Citations

Abstract Branched-chain amino acid transaminase 1 (BCAT1) is upregulated selectively in human isocitrate dehydrogenase (IDH) wildtype (WT) but not mutant glioblastoma multiforme (GBM) and promotes IDHWT GBM growth. Through a metabolic synthetic lethal screen, we report here that α-ketoglutarate (AKG) kills IDHWT GBM cells when BCAT1 protein is lost, which is reversed by reexpression of BCAT1 or supplementation with branched-chain α-ketoacids (BCKA), downstream metabolic products of BCAT1. In patient-derived IDHWT GBM tumors in vitro and in vivo, cotreatment of BCAT1 inhibitor gabapentin and AKG resulted in synthetic lethality. However, AKG failed to evoke a synthetic lethal effect with loss of BCAT2, BCKDHA, or GPT2 in IDHWT GBM cells. Mechanistically, loss of BCAT1 increased the NAD+/NADH ratio but impaired oxidative phosphorylation, mTORC1 activity, and nucleotide biosynthesis. These metabolic alterations were synergistically augmented by AKG treatment, thereby causing mitochondrial dysfunction and depletion of cellular building blocks, including ATP, nucleotides, and proteins. Partial restoration of ATP, nucleotides, proteins, and mTORC1 activity by BCKA supplementation prevented IDHWT GBM cell death conferred by the combination of BCAT1 loss and AKG. These findings define a targetable metabolic vulnerability in the most common subset of GBM that is currently incurable. Significance: Metabolic synthetic lethal screening in IDHWT glioblastoma defines a vulnerability to ΑΚG following BCAT1 loss, uncovering a therapeutic strategy to improve glioblastoma treatment. See related commentary by Meurs and Nagrath, p. 2354

Background and Objectives: Peroxisome proliferator activated receptor-gamma agonists, such as pioglitazone (PIO) enhanced hematoma resolution and improved functional recovery in our animal model of intracerebral hemorrhage (ICH). We conducted a translational Phase II randomized, controlled clinical trial to determine the maximum tolerated dose (MTD) of PIO in patients with spontaneous ICH and to explore the rate of hematoma resolution and clinical outcome. Methods: Patients with spontaneous ICH within 24 hours of symptom onset were randomly allocated 1:1 to placebo or PIO. Patients received escalating doses of PIO daily for three days, followed by a 30mg maintenance dose for the duration of treatment. Duration of treatment was when 75% of the ICH had resolved as determined by serial MRI or 10 weeks of treatment, whichever occurred first. The primary safety outcome was mortality at Day 14. Secondary measures of safety include any mortality, symptomatic cerebral edema, congestive heart failure, edema, hypoglycemia, anemia, and hepatotoxicity. Secondary measures of efficacy include hematoma resolution and clinical outcome. The MTD was determined using the Continual Reassessment Method. Results: From March 2009 to April 2013, 84 patients (42 PIO, 42 control) were enrolled into 11 dose tiers, with a planned range from 0.1-2.0 mg/kg/d. Table 1 demonstrates preliminary baseline and clinical characteristics of patients by treatment group. Overall, 2/84 patients died within 2 weeks after ICH; however mortality rate never exceeded prespecified criteria. The study will be complete in October 2013 and the treatment team remains blinded to treatment allocation. Secondary outcomes by treatment group and the MTD of PIO will be reported. Conclusions: We have completed the treatment phase of the SHRINC Trial. Long term follow-up is on-going. These results will provide the foundation for an efficacy trial evaluating PIO as a potential treatment for patients with spontaneous ICH.

Integrins are heterodimeric (α/β) membrane proteins that play fundamental roles in many biological processes, e.g. cell adhesion and spreading, which are important for platelet function and hemostasis. Integrin function is modulated by bi-directional transmembrane signaling: inside-out and outside-in, which is mediated through the interactions between integrin cytoplasmic tails and intracellular, regulatory proteins. Here, we show that VPS33B, a member of the Sec1/Munc18 (SM) family and component of the Class C core of the CORVET/HOPS sorting complexes, binds directly to the β subunit. Overexpression of VPS33B in CHO cells potentiated α IIb β 3 outside-in signaling but not inside-out signaling. Platelets, from megakaryocyte- and platelet-specific VPS33B conditional knockout mice we generated, had normal morphology yet their spreading on fibrinogen was impaired and they failed to support clot retraction. Platelet aggregation and ATP secretion in response to low-dose thrombin were reduced in the VPS33B knockout mice. α IIb β 3 -mediated endocytosis of fibrinogen was also defective. Tail bleeding times were prolonged in the VPS33B knockout mice. Furthermore, VPS33B acted upstream of the RhoA-ROCK-MLC and Rac1 dependent pathways that leads to clot retraction and cell spreading, respectively. Our work demonstrates that vesicular trafficking complexes are a novel class of modifiers of integrin function and in hemostasis. Our data also provide insights into the molecular mechanism and treatment of ARC syndrome.

Abstract Background: The etiology of colorectal cancer is not fully understood. Methods: Using genetic variants and metabolomics data including 217 metabolites from the Framingham Heart Study (n = 1,357), we built genetic prediction models for circulating metabolites. Models with prediction R2 > 0.01 (Nmetabolite = 58) were applied to predict levels of metabolites in two large consortia with a combined sample size of approximately 46,300 cases and 59,200 controls of European and approximately 21,700 cases and 47,400 controls of East Asian (EA) descent. Genetically predicted levels of metabolites were evaluated for their associations with colorectal cancer risk in logistic regressions within each racial group, after which the results were combined by meta-analysis. Results: Of the 58 metabolites tested, 24 metabolites were significantly associated with colorectal cancer risk [Benjamini–Hochberg FDR (BH-FDR) < 0.05] in the European population (ORs ranged from 0.91 to 1.06; P values ranged from 0.02 to 6.4 × 10−8). Twenty one of the 24 associations were replicated in the EA population (ORs ranged from 0.26 to 1.69, BH-FDR < 0.05). In addition, the genetically predicted levels of C16:0 cholesteryl ester was significantly associated with colorectal cancer risk in the EA population only (OREA: 1.94, 95% CI, 1.60−2.36, P = 2.6 × 10−11; OREUR: 1.01, 95% CI, 0.99−1.04, P = 0.3). Nineteen of the 25 metabolites were glycerophospholipids and triacylglycerols (TAG). Eighteen associations exhibited significant heterogeneity between the two racial groups (PEUR-EA-Het < 0.005), which were more strongly associated in the EA population. This integrative study suggested a potential role of lipids, especially certain glycerophospholipids and TAGs, in the etiology of colorectal cancer. Conclusions: This study identified potential novel risk biomarkers for colorectal cancer by integrating genetics and circulating metabolomics data. Impact: The identified metabolites could be developed into new tools for risk assessment of colorectal cancer in both European and EA populations.

Conventional imaging has been the standard imaging modality for assessing prostate cancer recurrence and is utilized to determine treatment response to therapy. Molecular imaging with PSMA PET–CT has proven to be more accurate, sensitive, and specific at identifying pelvic or distant metastatic disease, resulting in earlier diagnosis of advanced disease. Since advanced disease may not be seen on conventional imaging, due to its lower sensitivity, but can be identified by molecular imaging, this reveals that metastatic prostate cancer occurs on a continuum from negative PSMA PET–CT and negative conventional imaging to positive PSMA PET–CT and positive conventional imaging. Understanding this continuum, the accuracy of these modalities, and treatment related outcomes based on imaging, will allow the clinician to counsel patients on management. This review will highlight the differences in conventional and molecular imaging in prostate cancer and how PSMA PET–CT can be used for the management of prostate cancer patients in different clinical scenarios, while providing cautionary notes for overtreatment.

Abstract Intrathecal application of contulakin-G (CGX), a conotoxin peptide and a neurotensin analogue, has been demonstrated to be safe and potentially analgesic in humans. However, the mechanism of action for CGX analgesia is unknown. We hypothesized that spinal application of CGX produces antinociception through activation of the presynaptic neurotensin receptor (NTSR)2. In this study, we assessed the mechanisms of CGX antinociception in rodent models of inflammatory and neuropathic pain. Intrathecal administration of CGX, dose dependently, inhibited thermal and mechanical hypersensitivities in rodents of both sexes. Pharmacological and clustered regularly interspaced short palindromic repeats/Cas9 editing of NTSR2 reversed CGX-induced antinociception without affecting morphine analgesia. Electrophysiological and gene editing approaches demonstrated that CGX inhibition was dependent on the R-type voltage-gated calcium channel (Cav2.3) in sensory neurons. Anatomical studies demonstrated coexpression of NTSR2 and Cav2.3 in dorsal root ganglion neurons. Finally, synaptic fractionation and slice electrophysiology recordings confirmed a predominantly presynaptic effect. Together, these data reveal a nonopioid pathway engaged by a human-tested drug to produce antinociception.

Abstract Venomous snakebite is an important cause of preventable death. The World Health Organization (WHO) set a goal to halve snakebite mortality by 2030. We used verbal autopsy and vital registration data to model the proportion of venomous animal deaths due to snakes by location, age, year, and sex, and applied these proportions to venomous animal contact mortality estimates from the Global Burden of Disease 2019 study. In 2019, 63,400 people (95% uncertainty interval 38,900–78,600) died globally from snakebites, which was equal to an age-standardized mortality rate (ASMR) of 0.8 deaths (0.5–1.0) per 100,000 and represents a 36% (2–49) decrease in ASMR since 1990. India had the greatest number of deaths in 2019, equal to an ASMR of 4.0 per 100,000 (2.3-5.0). We forecast mortality will continue to decline, but not sufficiently to meet the WHO’s goals. Improved data collection should be prioritized to help target interventions, improve burden estimation, and monitor progress.