Joon-Khim Loh

Background and Objectives: Pediatric traumatic brain injury (pTBI) remains a major pediatric public health problem, despite well-developed injury prevention programs. The purpose of this study is to analyze the emergency surgical outcomes of pTBI in a single institute ten-year retrospective study to offer a real-world clinical result. Materials and Methods: Our institute presented a clinical retrospective, single-institute research study of 150 pediatric TBI cases that were diagnosed and underwent emergency surgical treatment from 2010 to 2019. Results: The incidence of radiological findings is detailed as follows: brain edema (30%, 45/150), followed by acute subdural hematoma (27.3%, 41/150), epidural hematoma (21.3%, 32/150), chronic subdural hemorrhage (10%, 15/150), skull fracture (6.7%, 10/150), and traumatic subarachnoid hemorrhage (4.7%, 7/150). Surgical intervention data revealed that decompressive craniectomy was still the main effective surgical method. The results showed longer hospital stays and higher morbidity rates in the brain edema, acute subdural hematoma, and chronic subdural hemorrhage groups, which were viewed as poor surgical outcome groups. Epidural hematoma, skull fracture and traumatic subarachnoid hemorrhage were categorized into good surgical outcome groups. Notably, the data revealed gross improvement in Glasgow Coma Scale/Score (GCS) evolution after surgical interventions, and the time to cranioplasty was a significant factor in the development of post-traumatic hydrocephalus (PTH). Conclusions: Our study provided real-world data for the distribution of etiology in pTBI and also categorized it into six groups, indicating disease-orientated treatment. In addition, our data supported that decompressive craniectomy (DC) remains a mainstay surgical treatment in pTBI and early cranioplasty could decrease the incidence of PTH.

Drp1 is considered the master regulator of mitochondrial fission and affects the proper segregation during mitosis. Here, we identified two clusters on mitochondria, including Drp1-Ser-616/Mff/Mid51 and-Drp1-Ser637/Fis1/Mid49 for midzone fission (division) and peripheral fission signatures, respectively. This study revealed that phospho-Drp1-Ser637 is involved in mitigating mitochondrial oxidative stress, resolving a long-standing localization issue. Additionally, we demonstrated that Mid49 and Mid51 exhibit distinct functions in recruiting Drp1 for mitochondrial fission. It also confirmed the essential role of the Fis1 and Mid49 adaptors contributed into mitochondrial fission within the phospho-Drp1-Ser637/Fis1/Mid49 cluster during M-phase. Moreover, it suggested that there is mutual exclusivity between two clusters of phospho-Drp1 with four adaptors on mitochondria, as well as varied responses to specific anti-cancer drugs during mitotic arrest. Remarkably, the upregulation of the spindle assembly checkpoint (SAC) was also observed, ensuring the prolongation of M-phase with the formation of multipolar spindles. Collectively, the phospho-Drp1-637/Fis1/Mid49 cluster may not only function in peripheral fission (mitophagy) but also serve as a key SAC coordinator for the regulation of spindle assembly during mitotic arrest. These findings appear to be mutually exclusive of phospho-Drp1 with four adaptors on mitochondria and vary in response to specific anti-cancer drugs.

GSK3β interacting protein (GSKIP) is a small A-kinase anchor protein previously reported to mediate the N-cadherin/β-catenin pool for differentiation in SH-SY5Y cells through overexpression of GSKIP to present the neuron outgrowth phenotype. To further investigate how GSKIP functions in neurons, CRISPR/Cas9 technology was utilized to knock out GSKIP (GSKIP-KO) in SH-SY5Y. Several GSKIP-KO clones resulted in an aggregation phenotype and reduced cell growth without retinoic acid (RA) treatment. However, neuron outgrowth was still observed in GSKIP-KO clones treated with RA. The GSKIP-KO clones exhibited an aggregation phenotype through suppression of GSK3β/β-catenin pathways and cell cycle progression rather than cell differentiation. Gene set enrichment analysis indicated that GSKIP-KO was related to epithelial mesenchymal transition/mesenchymal epithelial transition (EMT/MET) and Wnt/β-catenin/cadherin signaling pathways, suppressing cell migration and tumorigenesis through the inhibition of Wnt/β-catenin mediated EMT/MET. Conversely, reintroduction of GSKIP into GSKIP-KO clones restored cell migration and tumorigenesis. Notably, phosphor-β-catenin (S675) and β-catenin (S552) but not phosphor-β-catenin (S33/S37/T41) translocated into the nucleus for further gene activation. Collectively, these results suggested that GSKIP may function as an oncogene to form an aggregation phenotype for cell survival in harsh environments through EMT/MET rather than differentiation in the GSKIP-KO of SH-SY5Y cells. Graphical abstract

Numerous studies have considered galectin-3 or Glycogen synthase kinase 3 beta (GSK3B) as a potential prognosis marker for various cancers. However, the correlation between the protein expression of galectin-3/GSK3B and the clinical parameters of astrocytoma has not been reported. This study aims to validate the correlation between the clinical outcomes and protein expression of galectin-3/GSK3B in astrocytoma. Immunohistochemistry staining was performed to detect galectin-3/GSK3B protein expression in patients with astrocytoma. The Chi-square test, Kaplan−Meier evaluation, and Cox regression analysis were used to determine the correlation between clinical parameters and galectin-3/GSK3B expression. Cell proliferation, invasion, and migration were compared between a non-siRNA group and a galectin-3/GSK3B siRNA group. Protein expression in galectin-3 or GSK3B siRNA-treated cells was evaluated using western blotting. Galectin-3 and GSK3B protein expression were significantly positively correlated with the World Health Organization (WHO) astrocytoma grade and overall survival time. Multivariate analysis revealed that WHO grade, galectin-3 expression, and GSK3B expression were independent prognostic factors for astrocytoma. Galectin-3 or GSK3B downregulation induced apoptosis and decreased cell numbers, migration, and invasion. siRNA-mediated gene silencing of galectin-3 resulted in the downregulation of Ki-67, cyclin D1, VEGF, GSK3B, p-GSK3B Ser9 (p-GSK3B S9), and β-catenin. In contrast, GSK3B knockdown only decreased Ki-67, VEGF, p-GSK3B S9, and β-catenin protein expression but did not affect cyclin D1 and galectin-3 protein expression. The siRNA results indicated that GSK3B is downstream of the galectin-3 gene. These data support that galectin-3 mediated tumor progression by upregulating GSK3B and β-catenin protein expression in glioblastoma. Therefore, galectin-3 and GSK3B are potential prognostic markers, and their genes may be considered to be anticancer targets for astrocytoma therapy.

We examined the apoptotic response of two glioblastoma cells, p53 wild type U87 and p53 mutated T98G, to doxorubicin, bortezomib, and vorinostat, which respectively target DNA, 26S proteasome and histone deacetylase, to clarify p53ʹs function in apoptosis. We demonstrated that doxorubicin induced apoptosis in U87 cells but not in T98G cells. The level of p53 was definitively correlated to the extent of DNA damage and apoptosis initiation. Dominant-negative p53 reduced p21 expression, but did not affect doxorubicin-induced apoptosis, so the transcriptional activity of p53 seemed not to participate in doxorubicin-induced apoptosis. However, p53 concentrated into the nucleus during heavy apoptosis. Bortezomib could induce apoptosis in U87 with high sensitivity and T98G cells with low sensitivity. In contrast, vorinostat promoted apoptosis in both U87 and T98G cells and reduced the basal level of p53 in U87 cells, indicating that p53 played no role in the vorinostat-induced apoptosis. To clearly define the role of p53 in bortezomib- and doxorubicin-induced apoptosis, we combined doxorubicin with bortezomib to treat U87 cells to assess this combination’s effect on apoptosis and p53 status. Interestingly, the combination of doxorubicin with bortezomib engendered compound stress, resulting in a synergistic outcome for apoptosis in U87 cells. However, the amounts of p53 in the total count and in the nucleus were much lower with the combination than with doxorubicin alone, suggesting that p53 played no role in either the compound stress, doxorubicin-only or bortezomib-induced apoptosis.

We previously revealed the origin of mammalian simple-type glycogen synthase kinase interaction protein (GSKIP), which served as a scavenger and a competitor in the Wnt signaling pathway during evolution. In this study, we investigated the conserved and nonconserved regions of the composite-type GSKIP by utilizing bioinformatics tools, site-directed mutagenesis, and yeast two-hybrid methods. The regions were denoted as the pre-GSK3β binding site, which is located at the front of GSK3β-binding sites. Our data demonstrated that clustered mitochondria protein 1 (CLU1), a type of composite-type GSKIP that exists in the mitochondria of all eukaryotic organisms, possesses the protein known as domain of unknown function 727 (DUF727), with a pre-GSK3β-binding site and a mutant GSK3β-binding flanking region. Another type of composite-type GSKIP, armadillo repeat containing 4 (ARMC4), which is known for cilium movement in vertebrates, contains an unintegrated DUF727 flanking region with a pre-GSK3β-binding site (115SPxF118) only. In addition, the sequence of the GSK3β-binding site in CLU1 revealed that Q126L and V130L were not conserved, differing from the ideal GSK3β-binding sequence of simple-type GSKIP. We further illustrated two exceptions, namely 70 kilodalton heat shock proteins (Hsp70/DnaK) and Mitofilin in nematodes, that presented an unexpected ideal GSK3β-binding region with a pre-GSK3β sequence; this composite-type GSKIP could only occur in vertebrate species. Furthermore, we revealed the importance of the pre-GSK3β-binding site (118F or 118Y) and various mutant GSK3β-binding sites of composite-type GSKIP. Collectively, our data suggest that the new composite-type GSKIP starts with a DUF727 domain followed by a pre-GSK3β-binding site, with the subsequent addition of the GSK3β-binding site, which plays vital roles for CLU1, Mitofilin, and ARMC4 in mitochondria and Wnt signaling pathways during evolution.

Although histone deacetylase 8 (HDAC8) plays a role in glioblastoma multiforme (GBM), whether its inhibition facilitates the treatment of temozolomide (TMZ)-resistant GBM (GBM-R) remains unclear. By assessing the gene expression profiles from short hairpin RNA of HDAC8 in the new version of Connectivity Map (CLUE) and cells treated by NBM-BMX (BMX)-, an HDAC8 inhibitor, data analysis reveals that the Wnt signaling pathway and apoptosis might be the underlying mechanisms in BMX-elicited treatment. This study evaluated the efficacy of cotreatment with BMX and TMZ in GBM-R cells. We observed that cotreatment with BMX and TMZ could overcome resistance in GBM-R cells and inhibit cell viability, markedly inhibit cell proliferation, and then induce cell cycle arrest and apoptosis. In addition, the expression level of β-catenin was reversed by proteasome inhibitor via the β-catenin/ GSK3β signaling pathway to reduce the expression level of c-Myc and cyclin D1 in GBM-R cells. BMX and TMZ cotreatment also upregulated WT-p53 mediated MGMT inhibition, thereby triggering the activation of caspase-3 and eventually leading to apoptosis in GBM-R cells. Moreover, BMX and TMZ attenuated the expression of CD133, CD44, and SOX2 in GBM-R cells. In conclusion, BMX overcomes TMZ resistance by enhancing TMZ-mediated cytotoxic effect by downregulating the β-catenin/c-Myc/SOX2 signaling pathway and upregulating WT-p53 mediated MGMT inhibition. These findings indicate a promising drug combination for precision personal treating of TMZ-resistant WT-p53 GBM cells.

Therapeutic resistance in recurrent glioblastoma multiforme (GBM) after concurrent chemoradiotherapy (CCRT) is a challenging issue. Although standard fractionated radiation is essential to treat GBM, it has led to local recurrence along with therapy-resistant cells in the ionizing radiation (IR) field. Lines of evidence showed cancer stem cells (CSCs) play a vital role in therapy resistance in many cancer types, including GBM. However, the molecular mechanism is poorly understood. Here, we proposed that autophagy could be involved in GSC induction for radioresistance. In a clinical setting, patients who received radiation/chemotherapy had higher LC3II expression and showed poor overall survival compared with those with low LC3 II. In a cell model, U87MG and GBM8401 expressed high level of stemness markers CD133, CD44, Nestin, and autophagy marker P62/LC3II after receiving standard fractionated IR. Furthermore, Wnt/β-catenin proved to be a potential pathway and related to P62 by using proteasome inhibitor (MG132). Moreover, pharmacological inhibition of autophagy with BAF and CQ inhibit GSC cell growth by impairing autophagy flux as demonstrated by decrease Nestin, CD133, and SOX-2 levels. In conclusion, we demonstrated that fractionated IR could induce GSCs with the stemness phenotype by P62-mediated autophagy through the Wnt/β-catenin for radioresistance. This study offers a new therapeutic strategy for targeting GBM in the future.

Mitochondrial fission and fusion cycles are integrated with cell cycle progression. Here we first re-visited how mitochondrial ETC inhibition disturbed mitosis progression, resulting in multipolar spindles formation in HeLa cells. Inhibitors of ETC complex I (rotenone, ROT) and complex III (antimycin A, AA) decreased the phosphorylation of Plk1 T210 and Aurora A T288 in the mitotic phase (M-phase), especially ROT, affecting the dynamic phosphorylation status of fission protein dynamin-related protein 1 (Drp1) and the Ser637/Ser616 ratio. We then tested whether specific Drp1 inhibitors, Mdivi-1 or Dynasore, affected the dynamic phosphorylation status of Drp1. Similar to the effects of ROT and AA, our results showed that Mdivi-1 but not Dynasore influenced the dynamic phosphorylation status of Ser637 and Ser616 in Drp1, which converged with mitotic kinases (Cdk1, Plk1, Aurora A) and centrosome-associated proteins to significantly accelerate mitotic defects. Moreover, our data also indicated that evoking mito-Drp1-Ser637 by protein kinase A (PKA) rather than Drp1-Ser616 by Cdk1/Cyclin B resulted in mitochondrial fission via the PINK1/Parkin pathway to promote more efficient mitophagy and simultaneously caused multipolar spindles. Collectively, this study is the first to uncover that mito-Drp1-Ser637 by PKA, but not Drp1-Ser616, drives mitophagy to exert multipolar spindles formation during M-phase.