Role of LKB1 in stem cell fate determination and tumorigenesis

The tumor suppressor kinase, LKB1 (encoded by STK11), plays important functions in regulating diverse cell processes, including cell growth, metabolism, and polarity. As a bioenergetic sensor, LKB1 is required for metabolic balancing and maintenance of stem cell homeostasis in the haematopoietic system (Gurumurthy et al. 2010; Gan et al. 2010; Nakada, Saunders, and Morrison 2010) and in muscle (Shan et al. 2014). Intestinal stem cells (ISCs) are regulated by various cues from their niche-derived paracrine signals such as NOTCH and WNT (Clevers and Batlle 2013), and metabolic status (Rodríguez-Colman et al. 2017; Schell et al. 2017). Study I of this thesis aimed to investigate whether the metabolic regulator, LKB1, has a role in actively cycling ISCs, and identified it as a critical factor for maintaining ISC homeostasis. Mechanistically, LKB1 represses the transcription of the secretory lineage gatekeeper, Atoh1, via pyruvate dehydrogenase kinase 4 (PDK4) in ISCs and restricts ISC differentiation towards secretory cell lineages. These findings define LKB1 as an essential regulator of ISCs, and provide a connection between metabolism and fate determination of ISCs. Germline mutations inactivating LKB1 lead to gastrointestinal tumorigenesis in Peutz-Jeghers Syndrome (PJS) patients (Ylikorkala et al. 1999) and mouse models (Rossi et al. 2002; Bardeesy et al. 2002). However, little is known about the cell types and signaling pathways that underlie tumor formation, not much has been learnt about the progression of PJS polyposis neither. The upregulation of Cyclooxygenase-2 (COX-2) is a feature of PJS polyposis (Rossi et al. 2002; H. Takeda et al. 2004), and COX-2 inhibition reduces polyp growth in Lkb1+/− mice modelling PJS polyposis (Udd et al. 2004). Study II of this thesis evaluated the effect of the mutagenic carcinogen, N-methylnitrosourea (MNU), on gastrointestinal tumorigenesis in Lkb1+/− mice and concluded that MNU aggravates Peutz-Jeghers polyposis independently of COX-2. Study III of this thesis demonstrated that the loss of Lkb1 in mesenchymal progenitor or stromal fibroblasts leads to the clonal expansion of stromal cells and to the induction of an inflammatory program involving the IL-11–JAK/STAT3 pathway, which is critical for tumorigenesis. The findings from Studies II and III provide further understanding of the function of LKB1 in Peutz-Jeghers tumorigenesis, and suggest potential therapeutic avenues for related tumor diseases.Tuumorinsuppressorikinaasi LKB1 (STK11) säätelee useita erilaisia ​​soluprosesseja, kuten solujen jakautumista, aineenvaihduntaa ja polaarisuutta. LKB1 ylläpitää homeostaasia ja metabolista tasapainoa veren kantasoluissa (Gurumurthy ym. 2010; Gan ym. 2010; Nakada, Saunders ja Morrison 2010) sekä lihaksissa (Shan ym. 2014). Suolen kantasolujen homeostaasia säätelevät erilaiset kantasolujen mikroympäristön solujen lähettämät parakriinisignaalit, kuten NOTCH ja WNT -ligandit (Clevers ja Batlle 2013). Tämä lisäksi suolen kantasolujen toimintaa säätelee myös solun metabolinen tila (Rodríguez-Colman ym. 2017; Schell ym. 2017). Tämän väitöskirjatyön ensimmäisen osatyössä osoitettiin, että LKB1 ylläpitää suolen kantasoluja estämällä transkriptiofaktori Atoh1:n ilmentymistä pyruvaattidehydrogenaasikinaasi 4: n välityksellä kantasoluissa, ja rajoittaa täten suolen epiteelisolujen erilaistumista erityssoluiksi. Nämä löydokset osoittavat, että LKB1 ylläpitää solun metabolista tasapainoa ja sitä kautta säätelee suolen kantasolujen toimintaa. Ituratamutaatiot LKB1:ssa aiheuttavat perinnöllistä Peutz-Jeghersin syndroomaa (PJS), jossa potilaille kehittyy mahasuolikanavan kasvaimia. Tuumorigeneesiä aiheuttavat solutyypit ja mekanismit ovat suurelta osin tuntemattomia. Cyclooxygenase-2 (COX-2) -entsyymin aktivaatio on yleistä PJS polypoosissa (Rossi et al. 2002; H. Takeda et al. 2004), ja COX-2 inhibitio vähentää tuumorigeneesiä Lkb1+/− -hiirissä, jotka toimivat PJS:n hiirimallina (Udd et al. 2004). Tämän tutkimuksen toisessa osatyössä tutkittiin mutageenisen syöpää aiheuttavan N-metyylnitrosourean (MNU) vaikutusta maha-suolikanavan tuumorigeneesiin Lkb1+/− -hiirissä. Työssä osoitettiin, että MNU pahentaa PJS-polypoosia COX-2:sta riippumatta. Kolmannessa osatyössä osoitettiin, että Lkb1:n poisto mesenkyymin esiastesoluissa tai fibroblasteissa johtaa stroomasolujen klonaaliseen laajentumiseen ja tulehdusvasteeseen, joka aktivoi tuumorigeneesille kriittisen IL-11 – JAK/STAT3-signaalireitin. Osatöistä II ja III saadut tulokset lisäävät tietoa LKB1:n toiminnasta PJS-tuumorigeneesissä, ja avaavat uusia näkökulmia PJS-tuumorigeneesin hoidon kehittämiseen

Sevoflurane Pre-conditioning Ameliorates Diabetic Myocardial Ischemia/Reperfusion Injury Via Differential Regulation of p38 and ERK.

Diabetes mellitus (DM) significantly increases myocardial ischemia/reperfusion (MI/R) injury. During DM, cardioprotection induced by conventional pre-conditioning (PreCon) is decreased due to impaired AMP-activated protein kinase (AMPK) signaling. The current study investigated whether PreCon with inhaled anesthetic sevoflurane (SF-PreCon) remains cardioprotective during DM, and identified the involved mechanisms. Normal diet (ND) and high-fat diet (HFD)-induced DM mice were randomized into control and SF-PreCon (3 cycles of 15-minute period exposures to 2% sevoflurane) groups before MI/R. SF-PreCon markedly reduced MI/R injury in DM mice, as evidenced by improved cardiac function (increased LVEF and ±Dp/dt), decreased infarct size, and decreased apoptosis. To determine the relevant role of AMPK, the effect of SF-PreCon was determined in cardiac-specific AMPKα2 dominant negative expressing mice (AMPK-DN). SF-PreCon decreased MI/R injury in AMPK-DN mice. To explore the molecular mechanisms responsible for SF-PreCon mediated cardioprotection in DM mice, cell survival molecules were screened. Interestingly, in ND mice, SF-PreCon significantly reduced MI/R-induced activation of p38, a pro-death MAPK, without altering ERK and JNK. In DM and AMPK-DN mice, the inhibitory effect of SF-PreCon upon p38 activation was significantly blunted. However, SF-PreCon significantly increased phosphorylation of ERK1/2, a pro-survival MAPK in DM and AMPK-DN mice. We demonstrate that SF-PreCon protects the heart via AMPK-dependent inhibition of pro-death MAPK in ND mice. However, SF-PreCon exerts cardioprotective action via AMPK-independent activation of a pro-survival MAPK member in DM mice. SF-PreCon may be beneficial compared to conventional PreCon in diabetes or clinical scenarios in which AMPK signaling is impaired

The role of the fronto-parietal network in modulating sustained attention under sleep deprivation: an functional magnetic resonance imaging study

ObjectiveThe intricate relationship between sleep deprivation (SD) and cognitive performance has long been a subject of research. Our study offers a novel angle by closely examining the neurobiological underpinnings of sustained attention deficits through the lens of the fronto-parietal network (FPN). Using state-of-the-art imaging techniques, we delve into the changes in spontaneous brain activity after SD and explore their associations with performance on the psychomotor vigilance task (PVT).MethodsWe conducted an elaborate investigation involving 64 healthy, right-handed participants who underwent resting-state functional MRI scans before and after experiencing 24 h of sleep deprivation. Employing sophisticated statistical analyses, we scrutinized the changes in fractional amplitude of low-frequency fluctuations (fALFF) through paired t-tests. Pearson correlation analyses were then applied to dissect the associations between these neurobiological shifts and behavioral outcomes in PVT.ResultsThe study yielded remarkable findings, revealing a dramatic decrease in fALFF values within critical areas of the FPN following SD. These alterations predominantly occurred in the frontal and parietal gyri and were inversely correlated with PVT performance metrics. Furthermore, we discovered that baseline fALFF values in the left dorsolateral prefrontal cortex (DLPFC) have the potential to serve as compelling neurobiological markers, with high discriminatory power in identifying individual responses to the adverse effects of SD on cognitive performance.ConclusionOur groundbreaking research underscores the pivotal role that the FPN plays in modulating attention and executive function, especially under the challenging conditions brought about by sleep deprivation. The findings offer critical insights that could shape the way we understand, assess, and potentially mitigate the cognitive impacts of SD, setting the stage for future research in this riveting domain

Cytokine-Induced Killer Cells As Pharmacological Tools for Cancer Immunotherapy

Cytokine-induced killer (CIK) cells are a heterogeneous population of effector CD3+CD56+ natural killer T cells, which can be easily expanded in vitro from peripheral blood mononuclear cells. CIK cells work as pharmacological tools for cancer immunotherapy as they exhibit MHC-unrestricted, safe, and effective antitumor activity. Much effort has been made to improve CIK cells cytotoxicity and treatments of CIK cells combined with other antitumor therapies are applied. This review summarizes some strategies, including the combination of CIK with additional cytokines, dendritic cells, check point inhibitors, antibodies, chemotherapeutic agents, nanomedicines, and engineering CIK cells with a chimeric antigen receptor. Furthermore, we briefly sum up the clinical trials on CIK cells and compare the effect of clinical CIK therapy with other immunotherapies. Finally, further research is needed to clarify the pharmacological mechanism of CIK and provide evidence to formulate uniform culturing criteria for CIK expansion

Ginsenoside Rd attenuates myocardial ischemia/reperfusion injury via Akt/GSK-3β signaling and inhibition of the mitochondria-dependent apoptotic pathway.

Evidence suggests Ginsenoside Rd (GSRd), a biologically active extract from the medical plant Panax Ginseng, exerts antioxidant effect, decreasing reactive oxygen species (ROS) formation. Current study determined the effect of GSRd on myocardial ischemia/reperfusion (MI/R) injury (a pathological condition where ROS production is significantly increased) and investigated the underlying mechanisms. The current study utilized an in vivo rat model of MI/R injury and an in vitro neonatal rat cardiomyocyte (NRC) model of simulated ischemia/reperfusion (SI/R) injury. Infarct size was measured by Evans blue/TTC double staining. NRC injury was determined by MTT and lactate dehydrogenase (LDH) leakage assay. ROS accumulation and apoptosis were assessed by flow cytometry. Mitochondrial membrane potential (MMP) was determined by 5, 5\u27, 6, 6\u27-tetrachloro-1, 1\u27, 3, 3\u27-tetrathylbenzimidazol carbocyanine iodide (JC-1). Cytosolic translocation of mitochondrial cytochrome c and expression of caspase-9, caspase-3, Bcl-2 family proteins, and phosphorylated Akt and GSK-3β were determined by western blot. Pretreatment with GSRd (50 mg/kg) significantly augmented rat cardiac function, as evidenced by increased left ventricular ejection fraction (LVEF) and ±dP/dt. GSRd reduced myocardial infarct size, apoptotic cell death, and blood creatine kinase/lactate dehydrogenase levels after MI/R. In NRCs, GSRd (10 µM) inhibited SI/R-induced ROS generation (

Identification and validation of signature for prognosis and immune microenvironment in gastric cancer based on m6A demethylase ALKBH5

BackgroundN6-methyladenosine (m6A) RNA regulators play important roles in cancers, but their functions and mechanism have not been demonstrated clearly in gastric cancer (GC).MethodsIn this study, the GC samples with clinical information and RNA transcriptome were downloaded from The Cancer Genome Atlas database. The different expression genes were compared by the absolute value and median ± standard deviation. Samples with complete information were randomly divided into a training dataset and a test dataset. The differential expression genes (DEGs) between ALKBH5-low and ALKBH5-high subgroups were identified in the training dataset and constructed a risk model by Cox and least absolute shrinkage and selection operator regression. The model was testified in test datasets, overall survival (OS) was compared with the Kaplan–Meier method, and immune cell infiltration was calculated by the CIBERSORT algorithm in the low-risk and high-risk subgroups based on the model. The protein levels of ALKBH5 were detected with immunohistochemistry. The relative expression of messenger-ribonucleic acid (mRNA) was detected with quantitative polymerase chain reaction.ResultsALKBH5 was the only regulator whose expression was lower in tumor samples than that in normal samples. The low expression of ALKBH5 led to the poor OS of GC patients and seemed to be an independent protective factor. The model based on ALKBH5-regulated genes was validated in both datasets (training/test) and displayed a potential capacity to predict a clinical prognosis. Gene Ontology analysis implied that the DEGs were involved in the immune response; CIBERSORT results indicated that ALKBH5 and its related genes could alter the immune microenvironment of GC. The protein levels of ALKBH5 were verified as lowly expressed in GC tissues. SLC7A2 and CGB3 were downregulated with ALKBH5 knockdown.ConclusionsIn this study, we found that ALKBH5 might be a suppressor of GC; ALKBH5 and its related genes were latent biomarkers and immunotherapy targets

Study of power flow algorithm of AC/DC distribution system including VSC-MTDC

In recent years, distributed generation and a large number of sensitive AC and DC loads have been connected to distribution networks, which introduce a series of challenges to distribution network operators (DNOs). In addition, the advantages of DC distribution networks, such as the energy conservation and emission reduction, mean that the voltage source converter based multi-terminal direct current (VSC-MTDC) for AC/DC distribution systems demonstrates a great potential, hence drawing growing research interest. In this paper, considering losses of the reactor, the filter and the converter, a mathematical model of VSC-HVDC for the load flow analysis is derived. An AC/DC distribution network architecture has been built, based on which the differences in modified equations of the VSC-MTDC-based network under different control modes are analyzed. In addition, corresponding interface functions under five control modes are provided, and a back/forward iterative algorithm which is applied to power flow calculation of the AC/DC distribution system including VSC-MTDC is proposed. Finally, by calculating the power flow of the modified IEEE14 AC/DC distribution network, the efficiency and validity of the model and algorithm are evaluated. With various distributed generations connected to the network at appropriate locations, power flow results show that network losses and utilization of transmission networks are effectively reduced

Prediction of prognosis and pathologic grade in follicular lymphoma using 18F-FDG PET/CT

PurposeWe investigated the utility of a new baseline PET parameter expressing lesion dissemination and metabolic parameters for predicting progression-free survival (PFS) and pathologic grade in follicular lymphoma (FL).MethodsThe baseline 18F-FDG PET/CT images of 126 patients with grade 1–3A FL were retrospectively analyzed. A novel PET/CT parameter characterizing lesion dissemination, the distance between two lesions that were furthest apart (Dmax), was calculated. The total metabolic tumor volume and total lesion glycolysis (TLG) were computed by using 41% of the maximum standardized uptake value (SUVmax) thresholding method.ResultsThe 5-year PFS rate was 51.9% for all patients. In the multivariate analysis, high Dmax [P = 0.046; hazard ratio (HR) = 2.877], high TLG (P = 0.004; HR = 3.612), and elevated serum lactate dehydrogenase (P = 0.041; HR = 2.287) were independent predictors of PFS. A scoring system for prognostic stratification was established based on these three adverse factors, and the patients were classified into three risk categories: low risk (zero to one factor, n = 75), intermediate risk (two adverse factors, n = 29), and high risk (three adverse factors, n = 22). Patients in the high-risk group had a shorter 3-year PFS (21.7%) than those in the low- and intermediate-risk groups (90.6 and 44.6%, respectively) (P < 0.001). The C-index of our scoring system for PFS (0.785) was superior to the predictive capability of the Follicular Lymphoma International Prognostic Index (FLIPI), FLIPI2, and PRIMA-Prognostic Index (C-index: 0.628–0.701). The receiver operating characteristic curves and decision curve analysis demonstrated that the scoring system had better differentiation and clinical utility than these existing indices. In addition, the median SUVmax was significantly higher in grade 3A (36 cases) than in grades 1 and 2 FL (90 cases) (median: 13.63 vs. 11.45, P = 0.013), but a substantial overlap existed (range: 2.25–39.62 vs. 3.17–39.80).ConclusionTLG and Dmax represent two complementary aspects of the disease, capturing the tumor burden and lesion dissemination. TLG and Dmax are promising metrics for identifying patients at a high risk of progression or relapse. Additionally, SUVmax seems to have some value for distinguishing grade 3A from low-grade FL but cannot substitute for biopsy

Adiponectin inhibits tumor necrosis factor-α-induced vascular inflammatory response via caveolin-mediated ceramidase recruitment and activation.

RATIONALE: Anti-inflammatory and vascular protective actions of adiponectin are well recognized. However, many fundamental questions remain unanswered. OBJECTIVE: The current study attempted to identify the adiponectin receptor subtype responsible for adiponectin\u27s vascular protective action and investigate the role of ceramidase activation in adiponectin anti-inflammatory signaling. METHODS AND RESULTS: Adiponectin significantly reduced tumor necrosis factor (TNF)α-induced intercellular adhesion molecule-1 expression and attenuated TNFα-induced oxidative/nitrative stress in human umbilical vein endothelial cells. These anti-inflammatory actions were virtually abolished by adiponectin receptor 1 (AdipoR1-), but not AdipoR2-, knockdown (KD). Treatment with adiponectin significantly increased neutral ceramidase (nCDase) activity (3.7-fold; P87% of adiponectin-induced nCDase activation was lost. Whereas adiponectin treatment failed to inhibit TNFα-induced intercellular adhesion molecule-1 expression, treatment with sphingosine-1-phosphate or SEW (sphingosine-1-phosphate receptor agonist) remained effective in Cav1-KD cells. AdipoR1 and Cav1 colocalized and coprecipitated in human umbilical vein endothelial cells. Adiponectin treatment did not affect this interaction. There is weak basal Cav1/nCDase interaction, which significantly increased after adiponectin treatment. Knockout of AdipoR1 or Cav1 abolished the inhibitory effect of adiponectin on leukocyte rolling and adhesion in vivo. CONCLUSIONS: These results demonstrate for the first time that adiponectin inhibits TNFα-induced inflammatory response via Cav1-mediated ceramidase recruitment and activation in an AdipoR1-dependent fashion

C1q/tumor necrosis factor-related protein-3, a newly identified adipokine, is a novel antiapoptotic, proangiogenic, and cardioprotective molecule in the ischemic mouse heart.

BACKGROUND: Obesity and diabetes mellitus adversely affect postischemic heart remodeling via incompletely understood mechanisms. C1q/tumor necrosis factor-related protein-3 (CTRP3) is a newly identified adipokine exerting beneficial metabolic regulation, similar to adiponectin. The aim of the present study was to determine whether CTRP3 may regulate postischemic cardiac remodeling and cardiac dysfunction, and, if so, to elucidate the underlying mechanisms. METHODS AND RESULTS: Male adult mice were subjected to myocardial infarction (MI) via left anterior descending coronary artery occlusion. Both the effect of MI on endogenous CTRP3 expression/production and the effect of exogenous CTRP3 (adenovirus or recombinant CTRP3) replenishment on MI injury were investigated. MI significantly inhibited adipocyte CTRP3 expression and reduced the plasma CTRP3 level, reaching a nadir 3 days after MI. CTRP3 replenishment improved survival rate (P CONCLUSION: CTRP3 is a novel antiapoptotic, proangiogenic, and cardioprotective adipokine, the expression of which is significantly inhibited after MI