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Emerging evidence suggests that BRCA1 pathway contributes to the behavior of sporadic triple negative breast cancer (TNBC), but little is known about the mechanisms underlying this association. Considering the central role that microRNAs (miRNAs) play in gene expression regulation, the aim of this study was to identify miRNAs specifically deregulated in TNBC and investigate their involvement in BRCA1 regulation. Using locked nucleic acid (LNA)-based microarrays, expression levels of 1919 miRNAs were measured in paraffin-embedded tissues from 122 breast tumors and 11 healthy breast tissue samples. Differential miRNA expression was explored among the main subtypes of breast cancer, and 105 miRNAs were identified as specific for triple negative tumors. In silico prediction revealed that miR-498 and miR-187-5p target BRCA1, and these results were confirmed by luciferase reporter assay. While miR-187-5p was found overexpressed in a luminal B cell line, miR-498 was highly expressed in a triple negative cell line, Hs578T, and its expression was negatively correlated with the levels of BRCA1. We functionally demonstrated that miR-498 inhibits BRCA1 in breast cancer cell lines, and showed that inhibition of miR-498 led to reduced proliferation in the triple negative cell line Hs578T. Our results indicate that miR-498 regulates BRCA1 expression in breast cancer and its overexpression could contribute to the pathogenesis of sporadic TNBC via BRCA1 downregulation. We thank all members of the Human Cancer Genetics Programme of the Spanish National Cancer Research Centre for all their support. We want to particularly acknowledge the patients, the INCLIVA BioBank (PT13/0010/0004) integrated in the Spanish National Biobanks Network, and Pablo Isidro Marrón, coordinator of Biobanco del Principado de Asturias, for their collaboration. This work has been funded by grants from the Spanish Ministry of Economy and Competitiveness (INNPRONTA LIFE project) and FIS PI11/01059 (BM-D). Sí

Producción Científica, GASH:Sal hamster strain and the control Syrian hamsters. The GASH:Sal constitutes an experimental model of reflex epilepsy of audiogenic origin derived from an autosomal recessive disorder. Thus, the GASH:Sal exhibits generalized tonic–clonic seizures, characterized by a short latency period after auditory stimulation, followed by wild running, a convulsive phase, and finally stupor, with origin in the brainstem. The seizure profile of the GASH:Sal is similar to those exhibited by other models of inherited AGS susceptibility, which decreases after six months of age, but the proneness across generations is maintained. The GASH:Sal can be considered a reliable model of audiogenic seizures, suitable to investigate current antiepileptic pharmaceutical treatments as well as novel therapeutic drugs.

BACKGROUND The identification of novel biomarkers for early breast cancer detection would be a great advance. Because of their role in tumorigenesis and stability in body fluids, microRNAs (miRNAs) are emerging as a promising diagnostic tool. Our aim was to identify miRNAs deregulated in breast tumors and evaluate the potential of circulating miRNAs in breast cancer detection. METHODS We conducted miRNA expression profiling of 1919 human miRNAs in paraffin-embedded tissue from 122 breast tumors and 11 healthy breast tissue samples. Differential expression analysis was performed, and a microarray classifier was generated. The most relevant miRNAs were analyzed in plasma from 26 healthy individuals and 83 patients with breast cancer (36 before and 47 after treatment) and validated in 116 healthy individuals and 114 patients before treatment. RESULTS We identified a large number of miRNAs deregulated in breast cancer and generated a 25-miRNA microarray classifier that discriminated breast tumors with high diagnostic sensitivity and specificity. Ten miRNAs were selected for further investigation, of which 4 (miR-505-5p, miR-125b-5p, miR-21-5p, and miR-96-5p) were significantly overexpressed in pretreated patients with breast cancer compared with healthy individuals in 2 different series of plasma. MiR-505-5p and miR-96-5p were the most valuable biomarkers (area under the curve 0.72). Moreover, the expression levels of miR-3656, miR-505-5p, and miR-21-5p were decreased in a group of treated patients. CONCLUSIONS Circulating miRNAs reflect the presence of breast tumors. The identification of deregulated miRNAs in plasma of patients with breast cancer supports the use of circulating miRNAs as a method for early breast cancer detection.

Telomere shortening is a common event involved in malignant transformation. Critically short telomeres may trigger chromosomal aberrations and produce genomic instability leading to cancer development. Therefore, telomere shortening is a frequent molecular alteration in early stages of many epithelial tumors and in breast cancer correlates with stage and prognosis. A better understanding of the involvement of short telomeres in tumors may have a significant impact on patient management and the design of more specific treatments. To understand the role of telomere length (TL) in breast cancer etiology we measured the length of individual telomere signals in single cells by using quantitative telomere in situ hybridization in paraffin-embedded tissue from hereditary and sporadic breast cancers. A total of 104 tumor tissue samples from 75 familial breast tumors (BRCA1, n = 14; BRCA2, n = 13; non-BRCA1/2, n = 48) and 29 sporadic tumors were analyzed. Assessment of telomere signal intensity allowed estimation of the mean TL and related variables, such as percentage of critically short telomeres and percentage of cells with short telomeres. These data were correlated with the immunohistochemical expression of molecular breast cancer markers. Hereditary BRCA1, BRCA2, and non-BRCA1/2 tumors were characterized by shorter TL comparing to sporadic tumors. Considering all tumors, tumor grade was a strong risk factor determining the proportion of short telomeres or short telomere cells. Moreover, some histopathological features appeared to be differentially associated to hereditary or sporadic subgroups. Short telomeres correlated with ER-negative tumors in sporadic cases but not in familial cases, whereas a high level of apoptosis was associated with shorter telomeres in hereditary BRCA1 and BRCA2 tumors. In addition, TL helped to define a subset of non-BRCA1/2 tumors with short telomeres associated with increased expression of antiapoptotic proteins. These findings highlight the potential interest of TL measurements as markers of aggressiveness in breast cancer.

[Background]: Alterations in telomere maintenance mechanisms leading to short telomeres underlie different genetic disorders of ageing and cancer predisposition syndromes. It is known that short telomeres and subsequent genomic instability contribute to malignant transformation, and it is therefore likely that people with shorter telomeres are at higher risk for different types of cancer. Recently, the authors demonstrated that the genes BRCA1 and BRCA2 are modifiers of telomere length (TL) in familial breast cancer. The present study analysed TL in peripheral blood leucocytes of hereditary and sporadic ovarian cancer cases, as well as in female controls, to evaluate whether TL contributes to ovarian cancer risk. [Methods]: TL was measured by quantitative PCR in 178 sporadic and 168 hereditary ovarian cases (46 BRCA1, 12 BRCA2, and 110 BRCAX) and compared to TL in 267 controls. [Results]: Both sporadic and hereditary cases showed significantly shorter age adjusted TLs than controls. Unconditional logistic regression analysis revealed an association between TL and ovarian cancer risk with a significant interaction with age (p, This work was supported by Genetic Counseling Programme in Hereditary Cancer (Junta de Castilla y León) grant number FIS PI10/00219 (RGS); the Spanish Association Against Cancer (AECC), FIS PI08-1120 and by Red Tematica de investigacion Cooperativa en Cancer grant number RETICC RD06/0020/1060 (JB), and RETICC 06/0020/0021 (TC and MH); by the Xunta de Galicia grant number 10PXIB 9101297PR and Fundación Mutua Madrileña (AV).

There is increasing evidence suggesting that short telomeres and subsequent genomic instability contribute to malignant transformation. Telomere shortening has been described as a mechanism to explain genetic anticipation in dyskeratosis congenita and Li-Fraumeni syndrome. Since genetic anticipation has been observed in familial breast cancer, we aimed to study telomere length in familial breast cancer patients and hypothesized that genetic defects causing this disease would affect telomere maintenance resulting in shortened telomeres. Here, we first investigated age anticipation in mother-daughter pairs with breast cancer in 623 breast cancer families, classified as BRCA1, BRCA2, and BRCAX. Moreover, we analyzed telomere length in DNA from peripheral blood leukocytes by quantitative PCR in a set of 198 hereditary breast cancer patients, and compared them with 267 control samples and 71 sporadic breast cancer patients. Changes in telomere length in mother-daughter pairs from breast cancer families and controls were also evaluated to address differences through generations. We demonstrated that short telomeres characterize hereditary but not sporadic breast cancer. We have defined a group of BRCAX families with short telomeres, suggesting that telomere maintenance genes might be susceptibility genes for breast cancer. Significantly, we described that progressive telomere shortening is associated with earlier onset of breast cancer in successive generations of affected families. Our results provide evidence that telomere shortening is associated with earlier age of cancer onset in successive generations, suggesting that it might be a mechanism of genetic anticipation in hereditary breast cancer., Author Summary The fact that accelerated telomere shortening accompanies different premature aging syndromes and seems to be associated with increased risk of cancer development prompted us to analyze the role of telomere length in hereditary breast cancer. In this study we found that telomeres of peripheral blood cells from familial breast cancer patients were significantly shorter than those from the control population. Women carrying a mutation in BRCA1 or BRCA2 genes, and a subset of BRCAX families, were characterized by short telomeres. We also demonstrated that genetic anticipation, the successive earlier age of onset of cancer, in these families was associated with a decrease of the telomere length in affected daughters compared to their mothers. This is the first study suggesting that telomere shortening may contribute to anticipation in breast cancer families and that analysis of telomere length in hereditary breast cancer may affect the design of surveillance programs for affected families.