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result(s) for
"Lim, Sanghee"
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Identification of the kinase STK25 as an upstream activator of LATS signaling
2019
The Hippo pathway maintains tissue homeostasis by negatively regulating the oncogenic transcriptional co-activators YAP and TAZ. Though functional inactivation of the Hippo pathway is common in tumors, mutations in core pathway components are rare. Thus, understanding how tumor cells inactivate Hippo signaling remains a key unresolved question. Here, we identify the kinase STK25 as an activator of Hippo signaling. We demonstrate that loss of STK25 promotes YAP/TAZ activation and enhanced cellular proliferation, even under normally growth-suppressive conditions both in vitro and in vivo. Notably, STK25 activates LATS by promoting LATS activation loop phosphorylation independent of a preceding phosphorylation event at the hydrophobic motif, which represents a form of Hippo activation distinct from other kinase activators of LATS.
STK25
is significantly focally deleted across a wide spectrum of human cancers, suggesting
STK25
loss may represent a common mechanism by which tumor cells functionally impair the Hippo tumor suppressor pathway.
Hippo pathway inactivation plays a role in many cancers, although how tumor cells depress signaling is unclear. Here, Lim et al. identify STK25, which activates LATS in a manner distinct from other upstream kinases and is focally deleted from a range of human cancers.
Journal Article
Early postnatal exposure to isoflurane causes cognitive deficits and disrupts development of newborn hippocampal neurons via activation of the mTOR pathway
2017
Clinical and preclinical studies indicate that early postnatal exposure to anesthetics can lead to lasting deficits in learning and other cognitive processes. The mechanism underlying this phenomenon has not been clarified and there is no treatment currently available. Recent evidence suggests that anesthetics might cause persistent deficits in cognitive function by disrupting key events in brain development. The hippocampus, a brain region that is critical for learning and memory, contains a large number of neurons that develop in the early postnatal period, which are thus vulnerable to perturbation by anesthetic exposure. Using an in vivo mouse model we demonstrate abnormal development of dendrite arbors and dendritic spines in newly generated dentate gyrus granule cell neurons of the hippocampus after a clinically relevant isoflurane anesthesia exposure conducted at an early postnatal age. Furthermore, we find that isoflurane causes a sustained increase in activity in the mechanistic target of rapamycin pathway, and that inhibition of this pathway with rapamycin not only reverses the observed changes in neuronal development, but also substantially improves performance on behavioral tasks of spatial learning and memory that are impaired by isoflurane exposure. We conclude that isoflurane disrupts the development of hippocampal neurons generated in the early postnatal period by activating a well-defined neurodevelopmental disease pathway and that this phenotype can be reversed by pharmacologic inhibition.
Journal Article
Development and implementation of patient-level prediction models of end-stage renal disease for type 2 diabetes patients using fast healthcare interoperability resources
2022
This study aimed to develop a model to predict the 5-year risk of developing end-stage renal disease (ESRD) in patients with type 2 diabetes mellitus (T2DM) using machine learning (ML). It also aimed to implement the developed algorithms into electronic medical records (EMR) system using Health Level Seven (HL7) Fast Healthcare Interoperability Resources (FHIR). The final dataset used for modeling included 19,159 patients. The medical data were engineered to generate various types of features that were input into the various ML classifiers. The classifier with the best performance was XGBoost, with an area under the receiver operator characteristics curve (AUROC) of 0.95 and area under the precision recall curve (AUPRC) of 0.79 using three-fold cross-validation, compared to other models such as logistic regression, random forest, and support vector machine (AUROC range, 0.929–0.943; AUPRC 0.765–0.792). Serum creatinine, serum albumin, the urine albumin-to-creatinine ratio, Charlson comorbidity index, estimated GFR, and medication days of insulin were features that were ranked high for the ESRD risk prediction. The algorithm was implemented in the EMR system using HL7 FHIR through an ML-dedicated server that preprocessed unstructured data and trained updated data.
Journal Article
Ibrutinib disrupts blood-tumor barrier integrity and prolongs survival in rodent glioma model
by
Frye, William J. E.
,
Dalmage, Mahalia
,
Nuechterlein, Nicholas
in
ABC transporters
,
Adenine - analogs & derivatives
,
Animals
2024
In malignant glioma, cytotoxic drugs are often inhibited from accessing the tumor site due to the blood-tumor barrier (BTB). Ibrutinib, FDA-approved lymphoma agent, inhibits Bruton tyrosine kinase (BTK) and has previously been shown to independently impair aortic endothelial adhesion and increase rodent glioma model survival in combination with cytotoxic therapy. Yet additional research is required to understand ibrutinib’s effect on BTB function. In this study, we detail baseline BTK expression in glioma cells and its surrounding vasculature, then measure endothelial junctional expression/function changes with varied ibrutinib doses in vitro. Rat glioma cells and rodent glioma models were treated with ibrutinib alone (1–10 µM and 25 mg/kg) and in combination with doxil (10–100 µM and 3 mg/kg) to assess additive effects on viability, drug concentrations, tumor volume, endothelial junctional expression and survival. We found that ibrutinib, in a dose-dependent manner, decreased brain endothelial cell–cell adhesion over 24 h, without affecting endothelial cell viability (
p
< 0.005). Expression of tight junction gene and protein expression was decreased maximally 4 h after administration, along with inhibition of efflux transporter, ABCB1, activity. We demonstrated an additive effect of ibrutinib with doxil on rat glioma cells, as seen by a significant reduction in cell viability (
p
< 0.001) and increased CNS doxil concentration in the brain (56 ng/mL doxil alone vs. 74.6 ng/mL combination,
p
< 0.05). Finally, Ibrutinib, combined with doxil, prolonged median survival in rodent glioma models (27 vs. 16 days,
p
< 0.0001) with brain imaging showing a − 53% versus − 75% volume change with doxil alone versus combination therapy (
p
< 0.05). These findings indicate ibrutinib’s ability to increase brain endothelial permeability via junctional disruption and efflux inhibition, to increase BTB drug entry and prolong rodent glioma model survival. Our results motivate the need to identify other BTB modifiers, all with the intent of improving survival and reducing systemic toxicities.
Journal Article
Effects of Neonatal Hypoxic-Ischemic Injury and Hypothermic Neuroprotection on Neural Progenitor Cells in the Mouse Hippocampus
by
Ryu, Yun Kyoung
,
Kang, Eunchai
,
Kwak, Minhye
in
Animals
,
Animals, Newborn
,
Dentate Gyrus - cytology
2015
Neonatal hypoxic-ischemic injury (HI) results in widespread cerebral encephalopathy and affects structures that are essential for neurocognitive function, such as the hippocampus. The dentate gyrus contains a reservoir of neural stem and progenitor cells (NSPCs) that are critical for postnatal development and normal adult function of the hippocampus, and may also facilitate the recovery of function after injury. Using a neonatal mouse model of mild-to-moderate HI and immunohistochemical analysis of NSPC development markers, we asked whether these cells are vulnerable to HI and how they respond to both injury and hypothermic therapy. We found that cleaved caspase-3 labeling in the subgranular zone, where NSPCs are located, is increased by more than 30-fold after HI. The population of cells positive for both proliferating cell nuclear antigen and nestin (PCNA+Nes+), which represent primarily actively proliferating NSPCs, are acutely decreased by 68% after HI. The NSPC population expressing NeuroD1, a marker for NSPCs transitioning to become fate-committed neural progenitors, was decreased by 47%. One week after HI, there was a decrease in neuroblasts and immature neurons in the dentate gyrus, as measured by doublecortin (DCX) immunolabeling, and at the same time PCNA+Nes+ cell density was increased by 71%. NSPCs expressing Tbr2, which identifies a highly proliferative intermediate neural progenitor population, increased by 107%. Hypothermia treatment after HI partially rescues both the acute decrease in PCNA+Nes+ cell density at 1 day after injury and the chronic loss of DCX immunoreactivity and reduction in NeuroD1 cell density measured at 1 week after injury. Thus, we conclude that HI causes an acute loss of dentate gyrus NSPCs, and that hypothermia partially protects NSPCs from HI.
Journal Article
The changes of oligodendrocytes induced by anesthesia during brain development
by
Danye Jiang Sanghee Lim Minhye Kwak Yun Kyoung Ryu C. David Mintz
in
Anesthesia
,
Apoptosis
,
Brain
2015
With the advent of modern techniques, drugs, and monitoring, general anesthesia has come to be considered an unlikely cause of harm, particularly for healthy patients. While this is largely true, newly emerging clinical and laboratory studies have sug- gested that exposure to anesthetic agents during early childhood may have long-lasting adverse effects on cognitive function. This concern has been the focus of intense study in the field of anesthesia research. A recent high-profile review by Rappaport et al. (2015) concluded that while many questions remain un- answered, there is strong evidence from laboratory studies that commonly used anesthetics interfere with brain development and that clinical studies suggest a correlation between early childhood exposure to these agents and subsequent effects on learning and cognition. The issue is of sufficient public health importance that a public-private partnership known as Smar- Tots (Strategies for Mitigating Anesthesia-Related Neurotoxicity in Tots) was developed by the FDA to study pediatric anesthetic neurotoxicity. The mechanism of injury underlying this phe- nomenon has yet to be fully elucidated, and there is evidence to suggest that anesthetics may have direct cytotoxic effects on neurons leading to cell death or suppressed neurogenesis (Strat- mann et al., 2010) and that they may interfere with key pro- cesses in neuronal growth and development that underlie brain circuit development (Wagner et al., 2014).
Journal Article
Digital self-harm: an empirical analysis of the effects of broadband adoption on suicide
2021
PurposePast literature offered competing predictions of the effect of broadband Internet on suicide. The Internet facilitates suicide by providing suicide-related information and ruining mental health. In contrast, Internet prevents suicide by offering social interaction and online mental treatment. This study aims to solve this tension by empirically examining the effect of broadband Internet on suicide with large-scale panel set.Design/methodology/approachThis study takes instrument approach with the US county-level panel set for the period 2013–17. This study uses the number of household broadband Internet subscriptions as the measure of broadband and leverages the number of telecommunication carriers as an instrument to address concern for endogenous relationship.FindingsThere exists a positive and significant association between broadband Internet adoption and suicide on average. This study provides empirical evidence that this association is attributable to the Internet's role in leading to a general decline in the mental well-being and in providing suicide-relevant information. This association is more evident in areas with high poverty and low social capital.Originality/valueThis study contributes to literatures that address the dark side of information systems in general and that address how Internet adoption can influence public health and well-being in particular. Results of underlying mechanisms why Internet affects suicide, and heterogeneous effect of Internet by poverty and social capital provide insight for governments to enact proactive regulations to address continuing rise of suicide.
Journal Article
Mechanisms of Kinase-Dependent Regulation of Hippo Tumor Suppressor Signaling
2021
The Hippo pathway is frequently deregulated in human cancers, but mutations and deletions of core signalome members are rare, suggesting that our understanding of its upstream regulators remains incomplete. A focused RNAi-based kinome screen identified novel candidate regulators of Hippo signaling, including STK25 and MST4. Here, we characterize the kinase STK25 as a novel upstream activator of LATS signaling. Depletion of STK25 was found to significantly reduce YAP phosphorylation in response to Hippo-activating stimuli, with consequent increases in YAP/TAZ activity and increased proliferation and resistance to cell cycle arrest. Mechanistically, STK25 activates LATS independently of the canonical MST/MAP4K axis, wherein STK25 directly promotes the phosphorylation of the LATS kinase activation loop in the absence of a preceding hydrophobic motif phosphorylation event. This differentiates STK25 from all other identified Hippo kinases to date, which may explain why singular loss of this kinase cannot be compensated for by the presence of other Hippo kinases. We also find that loss of STK25 increases YAP/TAZ signaling in vivo and that this promotes organ overgrowth in murine models. Interestingly, STK25 is frequently focally deleted in a spectrum of human cancers, suggesting that its loss might represent a way by which cancer cells functionally inactivate Hippo signaling. We also report that STK25 may be a novel regulator of mTOR signaling, as loss of STK25 hyper-activates mTOR signaling in response to amino acids and growth factors, but not to energy stresses. Interestingly, we find that MST4, a kinase closely related to STK25, appears to have highly context-specific Hippo regulatory functions; loss of MST4 was found to modulate Hippo signaling only in non-polarized cell lines, suggesting that polarity-responsive subcellular localization of MST4 may dictate its ability to interact with Hippo signaling. Lastly, we describe a novel role for Hippo signaling as a surveillance system for abnormal prolongation of mitosis, in which the LATS kinases regulate cell fate following abnormal mitosis via its control over p53-p21 signaling and YAP/TAZ signaling. This work thus identifies new roles and mechanisms by which kinases interact in the context of this major tumor suppressor pathway to control cellular processes critical to physiologic homeostasis.
Dissertation
Bevacizumab exerts dose-dependent risk for intracranial hemorrhage in patients with malignant gliomas
by
Caron, Samantha J.
,
Carabenciov, Ivan D.
,
Clarke, Nathan H.
in
Adult
,
Aged
,
Angiogenesis Inhibitors - adverse effects
2025
Purpose
Bevacizumab, an anti-VEGF monoclonal antibody, has become a mainstay therapeutic in the management of malignant glioma. It is unknown if the risk of intracranial hemorrhage (ICH), a major complication associated with bevacizumab use, is dose-dependent.
Methods
This was a single institution retrospective analysis of patients treated with bevacizumab for the management of gliomas between 2009 and 2022. Incidence rates of ICH between patients receiving low-dose (< 5 mg/kg/week) and conventional-dose (5 mg/kg/week) bevacizumab regimens were compared via competing risk analysis over time. We evaluated post-progression survival (PPS) as a secondary outcome using multivariate Cox regression.
Results
One hundred and seventy-three patients were identified (low-dose group,
n
= 51, conventional-dose group,
n
= 122) for inclusion in our analysis. Cumulative incidence rates of all cases of ICH and clinically symptomatic cases of ICH were higher in the conventional-dose (17.2% for all cases, 13.7% for symptomatic) relative to the low-dose group (3.9% for all cases, 2.0% for symptomatic); p-value 0.0296 for all cases, p-value 0.0274 for symptomatic cases. On multivariate Fine-Gray regression, conventional-dose bevacizumab therapy remained significantly associated with increased risk for symptomatic ICH (SHR 8.0560; p-value 0.0442). No difference in PPS was observed between the low-dose versus conventional-dose groups.
Conclusions
Conventional-dose bevacizumab therapy (5 mg/kg/week) is associated with increased incidence of ICH in patients with malignant glioma compared to lower dose bevacizumab (< 5 mg/kg/week) in this single center retrospective cohort. No difference in PPS was observed between the low-dose versus conventional-dose groups.
Journal Article