Orland Diez

PI3K Inhibition Impairs BRCA1/2 Expression and Sensitizes BRCA-Proficient Triple-Negative Breast Cancer to PARP Inhibition

UNLABELLED PARP inhibitors are active in tumors with defects in DNA homologous recombination (HR) due to BRCA1/2 mutations. The phosphoinositide 3-kinase (PI3K) signaling pathway preserves HR steady state. We hypothesized that in BRCA-proficient triple-negative breast cancer (TNBC), PI3K inhibition would result in HR impairment and subsequent sensitization to PARP inhibitors. We show in TNBC cells that PI3K inhibition leads to DNA damage, downregulation of BRCA1/2, gain in poly-ADP-ribosylation, and subsequent sensitization to PARP inhibition. In TNBC patient-derived primary tumor xenografts, dual PI3K and PARP inhibition with BKM120 and olaparib reduced the growth of tumors displaying BRCA1/2 downregulation following PI3K inhibition. PI3K-mediated BRCA downregulation was accompanied by extracellular signal-regulated kinase (ERK) phosphorylation. Overexpression of an active form of MEK1 resulted in ERK activation and downregulation of BRCA1, whereas the MEK inhibitor AZD6244 increased BRCA1/2 expression and reversed the effects of MEK1. We subsequently identified that the ETS1 transcription factor was involved in the ERK-dependent BRCA1/2 downregulation and that knockdown of ETS1 led to increased BRCA1/2 expression, limiting the sensitivity to combined BKM120 and olaparib in 3-dimensional culture. SIGNIFICANCE Treatment options are limited for patients with TNBCs. PARP inhibitors have clinical activity restricted to a small subgroup of patients with BRCA mutations. Here, we show that PI3K blockade results in HR impairment and sensitization to PARP inhibition in TNBCs without BRCA mutations, providing a rationale to combine PI3K and PARP inhibitors in this indication. Our findings could greatly expand the number of patients with breast cancer that would benefit from therapy with PARP inhibitors. On the basis of our findings, a clinical trial with BKM120 and olaparib is being initiated in patients with TNBCs.

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

SummaryFamilial 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 IIα. 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.

BRCA in breast cancer: ESMO Clinical Practice Guidelines

BRCA in breast cancer: ESMO Clinical Practice Guidelines J. Balmana, O. Diez, I. Rubio & M. Castiglione On behalf of the ESMO Guidelines Working Group* Department of Medical Oncology; Oncogenetics Laboratory, University Hospital Vall d’Hebron; Vall d’Hebron Institute of Oncology (VHIO); Breast Cancer Surgical Unit, Breast Cancer Center, University Hospital Vall d’Hebron, Barcelona, Spain; RGT, University of Geneva, Geneva, Switzerland

The breast cancer low‐penetrance allele 1100delC in the CHEK2 gene is not present in Spanish familial breast cancer population

Searching for low‐penetrance genes involved in breast cancer susceptibility has been a field of interest in the last few years. Recently, the CHEK 2 gene, involved in DNA damage and replication checkpoints, has been pointed out as a good candidate; moreover, a specific variant in this gene,1100delC, has been found to increase breast cancer susceptibility among familial breast cancer cases not attributable to mutations in BRCA1 or BRCA2 genes. In our present study, we evaluated the role of the 1100delC variant as a susceptibility allele in breast cancer in the Spanish population. However, our results suggest that this variant is absent or very infrequent in our population, making its screening irrelevant from the practical point of view.

The Average Cumulative Risks of Breast and Ovarian Cancer for Carriers of Mutations in BRCA1 and BRCA2 Attending Genetic Counseling Units in Spain

Purpose: It is not clear that the published estimates of the breast and ovarian cancer penetrances of mutations in BRCA1 and BRCA2 can be used in genetic counseling in countries such as Spain, where the incidence of breast cancer in the general population is considerably lower, the prevalence of BRCA2 mutations seems to be higher, and a distinct spectrum of recurrent mutations exists for both genes. We aimed to estimate these penetrances for women attending genetic counseling units in Spain. Experimental Design: We collected phenotype and genotype data on 155 BRCA1 and 164 BRCA2 mutation carrier families from 12 centers across the country. Average age-specific cumulative risks of breast cancer and ovarian cancer were estimated using a modified segregation analysis method. Results: The estimated average cumulative risk of breast cancer to age 70 years was estimated to be 52% [95% confidence interval (95% CI), 26-69%] for BRCA1 mutation carriers and 47% (95% CI, 29-60%) for BRCA2 mutation carriers. The corresponding estimates for ovarian cancer were 22% (95% CI, 0-40%) and 18% (95% CI, 0-35%), respectively. There was some evidence (two-sided P = 0.09) that 330A>G (R71G) in BRCA1 may have lower breast cancer penetrance. Conclusions: These results are consistent with those from a recent meta-analysis of practically all previous penetrance studies, suggesting that women with BRCA1 and BRCA2 mutations attending genetic counseling services in Spain have similar risks of breast and ovarian cancer to those published for other Caucasian populations. Carriers should be fully informed of their mutation- and age-specific risks to make appropriate decisions regarding prophylactic interventions such as oophorectomy.

Immunohistochemical Expression of DNA Repair Proteins in Familial Breast Cancer Differentiate BRCA2-Associated Tumors

PURPOSE Morphologic and immunohistochemical studies of familial breast cancers have identified specific characteristics associated with BRCA1 mutation-associated tumors when compared with BRCA2 and non-BRCA1/2 tumors, but have not identified differences between BRCA2 and non-BRCA1/2 tumors. Because BRCA1 and BRCA2 genes participate in the DNA repair pathway, we have performed an immunohistochemical study with markers related to this pathway to establish the profile of the three groups. MATERIALS AND METHODS We have studied two tissue microarrays that include 103 familial and 104 sporadic breast tumors, with a panel of DNA repair markers including ATM, CHEK2, RAD51, RAD50, XRCC3, and proliferating cell nuclear antigen. RESULTS We found more frequent expression of CHEK2 in BRCA1 and BRCA2 tumors than in non-BRCA1/2 and sporadic tumors. We found absence of nuclear expression and presence of cytoplasmic expression of RAD51 in BRCA2 tumors that differentiate them from other familial tumors. We validated these results with a new series of patient cases. The final study with 253 familial patient cases (74 BRCA1, 71 BRCA2, 108 non-BRCA1/2), and 288 sporadic patient cases, has allowed us to confirm our preliminary results. Because BRCA2 tumors present a specific immunohistochemical profile for RAD51 and CHEK2 markers that is different from non-BRCA1/2 tumors, we have built a multivariate model with these markers that distinguish both tumors with an estimated probability of at least 76%. CONCLUSION Our results suggest that BRCA2 tumors demonstrate more cytoplasmic and less nuclear RAD51 staining, and increased CHEK2 staining. This pattern may distinguish BRCA2 from familial non-BRCA1/2 tumors.

Effect of Mammography on Breast Cancer Risk in Women with Mutations in BRCA1 or BRCA2

Women who carry mutations in either the BRCA1 or BRCA2 genes are at risk for early-onset breast cancer and are recommended to begin screening mammography at age 25 to 30 years. Results of in vitro and animal studies suggest that BRCA1/BRCA2 mutation carriers are hypersensitive to ionizing radiation and possibly to radiation-induced breast cancer. This study was undertaken to investigate the association of low-dose radiation exposure from mammograms with breast cancer status in BRCA mutation carriers. One hundred sixty-two female mutation carriers provided information at time of genetic testing about exposure to mammograms before enrollment. Using unconditional logistic regression, breast cancer status was not associated with number of mammograms received before diagnosis (affected women) or ascertainment [unaffected women; adjusted odds ratio (OR), 0.94; P = not significant]. A larger group of 213 women provided information about lifetime number of mammograms. There was no association between mammogram exposure and risk in the group as a whole (adjusted OR, 1.04; P = not significant), although there was a modest association in BRCA1 carriers (adjusted OR, 1.08; P = 0.03). These findings indicate that screening mammography is unlikely to be associated with a large increase in breast cancer risk in this population. (Cancer Epidemiol Biomarkers Prev 2006;15(11):2311–3)

Immunohistochemical classification of non- BRCA1/2 tumors identifies different groups that demonstrate the heterogeneity of BRCAX families

Around 25% of hereditary breast and ovarian cancer families have mutations in the BRCA1 and BRCA2 genes. The search for other genes has until now failed, probably because there is not one single BRCAX gene, but rather various genes that may each be responsible for a small number of breast cancer families and/or may interact according to a polygenic model. We have studied 50 tumors from probands belonging to non-BRCA1/2 breast cancer families (BRCAX), using 25 immunohistochemical markers. The objective was to classify these tumors and confirm that they are heterogeneous. Unsupervised cluster analysis showed the existence of the following two main groups of tumors: high-grade and estrogen receptor (ER)-negative tumors (50%), and low-grade and ER-positive tumors (50%). In addition we identified five subgroups, three among the high-grade and two among the low-grade groups; one overexpressing HER-2 (18%); one with a basal-like phenotype (14%); one with a normal breast-like phenotype (18%); a luminal A subgroup (36%), and a luminal B subgroup (14%). Hypermethylation of the BRCA1 gene was observed in 42% of the cases, spread across all five subgroups, but only 37% of those had loss of heterozygosity as well. These latter cases were all clustered in the high-grade group and the majority of them in the basal-like subgroup. Our results show that familial non-BRCA1/2 tumors are heterogeneous and suggest a polygenic model for explaining the majority of BRCAX families. In addition we have defined a subset of them that have somatic inactivation of the BRCA1 gene.

Loss of heterozygosity on chromosome 13q12-q14, BRCA-2 mutations and lack of BRCA-2 promoter hypermethylation in sporadic epithelial ovarian tumors.

BRCA‐1 and BRCA‐2 are tumor suppressor genes in familial breast‐ovarian carcinoma syndrome. BRCA‐1 is also a tumor suppressor gene in sporadic ovarian carcinomas. However, the role of BRCA‐2 in sporadic ovarian tumors remains unclear.

BRCA2 germ-line mutations in Spanish male breast cancer patients.

BACKGROUND Mutations in the BRCA2 gene account for the majority of the families with male and female breast cancer cases, and a number of BRCA2 mutations have been reported in males with breast cancer. The aim of this study was to characterise BRCA2 germ-line mutations in Spanish male breast cancer patients. PATIENTS AND METHODS We screened DNA from 11 affected men and 6 women with breast cancer (BC) who had an affected male relative (father or brother). Exons 2-9 and 12-27 were screened by SSCP, and exons 10 and 11 were screened by PTT. PCR products with a variant band were sequenced. RESULTS Three BRCA2 frameshift mutations were identified (17.6%): the 3374delA in codon 1049 (exon 11), 6857delAA in codon 2010 (exon 11), and 9254delATCAT in codon 3009 (exon 23). These mutations were present in patients with affected first-degree relatives (3 of 9, 33%). The proportion of male patients with a family history of BC in at least one first-degree relative was 53%. CONCLUSIONS There is an association between BRCA2 mutations and male breast cancer, especially in those with a family history of BC. The high prevalence of BRCA2 mutations among males should be considered when estimating risk for female relatives. All new male cases of BC should be regarded as being possibly inherited and should be fully investigated.