Activation of Yes-Associated Protein in Low-Grade Meningiomas Is Regulated by Merlin, Cell Density, and Extracellular Matrix Stiffness.

The NF2 gene product Merlin is a protein containing ezrin, radixin, and moesin domains; it is a member of the 4.1 protein superfamily associated with the membrane cytoskeleton and also interacts with cell surface molecules. The mammalian Hippo cascade, a downstream signaling cascade of merlin, inactivates the Yes-associated protein (YAP). Yes-associated protein is activated by loss of the NF2 gene and functions as an oncogene in meningioma cells; however, the factors controlling YAP expression, phosphorylation, and subcellular localization in meningiomas have not been fully elucidated. Here, we demonstrate that merlin expression is heterogeneous in 1 NF2 gene-negative and 3 NF2 gene-positive World Health Organization grade I meningiomas. In the NF2 gene-positive meningiomas, regions with low levels of merlin (tumor rims) had greater numbers of cells with nuclear YAP versus regions with high merlin levels (tumor cores). Merlin expression and YAP phosphorylation were also affected by cell density in the IOMM-Lee and HKBMM human meningioma cell lines; nuclear localization of YAP was regulated by cell density and extracellular matrix (ECM) stiffness in IOMM-Lee cells. These results suggest that cell density and ECM stiffness may contribute to the heterogeneous loss of merlin and increased nuclear YAP expression in human meningiomas.

Blockade of gap junction hemichannel protects secondary spinal cord injury from activated microglia-mediated glutamate exitoneurotoxicity.

We previously demonstrated that activated microglia release excessive glutamate through gap junction hemichannels and identified a novel gap junction hemichannel blocker, INI-0602, that was proven to penetrate the blood-brain barrier and be an effective treatment in mouse models of amyotrophic lateral sclerosis and Alzheimer disease. Spinal cord injury causes tissue damage in two successive waves. The initial injury is mechanical and directly causes primary tissue damage, which induces subsequent ischemia, inflammation, and neurotoxic factor release resulting in the secondary tissue damage. These lead to activation of glial cells. Activated glial cells such as microglia and astrocytes are common pathological observations in the damaged lesion. Activated microglia release glutamate, the major neurotoxic factor released into the extracellular space after neural injury, which causes neuronal death at high concentration. In the present study, we demonstrate that reduction of glutamate-mediated exitotoxicity via intraperitoneal administration of INI-0602 in the microenvironment of the injured spinal cord elicited neurobehavioral recovery and extensive suppression of glial scar formation by reducing secondary tissue damage. Further, this intervention stimulated anti-inflammatory cytokines, and subsequently elevated brain-derived neurotrophic factor. Thus, preventing microglial activation by a gap junction hemichannel blocker, INI-0602, may be a promising therapeutic strategy in spinal cord injury.

[On the correlation between histological and cytological diagnosis, and the intrinsic 5 subtypes].

Japanese General Rules presented by the Japanese Breast Cancer Society have been long time applied in Japan. This classification uniquely adds subtypes into the group of invasive ductal carcinomas (IDC) and reported to be correlated to patients' clinical course. The latest St. Gallen consensus meeting reported the use of 5 molecules, and introduced alternative definition in the breast cancer classification. The purpose of this study is to relate the Japanese subgrouping of IDC with the 5 subtypes and to investigate whether these classifications could predict early and late recurrence and whether cytological diagnosis is influenced by the tumor phenotypes. Analyzing 127 cases, we observed that the Ki-67 labeling index (LI) of the 5 subtypes, luminal A, luminal B-Her2--/- Her2+, Her2-subtype and basal-like, is increased in this order. Though the Japanese histological groups, papillotubular, solid-tubular and scirrhous, included more or less those subtypes, the luminal types were more represented in papillotubular and scirrhous subtypes, and the solid-tubular type in non luminal subtypes. The Ki-67 LI 14% served as a cutoff for differentiating invasive from non-invasive ductal carcinomas. Breast cancers recur within 5 years after the clinical onset when the Ki-67 LI exceeded 14%. These data suggest that, (1) the intrinsic subtyping is an accurate modality in diagnosing breast cancers, (2) it can predict the recurrence duration, (3) the solid-tubular type of the Japanese classification is likely an aggressive form among breast cancers, and (4) the cytological diagnosis is presently a powerful tool in determining malignancy.

Interferon-ß delivery via human neural stem cell abates glial scar formation in spinal cord injury.

Glial scar formation is the major impedance to axonal regrowth after spinal cord injury (SCI), and scar-modulating treatments have become a leading therapeutic goal for SCI treatment. In this study, human neural stem cells (NSCs) encoding interferon-ß (INF-ß) gene were administered intravenously to mice 1 week after SCI. Animals receiving NSCs encoding IFN-ß exhibited significant neurobehavioral improvement, electrophysiological recovery, suppressed glial scar formation, and preservation of nerve fibers in lesioned spinal cord. Systemic evaluation of SCI gliosis lesion site with lesion-specific microdissection, genome-wide microarray, and MetaCore pathway analysis identified upregulation of toll-like receptor 4 (TLR4) in SCI gliosis lesion site, and this led us to focus on TLR4 signaling in reactive astrocytes. Examination of primary astrocytes from TLR4 knockout mice, and in vivo inhibition of TLR4, revealed that the effect of IFN-ß on the suppression of glial scar formation in SCI requires TLR4 stimulation. These results suggest that IFN-ß delivery via intravenous injection of NSCs following SCI inhibits glial scar formation in spinal cord through stimulation of TLR4 signaling.