Modulation of the expression of genes related to the system of amyloid-beta metabolism in the brain as a novel mechanism of ceftriaxone neuroprotective properties.

BACKGROUND: The dominant hypothesis about the pathogenesis of Alzheimer's disease (AD) is the "amyloid cascade" concept and modulating the expression of proteins involved in the metabolism of amyloid-beta (Aß) is proposed as an effective strategy for the prevention and therapy of AD. Recently, we found that an antibiotic ceftriaxone (CEF), which possesses neuroprotective activity, reduced cognitive deficits and neurodegenerative changes in OXYS rats, a model of sporadic AD. The molecular mechanisms of this effect are not completely clear, we suggested that the drug might serve as the regulator of the expression of the genes involved in the metabolism of Aß and the pathogenesis of AD. The study was aimed to determine the effects of CEF on mRNA levels of Bace1 (encoding ß-secretase BACE1 involved in Aß production), Mme, Ide, Ece1, Ace2 (encoding enzymes involved in Aß degradation), Epo (encoding erythropoietin related to endothelial function and clearance of Aß across the blood brain barrier) in the frontal cortex, hippocampus, striatum, hypothalamus, and amygdala of OXYS and Wistar (control strain) male rats. Starting from the age of 14 weeks, animals received CEF (100 mg/kg/day, i.p., 36 days) or saline. mRNA levels were evaluated with RT-qPCR method. Biochemical parameters of plasma were measured for control of system effects of the treatment. RESULTS: To better understand strain variations studied here, we compared the gene expression between untreated OXYS and Wistar rats. This comparison showed a significant decrease in mRNA levels of Ace2 in the frontal cortex and hypothalamus, and of Actb in the amygdala of untreated OXYS rats. Analysis of potential effects of CEF revealed its novel targets. In the compound-treated OXYS cohort, CEF diminished mRNA levels of Bace1 and Ace2 in the hypothalamus, and Aktb in the frontal cortex. Furthermore, CEF augmented Mme, Ide, and Epo mRNA levels in the amygdala as well as the levels of Ece1 and Aktb in the striatum. Finally, CEF also attenuated the activity of ALT and AST in plasma of OXYS rats. CONCLUSION: Those findings disclosed novel targets for CEF action that might be involved into neuroprotective mechanisms at early, pre-plaque stages of AD-like pathology development.

BRCA1 gene mutations frequency estimation by allele-specific real-time PCR of pooled genomic DNA samples.

The frequencies of four mutations in the BRCA1 gene (185delAG, T300G, 4153delA, and 5382insC) were estimated in the Russian population. The mutations were analyzed in 7920 DNA samples obtained from randomly selected Novosibirsk citizens and 570 samples from breast cancer patients at Siberian hospitals. The mutations were detected by allele-specific real-time PCR. The mutation analysis was performed with pooled DNA samples to reduce the cost of the study. The 5382insC mutation was found in 20 of 7920 (0.25%) population DNA samples and in 14 of 570 (2.46%) breast cancer samples; the T300G mutation was detected in 4 population samples (0.05%) and in 2 breast cancer samples (0.35%); the 185delAG or 4153delA mutations were not identified in any of the 7920 samples and were detected in 1 (0.18%) breast cancer case each.

Non-founder BRCA1 mutations in Russian breast cancer patients.

A few founder BRCA1 mutations (5382insC, 4154delA, 185delAG) account for up to 15% of high-risk (young-onset or familial or bilateral) breast cancer (BC) cases in Russia. The impact of non-founder BRCA1 mutations in this country is less studied; in particular, there are no reports analyzing gross rearrangements of this gene in the Russian patient series. We selected for the study 95 founder mutation negative high-risk BC cases. Combination of high-resolution melting (HRM) and sequencing revealed six presumably BC-associated alleles (2080delA, 4808C>G, 5214C>T, 5236G>A, 5460G>T, 5622C>T) and one variant of an unknown significance (4885G>A). The pathogenic role of the 5236G>A mutation leading to G1706E substitution was further confirmed by the loss of heterozygosity analysis of the corresponding tumor tissue. Multiplex ligation-dependent probe amplification (MLPA) revealed two additional BRCA1 heterozygotes, which carried BRCA1 deletions involving exons 1-2 and 3-7, respectively. Based on the results of this investigation and the review of prior Russian studies, three BRCA1 mutations (2080delA, 3819del5, 3875del4) were considered with respect to their possible founder effect and tested in the additional series of 210 high-risk BC patients; two BRCA heterozygotes (2080delA and 3819del5) were revealed. We conclude that the non-founder mutations constitute the minority of BRCA1 defects in Russia.

Large family with both parents affected by distinct BRCA1 mutations: implications for genetic testing.

Although the probability of both parents being affected by BRCA1 mutations is not negligible, such families have not been systematically described in the literature. Here we present a large breast-ovarian cancer family, where 3 sisters and 1 half-sister inherited maternal BRCA1 5382insC mutation while the remaining 2 sisters carried paternal BRCA1 1629delC allele. No BRCA1 homozygous mutations has been detected, that is consistent with the data on lethality of BRCA1 knockout mice. This report exemplifies that the identification of a single cancer-predisposing mutation within the index patient may not be sufficient in some circumstances. Ideally, all family members affected by breast or ovarian tumor disease have to be subjected to the DNA testing, and failure to detect the mutation in any of them calls for the search of the second cancer-associated allele.