Proteasomal Degradation of the EWS-FLI1 Fusion Protein Is Regulated by a Single Lysine Residue.

E-26 transformation-specific (ETS) proteins are transcription factors directing gene expression through their conserved DNA binding domain. They are implicated as truncated forms or interchromosomal rearrangements in a variety of tumors including Ewing sarcoma, a pediatric tumor of the bone. Tumor cells express the chimeric oncoprotein EWS-FLI1 from a specific t(22;11)(q24;12) translocation. EWS-FLI1 harbors a strong transactivation domain from EWSR1 and the DNA-binding ETS domain of FLI1 in the C-terminal part of the protein. Although Ewing cells are crucially dependent on continuous expression of EWS-FLI1, its regulation of turnover has not been characterized in detail. Here, we identify the EWS-FLI1 protein as a substrate of the ubiquitin-proteasome system with a characteristic polyubiquitination pattern. Using a global protein stability approach, we determined the half-life of EWS-FLI1 to lie between 2 and 4 h, whereas full-length EWSR1 and FLI1 were more stable. By mass spectrometry, we identified two ubiquitin acceptor lysine residues of which only mutation of Lys-380 in the ETS domain of the FLI1 part abolished EWS-FLI1 ubiquitination and stabilized the protein posttranslationally. Expression of this highly stable mutant protein in Ewing cells while simultaneously depleting the endogenous wild type protein differentially modulates two subgroups of target genes to be either EWS-FLI1 protein-dependent or turnover-dependent. The majority of target genes are in an unaltered state and cannot be further activated. Our study provides novel insights into EWS-FLI1 turnover, a critical pathway in Ewing sarcoma pathogenesis, and lays new ground to develop novel therapeutic strategies in Ewing sarcoma.

Activation of concurrent apoptosis and necroptosis by SMAC mimetics for the treatment of refractory and relapsed ALL.

More precise treatment strategies are urgently needed to decrease toxicity and improve outcomes for treatment-refractory leukemia. We used ex vivo drug response profiling of high-risk, relapsed, or refractory acute lymphoblastic leukemia (ALL) cases and identified a subset with exquisite sensitivity to small-molecule mimetics of the second mitochondria-derived activator of caspases (SMAC) protein. Potent ex vivo activity of the SMAC mimetic (SM) birinapant correlated with marked in vivo antileukemic effects, as indicated by delayed engraftment, decreased leukemia burden, and prolonged survival of xenografted mice. Antileukemic activity was dependent on simultaneous execution of apoptosis and necroptosis, as demonstrated by functional genomic dissection with a multicolored lentiCRISPR approach to simultaneously disrupt multiple genes in patient-derived ALL. SM specifically targeted receptor-interacting protein kinase 1 (RIP1)-dependent death, and CRISPR-mediated disruption of RIP1 completely blocked SM-induced death yet had no impact on the response to standard antileukemic agents. Thus, SM compounds such as birinapant circumvent escape from apoptosis in leukemia by activating a potent dual RIP1-dependent apoptotic and necroptotic cell death, which is not exploited by current therapy. Ex vivo drug activity profiling could provide important functional diagnostic information to identify patients who may benefit from targeted treatment with birinapant in early clinical trials.

The PML domain of PML-RARα blocks senescence to promote leukemia.

In most acute promyelocytic leukemia (APL) cases, translocons produce a promyelocytic leukemia protein-retinoic acid receptor α (PML-RARα) fusion gene. Although expression of the human PML fusion in mice promotes leukemia, its efficiency is rather low. Unexpectedly, we find that simply replacing the human PML fusion with its mouse counterpart results in a murine PML-RARα (mPR) hybrid protein that is transformed into a significantly more leukemogenic oncoprotein. Using this more potent isoform, we show that mPR promotes immortalization by preventing cellular senescence, impeding up-regulation of both the p21 and p19(ARF) cell-cycle regulators. This induction coincides with a loss of the cancer-associated ATRX/Daxx-histone H3.3 predisposition complex and suggests inhibition of senescence as a targetable mechanism in APL therapy.

Transcriptional dysregulation of the multifunctional zinc finger factor 423 in acute lymphoblastic leukemia of childhood.

Differentiation arrest is a hallmark of acute lymphoblastic leukemia (ALL). Among a variety of structural and chromosomal alterations, especially mutations in genes encoding for regulators of B cell differentiation are common. The objective of this study was a comprehensive assessment of transcriptional dysregulation and high-resolution genomic profiling of B cell differentiation factors. Here we provide extended materials and methods regarding transcriptome and genome-wide copy number variation analyses published by Harder et al. [1]. Our data provide a resource for the identification of yet undefined factors that play a putative functional role in leukemogenesis such as ZNF423, whose aberrant expression interferes with B-cell differentiation.

ZNF423: Transcriptional modulation in development and cancer.

Krüppel-like zinc finger proteins are versatile players in biology that have been implicated in mammalian development and disease. Among these proteins, ZNF423 and its mouse ortholog Zfp423 were initially implicated in midline patterning of the central nervous system but have emerged as critical transcriptional modulators in cancer. Epigenetically uncurbed ZNF423 interferes with lymphopoiesis by sequestration of the essential early B-cell factor 1 (EBF1) causing B-cell maturation arrest, a hallmark of acute lymphoblastic leukemia. Conversely, its presence in neuroblastoma, a primitive neuroectodermal tumor of childhood, allows retinoic acid-induced differentiation and is associated with a favorable outcome of neuroblastoma patients. Such opposing effects may be explained by the cellular context, but also by the multifunctionality of ZNF423 that is mediated by 30 zinc fingers forming various functional domains. This review summarizes current knowledge of ZNF423, focusing on its role in development and cancer.

Aberrant ZNF423 impedes B cell differentiation and is linked to adverse outcome of ETV6-RUNX1 negative B precursor acute lymphoblastic leukemia.

Differentiation arrest is a hallmark of acute leukemia. Genomic alterations in B cell differentiation factors such as PAX5, IKZF1, and EBF-1 have been identified in more than half of all cases of childhood B precursor acute lymphoblastic leukemia (ALL). Here, we describe a perturbed epigenetic and transcriptional regulation of ZNF423 in ALL as a novel mechanism interfering with B cell differentiation. Hypomethylation of ZNF423 regulatory sequences and BMP2 signaling result in transactivation of ZNF423α and a novel ZNF423ß-isoform encoding a nucleosome remodeling and histone deacetylase complex-interacting domain. Aberrant ZNF423 inhibits the transactivation of EBF-1 target genes and leads to B cell maturation arrest in vivo. Importantly, ZNF423 expression is associated with poor outcome of ETV6-RUNX1-negative B precursor ALL patients. Our work demonstrates that ALL is more than a genetic disease and that epigenetics may uncover novel mechanisms of disease with prognostic implications.

Long-term effects of radiofrequency ablation of the soft palate on snoring.

The objective of the study was to evaluate short- and long-term effects of radiofrequency treatment of the soft palate on snoring. Twenty-nine patients with habitual snoring were studied prospectively and treated up to four times at 4-6 week intervals with an Ellman Surgitrone®. Electromyography (EMG) of m. palatoglossus was performed in ten patients. Patients and partners evaluated snoring, sleep quality and daytime sleepiness 1 week preoperatively, 6 months and 3-4 years postoperatively. Snoring was reduced postoperatively (P < 0.0001). Sleep time increased, daytime sleepiness was reduced, and the partners slept better after 6 months. However, 3-4 years postoperatively only 25% of patients were satisfied. Another 25% had received additional treatment. EMG was normal in 6/10 patients preoperatively. They all continued to snore postoperatively. Four patients had pathological EMGs; three were responders. In conclusion, radiofrequency treatment for snoring may lead to long-term improvement in one out of four cases. Pre-evaluation with EMG may predict the outcome.

To treat snoring with nasal steroids - effects on more than one level?

CONCLUSION: An inflammatory swelling in the uvula and nose due to vibration might be a contributing factor in snoring. The presence of corticosteroid receptors in the uvula indicates the possibility for treatment with local steroids. Use of mometasone furoate (MF) for 3 months reduced snoring and related symptoms in some patients. OBJECTIVE: To investigate the effect of a nasal steroid, MF, on snoring and related discomfort. SUBJECTS AND METHODS: In the first part of the study, uvular and nasal biopsies from six patients with social snoring were examined using immunohistochemistry to evaluate whether corticosteroid receptors were present. Then 100 snoring patients were invited to participate in the second part of the study. In all, 72 men and 22 women with a mean age of 47 years and BMI 27 answered a questionnaire about symptoms, had ENT status assessed and reported sleep and related variables for a 7 day period. After randomization to placebo or MF, they used a nasal spray for 3 months at a dosage of 200 microg. Thereafter the procedure was repeated. RESULTS: Corticosteroid receptors were present in the mucous membranes and around the blood vessels in all uvulas examined. A total of 84 patients were evaluated. No decrease in 'mean snoring score' was seen. Daytime sleepiness showed a slight improvement in the MF group and partners were less disturbed. Minor side effects were equal for both groups.

Association of Type D personality to perceived side effects and adherence in CPAP-treated patients with OSAS.

Continuous positive airway pressure (CPAP) is the treatment of choice for obstructive sleep apnoea syndrome (OSAS), but side effects are common and long-term adherence low. The Type D (distressed) personality is defined as a combination of negative affectivity and social inhibition. The association of Type D personality with adherence has not been studied in CPAP-treated patients with OSAS. This study aimed to describe the prevalence of Type D personality in OSAS patients with CPAP treatment longer than 6 months and the association with self-reported side effects and adherence. A cross-sectional descriptive design was used. A total of 247 OSAS patients with a mean use of CPAP treatment for 55 months (6-182 months) were included. Data collection was achieved by two questionnaires; the Type D scale 14 (DS14) (Type D personality), SECI (side effects of CPAP), as well as from medical records (clinical variables and objective adherence to CPAP treatment). Type D personality occurred in 30% of the patients with OSAS and significantly (P < 0.05-0.001) increased the perceived frequency and severity of a broad range of side effects. The objective adherence was significantly lower (P < 0.001) for OSAS patients with Type D compared to OSAS patients without Type D, both with regard to a mean use of 4 h per night and 85% of the self-rated sleep time per night. The additional effect of a Type D personality on perceived side effects and adherence to CPAP treatment found in this study could be used by healthcare personnel when evaluating patients waiting for treatment.

A stomatin-domain protein essential for touch sensation in the mouse.

Touch and mechanical pain are first detected at our largest sensory surface, the skin. The cell bodies of sensory neurons that detect such stimuli are located in the dorsal root ganglia, and subtypes of these neurons are specialized to detect specific modalities of mechanical stimuli. Molecules have been identified that are necessary for mechanosensation in invertebrates but so far not in mammals. In Caenorhabditis elegans, mec-2 is one of several genes identified in a screen for touch insensitivity and encodes an integral membrane protein with a stomatin homology domain. Here we show that about 35% of skin mechanoreceptors do not respond to mechanical stimuli in mice with a mutation in stomatin-like protein 3 (SLP3, also called Stoml3), a mammalian mec-2 homologue that is expressed in sensory neurons. In addition, mechanosensitive ion channels found in many sensory neurons do not function without SLP3. Tactile-driven behaviours are also impaired in SLP3 mutant mice, including touch-evoked pain caused by neuropathic injury. SLP3 is therefore indispensable for the function of a subset of cutaneous mechanoreceptors, and our data support the idea that this protein is an essential subunit of a mammalian mechanotransducer.