Toshihide Tanaka

Viral vector transduction of the human deoxycytidine kinase cDNA sensitizes glioma cells to the cytotoxic effects of cytosine arabinoside in vitro and in vivo

Cytosine arabinoside (ara–C) is a cytidine analog that incorporates into replicating DNA and induces lethal DNA strand breaks. Although ara–C is a potent antitumor agent for hematologic malignancies, it has only minimal activity against most solid tumors. The rate–limiting step in intracellular ara–C activation is phosphorylation of the prodrug by deoxycytidine kinase (dCK). The present results demonstrate that both retroviral and adenoviral vector–mediated transduction of the dCK cDNA results in marked sensitization of glioma cell lines to the cytotoxic effects of ara–C in vitro. We also demonstrate that ara–C treatment of established intradermal and intracerebral gliomas transduced with dCK results in significant antitumor effects in vivo. These data suggest that viral vector transduction of the dCK gene followed by treatment with ara–C represents a new chemosensitization strategy for cancer gene therapy.

Monocyte chemoattractant protein-1 (MCP-1) gene transduction: an effective tumor vaccine strategy for non-intracranial tumors

Recently, there has been renewed interest in the concept of tumor vaccines using genetically engineered tumor cells expressing a variety of cytokines to increase their immunogenicity. Human MCP-1 (JE) is a potent chemoattractant and activator of monocytes and T lymphocytes and thus a good candidate gene for a tumor vaccine. We therefore evaluated the efficacy of vaccines consisting of irradiated tumor cells transduced with the murine MCP-1 gene in the syngeneic 9L gliosarcoma brain tumor model. 9L cell lines stably expressing murine MCP-1 (9L-JE) and control cell lines expressing neomycin 3′ phosphotransferase (9L-Neo) were generated by infection with a Moloney murine leukemia retroviral vector. Fisher 344 rats were immunized with intradermal injections of 5×105 or 2×106 irradiated (5000 cGy) 9L-JE, 9L-Neo, and wild-type 9L (9L-WT) cells. Two weeks later immunized an non-immunized animals were challenged with varyious doses of intradermal (5×106–5×107) or intracerebral (2×104–5×105) 9L-WT cells. Intradermal tumors grew in all non-immunized animals. No tumors grew in animals immunized with irradiated 9L-JE or 9L-Neo cells and challenged with inocula of fewer than 5×105 9L-WT cells. With higher inocula up to 107 cells, tumors appeared in all the animals. Tumors in animals immunized with 9L-JE were always smaller than tumors in the other groups. In addition, only the 9L-JE vaccine protected against tumor inocula of 5×107 cells. Thus vaccination with MCP-1-expressing cells was able to protect animals against at least a 100-fold larger number of challenge tumor cells than vaccination with control cells. In contrast to studies with intradermal tumors, immunization with 9L-JE and 9L-Neo produced only minimal protection against intracerebral tumors. There was no significant difference between the 9L-JE and 9L-Neo vaccines in intracerebral challenge. This study suggests that tumor vaccines expressing cytokine genes such as MCP-1 can increase the antitumor response. However, the protective effect of these vaccines appears to be largely limited to intradermal tumors rather than intracerebral tumors.

Cotransfection of Poly(I: C) and siRNA of IL-10 into fusions of dendritic and glioma cells enhances antitumor T helper type 1 induction in patients with glioma.

Apart from generating T-helper (Th) effector responses, dendritic cells (DCs) are capable of initiating tolerance against the inciting antigens. Therefore, successful DC-based immunotherapy against malignant tumors requires an additional strategy to activate antigen-processing DCs. We studied the antitumor immune responses conferred by fusions of DCs and glioma cells in vitro. Fusion cells (FCs) were stimulated with polyriboinosinic polyribocytidylic acid [Poly(I:C)] and/or small interference RNA (siRNA) of IL-10 (IL-10-siRNA). Increased IFN-&bgr; expression induced by Poly(I:C) transfection was accompanied by enhanced production of IL-10 and IL-12p70 in the FCs. We also found that the ability of Poly(I:C)-transfected FCs to produce IL-12p70, but not IFN-&bgr;, was preserved when endogenous IL-10 was suppressed by IL-10-siRNA. To analyze the antigen-presenting function further, DCs, glioma cells, and peripheral lymphocytes were established from patients newly diagnosed with glioma. In this experiment, peripheral lymphocytes were stimulated with autologous FCs and restimulated with autologous glioma cells. CD4+T cells isolated from the stimulated lymphocytes were subjected to the ELISPOT and WST-1 assays, which revealed that the IL-10-siRNA/Poly(I:C)-cotransfected FCs elicit an efficient tumor-specific Th1 response. These findings support the relevance of using Poly(I:C) and IL-10-siRNA in clinical immunotherapy protocols with an FC-based vaccine for patients with malignant glioma as a means of promoting Th1-induced tumor antigen presentation.

Multiple Pulmonary Metastases following Total Removal of a Bilateral Parasagittal Meningioma with Complete Occlusion of the Superior Sagittal Sinus: Report of a Case

Pulmonary metastases of benign meningiomas are extremely rare. The case of a 34-year-old man with bilateral parasagittal meningioma who developed pulmonary metastases is described. The meningioma was an enormous hypervascular tumor with invasion of the superior sagittal sinus. The tumor was resected completely and histologically diagnosed as transitional meningioma. The Ki-67 labeling index was 5%. Four months after operation, the patient subsequently developed bilateral multiple lung lesions later identified as metastases. The lung lesions were partially removed surgically and histologically diagnosed as meningothelial meningioma WHO grade I. The Ki-67 labeling index was 2%. The histological findings demonstrated that the tumor occupied the arterial lumen and the perivascular space, suggesting that pulmonary tumors might metastasize via the vascular route. The histopathological features and mechanisms of metastasizing meningiomas are reviewed and discussed.

Chronic Encapsulated Expanding Thalamic Hematoma Associated with Obstructive Hydrocephalus following Radiosurgery for a Cerebral Arteriovenous Malformation: A Case Report and Literature Review.

Chronic encapsulated intracerebral hematoma is a unique type of intracerebral hematoma accompanied by a capsule that is abundant in fragile microvasculature occasionally causing delayed regrowth. A 37-year-old man who had undergone radiosurgery for an arteriovenous malformation (AVM) causing intracerebral hematoma in the left parietal lobe presented with headache, vomiting, and progressive truncal ataxia due to a cystic lesion that had been noted in the left thalamus, leading to progressive obstructive hydrocephalus. He underwent left frontal craniotomy via a transsylvian fissure approach, and the serous hematoma was aspirated. The hematoma capsule was easy to drain and was partially removed. Pathological findings demonstrated angiomatous fibroblastic granulation tissue with extensive macrophage invasion. The concentration of vascular endothelial growth factor (VEGF) was high in the hematoma (12012 pg/mL). The etiology and pathogenesis of encapsulated hematoma are unclear, but the gross appearance and pathological findings are similar to those of chronic subdural hematoma. Based on the high concentration of VEGF in the hematoma, expansion of the encapsulated hematoma might have been caused by the promotion of vascular permeability of newly formed microvasculature in the capsule.

Metastatic Cerebellar Gastrointestinal Stromal Tumor with Obstructive Hydrocephalus Arising from the Small Intestine: A Case Report and Review of the Literature

Gastrointestinal stromal tumor (GIST) is defined as a c-kit-positive gastrointestinal, mesenteric, or omental mesenchymal tumor that very rarely metastasizes to the brain. Metastasis to the cerebellum is particularly rare. An 80-year-old man presented with nausea and vomiting with disturbance of consciousness. Magnetic resonance imaging (MRI) revealed tumor in the cerebellar vermis causing obstructive hydrocephalus. The patient subsequently underwent midline suboccipital craniotomy, and the tumor was totally removed. Immunohistochemical analysis showed tumor cells positive for c-kit and CD34, and cerebellar metastasis of GIST was diagnosed. Postoperative radiotherapy was administered. Following surgery and radiotherapy, the patient developed ileus caused by tumor in the small intestine and underwent laparotomy for tumor removal. Following abdominal surgery, left hemiparesis and consciousness disturbance were noted. Computed tomography showed recurrent large tumor with perifocal edema in the right frontal lobe of the brain. The patient died 3 months after initial craniotomy. Intracranial metastasis of GIST is extremely rare. In cases such as the present, where the condition of the patient rapidly deteriorates and features such as rising intracranial pressure and ileus prevent the use of oral agents, molecular-targeted agents administered by intravenous infusion should be utilized.

Long-Term Survival following Gross Total Resection of Pediatric Supratentorial Ependymomas without Adjuvant Therapy

Pediatric supratentorial ependymoma is very rare. In pediatric patients with supratentorial ependymoma, surgery alone may be an acceptable treatment when postoperative imaging confirms a gross total resection. Surgical resection is the standard and the most important treatment for ependymoma. The role of radiation therapy and/or chemotherapy following a gross total resection of supratentorial ependymoma has been uncertain. We report 2 cases of pediatric supratentorial ependymomas treated by gross total resection without postoperative adjuvant therapy. The first patient was a 7-year-old girl who presented with motor weakness and a hemiconvulsion of the right leg. Magnetic resonance imaging (MRI) revealed a large heterogeneously enhanced tumor in the left frontal lobe. The second patient was an 8-year-old girl who presented with headache. MRI revealed a huge heterogeneously enhanced tumor in the left frontal lobe. Gross total resection was achieved in both patients. Postoperative radiotherapy and chemotherapy were avoided following gross total resection. Histologically, the lesions demonstrated grade II ependymoma and anaplastic ependymoma, respectively. After follow-up of 120 months, neither patient had recurrence or dissemination. These results suggest that patients with pediatric supratentorial ependymoma treated by gross total resection alone have a favorable outcome, and postoperative radiotherapy and chemotherapy may be avoided.

Identification of a Persistent Primitive Trigeminal Artery Following the Transposition Technique for Trigeminal Neuralgia: A Case Report

A patient who presented with trigeminal neuralgia associated with a persistent primitive trigeminal artery (PPTA) is presented. A 62-year-old woman suffering from right orbital pain was admitted to the hospital. Medical treatment for three months was ineffective, and her neuralgia had deteriorated and gradually spread in the maxillary division. Magnetic resonance imaging demonstrated the flow void signal attached to the right trigeminal nerve. Thus, microvascular decompression was performed. The superior cerebellar artery was the responsible artery, and it was transposed to decompress the trigeminal nerve. After this manoeuvre, an artery was identified running parallel to the trigeminal nerve toward Meckels cave. The artery, which turned out to be a PPTA, communicated with the basilar artery. The PPTA was carefully observed, and it was found not to be the artery causing the neuralgia because it did not compress the nerve at surgical observation. No additional procedure between the PPTA and the trigeminal nerve was performed. The patients symptom improved dramatically following surgery, and her postoperative course was uneventful. Postoperative three-dimensional computed tomography showed the PPTA. The findings in the present case suggest that transposition of the responsible artery effectively decompresses the root entry zone and assists in determining whether the PPTA is affecting the trigeminal nerve.

Lipoma in the Corpus Callosum Presenting with Epileptic Seizures Associated with Expanding Perifocal Edema: A Case Report and Literature Review

This report describes a rare case of a patient with lipoma presenting with epileptic seizures associated with expanding perifocal edema. The patient was a 48-year-old man who presented with loss of consciousness and convulsions. Magnetic resonance imaging (MRI) revealed a calcified mass in the corpus callosum with perifocal edema causing mass effect. An interhemispheric approach was used to biopsy the mass lesion. Histological examination revealed typical adipose cells, along with hamartomatous components. These components contained neurofilament and S-100-positive structures showing marked calcification. Fibrous cells immunoreactive for α-smooth muscle actin and epithelial membrane antigen proliferated with focal granulomatous inflammatory changes. MIB-1 index was approximately 5% in immature cells observed in granulomatous areas. We thus suspected a coexisting neoplastic component. The residual lesion persisted in a dormant state for 2 years following biopsy. Surgical resection of a lipoma is extremely difficult and potentially dangerous. However, in the present case, the lesion was accompanied by atypical, expanding, and perifocal edema. Surgical treatment was inevitable for the purpose of histological confirmation, considering differential diagnoses such as dermoid, epidermoid, and glioma. In the end, anticonvulsant therapy proved effective for controlling epileptic seizures.