Junya Fukai

EphA4 promotes cell proliferation and migration through a novel EphA4-FGFR1 signaling pathway in the human glioma U251 cell line

The Eph receptor tyrosine kinases and their ephrin ligands form a unique cell-cell contact-mediated bidirectional signaling mechanism for regulating cell localization and organization. High expression of Eph receptors in a wide variety of human tumors indicates some roles in tumor progression, which makes these proteins potential targets for anticancer therapy. For this purpose, we did gene expression profiling for 47 surgical specimens of brain tumors including 32 high-grade glioma using a microarray technique. The analysis, focused on the receptor tyrosine kinases, showed that EphA4 mRNA in the tumors was 4-fold higher than in normal brain tissue. To investigate the biological significance of EphA4 overexpression in these tumors, we analyzed EphA4-induced phenotypic changes and the signaling mechanisms using human glioma U251 cells. EphA4 promoted fibroblast growth factor 2-mediated cell proliferation and migration accompanied with enhancement of fibroblast growth factor 2-triggered mitogen-activated protein kinase and Akt phosphorylation. In addition, active forms of Rac1 and Cdc42 increased in the EphA4-overexpressing cells. Furthermore, we found that EphA4 formed a heteroreceptor complex with fibroblast growth factor receptor 1 (FGFR1) in the cells and that the EphA4-FGFR1 complex potentiated FGFR-mediated downstream signaling. Thus, our results indicate that EphA4 plays an important role in malignant phenotypes of glioblastoma by enhancing cell proliferation and migration through accelerating a canonical FGFR signaling pathway. [Mol Cancer Ther 2008;7(9):2768–78]

Antitumor activity of cetuximab against malignant glioma cells overexpressing EGFR deletion mutant variant III

Anti‐epidermal growth factor receptor (EGFR) monoclonal antibody, cetuximab, is a promising targeted drug for EGFR‐expressing tumors. Glioblastomas frequently overexpress EGFR including not only the wild type but also a deletion mutant form called ‘variant III (vIII)’, which lacks exon 2–7, does not bind to ligands, and is constitutively activated. In this study, we investigated the antitumor activity of cetuximab against malignant glioma cells overexpressing EGFRvIII. For this purpose, we transfected human malignant glioma cell lines with the retroviral vector containing cDNA for EGFRvIII, and analyzed the mode of cetuximab‐induced action on the EGFRvIII in the cells. Immunoprecipitation and immunofluorescence revealed binding of cetuximab to EGFRvIII. Notably, immunoblotting analyses showed that cetuximab treatment resulted in reduced expression levels of the EGFRvIII. However, cetuximab alone did not exhibit a growth‐inhibitory effect against the EGFRvIII‐expressing cells. On the other hand, an assay for antibody‐dependent cell‐mediated cytotoxicity (ADCC) demonstrated cetuximab‐induced cytolysis in the presence of human peripheral blood mononuclear cells in a dose‐dependent manner. These results suggest that deletion mutant EGFRvIII can be a target of cetuximab and that ADCC activity substantially contributes to the antitumor efficacy of cetuximab against the EGFRvIII‐expressing glioma cells. Thus, cetuximab could be a promising therapy in malignant gliomas that express EGFRvIII. (Cancer Sci 2008; 99: 2062–2069)

A combination of TERT promoter mutation and MGMT methylation status predicts clinically relevant subgroups of newly diagnosed glioblastomas

The prognostic impact of TERT mutations has been controversial in IDH-wild tumors, particularly in glioblastomas (GBM). The controversy may be attributable to presence of potential confounding factors such as MGMT methylation status or patients’ treatment. This study aimed to evaluate the impact of TERT status on patient outcome in association with various factors in a large series of adult diffuse gliomas. We analyzed a total of 951 adult diffuse gliomas from two cohorts (Cohort 1, n = 758; Cohort 2, n = 193) for IDH1/2, 1p/19q, and TERT promoter status. The combined IDH/TERT classification divided Cohort 1 into four molecular groups with distinct outcomes. The overall survival (OS) was the shortest in IDH wild-type/TERT mutated groups, which mostly consisted of GBMs (P < 0.0001). To investigate the association between TERT mutations and MGMT methylation on survival of patients with GBM, samples from a combined cohort of 453 IDH-wild-type GBM cases treated with radiation and temozolomide were analyzed. A multivariate Cox regression model revealed that the interaction between TERT and MGMT was significant for OS (P = 0.0064). Compared with TERT mutant-MGMT unmethylated GBMs, the hazard ratio (HR) for OS incorporating the interaction was the lowest in the TERT mutant-MGMT methylated GBM (HR, 0.266), followed by the TERT wild-type-MGMT methylated (HR, 0.317) and the TERT wild-type-MGMT unmethylated GBMs (HR, 0.542). Thus, patients with TERT mutant-MGMT unmethylated GBM have the poorest prognosis. Our findings suggest that a combination of IDH, TERT, and MGMT refines the classification of grade II-IV diffuse gliomas.

Transarterial intravenous coil embolization of dural arteriovenous fistula involving the superior sagittal sinus.

BACKGROUND We report a rare case of traumatic dural arteriovenous fistula involving the superior sagittal sinus successfully treated by transarterial intravenous coil embolization. CASE PRESENTATION A 38-year-old woman presented with tension headache. She had a past history of severe head injury at the age of three. Computed tomography scanning showed a heterogenous low-density area in the right frontal lobe, and magnetic resonance imaging demonstrated abnormal vascular structures in the same area. Angiography revealed a dural arteriovenous fistula involving the lateral wall of the fully patent superior sagittal sinus. The fistula was fed by scalp, meningeal, and cortical arteries, and drained into a cortical vein leading to the superior sagittal sinus. Femoral transarterial intravenous embolization with microcoils completely occluded the dural arteriovenous fistula. CONCLUSION Severe head injury may lead to asymptomatic dural arteriovenous fistulas after a long time. Transarterial intravenous coil embolization can be effective in the treatment of dural arteriovenous fistulas involving the superior sagittal sinus.

Enhanced Anti-Tumor Effect of Zoledronic Acid Combined with Temozolomide against Human Malignant Glioma Cell Expressing O6-Methylguanine DNA Methyltransferase

Temozolomide (TMZ), a DNA methylating agent, is widely used in the adjuvant treatment of malignant gliomas. O6-methylguanine-DNA methyltranferase (MGMT), a DNA repair enzyme, is frequently discussed as the main factor that limits the efficacy of TMZ. Zoledronic acid (ZOL), which is clinically applied to treat cancer-induced bone diseases, appears to possess direct anti-tumor activity through apoptosis induction by inhibiting mevalonate pathway and prenylation of intracellular small G proteins. In this study, we evaluated whether ZOL can be effectively used as an adjuvant to TMZ in human malignant glioma cells that express MGMT. Malignant glioma cell lines, in which the expression of MGMT was detected, did not exhibit growth inhibition by TMZ even at a longer exposure. However, combination experiment of TMZ plus ZOL revealed that a supra-additive effect resulted in a significant decrease in cell growth. In combined TMZ/ZOL treatment, an increased apoptotic rate was apparent and significant activation of caspase-3 and cleavage of poly-(ADP-ribose) polymerase were observed compared with each single drug exposure. There were decreased amounts of Ras-GTP, MAPK and Akt phosphorylation and MGMT expression in the ZOL-treated cells. Subcutanous xenograft models showed significant decrease of tumor growth with combined TMZ/ZOL treatment. These results suggest that ZOL efficaciously inhibits activity of Ras in malignant glioma cells and potentiates TMZ-mediated cytotoxicity, inducing growth inhibition and apoptosis of malignant glioma cells that express MGMT and resistant to TMZ. Based on this work, combination of TMZ with ZOL might be a potential therapy in malignant gliomas that receive less therapeutic effects of TMZ due to cell resistance.

Intraoperative hemorrhage in medulloblastoma: a case report and review of the literature

HeadingAbstract Object. We present the first case of intraoperative hemorrhage in a medulloblastoma. Case report. A 10-year-old girl presented with a 4-week history of headache, nausea, and vomiting. Radiological examination showed a space-occupying mass in the cerebellar vermis. Surgical removal was performed via a midline suboccipital approach. When the dura was incised and the occipital sinus was ligated after suboccipital craniectomy, bleeding occurred in the tumor. Macroscopically, hematoma was found only in the left part of the tumor and not in the right part. Microscopically, different architectures of tumor vessels, thin-walled and thick-walled, were found between the left part and the right part, respectively. The tumoral contents and hematoma were totally removed. Histological examination revealed a medulloblastoma. Conclusion. We experienced a very rare case of medulloblastoma in which intratumoral hemorrhage occurred during operation. We speculate that ligation of the occipital sinus and thin-walled vessels within the tumor might have caused the hemorrhage in our case.

Immunoglobulin D multiple myeloma involving the sella manifesting as oculomotor palsy: case report.

OBJECTIVEImmunoglobulin D multiple myeloma (IgD MM) is an uncommon type of MM characterized by an aggressive clinical behavior and a short survival time. We report a rare case in which oculomotor palsy caused by a sellar lesion was the initial manifestation of IgD MM; systemic treatments were beneficial in this case. CLINICAL PRESENTATIONA 61-year-old man presented with diplopia, left-sided ptosis, and retro-orbital pain. An examination revealed left cranial nerve (CN) III and IV palsies. CT scanning demonstrated a mass in the sellar and parasellar regions and partial destruction of the left side of the dorsum sellae. MRI revealed that the mass extended into the left cavernous sinus with minimal suprasellar extension. An endocrinologic evaluation did not reveal any abnormality. At the time of admission, the patient had no symptoms of MM. INTERVENTIONA transsphenoidal resection was performed. Histopathologic examination revealed a tumor consisting of plasma cells. Appropriate laboratory studies, a bone scan, and a bone marrow biopsy led to a diagnosis of IgD lambda-type MM. High-dose chemotherapy followed by autologous peripheral blood stem cell transplantation was therapeutically beneficial. The patients symptoms were gradually relieved. CONCLUSIONThis case demonstrates that an unusual sellar tumor might be the first manifestation of IgD MM. Careful observation can suggest a possible non-pituitary etiology for a tumor, leading to appropriate diagnostic and therapeutic procedures.

Ruptured Internal Carotid Artery Aneurysm Presenting with Catastrophic Epistaxis after Repeated Stereotactic Radiotherapies for Anterior Skull Base Tumor: Case Reports and Review of the Literature

Objectives Radiation-induced aneurysm is a rare complication for head and neck tumors. Only seven cases of an aneurysm after stereotactic radiosurgery and/or stereotactic radiotherapy (SRT) have been described. We report two patients with a ruptured internal carotid artery (ICA) aneurysm presenting with catastrophic epistaxis after repeated SRT for an anterior skull base tumor. Results Two male patients received repeated SRT in various combinations following surgery for an anterior skull base tumor. They presented with significant epistaxis due to rupture of the aneurysm of the ICA 6 and 77 months after the final SRT, respectively. The aneurysms were located within the radiation field. Preoperative angiography had revealed no aneurysms. Thus the aneurysms in these cases were most likely induced by the repeated SRT. Conclusions This is a proven report of aneurysm formation following repeated SRT without conventional radiotherapy. SRT may be very effective to control malignant skull base tumors. However, the possible development of radiation-induced aneurysm of the ICA should be considered in the case of repeated SRT. The surviving patients who have received SRT should undergo sequential follow-up for possible vascular involvement.

Reduced Expression of Mismatch Repair Genes MSH6/MSH2 Directly Promotes Pituitary Tumor Growth via the ATR–Chk1 Pathway

Context The mechanisms of pituitary adenoma (PA) pathogenesis and proliferation remain largely unknown. Objectives To clarify the role of mismatch repair (MMR) genes in the molecular mechanism of PA proliferation. Design We performed quantitative analyses by real-time polymerase chain reaction and immunohistochemistry to detect MMR gene and protein expression in human PAs (n = 47). We also performed correlation analyses of expression levels and tumor volume doubling time (TVDT; n = 31). Specifically, correlation analyses were performed between genes with significant correlation and ataxiatelangiectasia and Rad3-related (ATR) expression in cell-cycle regulatory mechanism ATR-checkpoint kinase 1 (Chk1) pathway (n = 93). We investigated the effect of reduced gene expression on cell proliferation and ATR gene expression in AtT-20ins cells and primary cultures of human PAs. Results Expression of mutS homologs 6 and 2 (MSH6 and MSH2) was positively associated with TVDT (R = 0.52, P = 0.003, and R = 0.44, P = 0.01), as were the corresponding protein levels. Gene expression was positively associated with ATR expression (R = 0.47, P < 0.00001, and R = 0.49, P < 0.00001). In AtT-20ins, the reduction of MSH6 and/or MSH2 expression by small interfering RNA significantly promoted cell proliferation by decreasing ATR expression. This effect was also observed in primary culture. Conclusion Reduction of MSH6 and MSH2 expression at the messenger RNA and protein levels could be involved in direct PA proliferation by promoting cell-cycle progression or decreasing the rate of apoptosis through interference with the function of the ATR-Chk1 pathway.

Intra-axial pseudotumors in the central nervous system: clinicopathological analysis

Intra-axial pseudotumors in the central nervous system often mimic malignant brain tumors and cause difficulty in diagnosis and treatment. The present study investigates their radiologic and histological features to elucidate diagnostic clues. Six cases were included in the study, one man and five women, ranging in age from 44 to 87 years (mean age, 61 years). Histologically, three cases had demyelination, and one case each had abscess, angiitis, and non-Langerhans cell histiocytosis. All cases were evaluated radiologically on MRI, most of them by thallim-201 single photon emission tomography (201Tl-SPECT). These cases were examined using H&E, special stains, and immunohistochemical studies with a variety of antibodies. MRI demonstrated perifocal edema and ring-like or solid enhancement, mimicking the malignant tumors. Diffusionweighted MRI showed a hypo-iso-intensity with a hyperintensity on the apparent diffusion coefficient. A 201Tl-SPECT study revealed no uptake. Although there were various kinds of pathology, inflammatory cells were observed, associated with vascular proliferation and reactive astrocytosis. In addition, some cases showed demyelinating or destructive changes. These results suggested that intra-axial pseudotumors in the central nervous system contain various kinds of pathology, and detailed clinicopathological analysis is important from the point of view of differential diagnosis.