with a higher expression of the cell cycle proteins cyclin D1, cyclin D3, p27, p16, p21, CDK4, CDK2 and CDK1. In conclusion, our study in hereditary breast cancer tumors analyzing 37 immunohistochemical markers, define the molecular differences between BRCA1 and BRCA2 tumors with respect to hormonal receptors, cell cycle, apoptosis and basal cell markers.

Basal-like and triple-negative breast cancers: a critical review with an emphasis on the implications for pathologists and oncologists

“…82,83 The majority of tumors arising in BRCA1 germ-line mutation carriers, in particular those diagnosed before 50 years of age, have morphological features similar to those described in basal-like cancers 84,85 and show a basal-like phenotype as defined by immunohistochemistry 86,87 or expression arrays. 8 Both basal-like breast cancers and tumors arising in BRCA1 germ-line mutation carriers show a peculiar pattern of cell-cycle protein expression; 54,84,88,89 both rarely harbor CCND1 gene amplification; 54,88 however, they express significantly lower levels of p27, 84,89 and higher levels of Skp2, 84,89 cyclin E, 84,89 and caspase-3, 89 when compared with sporadic breast carcinomas and BRCA2 mutation tumors.…”

Distinct genomic aberration patterns are found in familial breast cancer associated with different immunohistochemical subtypes

“…We compiled 62 paraffin-embedded tumor tissues, which had been analysed previously both by IHC (Palacios et al, 2003(Palacios et al, , 2005Honrado et al, 2005b) and aCGH (Melchor et al, in press). These breast cancer samples were selected from families with at least three women affected with breast and/or ovarian cancer and at least one of them diagnosed before 50 years of age, or from families with female breast and/or ovarian cancer and at least one case of male breast cancer.…”

“…Two tissue cores were obtained from each specimen and included in Tissue Micro-Arrays (TMA), whose characteristics have been previously published (Palacios et al, 2003(Palacios et al, , 2005Honrado et al, 2005b).…”

“…For the 25 antibodies used in this study, dilutions and suppliers are listed in Supplementary Table 1. Between 150 and 200 cells per core were scored for the percentage of cells with positive nuclei or cytoplasm, depending upon the marker. We evaluated nuclear staining for ER, progesterone receptor, p53, Ki-67, cyclins D1, D3, E and A, p16, p27, p21, Skp2, retinoblastoma protein, E2F6, MDM2, topoisomerase IIa, survivin and CHEK2; evaluation of cytoplasmic staining was carried out for BCL2, vimentin, CK5/6, CK8 and cyclin B1, as described previously (Palacios et al, 2005). HER-2 expression was evaluated according to the four-category (0 to 3 þ ) Dako system proposed for the evaluation of the HercepTest, and HER-2 expression of 3 þ was the only value considered positive, as published earlier (Palacios et al, 2005).…”

Immunohistochemical heterogeneity of breast carcinomas negative for estrogen receptors, progesterone receptors and Her2/neu (basal-like breast carcinomas)

“…The mean Ki67 index of 46% and the overexpression of p53 in 53% of our cases is much higher than the mean values described in sporadic and familial breast carcinomas. 37 Cyclin D1 overexpression has been reported in 60% of DCIS and 70% of invasive cancers, 37,38 in association with a favorable clinical outcome and response to tamoxifen. 38 In the present series, cyclin D1 overexpression was present in 52% of tumors in association with loss of p27 nuclear expression, but unrelated to pAkt or ER.…”