MiR-124-3p/B4GALT1 axis plays an important role in SOCS3-regulated growth and chemo-sensitivity of CML.

BACKGROUND: Abnormal expression of SOCS3 has been implicated in myeloproliferative neoplasms, but the role of SOCS3 in the pathogenesis of leukemia remains largely unknown. Here, we examined the function of SOCS3 in the growth and chemo-sensitivity of chronic myeloid leukemia (CML) and explored the involved mechanisms. METHODS: Expression levels of SOCS3 in several leukemia cell lines and bone marrow mononuclear cells (BMNCs) from CML patients were determined using quantitative real-time PCR (qPCR) and Western blotting (WB). The roles of SOCS3 in the proliferation, apoptosis, and drug resistance of CML cells were examined by clonogenic progenitor cell assay, flow cytometry, and CCK-8 assay. A detailed analysis of the underlying mechanism of SOCS3 in K562 cells was performed using the Human HT-12 v4 Expression BeadChip, which has more than 48000 gene probes including 600 microRNAs (miRNA) probes. The correlation between the mRNA expression of SOCS3 and miR-124-3p in BMNCs from 30 CML patients was tested by qPCR and analyzed by Pearson correlation and linear regression analysis. The potential target of miR-124-3p in CML cells was explored using the luciferase reporter assay, qPCR, and WB. The effect of SOCS3 on the miR-124-3p/B4GALT1 axis was investigated by qPCR, WB, CCK-8 assay, and tumorigenicity assays in nude mice. RESULTS: SOCS3 was down-regulated in CML cell lines and most of BMNCs from CML patients, and the expression level of SOCS3 was associated with the inhibition of cell proliferation and drug resistance of CML cells. Over-expression of SOCS3 in K562 cells inhibited the expression of leukemia-specific genes and promoted the expression of some miRNAs, among which miR-124-3p was the highest. SOCS3 over-expression enhanced the expression of miR-124-3p and vice versa. The mRNA expression of miR-124-3p and SOCS3 in BMNCs from 30 CML patients was positively correlated. Consistently, the tumor suppressing effects of SOCS3 were partially neutralized by the miR-124-3p inhibitor. B4GALT1 was downstream of miR-124-3p and regulated by SOCS3/miR-124-3p in vitro. Furthermore, SOCS3 over-expression could inhibit the growth and B4GALT expression of K562 cells in vivo. CONCLUSIONS: SOCS3/miR-124-3p/B4GALT1 axis plays an important role in the pathogenesis of CML.

Exposure to 3G mobile phone signals does not affect the biological features of brain tumor cells.

BACKGROUND: The increase in mobile phone use has generated concerns about possible risks to human health, especially the development of brain tumors. Whether tumor patients should continue to use mobile telephones has remained unclear because of a paucity of information. Herein, we investigated whether electromagnetic fields from mobile phones could alter the biological features of human tumor cells and act as a tumor-promoting agent. METHODS: Human glioblastoma cell lines, U251-MG and U87-MG, were exposed to 1950-MHz time division-synchronous code division multiple access (TD-SCDMA) at a specific absorption rate (maximum SAR = 5.0 W/kg) for 12, 24, and 48 h. Cell morphologies and ultra-structures were observed by microscopy and the rates of apoptosis and cell cycle progression were monitored by flow cytometry. Additionally, cell growth was determined using the CKK-8 assay, and the expression levels of tumor and apoptosis-related genes and proteins were analyzed by real-time PCR and western blotting, respectively. Tumor formation and invasiveness were measured using a tumorigenicity assay in vivo and migration assays in vitro. RESULTS: No significant differences in either biological features or tumor formation ability were observed between unexposed and exposed glioblastoma cells. Our data showed that exposure to 1950-MHz TD-SCDMA electromagnetic fields for up to 48 h did not act as a cytotoxic or tumor-promoting agent to affect the proliferation or gene expression profile of glioblastoma cells. CONCLUSIONS: Our findings implied that exposing brain tumor cells in vitro for up to 48 h to 1950-MHz continuous TD-SCDMA electromagnetic fields did not elicit a general cell stress response.

Promotion of Erythropoietic Differentiation in Hematopoietic Stem Cells by SOCS3 Knock-Down.

Suppressor of cytokine signaling 3 (SOCS3) plays an important role in mice fetal liver erythropoiesis, but the roles of SOCS3 in human hematopoietic stem cells (HSCs) have not been well investigated. In the present study, lentiviral small interference RNA expression vectors (shRNA) of SOCS3 were constructed and stably transferred into HSCs. We found that SOCS3 knockdown induced erythroid expansion in HSCs. Conversely, Ectopic expression of SOCS3 in progenitor cells blocked erythroid expansion and erythroid colony formation of HSCs. To further explore the involved mechanism, we compared gene expression profiles of SOCS3-shRNA tranduced HSCs with that of control HSCs by whole genome microarrays. The results indicated that cell developmental process related genes, especially hematopoietic lineage-specific genes, associated with the responses to SOCS3 in HSCs.Downexpression of SOCS3 in HSCs or differentiated erythroid progenitor cells induced a transcriptional program enriched for erythroid development relative genes. Our results proved that SOCS3 down-expression induced lineage commitment towards erythroid progenitor cell fate by activation of erythroid-specific gene in HSCs and provided new insight into the mechanism of erythropoietic development.

Cold-inducible RNA-binding protein inhibits neuron apoptosis through the suppression of mitochondrial apoptosis.

Cold-inducible RNA-binding protein (CIRP) is induced by mild hypothermia in several mammals, but the precise mechanism by which CIRP mediates hypothermia-induced neuroprotection remains unknown. We aimed to investigate the molecular mechanisms by which CIRP protects the nervous system during mild hypothermia. Rat cortical neurons were isolated and cultured in vitro under mild hypothermia (32°C). Apoptosis was measured by annexin V and propidium iodide staining, visualized by flow cytometry. Neuron ultrastructure was visualized by transmission electron microscopy. CIRP overexpression and knockdown were achieved via infection with pL/IRES/GFP-CIRP and pL/shRNA/F-CIRP-A lentivirus. RT(2) Profiler PCR Array Pathway Analysis and western blotting were used to evaluate the effects of CIRP overexpresion/knockdown on the neurons׳ transcriptome. Neuron late apoptosis was significantly reduced at day 7 of culture by 12h hypothermia, but neuron ultrastructure remained relatively intact. RT(2) Profiler PCR Array Pathway Analysis of 84 apoptosis pathway-associated factors revealed that mild hypothermia and CIRP overexpression induce similar gene expression profiles, specifically alterations of genes implicated in the mitochondrial apoptosis pathway. Mild hypothermia-treated neurons up-regulated 12 and down-regulated 38 apoptosis pathway-associated genes. CIRP-overexpressing neurons up-regulated 15 and down-regulated 46 genes. CIRP-knocked-down hypothermia-treated cells up-regulated 9 and down-regulated 40 genes. Similar results were obtained at the protein level. In conclusion, CIRP may inhibit neuron apoptosis through the suppression of the mitochondria apoptosis pathway during mild hypothermia.

Restoration of tissue damage, and never activity after hypoxia-ischemia by implantation of peripheral blood mononuclear cells.

Hypoxia-ischemia (HI) encephalopathy is a frequent cause of disability and mortality with limited therapeutic options. Here, we collected peripheral blood mononuclear cells (PB-MNCs) from healthy donors and labeled them with CM-DiI before implanting these cells by tail-vein injection into rats at day 3 after hypoxia-ischemia (HI). For immune-suppression the animals received daily injections of cyclosporine throughout the experiment, commencing 24h before cell transplantation. Then we observed the PB-MNCs by fluorescent microscopy, examined motor function of rats by rotarod and cylinder tests, measured the lesion volume using image-pro plus software, and analyzed the apoptosis of neural cells in HI rats by tunnel assay. The results showed PB-MNCs could survive in the brain of hosts, migrate to the damage area and express neural marker. In addition, The HI rats that received PB-MNCs showed a reduction in motor function impairment, lesion volume and neural cell apoptosis. To better understand the mechanism of cell migration, PB-MNCs were also injected into normal rats via tail-vein. The expression of stromal cell-derived factor-1 (SDF-1) in the brain of normal and HI rats was measured by RT- PCR and western-blot, while the response of PB-MNCs in vitro to HI or normal brain extracts were measured by cell migration assay. Collectively these data suggest that the migration of PB-MNCs is directed to the damaged brain through an SDF-1-dependent pathway. Our results suggest that intravenous transplantation of PB-MNCs may be a feasible candidate for HI therapy.

Differential expression of the RNA-binding motif protein 3 in human astrocytoma.

BACKGROUND: The RNA-binding motif protein 3 (RBM3), which is transcriptionally induced by low temperature and hypoxia, has recently been found to be upregulated in human tumors. However, its expression status in human astrocytoma is not well defned. This article focuses on the differential expression of RBM3 in human astrocytomas of different grades and normal brain tissues. METHODS: RBM3 was detected in astrocytomas and normal brain tissues by quantitative real-time PCR, immunohistochemistry, and Western blotting. Analysis of variance was performed on the data from quantitative real-time PCR. The Fisher's exact test was used to analyze the immunohistochemistry results. A P-value of less than 0.05 indicates a statistically significant difference. RESULTS: On one hand, the mRNA expression levels of three X-chromosome-related RBM genes (RBMX, RBM3, and RBM10) were detected by quantitative real-time PCR. The results showed that there were no significant differences in RBMX and RBM10 mRNA expression levels in human astrocytomas of different grades and normal brain tissues. However, RBM3 mRNA expression levels were elevated in high-grade (World Health Organization (WHO) Grade III-IV) astrocytomas versus low-grade (WHO Grade I-II) astrocytomas (5.06 ± 0.66 vs. 1.60 ± 0.58; P < 0.05) or normal controls (5.06 ± 0.66 vs. 1.03 ± 0.22; P < 0.05) as determined by quantitative real-time PCR analysis. On the other hand, immunohistochemistry showed an increased RBM3 labeling index in astrocytomas of different grades and normal brain tissues (positive staining rate: astrocytoma Grade IV, 92.9%; astrocytoma Grade III, 81.8%; astrocytoma Grade I-II, 50%; normal brain tissues, 37.5%; high-grade astrocytoma versus normal brain tissues, P < 0.05; high-grade astrocytoma versus low-grade astrocytoma, P < 0.05). The higher protein levels of RBM3 were also validated in high-grade astrocytomas and low-grade astrocytomas compared with normal brain tissues by Western blotting. CONCLUSIONS: These data suggest that the overexpression of RBM3 may serve as an important molecular mechanism underlying astrocytic carcinogenesis. Moreover, RBM3 may have proliferative and/or proto-oncogenic functions in human astrocytomas.

Exposure to 1950-MHz TD-SCDMA electromagnetic fields affects the apoptosis of astrocytes via caspase-3-dependent pathway.

The usage of mobile phone increases globally. However, there is still a paucity of data about the impact of electromagnetic fields (EMF) on human health. This study investigated whether EMF radiation would alter the biology of glial cells and act as a tumor-promoting agent. We exposed rat astrocytes and C6 glioma cells to 1950-MHz TD-SCDMA for 12, 24 and 48 h respectively, and found that EMF exposure had differential effects on rat astroctyes and C6 glioma cells. A 48 h of exposure damaged the mitochondria and induced significant apoptosis of astrocytes. Moreover, caspase-3, a hallmark of apoptosis, was highlighted in astrocytes after 48 h of EMF exposure, accompanied by a significantly increased expression of bax and reduced level of bcl-2. The tumorigenicity assays demonstrated that astrocytes did not form tumors in both control and exposure groups. In contrast, the unexposed and exposed C6 glioma cells show no significant differences in both biological feature and tumor formation ability. Therefore, our results implied that exposure to the EMF of 1950-MHz TD-SCDMA may not promote the tumor formation, but continuous exposure damaged the mitochondria of astrocytes and induce apoptosis through a caspase-3-dependent pathway with the involvement of bax and bcl-2.

Platelet-derived growth factor-induced severe and chronic vasoconstriction of cerebral arteries: proposed growth factor explanation of cerebral vasospasm.

OBJECTIVE: After subarachnoid hemorrhage (SAH), platelet-derived growth factor-BB (PDGF-BB) is secreted in and around the cerebral arteries. To clarify the role of PDGF-BB in the development of vasospasm after SAH, we determined whether PDGF-BB alone can cause long-lasting vasoconstriction of a severity similar to that of vasospasm. In addition, the anti-vasospastic effect of trapidil, an antagonist of PDGF-BB function, was investigated. METHODS: We infused recombinant PDGF-BB (10 microg/mL saline as the vehicle) (n = 14) into the subarachnoid space of rabbits and analyzed alterations in the caliber of the basilar artery using repeated angiography. To study the role of PDGF-BB on the development of vasospasm, trapidil was administered continuously starting 1 hour after SAH, on day 0 (0.63-1.25 mg/kg /h or vehicle) for 47 hours (n = 24), or after the full development of cerebral vasospasm on day 2 (3.0 mg/kg/h or vehicle) for 0.5 hours (n = 17), and alterations in the caliber of the basilar artery were monitored. RESULTS: PDGF-BB caused long-lasting vasoconstriction, with maximum constriction of 56% (P < .001) of the control value (= 100%) on day 2, resembling vasospasm seen after SAH. Prolonged administration of intravenous trapidil, starting soon after SAH, prevented the development of vasospasm in a dose-dependent manner (P < .05, .01, or .001). Intravenous or intra-arterial administration of trapidil significantly dilated vasospasm (P < .01) on day 2, at least transiently. CONCLUSION: PDGF-BB, a growth factor synthesized in the subarachnoid space after SAH, can cause severe and long-lasting vasoconstriction. Significant prevention and resolution of vasospasm can be achieved by the PDGF-BB antagonist trapidil. We propose that excessive production of PDGF-BB, essentially aiming to repair injured arteries, causes cerebral vasospasm. Although the half-life of trapidil in serum may be shorter than that of PDGFG-BB-derived spasmogenic signaling, trapidil is a candidate drug for constructing a new therapeutic modality for preventing and resolving vasospasm.

Induced spreading depression evokes cell division of astrocytes in the subpial zone, generating neural precursor-like cells and new immature neurons in the adult cerebral cortex.

BACKGROUND AND PURPOSE: New immature neurons appear out of the germinative zone, in cortical Layers V to VI, after induced spreading depression in the adult rat brain. Because neural progenitors have been isolated in the cortex, we set out to determine whether a subgroup of mature cells in the adult cortex has the potential to divide and generate neural precursors. METHODS: We examined the expression of endogenous markers of mitotic activity, proliferating cell nuclear antigen, and vimentin as a marker for neuronal progenitor cells, if any, in the adult rat cortex after spreading depression stimulation. Immunohistochemical analysis was also performed using antibodies for proliferating cell nuclear antigen, for vimentin, and for nestin. Nestin is a marker for activity dividing neural precursors. RESULTS: At the end of spreading depression (Day 0), glial fibrillary acidic protein-positive cells in the subpial zone and cortical Layer I demonstrated increased mitotic activity, expressing vimentin and nestin. On Day 1, nestin(+) cells were found spreading in deeper cortical layers. On Day 3, vimentin(-)/nestin(+), neural precursor-like cells appeared in cortical Layers V to VI. On Day 6, new immature neurons appeared in cortical Layers V to VI. Induced spreading depression evokes cell division of astrocytes residing in the subpial zone, generating neural precursor-like cells. CONCLUSIONS: Although neural precursor-like cells found in cortical Layers V to VI might have been transferred from the germinative zone rather than the cortical subpial zone, astrocytic cells in the subpial zone may be potent neural progenitors that can help to reconstruct impaired central nervous system tissue. Special caution is required when observing or treating spreading depression waves accompanying pathological conditions in the brain.

Genetic increase in brain-derived neurotrophic factor levels enhances learning and memory.

Brain-derived neurotrophic factor (BDNF), a neurotrophin, is known to promote neuronal differentiation stimulating neurite outgrowth in the developing CNS, and is also known to modulate synaptic plasticity, thereby contributing to learning and memory in the mature brain. Here, we investigated the role of increased levels of intracerebral BDNF in learning and memory function. Using genetically engineered transgenic BDNF overexpressing mice (RTG-BDNF), young adult, homozygous (+/+), heterozygous (+/-), or wild-type (-/-) littermates, we analyzed escape latency to a hidden-platform and swimming velocity in the Morris Water Maze test (MWM) with modifications for the mice. The MWM comprised 4 trials per day over 5 consecutive days (sessions) without prior or subsequent training. In a separate set of animals, BDNF protein levels in the cortex, thalamostriatum and the hippocampus were measured quantitatively using ELISA. In the BDNF (+/-) mice, the BDNF levels in the cortex, the thalamostriatum and the hippocampus were significantly high, compared to the wild-type littermates; 238%, 158%, and 171%, respectively (P<0.01, one-way ANOVA and a post-hoc test in each region). The BDNF levels in the BDNF (+/+) mice were not elevated. The BDNF (+/-), but not the (+/+) mice, demonstrated significantly shorter escape latency, shorter total path length in the MWM, and more frequent arrivals at the location where the platform had been placed previously in the probe trial, compared with the wild-type littermates (P<0.05, at each time pint). Because the maximum swimming velocity was not affected in the BDNF-transgenic mice, increased BDNF levels in the brain were found to enhance spatial learning and memory function. Although it has been postulated that excessive BDNF is deteriorating for neuronal survival or neurite outgrowth, further investigations are needed to clarify the mechanism of paradoxical lack of increase in BDNF levels in the (+/+) mouse brain.

Induced spreading depression activates persistent neurogenesis in the subventricular zone, generating cells with markers for divided and early committed neurons in the caudate putamen and cortex.

BACKGROUND AND PURPOSE: Status epilepticus and cerebral ischemia stimulate persistent neurogenesis in the adult brain, but both conditions cause neuronal damage. We determined whether spreading depression, a common epiphenomenon of these conditions, stimulates persistent neurogenesis. METHODS: We analyzed the effect of KCl-induced spreading depression on persistent neurogenesis and the spatio-temporal distribution of cells exhibiting immunohistochemical markers for divided and early committed neurons (new neurons) in the adult rat brain. RESULTS: After induction of spreading depression for 48 hours, the density of mitotic cells, divided cells, and new neurons in the subventricular zone increased at days 1 to 3, days 3 to 6, and day 6, respectively (P<0.05). The divided cell density in the rostral migratory stream and the stream size increased at day 12 (P<0.001). Vehicle (saline) infusion or induction of spreading depression for 4 hours only did not increase the divided cell density, but the latter increased new neuron density in the subventricular zone (P<0.001). Double-labeled new neuron-like cells also appeared in the caudate putamen or cortex in ectopic fashion at day 3, with dramatic increases at days 6 and 12. Administration of the NMDA receptor antagonist, MK-801, which inhibits the propagation of spreading depression, abolished the increase in new neurons in the subventricular zone and the appearance of ectopic new neuron-like cells after 48-hour KCl infusion. There was no neuronal damage, as evidenced by mature neuron density, neurite density, and apoptotic cell appearance after spreading depression for 48 hours. CONCLUSIONS: Spreading depression has the potential to stimulate persistent neurogenesis or to produce ectopic new neuron-like cells.

Spreading depression induces long-lasting brain protection against infarcted lesion development via BDNF gene-dependent mechanism.

Preconditioning the rat brain with spreading depression for 48 h induces potent ischemic tolerance (infarct tolerance) after an interval of 12-15 days, consequently reducing the infarcted lesion size in the acute phase following focal cerebral ischemia. However, persistence of the morphological and functional neuroprotection has not yet been proven. We tested whether tolerance-derived neuroprotection against focal cerebral ischemia persists or merely delays the progress of cerebral infarction. Prolonged spreading depression was induced in mice by placing a depolarized focus with intracerebral microinfusion of KCl for 24 h; after intervals of 3, 6, 9 or 12 days, temporary focal ischemia was imposed. In the analysis of the infarcted lesion volume 24 h after ischemia, groups with 6 or 9 day interval demonstrated significantly smaller lesion volume compared to time-matched vehicle control group (P=0.002). Significant reduction in cerebral infarction was also observed at the chronic phase, namely 14 days after ischemia (33% reduction) (P=0.021) accompanied with less severe neurological deficits (38% reduction) (P=0.020). Using this technique, we also investigated if the mice with targeted disruption of a single BDNF allele (heterozygous BDNF-deficient mice) can gain the same potency of tolerance as the wild mice. In the result on infarcted lesion volumes following temporary focal ischemia, potent tolerance developed in the wild type (35% reduction) (P=0.007) but not in the heterozygous BDNF-deficient mice (<19% reduction) (P=0.155), indicating that BDNF expression level following spreading depression is contributing to infarct tolerance development.

Evaluation of MCAO stroke models in normotensive rats: standardized neocortical infarction by the 3VO technique.

The temporary three-vessel occlusion (3VO) technique with a surgical approach for middle cerebral artery (MCA) produces consistent cerebral infarction in the neocortex in normotensive rats. The intraluminal thread-occlusion technique with an endovascular approach targeting the MCA occlusion (MCAO) is more widely used since it does not require complicated intracranial procedures. The aim of this study was to review the methods/models for MCAO stroke in normotensive rats and to evaluate a 3VO stroke model that provides consistent degrees and variance of cortical stroke injury for additional discussion. First, we analyzed a model with modified temporary 3VO technique requiring less complicated procedures than the temporary 3VO model, i.e., temporary occlusion of the bilateral common carotid arteries (CCAs) superimposed on a permanent occlusion of the MCA, in Sprague-Dawley rats or C57BL/6J mice. In the microvascular tissue (cerebral) perfusion study, significant reductions in regional cerebral perfusion during the 3VO accompanied a rapid return to baseline after release of the CCAs, showing that the technique induces temporary focal ischemia. The average sizes and variances of the neocortical infarction in this model, together with those in the other normotensive rat models caused by the 3VO technique in the literature, indicated a standard size and variance of infarcted lesion in the control groups relative to the specific ischemic period. However, stroke injuries in the neocortex induced by the thread occlusion technique showed greater variability with less consistent lesion sizes. Inclusion/exclusion criteria to avoid inappropriate cases with too mild (no/faint infarction) or too great (huge/fatal infarction) severity in the ischemic injury may differ between laboratories in the thread occlusion model.