The ribonuclease DIS3 is one of the most frequently mutated genes in the hematological cancer multiple myeloma, yet the basis of its tumor suppressor function in this disease remains unclear. Herein, ...exploiting the TCGA dataset, we found that DIS3 plays a prominent role in the DNA damage response. DIS3 inactivation causes genomic instability by increasing mutational load, and a pervasive accumulation of DNA:RNA hybrids that induces genomic DNA double‐strand breaks (DSBs). DNA:RNA hybrid accumulation also prevents binding of the homologous recombination (HR) machinery to double‐strand breaks, hampering DSB repair. DIS3‐inactivated cells become sensitive to PARP inhibitors, suggestive of a defect in homologous recombination repair. Accordingly, multiple myeloma patient cells mutated for DIS3 harbor an increased mutational burden and a pervasive overexpression of pro‐inflammatory interferon, correlating with the accumulation of DNA:RNA hybrids. We propose DIS3 loss in myeloma to be a driving force for tumorigenesis via DNA:RNA hybrid‐dependent enhanced genome instability and increased mutational rate. At the same time, DIS3 loss represents a liability that might be therapeutically exploited in patients whose cancer cells harbor DIS3 mutations.
Synopsis
The ribonuclease DIS3 is frequently mutated in the blood cancer multiple myeloma. Here, DIS3 inactivation is found to cause accumulation of DNA:RNA hybrids, as well as to increases interferon responses and reduce homologous recombination.
DIS3 loss triggers a genome‐wide increase in DNA:RNA hybrids, which in turn leads to DNA fragmentation and genomic instability.
Hybrids accumulation at the sites of DNA damage prevents BRCA1 binding to DNA, impairing homologous recombination‐based DNA repair.
DIS3 loss is associated with increased mutational rate both in vitro and in patient samples with DIS3 mutations.
Myeloma cells derived from patients presenting DIS3 mutations display an intense interferon response.
DIS3 mutation in hematological cancer causes reduced homologous recombination repair, increased mutational burden, and overactivation of inflammatory interferon responses.
The study aimed to compare the quality of perioperative analgesia, the motor block duration, and the effects on main cardiovascular parameters of dexmedetomidine (1 μg/kg/nerve block) or magnesium ...sulphate (2 mg/kg/nerve block) as adjuvants to 0.3% ropivacaine for sciatic and saphenous nerves block in dogs undergoing tibial plateau leveling osteotomy (TPLO). Dogs randomly received perineural dexmedetomidine-ropivacaine (D group), magnesium sulphate-ropivacaine (M group), or ropivacaine (C group). Fentanyl was administered in case of intraoperative nociception. Postoperative pain was assessed using the Short Form-Glasgow Composite Measure Pain Scale (SF-GCMPS) and VAS scale. The duration of motor blockade and intra- and postoperative cardiovascular parameters were also recorded. Group M required significantly more fentanyl than D group (p = 0.04). Group M had a significantly higher SF-GCMPS score than group C at 4 (p = 0.002) and 5 h after extubation (p = 0.01), and a significantly higher VAS score than group D at 3 h after extubation (p = 0.03), and at 4 h if compared to group C (p = 0.009). No significant differences regarding the duration of motor blockade were detected between groups (p = 0.07). The heart rate was significantly lower in group D than in M and C groups intraoperatively and during the first 1.5 h post extubation. The addition of dexmedetomidine or magnesium sulphate as adjuvants to perineural ropivacaine did not improve the quality of perioperative analgesia and did not prolong the motor blockade in dogs undergoing sciatic and saphenous nerves block for TPLO surgery.
•Adding dexmedetomidine to perineural ropivacaine does not improve analgesia.•Perineural magnesium sulphate may increase peripheral nociceptive transmission.•Perineural dexmedetomidine or magnesium sulphate do not prolong motor blockade.•Perineural dexmedetomidine promotes the appearance of negligible systemic effects.
The oncogenic transcription factor Myc is required for the progression and maintenance of diverse tumors. This has led to the concept that Myc itself, Myc-activated gene products, or associated ...biological processes might constitute prime targets for cancer therapy. Here, we present an in vivo reverse-genetic screen targeting a set of 241 Myc-activated mRNAs in mouse B-cell lymphomas, unraveling a critical role for the mitochondrial ribosomal protein (MRP) Ptcd3 in tumor maintenance. Other MRP-coding genes were also up regulated in Myc-induced lymphoma, pointing to a coordinate activation of the mitochondrial translation machinery. Inhibition of mitochondrial translation with the antibiotic Tigecycline was synthetic-lethal with Myc activation, impaired respiratory activity and tumor cell survival in vitro, and significantly extended lifespan in lymphoma-bearing mice. We have thus identified a novel Myc-induced metabolic dependency that can be targeted by common antibiotics, opening new therapeutic perspectives in Myc-overexpressing tumors.
Isocitrate dehydrogenase 1 ( IDH1 ) is the most commonly mutated metabolic gene across human cancers. Mutant IDH1 (mIDH1) generates the oncometabolite (R)-2-hydroxyglutarate, disrupting enzymes ...involved in epigenetics and other processes. A hallmark of IDH1 -mutant solid tumors is T cell exclusion, whereas mIDH1 inhibition in preclinical models restores antitumor immunity. Here, we define a cell-autonomous mechanism of mIDH1-driven immune evasion. IDH1 -mutant solid tumors show selective hypermethylation and silencing of the cytoplasmic double-stranded DNA (dsDNA) sensor CGAS , compromising innate immune signaling. mIDH1 inhibition restores DNA demethylation, derepressing CGAS and transposable element (TE) subclasses. dsDNA produced by TE-reverse transcriptase (TE-RT) activates cGAS, triggering viral mimicry and stimulating antitumor immunity. In summary, we demonstrate that mIDH1 epigenetically suppresses innate immunity and link endogenous RT activity to the mechanism of action of a US Food and Drug Administration–approved oncology drug.
Editor’s summary Transposable elements (TEs) are relics of ancient viral infections scattered throughout mammalian genomes. TE reactivation and detection by cytosolic nucleic acid sensors acts as a cellular alarm, eliciting antiviral immunity (viral mimicry). Wu et al . report a new pathway for viral mimicry underlying the anticancer mechanism of mutant isocitrate dehydrogenase (mIDH1) inhibitors (see the Perspective by Pitarresi and Fitzgerald). mIDH1 affects cancer by producing the oncometabolite 2-hydroxyglutarate, which inactivates DNA- and histone-demethylating enzymes. The researchers show that the double-stranded DNA sensor cGAS is silenced by promoter DNA hypermethylation in mIDH1 liver and brain tumors. Conversely, mIDH1 inhibition causes DNA hypomethylation and transcriptional activation of cGAS, which results in the stimulation of a potent antitumor T cell response. —Pricilla N. Kelly
INTRODUCTION Mutations of the metabolic enzyme isocitrate dehydrogenase 1 (IDH1) promote tumorigenesis by generating (R)-2-hydroxyglutarate (R-2HG). Investigations of the unusual cancer-causing effects of this compound have given rise to the concept of the “oncometabolite.” R-2HG is not used by any primary metabolic pathways and instead accumulates to high levels in the cell, thereby disrupting many enzymes, including epigenetic and metabolic regulators, and leading to widespread biological dysregulation. A notable feature of mutant IDH1 (mIDH1) solid tumors is immune evasion marked by exclusion of cytotoxic CD8 + T cells. Pharmacological inhibitors of mIDH1 reduce R-2HG levels and demonstrate efficacy against mIDH1 cancers in both patients and animal models, and this is associated with CD8 + T cell recruitment and stimulation of antitumor immunity. Understanding how R-2HG influences immune function is important for improving mIDH1-targeted treatments and for providing broader insights into how aberrant metabolism alters tumor-immune interactions. RATIONALE The mechanisms by which immune evasion is caused by R-2HG and restored by mIDH1 inhibition have not been explored in detail, although recent evidence suggests multifaceted processes. Prior studies have shown that one contributor to immune evasion by mIDH1 tumor cells is their insensitivity to the T cell–derived antitumor cytokine interferon-γ (IFNγ). This resistance occurs due to R-2HG-mediated inactivation of TET2, a DNA-demethylating enzyme required for epigenetic activation of IFNγ-induced genes. Accordingly, R-2HG reduction after mIDH1 inhibitor treatment sensitizes these tumor cells to immune attack. However, the basis for the initial recruitment of T cells to these immunologically “cold” tumors after mIDH1 inhibition has been elusive. Here, we explore the mechanisms through which mIDH1 alters immune surveillance and how inhibition of this pathway facilitates T cell recruitment. RESULTS Investigation of the acute response to inhibition of mIDH1 using a mouse model of liver cancer revealed rapid DNA demethylation in tumor cells, followed by progressive reduction in tumor cell proliferation and the promotion of CD8 + T cell infiltration. Transcriptional analysis demonstrated early upregulation of a program of immune-stimulatory type I interferon (IFNβ) and viral response genes within the tumor cells. The trigger for this response was the epigenetic induction of “viral mimicry,” a cellular alarm mechanism in which normally silenced vestigial viral transcripts known as transposable elements (TEs), which are scattered throughout the genome, are derepressed and detected in the cytosol by double-stranded nucleic acid sensors. mIDH1 liver and brain tumors show a striking defect in this innate immune signaling program at baseline, with pronounced hypermethylation and silencing of the gene encoding the cytosolic dsDNA sensor cGAS. mIDH1 inhibition restores DNA demethylation, derepressing the promoter of CGAS and subclasses of TEs. dsDNA produced by TE-derived reverse transcriptase activates cGAS-STING-IRF3 signaling, triggering viral mimicry and stimulating immune surveillance in the mouse model. This program is potentiated by IFN-γ, resulting in a feedforward increase in antitumor immunity. CONCLUSION This study reveals impaired innate immune sensing as a central hallmark of mIDH1 cancers, attributable to hypermethylation and silencing of the cGAS locus. Moreover, these findings suggest a dual therapeutic mechanism of action for mIDH1 inhibition mediated by reactivation of the DNA demethylation machinery, leading to the induction of viral mimicry signaling coupled with the potentiating effect of restoration of IFNγ response. Our results establish a link between endogenous reverse transcriptase and the activity of a US Food and Drug Administration–approved oncology drug. This research lays the groundwork for future investigations into the mIDH1-related epigenetic control of immune evasion. Moreover, it suggests the development of targeted combination therapies for mIDH1 cancers using approaches that further enhance the viral mimicry response. mIDH1 inhibition restores immune surveillance. Cancers with mIDH1 accumulate high levels of the oncometabolite R-2HG, which inhibits the DNA-demethylating enzyme TET2, leading to defects in immune signaling pathways. Pharmacological inhibition of mIDH1 activates TET2, which induces dormant viral-like TEs throughout the genome and reactivates silenced genes in the cGAS-STING pathway that detect dsDNA generated by the TE-encoded reverse transcriptase. TET2 activation also enables tumor cells to respond to the antitumor cytokine IFNγ. These immune pathways cooperate to promote CD8 + T cell infiltration and elicit a robust antitumor response.
In December 2019, a novel coronavirus (severe acute respiratory syndrome coronavirus 2 SARS-CoV-2) emerged in China and has spread globally, creating a pandemic. Information about the clinical ...characteristics of infected patients who require intensive care is limited.
To characterize patients with coronavirus disease 2019 (COVID-19) requiring treatment in an intensive care unit (ICU) in the Lombardy region of Italy.
Retrospective case series of 1591 consecutive patients with laboratory-confirmed COVID-19 referred for ICU admission to the coordinator center (Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy) of the COVID-19 Lombardy ICU Network and treated at one of the ICUs of the 72 hospitals in this network between February 20 and March 18, 2020. Date of final follow-up was March 25, 2020.
SARS-CoV-2 infection confirmed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) assay of nasal and pharyngeal swabs.
Demographic and clinical data were collected, including data on clinical management, respiratory failure, and patient mortality. Data were recorded by the coordinator center on an electronic worksheet during telephone calls by the staff of the COVID-19 Lombardy ICU Network.
Of the 1591 patients included in the study, the median (IQR) age was 63 (56-70) years and 1304 (82%) were male. Of the 1043 patients with available data, 709 (68%) had at least 1 comorbidity and 509 (49%) had hypertension. Among 1300 patients with available respiratory support data, 1287 (99% 95% CI, 98%-99%) needed respiratory support, including 1150 (88% 95% CI, 87%-90%) who received mechanical ventilation and 137 (11% 95% CI, 9%-12%) who received noninvasive ventilation. The median positive end-expiratory pressure (PEEP) was 14 (IQR, 12-16) cm H2O, and Fio2 was greater than 50% in 89% of patients. The median Pao2/Fio2 was 160 (IQR, 114-220). The median PEEP level was not different between younger patients (n = 503 aged ≤63 years) and older patients (n = 514 aged ≥64 years) (14 IQR, 12-15 vs 14 IQR, 12-16 cm H2O, respectively; median difference, 0 95% CI, 0-0; P = .94). Median Fio2 was lower in younger patients: 60% (IQR, 50%-80%) vs 70% (IQR, 50%-80%) (median difference, -10% 95% CI, -14% to 6%; P = .006), and median Pao2/Fio2 was higher in younger patients: 163.5 (IQR, 120-230) vs 156 (IQR, 110-205) (median difference, 7 95% CI, -8 to 22; P = .02). Patients with hypertension (n = 509) were older than those without hypertension (n = 526) (median IQR age, 66 years 60-72 vs 62 years 54-68; P < .001) and had lower Pao2/Fio2 (median IQR, 146 105-214 vs 173 120-222; median difference, -27 95% CI, -42 to -12; P = .005). Among the 1581 patients with ICU disposition data available as of March 25, 2020, 920 patients (58% 95% CI, 56%-61%) were still in the ICU, 256 (16% 95% CI, 14%-18%) were discharged from the ICU, and 405 (26% 95% CI, 23%-28%) had died in the ICU. Older patients (n = 786; age ≥64 years) had higher mortality than younger patients (n = 795; age ≤63 years) (36% vs 15%; difference, 21% 95% CI, 17%-26%; P < .001).
In this case series of critically ill patients with laboratory-confirmed COVID-19 admitted to ICUs in Lombardy, Italy, the majority were older men, a large proportion required mechanical ventilation and high levels of PEEP, and ICU mortality was 26%.
Leukodystrophies are rare diseases caused by defects in the genes coding for lysosomal enzymes that degrade several glycosphingolipids. Gene therapy for leukodystrophies requires efficient ...distribution of the missing enzymes in CNS tissues to prevent demyelination and neurodegeneration. In this work, we targeted the external capsule (EC), a white matter region enriched in neuronal projections, with the aim of obtaining maximal protein distribution from a single injection site. We used bidirectional (bd) lentiviral vectors (LV) (bdLV) to ensure coordinate expression of a therapeutic gene (β-galactocerebrosidase, GALC; arylsulfatase A, ARSA) and of a reporter gene, thus monitoring simultaneously transgene distribution and enzyme reconstitution. A single EC injection of bdLV.GALC in early symptomatic twitcher mice (a murine model of globoid cell leukodystrophy) resulted in rapid and robust expression of a functional GALC protein in the telencephalon, cerebellum, brainstem and spinal cord. This led to global rescue of enzymatic activity, significant reduction of tissue storage and decrease of activated astroglia and microglia. Widespread protein distribution and complete metabolic correction were also observed after EC injection of bdLV.ARSA in a mouse model of metachromatic leukodystrophy. Our data indicated axonal transport, distribution through cerebrospinal fluid flow and cross-correction as the mechanisms contributing to widespread bioavailability of GALC and ARSA proteins in CNS tissues. LV-mediated gene delivery of lysosomal enzymes by targeting highly interconnected CNS regions is a potentially effective strategy that, combined with a treatment able to target the PNS and peripheral organs, may provide significant therapeutic benefit to patients affected by leukodystrophies.
Post-traumatic cerebral infarction (PTCI) is common after traumatic brain injury (TBI). It is unclear what the occurrence of a PTCI is, how it impacts the long-term outcome, and whether it adds ...incremental prognostic value to established outcome predictors.
This was a prospective multicenter cohort study of moderate and severe TBI patients. The primary objective was to evaluate if PTCI was an independent risk factor for the 6-month outcome assessed with the Glasgow Outcome Scale (GOS). We also assessed the PTCI occurrence and if it adds incremental value to the International Mission for Prognosis and Clinical Trial design in TBI (IMPACT) core and extended models.
We enrolled 143 patients, of whom 47 (32.9%) developed a PTCI. In the multiple ordered logistic regression, PTCI was retained in both the core and extended IMPACT models as an independent predictor of the GOS. The predictive performances increased significantly when PTCI was added to the IMPACT core model (AUC = 0.73, 95% C.I. 0.66-0.82; increased to AUC = 0.79, 95% CI 0.71-0.83, p = 0.0007) and extended model (AUC = 0.74, 95% C.I. 0.65-0.81 increased to AUC = 0.80, 95% C.I. 0.69-0.85; p = 0.00008). Patients with PTCI showed higher ICU mortality and 6-month mortality, whereas hospital mortality did not differ between the two groups.
PTCI is a common complication in patients suffering from a moderate or severe TBI and is an independent risk factor for long-term disability. The addition of PTCI to the IMPACT core and extended predictive models significantly increased their performance in predicting the GOS.
The present study was registered in ClinicalTrial.gov with the ID number NCT02430324.
The basal ganglia play a critical role in shaping motor behavior. For this function, the activity of medium spiny neurons (MSNs) of the striatonigral and striatopallidal pathways must be integrated. ...It remains unclear whether the activity of the two pathways is primarily coordinated by synaptic plasticity mechanisms. Using a model of Parkinson’s disease, we determined the circuit and behavioral effects of concurrently regulating cell-type-specific forms of corticostriatal long-term synaptic depression (LTD) by inhibiting small-conductance Ca2+-activated K+ channels (SKs) of the dorsolateral striatum. At striatopallidal synapses, SK channel inhibition rescued the disease-linked deficits in endocannabinoid (eCB)-dependent LTD. At striatonigral cells, inhibition of these channels counteracted a form of adenosine-mediated LTD by activating the ERK cascade. Interfering with eCB-, adenosine-, and ERK signaling in vivo alleviated motor abnormalities, which supports that synaptic modulation of striatal pathways affects behavior. Thus, our results establish a central role of coordinated synaptic plasticity at MSN subpopulations in motor control.
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•eCBs govern LTD in striatopallidal neurons and adenosine does so in striatonigral cells•Parkinson’s disease (PD)-like dopamine (DA) depletion impairs eCB-, but not adenosine-LTD•DA deficits are circumvented by resuming cell-type-specific eCB and ERK signaling•Segregated modulation of eCB and ERK signaling alleviates PD motor abnormalities
Trusel et al. highlight the motor implications of restoring functional integration of presynaptic and postsynaptic mechanisms of plasticity at striatal projection neurons, by resuming cell-type-specific activation of eCB and ERK signaling in dopamine-depleted mice.
Murine neural stem cells (mNSCs), either naive or genetically modified to express supranormal levels of β‐galactocerebrosidase (GALC), were transplanted into the brain of Twitcher mice, a murine ...model of globoid cell leukodystrophy, a severe sphingolipidosis. Cells engrafted long‐term into the host cytoarchitecture, producing functional GALC. Levels of enzyme activity in brain and spinal cord tissues were enhanced when GALC‐overexpressing NSC were used. Enzymatic correction correlated with reduced tissue storage, decreased activation of astroglia and microglia, delayed onset of symptoms, and longer lifespan. Mechanisms underlying the therapeutic effect of mNSC included widespread enzyme distribution, cross‐correction of host cells, anti‐inflammatory activity, and neuroprotection. Similar cell engraftment and metabolic correction were reproduced using human NSC. Thus, NSC gene therapy rapidly reconstitutes sustained and long‐lasting enzyme activity in central nervous system tissues. Combining this approach with treatments targeting the systemic disease associated with leukodystrophies may provide significant therapeutic benefit. STEM CELLS 2011;29:1559–1571
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