OLA1 gene sequencing in patients with BRCA1/2 mutation-negative suspected hereditary breast and ovarian cancer.

BACKGROUND: Of individuals with suspected hereditary breast and ovarian cancer (HBOC), approximately 30-70 % do not harbor mutations in either BRCA1 or BRCA2 gene, which suggests that these individuals have other genetic or epigenetic alterations that could lead to the onset of this hereditary disease. We have recently identified OLA1 as a novel BRCA1/BARD1-interacting protein. In the present study, we aimed to elucidate whether any genetic mutations in OLA1 are detected among patients with suspected HBOC without BRCA1 or BRCA2 mutations. METHODS: Among 53 patients with suspected HBOC enrolled at Hoshi General Hospital, 23 patients without any BRCA1 or BRCA2 mutations were analyzed for OLA1 mutations. Genomic DNA was extracted from the peripheral blood samples. PCR and Sanger sequencing were performed to elucidate whether there were any mutations in any of the ten exons and flanking introns of the OLA1 gene. RESULTS: No germline sequence variation was detected in the OLA1 gene among the 23 patients enrolled in this study. CONCLUSIONS: No germline mutations were found in the OLA1 gene among the cohort of patients with suspected HBOC without BRCA1 or BRCA2 mutations. Further studies are needed to clarify whether other mutations/epigenetic alterations are involved in the pathogenesis of BRCA1 or BRCA2 mutation-negative inherited disease with breast or ovarian cancer.

Somatic alteration and depleted nuclear expression of BAP1 in human esophageal squamous cell carcinoma.

BRCA1-associated protein 1 (BAP1) is a deubiquitinating enzyme that is involved in the regulation of cell growth. Recently, many somatic and germline mutations of BAP1 have been reported in a broad spectrum of tumors. In this study, we identified a novel somatic non-synonymous BAP1 mutation, a phenylalanine-to-isoleucine substitution at codon 170 (F170I), in 1 of 49 patients with esophageal squamous cell carcinoma (ESCC). Multiplex ligation-dependent probe amplification (MLPA) of BAP1 gene in this ESCC tumor disclosed monoallelic deletion (LOH), suggesting BAP1 alterations on both alleles in this tumor. The deubiquitinase activity and the auto-deubiquitinase activity of F170I-mutant BAP1 were markedly suppressed compared with wild-type BAP1. In addition, wild-type BAP1 mostly localizes to the nucleus, whereas the F170I mutant preferentially localized in the cytoplasm. Microarray analysis revealed that expression of the F170I mutant drastically altered gene expression profiles compared with expressed wild-type BAP1. Gene-ontology analyses indicated that the F170I mutation altered the expression of genes involved in oncogenic pathways. We found that one candidate, TCEAL7, previously reported as a putative tumor suppressor gene, was significantly induced by wild-type BAP1 as compared to F170I mutant BAP1. Furthermore, we found that the level of BAP1 expression in the nucleus was reduced in 44% of ESCC examined by immunohistochemistry (IHC). Because the nuclear localization of BAP1 is important for its tumor suppressor function, BAP1 may be functionally inactivated in a substantial portion of ESCC. Taken together, BAP1 is likely to function as a tumor suppressor in at least a part of ESCC.

Serotonin 5-HT2C receptor-independent expression of hypothalamic NOR1, a novel modulator of food intake and energy balance, in mice.

NOR1, Nur77 and Nurr1 are orphan nuclear receptors and members of the NR4A subfamily. Here, we report that the expression of hypothalamic NOR1 was remarkably decreased in mildly obese beta-endorphin-deficient mice and obese db/db mice with the leptin receptor mutation, compared with age-matched wild-type mice, whereas there were no genotypic differences in the expression of hypothalamic Nur77 or Nurr1 in these animals. The injection of NOR1 siRNA oligonucleotide into the third cerebral ventricle significantly suppressed food intake and body weight in mice. On the other hand, the decreases in hypothalamic NOR1 expression were not found in non-obese 5-HT2C receptor-deficient mice. Moreover, systemic administration of m-chlorophenylpiperazine (mCPP), a 5-HT2C/1B receptor agonist, had no effect on hypothalamic NOR1 expression, while suppressing food intake in beta-endorphin-deficient mice. These findings suggest that 5-HT2C receptor-independent proopiomelanocortin-derived peptides regulate the expression of hypothalamic NOR1, which is a novel modulator of feeding behavior and energy balance.

Novel modulators for body weight changes induced by fasting and re-feeding in mice.

Catch-up weight gain after malnutrition is a risk factor for metabolic syndrome. Here we show that social isolation enhanced fasting-induced weight loss and suppressed weight gain induced by re-feeding for 6 days following a 24-h fast in prepubertal wild-type mice. These effects of social isolation on weight gain were not associated with significant changes in daily average food consumption. Under the same housing condition, genetic deletion of beta-endorphin reduced the fasting-induced weight loss and enhanced the re-feeding-induced weight gain in prepubertal mice. These effects of social isolation or genetic deletion of beta-endorphin on these weight changes were attenuated and reversed in postpubertal mice. Moreover, genetic deletion of beta-endorphin attenuated these effects of social isolation on the catch-up weight gain in prepubertal mice and reversed them in postpubertal mice. Thus, social isolation, endogenous beta-endorphin, and age can be novel modulators for body weight changes induced by fasting and re-feeding in mice.

Serotonin systems upregulate the expression of hypothalamic NUCB2 via 5-HT2C receptors and induce anorexia via a leptin-independent pathway in mice.

NEFA/nucleobindin2 (NUCB2), a novel satiety molecule, is associated with leptin-independent melanocortin signaling in the central nervous system. Here, we show that systemic administration of m-chlorophenylpiperazine (mCPP), a serotonin 5-HT1B/2C receptor agonist, significantly increased the expression of hypothalamic NUCB2 in wild-type mice. The increases in hypothalamic NUCB2 expression induced by mCPP were attenuated in 5-HT2C receptor mutant mice. Systemic administration of mCPP suppressed food intake in db/db mice with leptin receptor mutation as well as lean control mice. On the other hand, the expression of hypothalamic NUCB2 and proopiomelanocortin (POMC) was significantly decreased in hyperphagic and non-obese 5-HT2C receptor mutants compared with age-matched wild-type mice. Interestingly, despite increased expression of hypothalamic POMC, hypothalamic NUCB2 expression was decreased in 5-HT2C receptor mutant mice with heterozygous mutation of beta-endorphin gene. These findings suggest that 5-HT systems upregulate the expression of hypothalamic NUCB2 via 5-HT2C receptors, and induce anorexia via a leptin-independent pathway in mice.