Toshihiro Mineta

Attenuated multi-mutated herpes simplex virus-1 for the treatment of malignant gliomas.

We have created a double mutant of the herpes simplex virus (HSV) type 1 (termed G207) with favourable properties for treating human malignant brain tumours: replication–competence in glioblastoma cells (and other dividing cells), attenuated neurovirulence, temperature sensitivity, ganciclovir hypersensitivity, and the presence of an easily detectable histochemical marker. G207 has deletions at both γ34.5 (RL1) loci and a lacZ gene insertion inactivating the ICP6 gene (UL39). G207 kills human glioma cells in monolayer cultures. In nude mice harbouring subcutaneous or intracerebral U–87MG gliomas, intraneoplastic inoculation with G207 causes decreased tumour growth and/or prolonged survival. G207 is avirulent upon intracerebral inoculation of mice and HSV–sensitive non–human primates. These results suggest that G207 should be considered for clinical evaluation in the treatment of glioblastomas.

Antisense expression of protein kinase C alpha inhibits the growth and tumorigenicity of human glioblastoma cells.

To investigate the role of protein kinase C (PKC) in the growth of astrocytic brain tumors, human glioblastoma cell line U-87 was stably transfected with the antisense complementary deoxyribonucleic acid encoding PKC alpha. The effect of selectively down-regulating the alpha isoform on other PKC isoforms, as well as serum-dependent proliferation and in vivo tumorigenicity, was determined. U-87 cells expressed high levels of PKC alpha and lesser amounts of the gamma, epsilon, and zeta isoforms, and a similar PKC isoform pattern was observed in two other human glioblastoma cell lines. Expression of the antisense PKC alpha complementary deoxyribonucleic acid resulted in no detectable PKC alpha by immunoblotting and a 95% reduction in total Ca2+/phospholipid-dependent PKC activity. U-87 cells expressing antisense PKC alpha exhibited an increase in doubling time in vitro, less serum-dependent growth, and reduced sensitivity to a selective PKC inhibitor, Ro 31-8220. The transplantation of U-87 cells expressing antisense PKC alpha into nude mice resulted in no tumor formation. These observations suggest that the inhibition of PKC alpha may be an important chemotherapeutic target for arresting the growth of glioblastomas.

AGM-1470 inhibits the growth of human glioblastoma cells in vitro and in vivo

Glioblastoma is the most malignant primary brain tumor. Inhibition of angiogenesis is one potential strategy for treating this fatal hypervascular tumor. AGM-1470 (also called TNP-470), a novel, potent, fungus-derived inhibitor of angiogenesis, was tested on the growth of human glioblastoma cells in culture and on the growth of the tumor in nude mice. In nude mice with subrenally implanted U-87 MG glioblastomas, AGM-1470 significantly inhibited tumor growth (P < 0.01), and in nude mice with intracranial U-87 MG glioblastomas, AGM-1470 prolonged survival. In addition to its expected action as an angiogenesis inhibitor, AGM-1470 also directly inhibited U-87 MG cells in culture at concentrations similar to those that inhibited endothelial cells. The combined inhibition of glioblastoma cell mitosis and of glioblastoma-induced neovascularization suggests that AGM-1470 should be considered for further investigation in the treatment of this fatal tumor.

Inhibition of angiogenesis and growth of human non-malignant and malignant meningiomas by TNP-470

SummaryMeningiomas are relatively common (22%) vascular brain tumors. 3–11% of meningiomas are malignant, and defy currently available therapy. Inhibition of neovascularization is one potential strategy for treating these hypervascular tumors. Inhibition of tumor-induced angiogenesis by TNP-470 (previously termed AGM-1470), a synthetic analogue of fumagillin, was tested on the growth of human non-malignant and malignant meningiomas in nude mice. TNP-470 significantly inhibited tumor neovascularization and tumor growth of both non-malignant and malignant meningiomas. TNP-470 is now in human trial and should be tested for efficacy in treating malignant or recurrent aggressive meningiomas.

Transcondylar Fossa (Supracondylar Transjugular Tubercle) Approach: Anatomic Basis for the Approach, Surgical Procedures, and Surgical Experience

The authors clarify the anatomic basis and the usefulness of the transcondylar fossa approach (T-C-F A), in which the posterior portion of the jugular tubercle is removed extradurally through the condylar fossa with the atlanto-occipital joint intact. The authors first performed an anatomic study to identify the area to be removed using cadaveric specimens and then applied the T-C-F A to foramen magnum surgeries. The surgeries included clipping a vertebral artery-posterior inferior cerebellar artery aneurysm in 11 cases, microvascular decompression for glossopharyngeal neuralgia in 15 cases, and removing intradural foramen magnum tumors in 17 cases. Only the condylar fossa was removed, but the approach offered very good visualization of the lateral part of the foramen magnum and sufficient working space. These surgeries were performed safely without major complications. This skull base approach is minimally invasive and is not difficult. Therefore, it can be a standard approach for accessing intradural lesions of the foramen magnum. It can be combined with the transcerebellomedullary fissure approach from the lateral side and can also be easily changed to the transcondylar approach, if necessary.

Stitched sling retraction technique for microvascular decompression: procedures and techniques based on an anatomical viewpoint

The success of microvascular decompression (MVD) depends on the permanent and complete transposition of the offending vessels. This paper describes the stitched sling retraction techniques for treating trigeminal neuralgia (TN), hemifacial spasm (HFS), and glossopharyngeal neuralgia (GPN), focusing on the stitching point for slinging the offending artery in the appropriate direction. Between January 2007 and March 2009, 28 patients with TN, 5 patients with HFS, and 3 patients with GPN underwent MVD with a sling retraction technique. In cases of TN, MVD was performed using the infratentorial lateral supracerebellar approach, and the offending superior cerebellar artery was superomedially transposed with a sling stitched to the tentorium cerebelli. In cases of HFS, MVD was performed using the lateral suboccipital infrafloccular approach, and the offending vertebral artery was superolaterally transposed with a sling stitched to the petrous dura. In cases of GPN, MVD was performed using the transcondylar fossa approach, in which the posterior inferior cerebellar artery was inferolaterally mobilized with a sling secured to the jugular tubercle. No patient suffered recurrence in the follow-up period. For the sling retraction technique to be performed successfully, it is important for a stitch to be placed at a suitable site to sling the offending vessel in the intended direction. An appropriate surgical approach must be used to obtain a sufficient operative field for performing the stitching procedures safely.

Microvascular decompression for glossopharyngeal neuralgia through the transcondylar fossa (supracondylar transjugular tubercle) approach.

OBJECTIVE Our surgical results were reviewed to clarify the cause of glossopharyngeal neuralgia (GPN) and the effects of the microvascular decompression (MVD) procedure. METHODS Fourteen cases of idiopathic GPN were operated on through the transcondylar fossa (supracondylar transjugular tubercle) approach. Their clinical data and operative records were retrospectively reviewed. RESULTS In every case, vascular compression on the glossopharyngeal nerve was found and MVD was performed without any major complications. In 13 of the 14 cases the neuralgia completely disappeared postoperatively. Recurrence of pain was found in 1 case. Offending vessels were the posterior inferior cerebellar artery (PICA) in 10 cases, the anterior inferior cerebellar artery (AICA) in 2 cases, and both arteries in 2 cases. In 10 of the 14 cases, the high-origin PICA formed an upward loop between the glossopharyngeal and vagus nerves, compressing the glossopharyngeal nerve upward. In those cases, the PICA was transposed and fixed to the dura mater by the stitched sling retraction technique, and MVD was very effective. CONCLUSION The offending artery was the PICA in most cases. MVD is expected to be very effective, especially when the radiological images show the following 3 findings: 1) high-origin PICA, 2) the PICA making an upward loop, and 3) the PICA coursing the supraolivary fossette. The transcondylar fossa approach is suitable for transposing the PICA by the stitched sling retraction technique, and provides sufficient surgical results.

Detrended fluctuation analysis of genome-wide copy number profiles of glioblastomas using array-based comparative genomic hybridization

We examined whole genomic aberrations of biopsied samples from 19 independent glioblastomas by array-based comparative genomic hybridization analysis. The highest frequencies of copy number gains were observed on RFC2 (73.3%), EGFR (63.2%), and FGR, ELN, CDKN1C , FES, TOP2A, and ARSA (57.9% each). The highest frequencies of copy number losses were detected on TBR1 (52.6%), BMI1 (52.6%), EGR2 (47.4%), DMBT1 (47.4%), MTAP (42.1%), and FGFR2 (42.1%). The copy number gains of CDKN1C and INS and the copy number losses of TBR1 were significantly correlated with longer survival of patients. High-level amplifications were identified on EGFR, SAS/CDK4, PDGFRA, MDM2, and ARSA. These genes are assumed to be involved in tumorigenesis or progression of glioblastomas. The first attempts to apply detrended fluctuation analysis to copy number profiles by considering the reading direction as the time axis demonstrated that higher long-term fractal scaling exponents (alpha2) correlated well with longer survival of glioblastoma patients. The present study indicates that array-based comparative genomic hybridization analysis has great potential for assessment of copy number changes and altered chromosomal regions of brain tumors. Furthermore, we show that nonlinear analysis methods of whole genome copy number profiles may provide prognostic information about glioblastoma patients.

Fas ligand expression and depletion of T-cell infiltration in astrocytic tumors

Fas (APO-1/CD95) ligand (FasL) and its receptor, Fas, play a key role in the regulation of apoptosis in the immune system. FasL acts as a cytotoxic effector molecule to Fas-expressing malignant tumor cells; however, it has recently been suggested that FasL also acts as a possible mediator of tumor immune privilege. We studied FasL expression in glioblastoma cell lines and a series of human glioma specimens by Western blotting and immunohistochemistry. In addition, quantitative analysis of T-cell infiltration in these tumors was performed. FasL expression was seen in all cell lines and in 9 of 14 specimens by Western blotting and immunohistochemistry. The distribution of FasL was recognized in the cytoplasm of tumor cells (5 of 9) and in the vascular endothelium (4 of 9). Both types of FasL expression were associated with a significant reduction (p<0.05) in T-cell infiltration when compared with FasL-negative areas within the same tumor or FasL-negative specimens. Since T-cell apoptosis could be induced by FasL-expressing tumor cells, the present findings suggest that apoptosis induction by FasL expressed on tumor cells and/or vascular endothelium might be one mechanism for T-cell depletion in astrocytic tumor tissues.

Induction of apoptosis in glioma cells by recombinant human Fas ligand.

OBJECTIVE Fas ligand (FasL) belongs to the tumor necrosis factor family and has the ability to induce apoptosis in susceptible target cells by binding to its receptor, Fas. It has been demonstrated recently that the FasL/Fas system plays a pivotal role in the cytocidal activity of T lymphocytes in the immune system. FasL may act as a cytotoxic effector molecule to Fas-expressing malignant tumor cells. We reported previously that Fas is commonly expressed in human brain tumor cells. In this study, we examine the possible application of FasL to therapy for malignant brain tumors. METHODS To develop an expression system yielding large amounts of FasL, we constructed a baculovirus vector containing complementary deoxyribonucleic acid of human FasL under the control of a polyhedrin promoter. We produced human FasL in Spodoptera frugiperda (Sf9) insect cells infected by the recombinant baculovirus carrying FasL complementary deoxyribonucleic acid and studied the cytocidal activity of FasL against the T98G human glioblastoma cell line. RESULTS FasL expression in Sf9 cells was confirmed immunocytochemically with rabbit antibody raised against the cytoplasmic domain of human FasL. The FasL released into the supernatant of cultured Sf9 cells was also verified by Western blotting, and it specifically induced apoptosis in T98G cells. The induced apoptosis by recombinant human FasL was confirmed by annexin V-fluorescein isothiocyanate staining. CONCLUSION The present results suggest that the induction of apoptosis by the Fas/FasL system could be a new strategy for the treatment of malignant brain tumors, which are resistant to conventional therapies.