Kenji Wakiya

O 6-methylguanine-DNA methyltransferase promoter methylation in 45 primary central nervous system lymphomas: quantitative assessment of methylation and response to temozolomide treatment

Favorable responses to temozolomide chemotherapy have recently been reported in primary central nervous system lymphoma (PCNSL) patients who are refractory to high-dose methotrexate therapy. The gene encoding the DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) is transcriptionally silenced by promoter methylation in several human tumors, including gliomas and systemic lymphomas. MGMT promoter methylation is also a prognostic marker in glioblastoma patients treated with temozolomide. To validate temozolomide treatment in PCNSL, we applied methylation-sensitive high resolution melting (MS-HRM) analysis to quantitate MGMT methylation in PCNSL. MGMT promoter methylation was detected in tumors from 23 (51%) of 45 PCNSL patients, 11 of which were considered to have high (more than 70.0%) methylation status. Of the five recurrent PCNSLs treated with temozolomide, four cases responded, with three achieving complete response and one, a partial response. All four responsive PCNSLs had methylated MGMT promoters, whereas the non-responsive recurrent PCNSL did not. Thus, the use of quantitative MS-HRM analysis for the detection of MGMT promoter methylation has been suggested in PCNSL for the first time. The assay allows rapid and high-throughput evaluation of the MGMT methylation status, and seems to be promising in clinical settings. MGMT promoter methylation may become a useful marker for predicting the response of PCNSLs to temozolomide.

Preoperative assessment of hemifacial spasm by the coronal heavily T2-weighted MR cisternography.

BackgroundMicrovascular decompression (MVD) has become a well-established surgical procedure for hemifacial spasm (HFS). Before surgery, it is essential to evaluate any possible deformity of the brainstem and establish the precise location of the offending vessels. In the present study of HFS patients we examined coronal sections taken by heavily T2-weighted MR cisternography in addition to routine axial sections, and assessed the usefulness of these images through comparison with intraoperative findings.MethodsEighty patients with HFS underwent preoperative coronal heavily T2-weighted MR cisternography before microvascular decompression surgery. Three neurosurgeons examined the preoperative axial and coronal MR images and evaluated vessel invagination into the brainstem. The usefulness of coronal sections was assessed statistically by the Mann-Whitney U test.ResultsInvagination of the offending vessel into the brainstem was observed in 24 cases (30.0%). In 19 patients, it was predicted preoperatively that compression of the flocculus and brainstem would be required in order to approach the offending vessels. Coronal MR cisternography was significantly more useful in cases with vessel invagination into the brainstem than in cases without invagination.ConclusionsCoronal sections obtained by MR cisternography are able to demonstrate the severity of vessel invagination into the brainstem as well as revealing the presence of the offending vessel. This information is helpful for planning a suitable approach to the root exit zone.

Does arteriosclerosis contribute to hemifacial spasm

BackgroundHemifacial spasm (HFS) is caused by pulsative vascular compression of the root exit zone (REZ) of the facial nerve. However, the mechanism that causes the offending vessels to compress the REZ has not been clarified. Elongation of intracranial arteries due to arteriosclerosis is one possibility, but such arteriosclerotic changes are not observed very frequently among patients with HFS. The aim of the present study was to investigate whether arteriosclerotic changes would contribute to the pathogenesis of HFS.MethodsThis study included 111 HFS patients, all of whom were Japanese. The prevalence rates of hypertension, hyperlipidemia, and diabetes mellitus were examined as risk factors of atherosclerosis, and the cardio-ankle vascular index (CAVI) was measured as an indicator of arteriosclerotic change. The severity of white matter lesions (WMLs) in HFS patients was measured by magnetic resonance imaging. These data were compared with data from healthy Japanese controls.ResultsThe prevalence rates of the risk factors for atherosclerosis in the HFS patients were not higher than those in the general Japanese population. The CAVI scores for the HFS patients were similar to, or lower than those in the healthy controls for all age groups except 60 to 69-year-old men. The severity of WMLs in the HFS patients was not significantly worse than that in the controls.ConclusionsIt is suggested that arteriosclerotic changes are not involved in the pathogenesis of HFS, and that vascular compression syndromes are attributable to anatomical features of the intracranial arteries and facial nerves formed during the prenatal stage.

Abstract 4144: Identification of molecules involved in PpIX accumulation in brain tumor induced by oral administration of 5-ALA

[Background and Purpose] 5-aminolevulinic acid (5-ALA) is one of leading compounds widely used in photodynamic diagnosis and therapy of solid tumors: 5-ALA is metabolically converted to protoporphyrin IX (PpIX), a fluorescent molecule in response to excitation with a laser beam of 405 nm wavelength, that accumulates specifically in tumor lesions. This is found to be very effective for intra-operative detection of malignant brain tumors such as glioblastoma multiforme (GBM). On the other hand, we occasionally encountered cancerous lesions that are apparently malignant under a white light, while showing no fluorescence of the PpIX during cyto-reductive operation of the GBM. In order to overcome this problem, we hereby searched for factors associated with either presence or absence of the PpIX fluorescence by means of comprehensive gene expression analysis. [Materials and Methods] Thirty-one patients of brain tumor (21 GBM, 3 pilocytic astrocytoma and 7 oligodendroglial tumors), orally-administrated with 5-ALA followed by operation under a fluorescence-guide, were enrolled in this study. Tumor specimens with or without the 5-ALA induced-fluorescence were collected from these patients and snap-frozen in liquid nitrogen. Total RNAs were extracted from the frozen tissues and were subjected to a comprehensive gene expression analysis using Whole Human Genome 4×44K Oligo Microarray (Agilent). We then compared gene expression levels between specimens with or without the fluorescence among individuals and selected candidate genes of which gene expression levels significantly differ between these. For validation, quantitative gene expression analyses were conducted for the candidates with real-time RT-PCR using gene specific-primers and probes. Knockdown experiments using specific siRNAs were also performed in cell lines derived from GBM to test their biological significance. [Results and Discussion] A total of 14 genes were initially selected as candidates that were associated with PpIX accumulation in GBM in the microarray analysis. Among these, CDH13 (cadherin 13) gene was expressed significantly higher in the fluorescence-positive GBMs than in negative ones. Knockdown of CDH13 gene expression in GBM cells treated with 5-ALA, attenuated the fluorescence intensity, indicating its possible role in PpIX accumulation. Further experiments are underway to elucidate molecular mechanisms of CDH13 in 5-ALA-induced PpIX fluorescence in brain tumor. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4144. doi:10.1158/1538-7445.AM2011-4144