Silencing dentate newborn neurons alters excitatory/inhibitory balance and impairs behavioral inhibition and flexibility.

Adult neurogenesis confers the hippocampus with unparalleled neural plasticity, essential for intricate cognitive functions. The specific influence of sparse newborn neurons (NBNs) in modulating neural activities and subsequently steering behavior, however, remains obscure. Using an engineered NBN-tetanus toxin mouse model (NBN-TeTX), we noninvasively silenced NBNs, elucidating their crucial role in impulse inhibition and cognitive flexibility as evidenced through Morris water maze reversal learning and Go/Nogo task in operant learning. Task-based functional MRI (tb-fMRI) paired with operant learning revealed dorsal hippocampal hyperactivation during the Nogo task in male NBN-TeTX mice, suggesting that hippocampal hyperexcitability might underlie the observed behavioral deficits. Additionally, resting-state fMRI (rs-fMRI) exhibited enhanced functional connectivity between the dorsal and ventral dentate gyrus following NBN silencing. Further investigations into the activities of PV+ interneurons and mossy cells highlighted the indispensability of NBNs in maintaining the hippocampal excitation/inhibition balance. Our findings emphasize that the neural plasticity driven by NBNs extensively modulates the hippocampus, sculpting inhibitory control and cognitive flexibility.

Thiophene Carboxamide Analogs with Long Alkyl Chains Comprising Ethylene Glycol Units Inhibit Glioblastoma Cell Proliferation by Activating AMPK.

Glioblastoma is a refractory malignant tumor that requires novel therapeutic strategies for effective treatment. We have previously reported that JCI-20679 (1), an analog of annonaceous acetogenins, shows potent antitumor activity against glioblastomas. However, the synthesis of 1 requires 23 steps, including 16 steps for the preparation of a tetrahydrofuran (THF) moiety. This study reports the design and synthesis of 11 analogs with a triethylene glycol moiety in place of the THF moiety in 1. Among these, the analog 2k with an n-decyl chain exhibited potent inhibitory activity against the growth of glioblastoma stem cells by inhibiting mitochondrial function and synergistically enhancing the effect of temozolomide (TMZ). Furthermore, 2k significantly suppressed tumor growth without critical toxicity in vivo. Hence, this study presents novel potential anticancer agents and a strategy for the development of these agents that can be produced easily.

JCI­20679 suppresses the proliferation of glioblastoma stem cells by activating AMPK and decreasing NFATc2 expression levels.

The prognosis of glioblastoma, which is the most frequent type of adult­onset malignant brain tumor, is extremely poor. Therefore, novel therapeutic strategies are needed. Previous studies report that JCI­20679, which is synthesized based on the structure of naturally occurring acetogenin, inhibits mitochondrial complex I and suppresses the growth of various types of cancer cells. However, the efficacy of JCI­20679 on glioblastoma stem cells (GSCs) is unknown. The present study demonstrated that JCI­20679 inhibited the growth of GSCs derived from a transposon system­mediated murine glioblastoma model more efficiently compared with the growth of differentiation­induced adherent cells, as determined by a trypan blue staining dye exclusion test. The inhibition of proliferation was accompanied by the blockade of cell­cycle entry into the S­phase, as assessed by a BrdU incorporation assay. JCI­20679 decreased the mitochondrial membrane potential, suppressed the oxygen consumption rate and increased mitochondrial reactive oxygen species generation, indicating that JCI­20679 inhibited mitochondrial activity. The mitochondrial inhibition was revealed to increase phosphorylated (phospho)­AMPKα levels and decrease nuclear factor of activated T­cells 2 (NFATc2) expression, and was accompanied by a decrease in calcineurin phosphatase activity. Depletion of phospho­AMPKα by knockdown of AMPKß recovered the JCI­20679­mediated decrease in NFATc2 expression levels, as determined by western blotting and reverse transcription­quantitative PCR analysis. Overexpression of NFATc2 recovered the JCI­20679­mediated suppression of proliferation, as determined by a trypan blue staining dye exclusion test. These results suggest that JCI­20679 inhibited mitochondrial oxidative phosphorylation, which activated AMPK and reduced NFATc2 expression levels. Moreover, systemic administration of JCI­20679 extended the event­free survival rate in a mouse model transplanted with GSCs. Overall, these results suggested that JCI­20679 is a potential novel therapeutic agent against glioblastoma.

Retroperitoneal Hemorrhage in Patients with COVID-19 Undergoing Hemodialysis: Three Case Reports.

A 73-year-old man receiving hemodialysis and antiplatelets was admitted with a mild case of COVID-19. Heparin was added, and iliopsoas hemorrhage developed. He was successfully treated by interventional radiology. A 76-year-old man receiving hemodialysis and antiplatelets was admitted with mild COVID-19. Heparin was added, and iliacus hemorrhage developed. Despite heparin discontinuation, he died of worsening pneumonia. A 74-year-old man undergoing hemodialysis was admitted with severe COVID-19. Gastrointestinal bleeding developed during continuous hemodiafiltration with heparin. Upon switching to nafamostat and increasing the dose, iliopsoas hemorrhage developed. Despite interventional radiology, he died of infectious complications. Attention to hemorrhagic complications is therefore needed in patients with COVID-19.

Stat5b inhibition blocks proliferation and tumorigenicity of glioblastoma stem cells derived from a de novo murine brain cancer model.

Glioblastoma (GBM) is the most common and malignant type of brain cancer in adults with poor prognosis. GBM stem cells (GSCs) reside within niches in GBM tissues and contribute to recurrence and therapy resistance. Previous studies have shown that expression of leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5), a Wnt pathway-related stem cell marker, correlates with a poor prognosis in GBM, and its knockdown in GSCs induces apoptosis accompanied with downregulation of signal transducer and activator of transcription 5b (Stat5b). Here, we show that Stat5b co-localizes with Lgr5 in hypoxia-inducible factor 2α (Hif2α)-positive regions in GBM tissues. Functional analyses using GSCs derived from a murine de novo GBM model induced by oncogenic genes transduction using the Sleeping-Beauty transposon system revealed that expression of Stat5b was induced by culturing under hypoxia together with Lgr5, repressed by Hif2α knockdown, and reduced by Lgr5 knockdown or a Wnt/ß-catenin signaling inhibitor ICG-001 treatment. Stat5b inhibition in the GSCs induced apoptosis and caused downregulation of Cyclin E2 resulted in blockade of entry into S-phase in the cell cycle. Disruption of Stat5b in an orthotopic transplantation model significantly prolongs event-free survival. These results suggest that Stat5b, regulated by hypoxia and the Wnt pathway, plays an important role in the maintenance and tumorigenicity of GSCs and may be a promising therapeutic molecular target to attack GSCs.

JCI-20679 suppresses autophagy and enhances temozolomide-mediated growth inhibition of glioblastoma cells.

Glioblastoma, a type of brain cancer, is one of the most aggressive and lethal types of malignancy. The present study shows that JCI-20679, an originally synthesized mitochondrial complex I inhibitor, enhances the anti-proliferative effects of suboptimal concentrations of the clinically used chemotherapeutic drug temozolomide in glioblastoma cells. Analysis of the effects of temozolomide combined with JCI-20679 using isobologram and combination index methods demonstrated that the combination had synergistic effects in murine and human glioblastoma cells. We found that JCI-20679 inhibited the temozolomide-mediated induction of autophagy that facilitates cellular survival. The autophagy induced by temozolomide increased ATP production, which confers temozolomide resistance in glioblastoma cells. JCI-20679 blocked temozolomide-mediated increases in ATP levels and increased the AMP/ATP ratio. Furthermore, JCI-20679 enhanced the therapeutic effects of temozolomide in an orthotopic transplantation model of glioblastoma. These results indicate that JCI-20679 may be promising as a novel agent for enhancing the efficacy of temozolomide against glioblastoma.

γ-Glutamylcyclotransferase, a novel regulator of HIF-1α expression, triggers aerobic glycolysis.

Metabolic reprogramming leading to aerobic glycolysis, termed the "Warburg effect," is a critical property of cancer cells. However, the precise mechanisms underlying this phenomenon are not fully understood. A growing body of evidence indicates that γ-glutamylcyclotransferase (GGCT), an enzyme involved in glutathione homeostasis that is highly expressed in many types of cancer, represents a promising therapeutic target. In this study, we identified GGCT as a novel regulator of hypoxia-inducible factor-1α (HIF-1α), a transcription factor that plays a role in hypoxia adaptation promoting aerobic glycolysis. In multiple human cancer cell lines, depletion of GGCT downregulated HIF-1α at the mRNA and protein levels. Conversely, in NIH3T3 mouse fibroblasts, overexpression of GGCT upregulated HIF-1α under normoxia. Moreover, depletion of GGCT downregulated HIF-1α downstream target genes involved in glycolysis, whereas overexpression of GGCT upregulated those genes. Metabolomic analysis revealed that modulation of GGCT expression induced a metabolic switch from the citric acid cycle to glycolysis under normoxia. In addition, we found that GGCT regulates expression of HIF-1α protein via the AMPK-mTORC1-4E-BP1 pathway in PC3 cells. Thus GGCT regulates the expression of HIF-1α in cancer cells, causing a switch to glycolysis.

Fluorizoline Blocks the Interaction between Prohibitin-2 and γ-Glutamylcyclotransferase and Induces p21Waf1/Cip1 Expression in MCF7 Breast Cancer Cells.

Prohibitin-2 (PHB2) is a scaffold protein that has pleiotropic functions, which include interacting with γ-glutamylcyclotransferase (GGCT) in the cytoplasm and repressing the transcriptional activities of the p21Waf1/Cip (p21) gene in the nucleus. The cytotoxic drug fluorizoline binds to PHB1/2 and exerts antiproliferative actions on cancer cells. However, the precise mechanism underlying the antiproliferative effects of fluorizoline is not fully elucidated. In the present study, we first show that fluorizoline induces p21 expression in several human cancer cell lines, including MCF7 breast cancer cells. Treatment of MCF7 cells with fluorizoline suppressed proliferation and prevented cells from entering into the DNA synthesis phase. Knockdown of p21 rescued the suppressed proliferation, indicating that fluorizoline inhibited MCF7 cell growth via the induction of p21. Overexpression of PHB2 in MCF7 cells prevented the induction of p21 expression by fluorizoline and restored the antiproliferative effects and blockade of cell cycle progression. Moreover, treatment of MCF7 cells with fluorizoline inhibited the interaction between endogenous PHB2 and GGCT proteins and reduced the level of nuclear localization of PHB2 proteins. These results indicate that targeting PHB2 with fluorizoline induces the expression of p21 and consequently blocks proliferation of cancer cells. SIGNIFICANCE STATEMENT: This study shows that fluorizoline may be a promising novel anticancer drug candidate that induces p21 expression and blocks cell-cycle progression in human cancer cell lines. In addition, we show that fluorizoline inhibits the interaction between PHB2 and GGCT and reduces the nuclear localization of PHB2 proteins.

Inhibition of Gli2 suppresses tumorigenicity in glioblastoma stem cells derived from a de novo murine brain cancer model.

The prognosis of glioblastoma remains poor despite intensive research efforts. Glioblastoma stem cells (GSCs) contribute to tumorigenesis, invasive capacity, and therapy resistance. Leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5), a stem cell marker, is involved in the maintenance of GSCs, although the properties of Lgr5-positive GSCs remain unclear. Here, the Sleeping-Beauty transposon-induced glioblastoma model was used in Lgr5-GFP knock-in mice identify GFP-positive cells in neurosphere cultures from mouse glioblastoma tissues. Global gene expression analysis showed that Gli2 was highly expressed in GFP-positive GSCs. Gli2 knockdown using lentiviral-mediated shRNA downregulated Hedgehog-related and Wnt signaling pathway-related genes, including Lgr5; suppressed tumor cell proliferation and invasion capacity; and induced apoptosis. Pharmacological Gli inhibition with GANT61 suppressed tumor cell proliferation. Silencing Gli2 suppressed the tumorigenicity of GSCs in an orthotopic transplantation model in vivo. These findings suggest that Gli2 affects the Hedgehog and Wnt pathways and plays an important role in GSC maintenance, suggesting Gli2 as a therapeutic target for glioblastoma treatment.

Incommensurately Modulated Crystal Structure and Photoluminescence Properties of Eu2O3- and P2O5-Doped Ca2SiO4 Phosphor.

We prepared four types of Eu2O3- and P2O5-doped Ca2SiO4 phosphors with different phase compositions but identical chemical composition, the chemical formula of which was (Ca1.950Eu3+0.013☐0.037)(Si0.940P0.060)O4 (☐ denotes vacancies in Ca sites). One of the phosphors was composed exclusively of the incommensurate (IC) phase with superspace group Pnma(0ß0)00s and basic unit-cell dimensions of a = 0.68004(2) nm, b = 0.54481(2) nm, and c = 0.93956(3) nm (Z = 4). The crystal structure was made up of four types of ß-Ca2SiO4-related layers with an interlayer. The incommensurate modulation with wavelength of 4.110 × b was induced by the long-range stacking order of these layers. When increasing the relative amount of the IC-phase with respect to the coexisting ß-phase, the red light emission intensity, under excitation at 394 nm, steadily decreased to reach the minimum, at which the specimen was composed exclusively of the IC-phase. The coordination environments of Eu3+ ion in the crystal structures of ß- and IC-phases might be closely related to the photoluminescence intensities of the phosphors.