Low expression levels of ATM may substitute for CHEK2 /TP53 mutations predicting resistance towards anthracycline and mitomycin chemotherapy in breast cancer

Introduction

Mutations affecting p53 or its upstream activator Chk2 are associated with resistance to DNA-damaging chemotherapy in breast cancer. ATM (Ataxia Telangiectasia Mutated protein) is the key activator of p53 and Chk2 in response to genotoxic stress. Here, we sought to evaluate ATM's potential role in resistance to chemotherapy.

Methods

We sequenced ATM and assessed gene expression levels in pre-treatment biopsies from 71 locally advanced breast cancers treated in the neoadjuvant setting with doxorubicin monotherapy or mitomycin combined with 5-fluorouracil. Findings were confirmed in a separate patient cohort treated with epirubicin monotherapy. Each tumor was previously analyzed for CHEK2 and TP53 mutation status.

Results

While ATM mutations were not associated with chemo-resistance, low ATM expression levels predicted chemo-resistance among patients with tumors wild-type for TP53 and CHEK2 (P = 0.028). Analyzing the ATM-chk2-p53 cascade, low ATM levels (defined as the lower 5 to 50% percentiles) or mutations inactivating TP53 or CHEK2 robustly predicted anthracycline resistance (P-values varying between 0.001 and 0.027 depending on the percentile used to define "low" ATM levels). These results were confirmed in an independent cohort of 109 patients treated with epirubicin monotherapy. In contrast, ATM-levels were not suppressed in resistant tumors harboring TP53 or CHEK2 mutations (P > 0.5).

Conclusions

Our data indicate loss of function of the ATM-Chk2-p53 cascade to be strongly associated with resistance to anthracycline/mitomycin-containing chemotherapy in breast cancer.     

水体中克雷伯菌属的分布及其在水源性急性肠道感染中的价值

俄罗斯不同气候地区不同功能水体中克雷伯菌属广泛分布。克雷伯菌属可见于遭受生物、化学污染的集中供水的地表水源,无防护的地下蓄水层,缺乏有效清洁、消毒系统的饮用水。研究表明,水体中的克雷伯菌属具有致病性和毒性,对现代药物和消毒剂(氯、紫外线)具有抗性,很容易穿透进入地下蓄水层。克雷伯菌属细菌有很强的致病性(粘附力、侵袭力、磷酸酯酶、卵磷脂酶、脱氧核糖核酸酶、溶血活性),含有致病性遗传标记cnf-1。克雷伯菌属(100 CFU/dm³)可引起急性肠道感染。在不检测总大肠菌群的情况下,检测水体尤其是饮用水中的克雷伯菌属,可以评估所用水的流行病学危险。     

Expansive growth of two glioblastoma stem-like cell lines is mediated by bFGF and not by EGF

Background

Patient-derived glioblastoma (GBM) stem-like cells (GSCs) represent a valuable model for basic and therapeutic research. GSCs are usually propagated in serum-free Neural Basal medium supplemented with bFGF and EGF. Yet, the exact influence of these growth factors on GSCs is still unclear. Recently it was suggested that GBM stem-like cells with amplified EGFR should be cultured in stem cell medium without EGF, as the presence of EGF induced rapid loss of EGFR amplification. However, patient biopsies are usually taken into culture before their genomic profiles are defined. Thus, an important question remains whether GBM cells without EGFR amplification also can be cultured in stem cell medium without EGF.

Meterials and methods

To address this question, we used two heterogeneous glioblastoma GSC lines (NCH421k and NCH644) that lack EGFR amplification.

Results

Although both cell lines showed very low EGFR expression under standard growth conditions, bFGF stimulation induced higher expression of EGFR in NCH644. In both cell lines, expression of the stem cell markers nestin and CD133 was higher upon stimulation with bFGF compared to EGF. Importantly, bFGF stimulated the growth of both cell lines, whereas EGF had no effect. We verified that the growth stimulation by bFGF was either mediated by proliferation (NCH421k) or resistance to apoptosis (NCH644).

Conclusions

We demonstrate that GSC cultures without EGFR amplification can be maintained and expanded with bFGF, while the addition of EGF has no significant effect and therefore can be omitted.     

Epidemiology of persistent diarrhea among Guatemalan rural children

A prospective, longitudinal two-year study to determine the epidemiology of persistent ( 14 days'duration) diarrhea in rural children of Guatemala was undertaken. Three-hundred and twenty-one children aged 0-35 months were kept under surveillance by twice-a-week home visits. The overall incidence of diarrhea was 0.147 per child-week; the incidence of persistent diarrhea was 0.014 per child-week. The peak of persistent diarrhea was observed in infants below six months of age, with a continuous decline thereafter. This trend in incidence of persistent diarrhea was associated with a higher proportion (16%) of illnesses persisting for more than 13 days in children younger than six months of age as compared to children 30-35 months old (4%). Males had more diarrhea (0.156 per child-week) than females (0.139 per child week). Among children above 18 months of age, the proportion of episodes that lasted for more than 13 days was lower in females than in males.     

In vitro genotoxicity of root canal sealers

Aim  To evaluate the effect of leakage on differences in genotoxicity of root canal sealers ex vivo according to their main components using two different cytogenetic assays.
Methodology  Six materials of different composition (GuttaFlow, Epiphany, Diaket, IRM, SuperEBA and Hermetic) were tested on human peripheral blood lymphocytes using the comet assay and chromosomal aberration analysis. Prepared materials were eluted in physiological solution for 1 h, 1 day, 5 and 30 days. Thereafter cultures were treated with 8 μg, 4 μg and 2 μg of each sealer. Frequencies of chromatide and chromosome breaks and accentric fragments were determined. Comet assay was used to evaluate primary DNA damage by measuring tail length and tail intensity. Chi-square, Fisher's PLSD (Protected Least Significant Difference) and Kruskall–Wallis non parametric tests were used for statistical analysis.
Results  After 1-h elution only the highest dose of Diaket, Hermetic and SuperEBA significantly ( P = 0.035, P  = 0.048, P  = 0.037 respectively) affected the measured cytogenetic parameters. The migration ability of DNA was more strongly affected than induction of chromosomal aberrations. After elutions longer than 24 h none of the tested sealers exhibited a genotoxic effect.
Conclusion  Under the conditions used in the study all sealers had acceptable biocompatibility in terms of genotoxicity.     

Autoerythrocyte sensitization syndrome (Gardner–Diamond syndrome): review of the literature**

A review of the literature concerning psychogenic purpura is presented. The diagnosis is usually based on typical anamnestic data, clinical presentation (painful inflammatory skin lesions, which progressed to ecchymoses during the next 24 h) and positive diagnostic tests with intracutaneous injections of 80% solution of washed autologous erythrocytes. No pathological findings of blood coagulation parameters are usually detected. Histopathological evaluations of lesional biopsies revealed non-specific changes. Taking into account the high frequency of psychic disorders and stress dependence of skin symptoms, therapy with psychotropic drugs (according to indications) and psychotherapy are pathogenetically grounded methods of treatment in psychogenic purpura, and should be provided together with symptomatic therapy.