Jianwei Ge

Notch1 promotes glioma cell migration and invasion by stimulating β‐catenin and NF‐κB signaling via AKT activation

The Notch signaling pathway has been implicated in both developmental processes and tumorigenesis. Aberrant Notch signaling has been repeatedly demonstrated to facilitate the proliferation and survival of glioma cells by regulating downstream effectors or other signaling pathways. In glioblastoma multiforme specimens from 59 patients, Notch1 was highly expressed in tumor tissues compared with normal brain tissues, and this expression was correlated with elevated AKT phosphorylation and Snail expression. Increased nuclear localization of β‐catenin and p50 as well as enhanced IKKα/AKT interaction were also observed in glioma tissues. In U87MG cells, the activation of Notch1 by DLL4 stimulation or by the overexpression of Notch intracellular domain (NICD) resulted in AKT activation and thereby promoted β‐catenin activity and NF‐κB signaling. Inhibition of EGFR partially blocked the β‐catenin and NF‐κB signaling stimulated by Notch1 activation. Furthermore, NICD overexpression in U87MG cells led to the upregulated expression of several metastasis‐associated molecules, which could be abrogated by the knockdown of either β‐catenin or p50. In U87MG and U251 cells, DLL4‐induced cellular migration and invasion could be inhibited by either β‐catenin or a p50 inhibitor. Collectively, these results indicate that Notch activation could stimulate β‐catenin and NF‐κB signaling through AKT activation in glioma cells. Thus, Notch activation‐stimulated β‐catenin and NF‐κB signaling synergistically promote the migratory and invasive properties of glioma cells. (Cancer Sci 2012; 103: 181–190)

C-Myc negatively controls the tumor suppressor PTEN by upregulating miR-26a in glioblastoma multiforme cells

The c-Myc oncogene is amplified in many tumor types. It is an important regulator of cell proliferation and has been linked to altered miRNA expression, suggesting that c-Myc-regulated miRNAs might contribute to tumor progression. Although miR-26a has been reported to be upregulated in glioblastoma multiforme (GBM), the mechanism has not been established. We have shown that ectopic expression of miR-26a influenced cell proliferation by targeting PTEN, a tumor suppressor gene that is inactivated in many common malignancies, including GBM. Our findings suggest that c-Myc modulates genes associated with oncogenesis in GBM through deregulation of miRNAs via the c-Myc-miR-26a-PTEN signaling pathway. This may be of clinical relevance.

A learning curve of endoscopic transsphenoidal surgery for pituitary adenoma.

Abstract Experience is an important point in the effectiveness of the surgical procedure and in the reduction of complications in pituitary surgery. Endoscopic pituitary surgery differs from microscopic surgery because it requires a steep learning curve for endoscopic skills. In this study, we investigated the learning curve of endoscopic transsphenoidal pituitary surgery in our department. Endoscopic transsphenoidal operations were performed on 80 patients, who were retrospectively examined and grouped as the early and late experience groups to evaluate the learning curve. The patients’ characteristics, gross total resection, endocrinological cure, visual field improvement, duration of surgery, postoperative hospital stay, and complications were noted. After examining our patients of the 2 groups of period, our experience showed that as the effectiveness of endoscopic surgery increases, the duration of surgery and postoperative hospital stay decrease. In this study, we identified a learning curve in endoscopic pituitary surgery.

The Up-Regulation of Voltage-Gated Sodium Channel NaV1.6 Expression Following Fluid Percussion Traumatic Brain Injury in Rats

BACKGROUNDThe influx of Na+ and the depolarization mediated by voltage-gated sodium channels (VGSCs) is an early event in traumatic brain injury (TBI) induced cellular abnormalities and is therefore well positioned as an upstream target for pharmacologic modulation of the pathological responses to TBI. Alteration in the expression of the VGSC α-subunit has occurred in a variety of neuropathological states including focal cerebral ischemia, spinal injury, and epilepsy. OBJECTIVEIn this study, changes in Nav1.6 mRNA and protein expression were investigated in rat hippocampus after TBI. METHODSForty-eight adult male Sprague Dawley rats were randomly assigned to control or TBI groups. TBI was induced with a lateral fluid percussion device. Expression of mRNA and protein for Nav1.6 in the bilateral hippocampus was examined at 2, 12, 24, and 72 hours after injury by real-time quantitative polymerase chain reaction and Western blot. Immunofluorescence was performed to localize the expression of Nav1.6 protein in the hippocampus. RESULTSExpression of >Nav1.6 mRNA was significantly up-regulated in the bilateral hippocampus at 2 and 12 hours post-TBI. Significant up-regulation of Nav1.6 protein was identified in the ipsilateral hippocampus from 2 to 72 hours post-TBI and in the contralateral hippocampus from 2 to 24 hours post-TBI. Expression of Nav1.6 occurred predominantly in neurons in the hippocampus. CONCLUSIONResults of the study showed significant up-regulation of mRNA and protein for Nav1.6 in rat hippocampal neurons after TBI.

Glioblastoma Multiforme with Subcutaneous Metastases, Case Report and Literature Review

Glioblastoma multiforme (GBM) is the most common primary brain tumor and the most malignant astrocytoma in adults, with rare extra-cranial metastases, especially for subcutaneous metastases. It could be easily misdiagnosed as primary subcutaneous tumor. In this report, we describe a patient with pontine GBM who developed a subcutaneous swelling at the ipsilateral posterior cervical region 8 months after operation, and the pathological and immunocytochemical examination carry the same characteristics as the primary intracranial GBM cells, which defined it as subcutaneous metastasis. GBM with subcutaneous metastasis is extremely rare, and knowledge of a prior intracranial GBM, pathological examinations and immunocytochemical tests with markers typically expressed by GBM are of vital importance for the diagnosis of GBM metastasis. Surgical resection of subcutaneous swelling, followed by chemotherapy and radiotherapy, could be the best strategy of treatment for the patients with GBM subcutaneous metastasis.

Effects of AQP5 gene silencing on proliferation, migration and apoptosis of human glioma cells through regulating EGFR/ERK/ p38 MAPK signaling pathway

We investigated the effects of aquaporin 5 (AQP5) gene silencing on the proliferation, migration and apoptosis of human glioma cells through regulating the EGFR/ERK/p38MAPK signaling pathway. qRT-PCR was applied to examine the mRNA expressions of AQP5 in five human glioma cell lines. U87-MG, U251 and LN229 cells were selected and assigned into blank, vector, AQP5 siRNA and FlagAQP5 groups. MTT assay was used to measure cell proliferation. Flow cytometry (FCM) with AnnexinV-FITC/PI double staining and PI staining were employed to analyze cell apoptosis and cell cycle respectively. Scratch test was used to detect cell migration. Western blotting was performed to determine the EGFR/ERK/p38 MAPK signaling pathway-related proteins. Results showed that the positive expression of AQP5 in primary glioblastoma was associated with the tumor size and whether complete excision was performed. The mRNA expressions of AQP5 in cell lines of U87-MG, U251 and LN229 were significantly higher than in U373 and T98G. The proliferation rates of U87-MG, U251 and LN229 cells in the AQP5 siRNA group were lower than in the vector and blank groups. The apoptosis rate increased in the AQP5 siRNA group compared with the vector group. Scratch test demonstrated that AQP5 gene silencing could suppress cell migration. Compared with the vector and blank groups, the AQP5 siRNA group showed decreased expressions of the ERK1/2, p38 MAPK, p-ERK1/2 and p-p38 MAPK proteins. AQP5 gene silencing could inhibit the cell proliferation, reduce cell migration and promote the cell apoptosis of U87-MG, U251 and LN229 by suppressing EGFR/ERK/p38 MAPK signaling pathway.

EphB4 is overexpressed in gliomas and promotes the growth of glioma cells

Glioma is one of the most common solid tumors, and the molecular mechanism for this disease is poorly understood. EphB4 tyrosine kinase receptor has been involved in various physiologic and pathologic processes, and the role of EphB4 in tumorigenesis has recently attracted much interest. However, its function in glioma remains largely unknown. In this study, we explored the function of EphB4 in glioma. We found that the expression of EphB4 was significantly upregulated in clinical glioma samples. Overexpression of EphB4 in glioma cell lines accelerated cell growth and tumorigenesis. In contrast, downregulation of EphB4 inhibited cell growth. Furthermore, we showed that EphB4 promoted cell growth by promoting EGFR signaling. Taken together, our findings suggest that EphB4 plays an important role in the progression of glioma by stimulating cell growth and EphB4 might be a potential therapeutic target for glioma.

Overexpression of isocitrate dehydrogenase-1R132H enhances the proliferation of A172 glioma cells via aerobic glycolysis

Gliomas are the most common type of primary malignancy of the central nervous system. The identification of mutations in the gene encoding isocitrate dehydrogenase‑1 (IDH1) represents a key area of investigation in studies on glioma. The IDH1R132H mutation is a heterozygous point mutation, which affects the amino acid arginine at position 132, however, the metabolic importance of this mutation in tumor cell growth remains to be elucidated. In the present study, A172 glioma cell lines stably overexpressing either wild‑type IDH1 or IDH1R132H were produced. The results demonstrated that the IDH1R132H mutation enhanced the proliferation of the A172 glioma cells in vitro. Furthermore, IDH1R132H performed this function by elevating the expression levels of hypoxia inducible factor‑1α, leading to an increase in the expression levels of the key glycolytic enzymes, glucose transporter 1 and hexokinase 2. Therefore, the metabolism was shifted towards aerobic glycolysis, leading to an increase in glucose uptake and lactate production. These findings demonstrated that the IDH1R132H molecular target was involved in orchestrating the Warburg effect in mutant IDH1R132H glioma cells.

PDGFR‐β‐activated ACK1‐AKT Signaling Promotes Glioma Tumorigenesis

Aberrant PDGF‐PDGFR signaling and its effects on downstream effectors have been implicated in glioma development. A crucial AKT regulator, ACK1 (TNK2) has been shown to be a downstream mediator of PDGF signaling; however, the exact underlying mechanisms in gliomas remain elusive. Here, we report that in glioma cells, PDGFR‐β activation enhanced the interaction between ACK1 and AKT, resulting in AKT activation. PDGF treatment consistently promoted the formation of complexes containing PDGFR‐β and ACK1. Mutational analysis suggested that Y635 of ACK1 is a PDGFR‐β phosphorylation site and that the ACK1 Y635F mutant abrogated the sequential activation of AKT. Moreover, PDK1 interacted with ACK1 during PDGF stimulation, which is required for the binding of ACK1 to PDGFR‐β. Further mutational analysis showed that T325 of ACK1 was crucial for the ACK1 and PDK1 interaction. ACK1 Y635F or T325A mutants abolished PDGFR‐β‐induced AKT activation, the subsequent nuclear translocation of β‐catenin and the expression of cyclin D1. Glioma cell cycle progression, proliferation and tumorigenesis were accordingly blocked by ACK1 Y635F or T325A. In glioblastoma multiforme samples from 51 patients, increased ACK1 tyrosine phosphorylation correlated with upregulated PDGFR‐β activity and AKT activation. Taken together, our data demonstrate that ACK1 plays a pivotal role in PDGF‐PDGFR‐induced AKT signaling in glioma tumorigenesis. This knowledge contributes to our understanding of glioma progression and may facilitate the identification of novel therapeutic targets for future glioma treatment.

ID1 regulates U87 human cell proliferation and invasion

Despite therapeutic advances, the prognosis of patients diagnosed with malignant glioma has not improved in recent years. In particular, the molecular mechanisms that mediate glioma invasion remain poorly understood. The importance of ID1 in promoting tumor invasion and metastasis has recently emerged and a role for ID1 as a possible molecular marker of tumor aggressiveness has been proposed. To investigate the biological function of ID1 in glioblastomas, ID1-silenced U87 glioblastoma multiforme (GBM) cells were constructed using a small hairpin RNA (shRNA) sequence. The effect of the knockdown of ID1 on proliferation and invasion in these cells was analyzed using the 5-bromo-2′-deoxy-uridine cell proliferation, Transwell invasion, scratch and cell adhesion assays. Compared with the controls, the U87 cells expressing ID1-shRNA exhibited a significantly decreased proliferation and invasion capacity (P<0.05), as well as increased cell adhesion. Furthermore, silencing ID1 reduced the expression of c-Myc, cyclin D1 and β-catenin, while increasing E-cadherin expression in U87 cells. This study showed that ID1 regulates the metastatic potential of GBM cells by controlling the epithelial-mesenchymal transition. Therefore, ID1 is a potential prognostic indicator and therapeutic target in glioblastomas.