The chloroethylating anticancer drug ACNU induces FRA1 that is involved in drug resistance of glioma cells

AbstractFRA1 belongs, together with c-Fos and FosB, to the family of Fos proteins that form with members of the ATF and Jun family the transcription factor AP-1 (activator protein 1). Previously we showed that c-Fos protects mouse embryonic fibroblasts against the cytotoxic effects of ultraviolet (UV) light by induction of the endonuclease XPF, leading to enhanced nucleotide excision repair (NER) activity. Here, we analyzed the regulation of FRA1 in glioma cells treated with the anticancer drug nimustine (ACNU) and its role in ACNU-induced toxicity. We show that FRA1 is upregulated in glioblastoma cells following ACNU on mRNA and protein levels. Knockdown of FRA1 by either siRNA or shRNA clearly sensitized glioma cells towards ACNU-induced cell death. Despite decreased AP-1 binding activity upon FRA1 knockdown, this effect is independent on regulation of the AP-1 target genes fasL, ercc1 and xpf. In addition, FRA1 knockdown does not affect DNA repair capacity. However, lack of FRA1 attenuated the ACNU-induced phosphorylation of CHK1 and led to a reduced arrest of cells in G2/M and, thereby, presumably leads to enhanced cell death in the subsequent cell cycle

Delayed c-Fos activation in human cells triggers XPF induction and an adaptive response to UVC-induced DNA damage and cytotoxicity

The oncoprotein c-Fos has been commonly found differently expressed in cancer cells. Our previous work showed that mouse cells lacking the immediate-early gene c-fos are hypersensitive to ultraviolet (UVC) light. Here, we demonstrate that in human diploid fibroblasts UV-triggered induction of c-Fos protein is a delayed and long-lasting event. Sustained upregulation of c-Fos goes along with transcriptional stimulation of the NER gene xpf, which harbors an AP-1 binding site in the promoter. Data gained on c-Fos knockdown and c-Fos overexpressing human cells provide evidence that c-Fos/AP-1 stimulates upregulation of XPF, thereby increasing the cellular repair capacity protecting from UVC-induced DNA damage. When these cells are pre-exposed to a low non-toxic UVC dose and challenged with a subsequent high dose of UVC irradiation, they show accelerated repair of UVC-induced DNA adducts and reduced cell kill. The data indicate a protective role of c-Fos induction by triggering an adaptive response pathway

Chemically synthesized zinc finger molecules as nano-addressable probes for double-stranded DNAs

Our experiments describe an alternative method of dsDNA recognition using zinc finger (ZF) molecules which bind DNA specifically and with high affinity. Our aim was to develop zinc finger probes which are able to bind to dsDNA molecules at predetermined sites. In our basic approach we used pairs of complementary oligonucleotides to form dsDNAs, containing one of the three SP1-transcription factor motifs as a zinc finger recognition site. Two zinc finger probes of the SP1 motif were chemically synthesized and modified with a Dy-633 fluorophore. The SP1 peptides were folded into functional zinc fingers using zinc chloride. The addressable dsDNAs were immobilized on optical fibres, and the kinetics and binding rates of the artificial zinc finger probes were measured by a fluorescence detecting device (photomultiplying tube). The two zinc fingers and their corresponding DNA recognition sites served as specific probes and controls for the matching site and vice versa. Our experiments showed that a variety of dsDNA-binding probes may be created by modification of the amino acid sequence of natural zinc finger proteins. Our findings offer an alternative approach of addressing dsDNA molecules, for example for use in a nanoarray device

Three prime exonuclease I (TREX1) is Fos/AP-1 regulated by genotoxic stress and protects against ultraviolet light and benzo(a)pyrene-induced DNA damage

Cells respond to genotoxic stress with the induction of DNA damage defence functions. Aimed at identifying novel players in this response, we analysed the genotoxic stress-induced expression of DNA repair genes in mouse fibroblasts proficient and deficient for c-Fos or c-Jun. The experiments revealed a clear up-regulation of the three prime exonuclease I (trex1) mRNA following ultraviolet (UV) light treatment. This occurred in the wild-type but not c-fos and c-jun null cells, indicating the involvement of AP-1 in trex1 induction. Trex1 up-regulation was also observed in human cells and was found on promoter, RNA and protein level. Apart from UV light, TREX1 is induced by other DNA damaging agents such as benzo(a)pyrene and hydrogen peroxide. The mouse and human trex1 promoter harbours an AP-1 binding site that is recognized by c-Fos and c-Jun, and its mutational inactivation abrogated trex1 induction. Upon genotoxic stress, TREX1 is not only up-regulated but also translocated into the nucleus. Cells deficient in TREX1 show reduced recovery from the UV and benzo(a)pyrene-induced replication inhibition and increased sensitivity towards the genotoxins compared to the isogenic control. The data revealed trex1 as a novel DNA damage-inducible repair gene that plays a protective role in the genotoxic stress response

c-Fos is required for excision repair of UV-light induced DNA lesions by triggering the re-synthesis of XPF

Cells deficient in c-Fos are hypersensitive to ultraviolet (UV-C) light. Here we demonstrate that mouse embryonic fibroblasts lacking c-Fos (fos−/−) are defective in the repair of UV-C induced DNA lesions. They show a decreased rate of sealing of repair-mediated DNA strand breaks and are unable to remove cyclobutane pyrimidine dimers from DNA. A search for genes responsible for the DNA repair defect revealed that upon UV-C treatment the level of xpf and xpg mRNA declined but, in contrast to the wild type (wt), did not recover in fos−/− cells. The observed decline in xpf and xpg mRNA is due to impaired re-synthesis, as shown by experiments using actinomycin D. Block of xpf transcription resulted in a lack of XPF protein after irradiation of fos−/− cells, whereas the XPF level normalized quickly in the wt. Although the xpg mRNA level was reduced, the amount of XPG protein was not altered in c-Fos-deficient cells after UV-C, due to higher stability of the XPG protein. The data suggest a new role for c-Fos in cells exposed to genotoxic stress. Being part of the transcription factor AP-1, c-Fos stimulates NER via the upregulation of xpf and thus plays a central role in the recovery of cells from UV light induced DNA damage

Implementation of a Modelica library for simulation of electromechanical actuators for aircraft and helicopters

The goal of the A2015 library presented in this paper is to develop a Modelica based, tool-independent standard for electromechanical actuators (EMA). This will contribute to the establishment of a “common language” throughout the development of EMAs for aircraft and helicopters and through the supply chain. All stages of the design and validation process (conceptual design, specification, development and validation) are covered. The modeling approach addresses specific aspects of the EMA design process not covered by existing tools. The library scope, engineering need and implementation are described. Modeling of selected EMA components is discussed in more detail. An application example of the library is given (linear actuator, A320 aileron

Preoperative smoking cessation program in patients undergoing intermediate to high-risk surgery: a randomized, single-blinded, controlled, superiority trial

BACKGROUND At present, effectively implementing smoking cessation programs in the health care system constitutes a major challenge. A unique opportunity to initiate smoking cessation focuses on smokers scheduled for surgery. These patients are not only highly motivated to quit smoking but also likely to benefit from a reduction in postoperative complications which may translate into a decrease of costs. Nevertheless, surgical patients are not routinely informed about the benefits of preoperative smoking cessation. Potential reasons for this missed opportunity may be the lack of time and training of surgeons and anaesthesiologists. We therefore aim to analyse the impact of a preoperative high-intensity smoking cessation intervention on surgical complications up to a 90-day postoperative period in patients of various surgical disciplines. The hypothesis is that a preoperative smoking cessation program improves outcomes in smokers undergoing intermediate to high-risk surgery. METHODS The present study is a single-centre, randomized trial with two parallel groups of smokers scheduled for surgery comparing surgery alone and surgery with preoperative smoking cessation. We plan to randomize 251 patients. The primary objective is to compare complications between patients with an institutional multifaceted smoking cessation intervention starting 4 weeks before surgery compared to patients in the advice-only group (control group) within a 90-day postoperative period. The primary endpoint is the Comprehensive Complication Index (CCI®) within 90 days of surgery. Secondary outcomes include the length of hospital stay, cost of care, quality of life, smoking abstinence, and reduction in nicotine consumption. DISCUSSION The hypothesis is that a preoperative smoking cessation program improves outcomes in smokers undergoing surgery. TRIAL REGISTRATION BASEC #2021-02004; ClinicalTrials.gov: NCT05192837 . Registered on January 14, 2022

Toward Precision Medicine in ADHD

Attention-Deficit Hyperactivity Disorder (ADHD) is a complex and heterogeneous neurodevelopmental condition for which curative treatments are lacking. Whilst pharmacological treatments are generally effective and safe, there is considerable inter-individual variability among patients regarding treatment response, required dose, and tolerability. Many of the non-pharmacological treatments, which are preferred to drug-treatment by some patients, either lack efficacy for core symptoms or are associated with small effect sizes. No evidence-based decision tools are currently available to allocate pharmacological or psychosocial treatments based on the patient's clinical, environmental, cognitive, genetic, or biological characteristics. We systematically reviewed potential biomarkers that may help in diagnosing ADHD and/or stratifying ADHD into more homogeneous subgroups and/or predict clinical course, treatment response, and long-term outcome across the lifespan. Most work involved exploratory studies with cognitive, actigraphic and EEG diagnostic markers to predict ADHD, along with relatively few studies exploring markers to subtype ADHD and predict response to treatment. There is a critical need for multisite prospective carefully designed experimentally controlled or observational studies to identify biomarkers that index inter-individual variability and/or predict treatment response