Kohkichi Hosoda

MicroRNA-10b is overexpressed in malignant glioma and associated with tumor invasive factors, uPAR and RhoC

MicroRNAs (miRNAs) are effective post‐transcriptional regulators of gene expression and are important in many biological processes. Although the oncogenic and tumor suppressive functions of several miRNAs have been characterized, the role of miRNAs in mediating tumor invasion and migration remains largely unexplored. Recently, miR‐10b was identified as an miRNA highly expressed in metastatic breast cancer, promoting cell migration and invasion. Here, we performed real‐time reverse transcriptase polymerase chain reaction (RT‐PCR) assays on 43 glioma samples (17 glioblastoma, 6 anaplastic astrocytoma, 10 low‐grade astrocytoma, 6 oligodendroglioma and 4 ependymoma) and 6 glioma cell lines. We found that miR‐10b expression was upregulated in all glioma samples compared to non‐neoplastic brain tissues. The expression levels of miR‐10b were associated with higher grade glioma. In addition, mRNA expressions of RhoC and urokinase‐type plasminogen activator receptor (uPAR), which were thought to be regulated by miR‐10b via HOXD10, were statistically significantly correlated with the expression of miR‐10b (p < 0.001, p = 0.001, respectively). Also, protein expression levels of RhoC and uPAR were associated with expression levels of miR‐10b (p = 0.009, p = 0.014, respectively). Finally, multifocal lesions on enhanced MRI of 7 malignant gliomas were associated with higher expression levels of miR‐10b (p = 0.02). Our data indicated that miR‐10b might play some role in the invasion of glioma cells.

Cerebral Vasoreactivity and Internal Carotid Artery Flow Help to Identify Patients at Risk for Hyperperfusion After Carotid Endarterectomy

Background and Purpose— Hyperperfusion syndrome is a rare but potentially devastating complication after carotid endarterectomy (CEA). The aim of this study was to investigate whether preoperative measurement of cerebral vasoreactivity (CVR) and intraoperative measurement of internal carotid artery (ICA) flow could identify patients at risk for hyperperfusion after CEA. Methods— For 26 patients with unilateral ICA stenosis ≥70%, cerebral blood flow (CBF) and CVR were investigated before and 1 month after CEA, with resting and acetazolamide-challenge single-photon emission CT. CBF on the first postoperative day was also measured. ICA flow was measured before and after reconstruction by electromagnetic flowmeter during surgery. Results— Ipsilateral CBF on the first postoperative day significantly increased relatively (56.6±53.2%) as well as absolutely (37.9±8.8 to 57.7±18.0 mL/100 g per minute) in the reduced CVR group (CVR <12%) but not in the normal CVR group (CVR ≥12%) (10.3±15.5% and 40.6±7.9 to 43.9±5.7 mL/100 g per minute, respectively). One month later, this difference almost disappeared. Two patients showed ipsilateral CBF increase of ≥100%. A significant association of intracerebral steal with hyperperfusion (CBF increase ≥100%) on the first postoperative day was also observed. ICA flow increase after reconstruction significantly correlated with CBF increase on the first postoperative day in the reduced CVR group but not in the normal CVR group. The threshold of ICA flow increase for hyperperfusion was estimated to be 330 mL/min in the reduced CVR group. Conclusions— Single-photon emission CT with acetazolamide challenge and ICA flow measurement during surgery could identify patients at risk for hyperperfusion after CEA, in whom careful monitoring and control of blood pressure should be initiated even intraoperatively.

Prediction of Hyperperfusion After Carotid Endarterectomy by Brain SPECT Analysis With Semiquantitative Statistical Mapping Method

Background and Purpose— Hyperperfusion syndrome is a rare but disastrous complication after carotid endarterectomy (CEA). The aim of this study was to investigate the relationship between preoperative cerebral blood flow (CBF) abnormalities and postoperative hyperperfusion through the use of statistical brain mapping analysis. Methods— For 41 patients with unilateral carotid stenosis ≥70%, CBF and cerebral vasoreactivity (CVR) were investigated with resting and acetazolamide-challenge single photon emission CT before CEA. CBF 1 day after CEA was also measured. Three-dimensional stereotactic surface projection (3D-SSP) analysis of CBF changes was performed by use of a control database of 20 subjects. Results— Patients with reduced CVR (CVR <10%, n=15) were categorized into 2 groups based on the severity of CBF reduction relative to the control database by 3D-SSP analysis without normalization: type I (ipsilateral CBF decrease <20%, n=8) and type II (ipsilateral CBF decrease ≥20%, n=7). With thalamic normalization, the patients were also categorized into 2 groups: type A (ipsilateral Z score ≤2, n=10) and type B (ipsilateral Z score >2, n=5). Severe CBF reduction (≥20% or Z score >2) was significantly associated with postoperative hyperperfusion (CBF increase ≥100%). However, 3D-SSP with thalamic normalization (Z score) demonstrated a higher predictive value (80%) and specificity (91%) for hyperperfusion than 3D-SSP without normalization (percent reduction) (57% and 73%, respectively). No patients with normal CVR (CVR ≥10%, n=26) demonstrated postoperative hyperperfusion. Conclusions— Objective evaluation of abnormalities of CBF and CVR with 3D-SSP could identify patients at risk for postoperative hyperperfusion.

Germ cell tumors of the thalamus and the basal ganglia

Two cases of germ cell tumors (GCTs) of the basal ganglia are presented and 40 previously reported cases are reviewed. The incidence of GCTs of the basal ganglia and thalamus was estimated as less than 14% of all intracranial GCTs. All patients except for two (95%) were male, aged 7–19 years. The clinical course was usually slow. The major symptoms were hemiparesis, mental deterioration such as dementia or character change, precocious puberty, diabetes insipidus, oculomotor palsy, speech disturbance, and hemianopsia. Signs of intracranial hypertension did not occur until the late stages of the disease. The plain CT finding was characterized by an irregularly defined, slightly high-density area frequently accompanied by central low-density areas without significant mass effect. The tumors showed mild to moderate and nonhomogeneous contrast enhancement. An ipsilateral cerebral hemiatrophy was often found. MR images demonstrated the corresponding findings. GCTs of the basal ganglia had a high possibility of containing components other than germinoma such as choriocarcinoma, endodermal sinus tumor, and embryonal carcinoma. Thus, tumor markers in the serum, CSF, or cyst fluid were frequently positive. With recent refinement of microsurgical techniques as well as immunohistochemical study and measurements of tumor markers of serum, CSF, and cyst fluid, major resections of tumor, accurate pretreatment histologic diagnosis, and early determination of the specific types of this tumor appear to be readily possible. This is essential for effective treatment of patients not only with radiosensitive germinoma, but also those with radioinsensitive nongerminoma variants and a combination of them located in this region.

Compensatory glutamine metabolism promotes glioblastoma resistance to mTOR inhibitor treatment

The mechanistic target of rapamycin (mTOR) is hyperactivated in many types of cancer, rendering it a compelling drug target; however, the impact of mTOR inhibition on metabolic reprogramming in cancer is incompletely understood. Here, by integrating metabolic and functional studies in glioblastoma multiforme (GBM) cell lines, preclinical models, and clinical samples, we demonstrate that the compensatory upregulation of glutamine metabolism promotes resistance to mTOR kinase inhibitors. Metabolomic studies in GBM cells revealed that glutaminase (GLS) and glutamate levels are elevated following mTOR kinase inhibitor treatment. Moreover, these mTOR inhibitor-dependent metabolic alterations were confirmed in a GBM xenograft model. Expression of GLS following mTOR inhibitor treatment promoted GBM survival in an α-ketoglutarate-dependent (αKG-dependent) manner. Combined genetic and/or pharmacological inhibition of mTOR kinase and GLS resulted in massive synergistic tumor cell death and growth inhibition in tumor-bearing mice. These results highlight a critical role for compensatory glutamine metabolism in promoting mTOR inhibitor resistance and suggest that rational combination therapy has the potential to suppress resistance.

Utility of diffusion tensor imaging in the acute stage of mild to moderate traumatic brain injury for detecting white matter lesions and predicting long-term cognitive function in adults

OBJECT Traumatic brain injury (TBI) often impairs cognitive function. Diffusion tensor (DT) imaging, a novel modality, permits evaluation of the effects of head trauma on white matter nerve fibers. The objectives of the current study were to investigate where the white matter injury following mild to moderate TBI is specifically located on DT imaging in the acute disease stage and to examine the relationship between the severity of the white matter lesion on DT imaging in the acute stage of TBI and future cognitive function in the chronic disease stage. METHODS Twenty adult patients with mild to moderate TBI (Glasgow Coma Scale score between 9 and 15) underwent conventional MR and DT imaging a median of 3.5 days after injury, and 27 matched healthy controls also underwent both imaging modalities. The patients with TBI were further subdivided into 2 groups, that is, mild and more severe TBI groups, based on clinical (mild or moderate TBI), CT (diffuse brain injury [DBI] I or II), or MR imaging (normal or pathological appearance) classification. Fractional anisotropies (FAs) were compared between patients and controls using the region of interest method. Regions of interest were located in 8 different areas including the genu, stem, and splenium of the corpus callosum and the corona radiata (CR), anterior limb of the internal capsule (ALIC), posterior limb of the internal capsule (PLIC), frontal white matter (FWM), and occipital white matter (OWM) of the periventricular white matter. Eleven patients with TBI also underwent neuropsychological testing, which included the Trail Making Test, Wisconsin Card Sorting Test, Wechsler Adult Intelligence Scale-Revised, and P300 testing in the chronic disease stage (median 364 days). RESULTS Region of interest analysis demonstrated significantly lower FA values in the genu, stem, and splenium of the corpus callosum in more severe TBI groups (moderate TBI on clinical classification, DBI II on CT classification, and pathological appearance on MR imaging classification) than in controls. A significant difference was also observed in the FA of the splenium between controls and the mild TBI group of the clinical classification. No significant difference was observed in the FA of the CR, ALIC, PLIC, FWM, and OWM between controls and any of the TBI groups of clinical or imaging classifications. No significant difference was observed in the FA of any regions between mild and more severe TBI groups of the clinical or imaging classifications. Multiple regression analysis showed a statistically significant positive linear relationship between FA in the splenium and total IQ (r = 0.79, p = 0.004). A significant negative linear relationship between FA in the FWM and P300 latency was also observed (r = 0.62, p = 0.04). CONCLUSIONS Fractional anisotropy reductions in the splenium and FWM in the acute stage of mild to moderate TBI may be a useful prognostic factor for long-term cognitive dysfunction.

Cerebrospinal fluid interleukin-10 is a potentially useful biomarker in immunocompetent primary central nervous system lymphoma (PCNSL)

The diagnosis of primary central nervous system lymphoma (PCNSL) by radiographical examination is often difficult because of its similarity to other brain tumors. To test whether interleukin-10 (IL-10) and IL-6 can be used to distinguish PCNSL from other brain tumors that are radiographically similar, cerebrospinal fluid (CSF) levels of IL-10 and IL-6 were measured in 66 patients with intracranial tumors (PCNSLs: 26 cases; other brain tumors: 40 cases). In the patients with PCNSLs, the median CSF levels of IL-10 and IL-6 were 27 pg/mL and 5.4 pg/mL, respectively. The CSF IL-10 and IL-6 levels were significantly higher in PCNSLs than in the other brain tumors. To validate the diagnostic value of CSF IL-10 in PCNSL, we prospectively examined 24 patients with brain lesions that were suspected to be PCNSL. We observed that the CSF IL-10 levels were significantly higher in PCNSLs than in other brain tumors. At an IL-10 cutoff level of 9.5 pg/mL, the sensitivity and specificity were 71.0% and 100%, respectively. After therapy, the CSF IL-10 levels were decreased in all patients and were increased at relapse in most of these patients. Immunohistochemically, all PCNSLs, except for 1 unclassified PCNSL, expressed both IL-10 and IL-10 receptor-A. In the patients with high CSF IL-10, IL-10 expression levels in tumor were relatively higher, compared with low CSF IL-10; however, there was no significant difference between these groups. In addition, elevated CSF level of IL-10 was significantly associated with having a shorter progression-free survival (hazard ratio, 3.37; 95% confidence interval, 0.985-11.528; log-rank, P= .038). These results indicate that the CSF level of IL-10 may be a useful diagnostic and prognostic biomarker in patients with PCNSLs.

Effect of clot removal and surgical manipulation on regional cerebral blood flow and delayed vasospasm in early aneurysm surgery for subarachnoid hemorrhage

BACKGROUND Effect of clot removal and surgical manipulation on cerebral blood flow (CBF) and delayed vasospasm was studied in early aneurysm surgery for subarachnoid hemorrhage (SAH). METHODS Thirty-two patients in this study fulfilled the following criteria: ruptured anterior communicating aneurysms, computed tomography (CT) within 2 days and unilateral pterional approach within 3 days after the ictus, bilaterally symmetrical clots without intracerebral hematoma, no postoperative complication, and CBF studies with single photon emission computed tomography (SPECT) with 123I-IMP. RESULTS Postoperative regional hypoperfusion due to brain retraction was frequently recognized on 123I-IMP-SPECT without infarction. The regional CBF (rCBF) showed a continuous fall during the first 4 weeks after the ictus, followed by improvement. The rCBF in the vicinity of the surgical route was significantly lower, especially in the acute stage (Day 3-7). A significant association between decrease of cisternal blood after surgery and the degree of local vasospasm and local CBF values during spasm stage was observed in the interhemispheric cisterns, A2 and medial frontal cortex, but not in the sylvian fissure or insular cisterns, M1 or M2, and frontal watershed and temporal cortex. CONCLUSIONS The present study provides evidence for the effectiveness of direct clot removal by early surgery for SAH on local vasospasm and CBF reduction. However, a potential improvement in local CBF with clot removal could be masked by brain retraction, which was demonstrated to affect rCBF adversely. Therefore, it is critical to perform brain retraction as gently as possible.

MicroRNA-183 upregulates HIF-1α by targeting isocitrate dehydrogenase 2 (IDH2) in glioma cells

MicroRNAs (miRs) are small, non-coding RNAs that regulate gene expression and contribute to cell proliferation, differentiation and metabolism. Our previous study revealed the extensive modulation of a set of miRs in malignant glioma. In that study, miR microarray analysis demonstrated the upregulation of microRNA-183 (miR-183) in glioblastomas. Therefore, we examined the expression levels of miR-183 in various types of gliomas and the association of miR-183 with isocitrate dehydrogenase 2 (IDH2), which has complementary sequences to miR-183 in its 3′-untranslated region (3′UTR). In present study, we used real-time PCR analysis to demonstrate that miR-183 is upregulated in the majority of high-grade gliomas and glioma cell lines compared with peripheral, non-tumorous brain tissue. The mRNA and protein expression levels of IDH2 are downregulated via the overexpression of miR-183 mimic RNA in glioma cells. Additionally, IDH2 mRNA expression is upregulated in glioma cells expressing anti-miR-183. We verified that miR-183 directly affects IDH2 mRNA levels in glioma cells using luciferase assays. In malignant glioma specimens, the expression levels of IDH2 were lower in tumors than in the peripheral, non-tumorous brain tissues. HIF-1α levels were upregulated in glioma cells following transfection with miR-183 mimic RNA or IDH2 siRNA. Moreover, vascular endothelial growth factor and glucose transporter 1, which are downstream molecules of HIF-1α, were upregulated in cells transfected with miR-183 mimic RNA. These results suggest that miR-183 upregulation in malignant gliomas induces HIF-1α expression by targeting IDH2 and may play a role in glioma biology.

Saccular Aneurysms of the Proximal (M1) Segment of the Middle Cerebral Artery

We report A series of 20 consecutive patients with 21 saccular aneurysms of the proximal (M1) segment of the middle cerebral artery. The incidence of M1 aneurysms was 3.0% among 660 patients with intracranial aneurysms and 12.9% among 155 patients with middle cerebral artery aneurysms in our center. Of the 20 patients, 2 were men and 18 were women. The aneurysms were classified into two types: the superior wall type (9 cases), arising at the origin of the lenticulostriate or fronto-orbital artery, and the inferior wall type (12 cases), arising at the origin of the early temporal branches. Twelve (60%) patients had ruptured M1 aneurysms. The incidence of multiple aneurysms was high (nine patients, 45%), and M1 aneurysms were responsible for subarachnoid hemorrhage in four patients. Of 14 M1 aneurysms greater than 5 mm in diameter, 11 (78.6%) ruptured. In contrast, only one (14.3%) of seven small (< or = 5 mm) aneurysms ruptured. In 12 patients with ruptured M1 aneurysms, intracerebral hematomas were recognized in 6 (50%). Intracerebral hematomas by the superior wall M1 aneurysms were located in the frontal lobe, and those by the inferior wall M1 aneurysms were in the temporal lobe. Fifteen patients (75%) made a useful recovery 6 months after surgery. Four patients (20%), who were in poor grade condition preoperatively, remained severely disabled. One patient died of sepsis 2 months after she recovered well from the operation. Special attention to the lenticulostriate arteries to avoid injury is critical for successful surgical treatment.