Berberine as a potential enhancer for 5-ALA-mediated fluorescence in glioblastoma: increasing detectability of infiltrating glioma stem cells to optimize 5-ALA-guided surgery.

OBJECTIVE: The prognosis of glioblastoma (GBM) correlates with residual tumor volume after surgery. In fluorescence-guided surgery, 5-aminolevulinic acid (ALA) has been used to maximize resection while avoiding neurological morbidity. However, not all tumor cells, particularly glioma stem cells (GSCs), display 5-ALA-mediated protoporphyrin IX (PpIX) fluorescence (5-ALA fluorescence). The authors searched for repositioned drugs that affect mitochondrial functions and energy metabolism, identifying berberine (BBR) as a potential enhancer of 5-ALA fluorescence. In this study, they investigated whether BBR can enhance 5-ALA fluorescence in GSCs and whether BBR can be applied to clinical practice as a 5-ALA fluorescence enhancer. METHODS: The effects of BBR on 5-ALA fluorescence in glioma and GSCs were evaluated by flow cytometry (fluorescence-activated cell sorting [FACS]) analysis. As 5-ALA is metabolized for heme synthesis, the effects of BBR on mRNA expressions of 7 enzymes in the heme-synthesis pathway were analyzed. Enzymes showing significantly higher expression than control in all cells were identified and protein analysis was performed. To examine clinical availability, the detectability and cytotoxicity of BBR in tumor-transplanted mice were analyzed. RESULTS: Fluorescence microscopy revealed much more intense 5-ALA fluorescence in both GSCs and non-stem cells with 5-ALA and BBR than with 5-ALA alone. FACS showed that BBR greatly enhanced 5-ALA fluorescence compared with 5-ALA alone, and enhancement was much higher for GSCs than for glioma cells. Among the 7 enzymes examined, BBR upregulated mRNA expressions of ALA synthetase 1 (ALAS1) more highly in all cells, and activated ALAS1 through deregulating ALAS1 activity inhibited by the negative feedback of heme. An in vivo study showed that 5-ALA fluorescence with 5-ALA and BBR was significantly stronger than with 5-ALA alone, and the sensitivity and specificity of BBR-enhanced fluorescence were both 100%. In addition, BBR did not show any cytotoxicity for normal brain tissue surrounding the tumor mass. CONCLUSIONS: BBR enhanced 5-ALA-mediated PpIX fluorescence by upregulating and activating ALAS1 through deregulation of negative feedback inhibition by heme. BBR is a clinically used drug with no side effects. BBR is expected to significantly augment fluorescence-guided surgery and photodynamic therapy.

Identification of CD44 as a Reliable Biomarker for Glioblastoma Invasion: Based on Magnetic Resonance Imaging and Spectroscopic Analysis of 5-Aminolevulinic Acid Fluorescence.

Recurrent glioblastoma multiforme (GBM) is largely attributed to peritumoral infiltration of tumor cells. As higher CD44 expression in the tumor periphery correlates with higher risk of GBM invasion, the present study analyzed the relationship between CD44 expression and magnetic resonance imaging (MRI)-based invasiveness of GBM on a large scale. We also quantitatively evaluated GBM invasion using 5-aminolevulinic acid (5-ALA) spectroscopy to investigate the relationship between CD44 expression and tumor invasiveness as evaluated by intraoperative 5-ALA intensity. Based on MRI, GBM was classified as high-invasive type in 28 patients and low-invasive type in 22 patients. High-invasive type expressed CD44 at a significantly higher level than low-invasive type and was associated with worse survival. To quantitatively analyze GBM invasiveness, the relationship between tumor density in the peritumoral area and the spectroscopic intensity of 5-ALA was investigated. Spectroscopy showed that the 5-ALA intensity of infiltrating tumor cells correlated with tumor density as represented by the Ki-67 staining index. No significant correlation between CD44 and degree of 5-ALA-based invasiveness of GBM was found, but invasiveness of GBM as evaluated by 5-ALA matched the classification from MRI in all except one case, indicating that CD44 expression at the GBM periphery could provide a reliable biomarker for invasiveness in GBM.

Clinical utility of new bone imaging using zero-echo-time sequence in neurosurgical procedures: Can zero-echo-time be used in clinical practice in neurosurgery?

PURPOSE: The purpose of this study was to evaluate the clinical usefulness of zero-echo-time (ZTE)-based magnetic resonance imaging (MRI) in planning the optimum surgical approach and applying ZTE for anatomical guidance during transcranial surgery. METHODS: Eleven of 26 patients who underwent transcranial surgery and carotid endarterectomy and in whom ZTE-based MRI and magnetic resonance angiography (MRA) data were obtained were analyzed by creating ZTE/MRA fusion images and 3D ZTE-based MRI models. We examined whether these images and models can be substituted for computed tomography imaging for neurosurgical procedures. Furthermore, the clinical usability of the 3D ZTE-based MRI models was evaluated by comparing them with actual surgical views. RESULTS: Zero-echo-time/MRA fusion images and 3D ZTE-based MRI models clearly illustrated the cranial and intracranial morphology without radiation exposure or the use of iodinated contrast medium. The models allowed determination of the optimum surgical approach to cerebral aneurysms, brain tumors near the brain surface, and cervical internal carotid artery stenosis by visualizing the relationship of lesions with adjacent bone structures. However, ZTE-based MRI did not provide useful information for surgery for skull base lesions such as vestibular schwannoma because bone structures of the skull base often include air components, which cause signal disturbance in MRI. CONCLUSIONS: Zero-echo-time sequences on MRI allowed distinct visualization of not only bone but also vital structures around the lesion. This technology has low invasiveness for patients and was useful for preoperative planning and guidance of the optimum approach during surgery in a subset of neurosurgical diseases.

What is the Best Preoperative Quantitative Indicator to Differentiate Primary Central Nervous System Lymphoma from Glioblastoma?

BACKGROUND: The role of surgery in primary central nervous system lymphoma (PCNSL) is to allow pathological diagnosis from tumor biopsy. However, PCNSL is often difficult to distinguish from other tumors, particularly glioblastoma multiforme (GBM). Quantitative evaluations to facilitate differentiation between PCNSL and GBM would be useful. Here, we investigated the best examinations for exact differentiation of PCNSL from GBM among preoperative examinations, including imaging studies and tumor markers. METHODS: Various examinations were performed for 68 patients with PCNSL , including serum soluble interleukin 2 receptor, ß2-microglobulin (MG) in cerebrospinal fluid (CSF), diffusion-weighted imaging, 11C-methionine-positron emission tomography (PET), and 18F-fluorodeoxyglucose (FDG)-PET. These results were compared with findings from 28 patients with consecutive GBM who underwent the same examinations to evaluate the utility and accuracy of different investigations. RESULTS: CSF ß2-MG ≥2.0 mg/L was relatively specific for PCNSL, offering 95.0% sensitivity and 85.7% specificity. Tumor-to-contralateral normal brain tissue ratio ≥2.4 on 18F-FDG-PET was also quite specific for PCNSL, offering 83.8% sensitivity and 95.2% specificity. No other examinations displayed any significant differences in quantitative differential markers between PCNSL and GBM. CONCLUSIONS: Both ß2-MG ≥2.0 mg/dL in CSF and tumor-to-contralateral normal brain tissue ratio ≥2.4 from 18F-FDG-PET allow quantitative differentiation of PCNSL from GBM, potentially representing clinically useful indicators. These findings could lead to innovative methods for differentiating PCNSL from GBM as well as new treatment strategies for other brain tumors.

Usefulness of intraoperative rapid immunohistochemistry in the surgical treatment of brain tumors.

In the treatment of primary central nervous system lymphoma (PCNSL), intraoperative rapid pathological diagnosis can dramatically change the surgical strategy, and more accurate diagnostic methods are required. In April 2020, we adopted intraoperative rapid immunohistochemistry (IHC) in addition to conventional rapid intraoperative diagnosis based on morphological assessment, mainly for patients with PCNSL. Here, we investigate the usefulness and significance of intraoperative rapid IHC based on our initial experience. We performed intraoperative rapid IHC using antibodies for cluster of differentiation (CD)20, CD3, leukocyte common antigen (LCA) and glial fibrillary acidic protein (GFAP) using enzyme-labeled antibody methods in 25 patients, including PCNSL patients, from April 2020 to July 2022. We examined the utility of this approach in determining treatment strategies for brain tumors. Postoperative final pathological diagnoses from paraffin-embedded sections were as follows: diffuse large B-cell lymphoma, 16 cases; glioblastoma, six cases; pilocytic astrocytoma, one case; adenocarcinoma, one case; and inflammatory disorder, one case. The entire process took 32 min and staining for CD20, CD3, LCA, and GFAP was comparable to that using paraffin-embedded sections. In all cases, the results of intraoperative rapid IHC were consistent with final pathological diagnoses from paraffin-embedded sections. In addition, in two cases, the results of conventional intraoperative rapid pathological diagnosis based on morphological assessments using frozen sections were drastically changed by adding intraoperative rapid IHC. Intraoperative rapid IHC contributes to deciding appropriate treatment strategies and facilitating early initiation of chemotherapy for PCNSL. This may allow new therapeutic strategies not only for PCNSL but also for other brain tumors.

Quantitative measurement of peritumoral concentrations of glutamate, N-acetyl aspartate, and lactate on magnetic resonance spectroscopy predicts glioblastoma-related refractory epilepsy.

BACKGROUND: Increased extracellular glutamate is known to cause epileptic seizures in patients with glioblastoma (GBM). However, predicting whether the seizure will be refractory is difficult. The present study investigated whether evaluation of the levels of various metabolites, including glutamate, can predict the occurrence of refractory seizure in GBM by quantitative measurement of metabolite concentrations on magnetic resonance spectroscopy (MRS). METHODS: Forty patients were treated according to the same treatment protocol for primary GBM at Ehime University Hospital between April 2017 and July 2021. Of these patients, 23 underwent MRS to determine concentrations of metabolites, including glutamate, N-acetylaspartate, creatine, and lactate, in the tumor periphery by applying LC-Model. The concentration of each metabolite was expressed as a ratio to creatine concentration. Patients were divided into three groups: Type A, patients with no seizures; Type B, patients with seizures that disappeared after treatment; and Type C, patients with seizures that remained unrelieved or appeared after treatment (refractory seizures). Relationships between concentrations of metabolites and seizure types were investigated. RESULTS: In 23 GBMs, seizures were confirmed in 11 patients, including Type B in four and Type C in seven. Patients with epilepsy (Type B or C) showed significantly higher glutamate and N-acetylaspartate values than did non-epilepsy patients (Type A) (p < 0.05). No significant differences in glutamate or N-acetylaspartate levels were seen between Types B and C. Conversely, Type C showed significantly higher concentrations of lactate than did Type B (p = 0.001). Cutoff values of lactate-to-creatine, glutamate-to-creatine, and N-acetylaspartate-to-creatine ratios for refractory seizure were > 1.25, > 1.09, and > 0.88, respectively. CONCLUSIONS: Extracellular concentrations of glutamate, N-acetylaspartate, and lactate in the tumor periphery were significantly elevated in patients with GBM with refractory seizures. Measurement of these metabolites on MRS may predict refractory epilepsy in such patients and could be an indicator for continuing the use of antiepileptic drugs.

A case of radical resection for brain metastases of pancreatic cancer after curative chemotherapy for para-aortic lymph node metastases.

BACKGROUND: The incidence of brain metastasis of pancreatic cancer has been reported to be approximately 0.3%. The blood-brain barrier of the central nervous system restricts the transfer of substances, including chemotherapeutic agents, from the bloodstream. It is hypothesized that brain metastasis may occur despite successful chemotherapy for the primary tumor. Herein, we report a case of brain metastases of pancreatic cancer that occurred after chemotherapy and discuss relevant literature. CASE PRESENTATION: A 64-year-old man underwent distal pancreatectomy with D2 lymph node dissection for resectable pancreatic tail cancer. Invasive ductal carcinoma of pancreas, pT3N2M0 pStageIII (TNM Classification of Malignant Tumors, UICC 8th edition) was diagnosed. S-1 adjuvant chemotherapy was initiated. Three months postoperatively, CA19-9 had increased to 619 U/mL. Additionally, contrast-enhanced computed tomography (CT) and fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT revealed local recurrence in the para-aortic lymph nodes. Chemotherapy was revised to a combined regimen of gemcitabine and nab-paclitaxel. After 4 cycles, tumor markers were normalized. After 5 cycles, recurrence could not be identified on contrast-enhanced CT; therefore, the patient was adjudged to be in complete remission. However, after 29 cycles of chemotherapy, the patient had symptoms of raised intracranial pressure. Magnetic resonance imaging showed two metastatic lesions of 20 mm and 32 mm in the left frontal lobe and cerebellum, respectively. Quasi-emergency resection of the metastatic brain tumors was performed. Pathological examination revealed that the resected specimens originated from primary pancreatic cancer. The patient was discharged on postoperative day 12, without any complications. Postoperatively, a total of 53 Gy of local brain radiation therapy was added. On postoperative day 30, blood carcinoembryonic antigen level had decreased to 5.4 ng/dl and all other tumor markers were negative. Additionally, tumor markers of the cerebrospinal fluid were markedly reduced and the cytology was negative for tumor cells. These results suggested complete resection of the metastatic brain tumors. CONCLUSIONS: Aggressive resection and salvage stereotactic radiotherapy for metastatic brain tumors may lead to complete cure and a good long-term prognosis.

Is Interstitial Chemotherapy with Carmustine (BCNU) Wafers Effective against Local Recurrence of Glioblastoma? A Pharmacokinetic Study by Measurement of BCNU in the Tumor Resection Cavity.

The effectiveness of carmustine (BCNU) wafers on local recurrence of glioblastoma (GBM) remains contentious. We investigated the accumulating high-dose effects of BCNU released from the wafers on the survival of GBM patients by measuring BCNU concentration in the resection cavity of GBM over time. BCNU wafers (Gliadel®) were implanted with an Ommaya device in 15 patients, including 12 patients with GBM. BCNU concentrations in the tumor resection cavity were measured for 30 days postoperatively. The area under the curve (AUC)all was calculated from BCNU concentration curves, and the relationships between AUCall and survival, tumor phenotypes on MRI, and recurrence patterns were analyzed. The BCNU concentration was maximal 1 h postoperatively, rapidly decreased within 24 h, and remained relatively high for 7 days. GBM patients were classified into two groups: early recurrence (ER) and late or no recurrence (LN), using median progression-free survival as the cut-off. AUCall tended to be lower in the ER group than in the LN group, but the difference was not significant. MRI revealed that all patients in the ER group had highly invasive GBMs, whereas all patients in the LN group had less-invasive GBMs. A total of 9 patients experienced recurrence, with 6 local, 2 diffuse, and 1 disseminated patterns. No differences in AUCall were seen between local and non-local recurrence groups. Total BCNU concentrations did not correlate with tumor progression or survival. However, a high concentration of BCNU may have potential to provide some survival benefit for less-invasive type GBM.

Simultaneous combined endoscopic endonasal and transcranial surgery for giant pituitary adenomas: Tips and traps in operative indication and procedure.

OBJECTIVES: This retrospective analysis of patients treated with endoscopic endonasal transsphenoidal surgery (ETSS) alone or simultaneous combined surgery investigated imaging features suitable for surgical methods and pitfalls in simultaneous combined surgery for giant pituitary adenoma. PATIENTS AND METHODS: Ten patients with giant pituitary adenoma treated by ETSS alone or simultaneous combined endoscopic endonasal and transcranial surgery were enrolled. By analyzing tumor imaging features on magnetic resonance imaging (MRI), operative findings and clinical outcomes, we examined types of imaging features suitable for each surgical method. RESULTS: Four patients received ETSS alone and six patients underwent simultaneous combined endonasal and transcranial surgery. Four patients treated by ETSS alone and three patients treated by combined surgery had high resection rates and good outcomes. The remaining three patients with combined surgery achieved partial resection and visual deterioration in one patient. MRI features suitable for ETSS included an enlarged sella, upward tumor extension, and round surface, whereas those for combined surgery included normal/enlarged sella, anterior and/or unilateral tumor extension, and a multilobulated surface. Tumors extending extensively bilaterally or upward and encasing neurovascular structures could not be effectively resected even under combined surgery. CONCLUSION: Both ETSS alone and simultaneous combined endonasal and transcranial surgery showed good results for giant pituitary adenoma when the surgical methods matched suitable imaging features. Tumors with unilateral or anterior extension and a multilobulated surface were maximally resected without neurological deficit by combined surgery, but tumors showing extensive multi-directional extension and full encasement of neurovascular structures were not effectively resected even with combined surgery.

Comparison of the Signal Intensity of Vestibular Schwannoma Between Growing and Nongrowing Tumors.

OBJECTIVES/HYPOTHESIS: To determine the relationship between signal intensity on gadolinium (Gd)-enhanced magnetic resonance images and growth of vestibular schwannomas (VSs). STUDY DESIGN: Cross-sectional study. METHODS: In this cross-sectional study, we retrospectively reviewed the data of 31 patients with VSs who underwent magnetic resonance imaging (MRI). The mean signal intensities within the regions of interest in the tumor, pons, and temporal muscles were measured on Gd-enhanced T1-weighted MRI. Relative intensity ratios were calculated as follows: T/N pons ratio (T/Np) is the tumor signal intensity/pons signal intensity and T/N muscle ratio (T/Nm) is the tumor signal intensity/temporal muscle signal intensity. Volume measurements were used to assess the tumor size. Growth rate was determined by assessing previous imaging studies. Growing VS was defined as a tumor with a growth rate >100 mm3 /year. RESULTS: The mean (standard deviation) T/Np and T/Nm were 1.47 (0.27) and 1.50 (0.24), respectively, in nongrowing tumors and 1.78 (0.17) and 1.90 (0.12), respectively, in growing tumors. The T/Np and T/Nm differed significantly between the two groups (T/Np, P < .001; T/Nm, P < .001). Receiver operating characteristic curve analysis showed that cutoffs of 1.56 and 1.76 for T/Np (93.33% sensitivity, 75.00% specificity) and T/Nm (100.00% sensitivity, 93.75% specificity), respectively, could be used to diagnose a growth rate of >100 mm3 /year. The area under the curve was 0.85 (95% confidence interval, 0.70-1.00) for T/Np and 0.94 (0.82-1.00) for T/Nm. CONCLUSION: Growing VSs show higher signal intensities on Gd-enhanced MRI. Thus, measuring the signal intensity of VS on Gd-enhanced MRI may aid in predicting VS growth. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:198-203, 2022.

Efficacy and safety of nivolumab in Japanese patients with first recurrence of glioblastoma: an open-label, non-comparative study.

BACKGROUND: An open-label, non-comparative study assessed the efficacy and safety of nivolumab in Japanese patients with first recurrence glioblastoma. METHODS: Patients with first recurrence of histologically confirmed World Health Organization Grade IV glioma, after treatment with temozolomide and radiotherapy, received nivolumab 3 mg/kg every 2 weeks until confirmed disease progression (Response Assessment in Neuro-Oncology criteria) or toxicity. Primary endpoint was 1-year overall survival rate assessed by Bayesian approach. The prespecified efficacy criterion was that the Bayesian posterior probability threshold for exceeding the 1-year overall survival of bevacizumab (34.5%) from the Japanese phase 2 study (JO22506) would be 93%. RESULTS: Of the 50 enrolled patients, 44 (88.0%) had recurrent malignant glioma (glioblastoma, gliosarcoma), and of these, 26 (59.1%) had at least one measurable lesion at baseline. The Bayesian posterior mean 1-year overall survival (90% Bayesian credible intervals) with nivolumab was 54.4% (42.27-66.21), and the Bayesian posterior probability of exceeding the threshold of the 1-year overall survival rate of bevacizumab (34.5%) was 99.7%. Median (90% confidence interval) overall and progression-free survival was 13.1 (10.4-17.7) and 1.5 (1.4-1.5) months, respectively. One partial response was observed (objective response rate 1/26 evaluable patients [3.8%]). Treatment-related adverse event rates were 14.0% for Grade 3-4 and 2.0% for Grade 5; most adverse events resolved and were manageable. CONCLUSIONS: The 1-year overall survival with nivolumab monotherapy in Japanese patients with glioblastoma met the prespecified efficacy criterion. The safety profile of nivolumab was consistent with that observed in other tumor types. CLINICAL TRIAL REGISTRATION: JapicCTI-152967.

Chloride intracellular channel protein 2 is secreted and inhibits MMP14 activity, while preventing tumor cell invasion and metastasis.

The abilities to invade surrounding tissues and metastasize to distant organs are the most outstanding features that distinguish malignant from benign tumors. However, the mechanisms preventing the invasion and metastasis of benign tumor cells remain unclear. By using our own rat distant metastasis model, gene expression of cells in primary tumors was compared with that in metastasized tumors. Among many distinct gene expressions, we have focused on chloride intracellular channel protein 2 (CLIC2), an ion channel protein of as-yet unknown function, which was predominantly expressed in the primary tumors. We created CLIC2 overexpressing rat glioma cell line and utilized benign human meningioma cells with naturally high CLIC2 expression. CLIC2 was expressed at higher levels in benign human brain tumors than in their malignant counterparts. Moreover, its high expression was associated with prolonged survival in the rat metastasis and brain tumor models as well as with progression-free survival in patients with brain tumors. CLIC2 was also correlated with the decreased blood vessel permeability likely by increased contents of cell adhesion molecules. We found that CLIC2 was secreted extracellularly, and bound to matrix metalloproteinase (MMP) 14. Furthermore, CLIC2 prevented the localization of MMP14 in the plasma membrane, and inhibited its enzymatic activity. Indeed, overexpressing CLIC2 and recombinant CLIC2 protein effectively suppressed malignant cell invasion, whereas CLIC2 knockdown reversed these effects. Thus, CLIC2 suppress invasion and metastasis of benign tumors at least partly by inhibiting MMP14 activity.

Prediction of Glioma Stemlike Cell Infiltration in the Non-Contrast-Enhancing Area by Quantitative Measurement of Lactate on Magnetic Resonance Spectroscopy in Glioblastoma.

BACKGROUND: We previously reported that glioma stemlike cells (GSCs) exist in the area of the tumor periphery showing no gadolinium enhancement on magnetic resonance imaging. In the present work, we analyzed glucose metabolism to investigate whether lactate could be predictive of tumor invasiveness and of use in detection of the tumor invasion area in glioblastoma multiforme (GBM). METHODS: The expression of lactate dehydrogenase A (LDH-A) and pyruvate dehydrogenase (PDH) was investigated in 20 patients. In GSC lines, LDH-A and PDH expression also was examined in parallel to assessments of mitochondrial respiration. We then investigated the relationship between lactate/creatine ratios in the tumor periphery measured by magnetic resonance spectroscopy, using learning-compression-model algorithms and phenotypes of GBMs. RESULTS: In 20 GBMs, high-invasive GBM expressed LDH-A at significantly higher expression than did low-invasive GBM, whereas low-invasive GBM showed significantly higher expression of PDH than did high-invasive GBM. The highly invasive GSC line showed higher expression of LDH-A and lower expression of PDH compared with low-invasive GSC lines. The highly invasive GSC line also showed the lowest consumption of oxygen and the lowest production of adenosine triphosphate. Lactate levels, as measured by magnetic resonance spectroscopy, showed a significant positive correlation with LDH-A transcript levels, permitting classification of the GBMs into high-invasive and low-invasive phenotypes based on a cutoff value of 0.66 in the lactate/creatine ratio. CONCLUSIONS: In the tumor periphery area of the highly invasive GBM, aerobic glycolysis was the predominant pathway for glucose metabolism, resulting in the accumulation of lactate. The level of lactate may facilitate prediction of the tumor-infiltrating area on GBM.

Hypoxia-induced phenotypic transition from highly invasive to less invasive tumors in glioma stem-like cells: Significance of CD44 and osteopontin as therapeutic targets in glioblastoma.

The poor prognosis of glioblastoma multiforme (GBM) is primarily due to highly invasive glioma stem-like cells (GSCs) in tumors. Upon GBM recurrence, GSCs with highly invasive and highly migratory activities must assume a less-motile state and proliferate to regenerate tumor mass. Elucidating the molecular mechanism underlying this transition from a highly invasive phenotype to a less-invasive, proliferative tumor could facilitate the identification of effective molecular targets for treating GBM. Here, we demonstrate that severe hypoxia (1% O2) upregulates CD44 expression via activation of hypoxia-inducible factor (HIF-1α), inducing GSCs to assume a highly invasive tumor. In contrast, moderate hypoxia (5% O2) upregulates osteopontin expression via activation of HIF-2α. The upregulated osteopontin inhibits CD44-promoted GSC migration and invasion and stimulates GSC proliferation, inducing GSCs to assume a less-invasive, highly proliferative tumor. These data indicate that the GSC phenotype is determined by interaction between CD44 and osteopontin. The expression of both CD44 and osteopontin is regulated by differential hypoxia levels. We found that CD44 knockdown significantly inhibited GSC migration and invasion both in vitro and in vivo. Mouse brain tumors generated from CD44-knockdown GSCs exhibited diminished invasiveness, and the mice survived significantly longer than control mice. In contrast, siRNA-mediated silencing of the osteopontin gene decreased GSC proliferation. These results suggest that interaction between CD44 and osteopontin plays a key role in tumor progression in GBM; inhibition of both CD44 and osteopontin may represent an effective therapeutic approach for suppressing tumor progression, thus resulting in a better prognosis for patients with GBM.

CD44 expression in the tumor periphery predicts the responsiveness to bevacizumab in the treatment of recurrent glioblastoma.

Antiangiogenic therapy with bevacizumab (Bev), a monoclonal antibody targeting vascular endothelial growth factor (VEGF), is a common treatment for recurrent glioblastoma (GBM), but its survival benefit is limited. Resistance to Bev is thought to be a major cause of ineffectiveness on Bev therapy. To optimize Bev therapy, identification of a predictive biomarker for responsiveness to Bev is required. Based on our previous study, we focused on the expression and functions of CD44 and VEGF in the Bev therapy. Here, we analyze a relationship between CD44 expression and responsiveness to Bev and elucidate the role of CD44 in anti-VEGF therapy. CD44 and VEGF expression in the tumor core and periphery of 22 GBMs was examined, and the relationship between expression of these molecules and progression-free time on Bev therapy was analyzed. The degree of CD44 expression in the tumor periphery was evaluated by the ratio of the mRNA expression in the tumor periphery to that in the tumor core (P/C ratio). VEGF expression was evaluated by the amount of the mRNA expression in the tumor periphery. To elucidate the roles of CD44 in the Bev therapy, in vitro and in vivo studies were performed using glioma stem-like cells (GSCs) and a GSC-transplanted mouse xenograft model, respectively. GBMs expressing high P/C ratio of CD44 were much more refractory to Bev than those expressing low P/C ratio of CD44, and the survival time of the former was much shorter than that of the latter. In vitro inhibition of VEGF with siRNA or Bev-activated CD44 expression and increased invasion of GSCs. Bev showed no antitumor effects in mice transplanted with CD44-overexpressing GSCs. The P/C ratio of CD44 expression may become a useful biomarker predicting responsiveness to Bev in GBM. CD44 reduces the antitumor effect of Bev, resulting in much more highly invasive tumors.

Met-PET uptake index for total tumor resection: identification of 11C-methionine uptake index as a goal for total tumor resection including infiltrating tumor cells in glioblastoma.

Glioblastoma multiforme (GBM) is largely due to glioma stem cells (GSCs) that escape from total resection of gadolinium (Gd)-enhanced tumor on MRI. The aim of this study is to identify the imaging requirements for maximum resection of GBM with infiltrating GSCs. We investigated the relationship of tumor imaging volume between MRI and 11C-methionine (Met)-PET and also the relationship between Met uptake index and tumor activity. In ten patients, tumor-to-contralateral normal brain tissue ratio (TNR) was calculated to evaluate metabolic activity of Met uptake areas which were divided into five subareas by the degrees of TNR. In each GBM, tumor tissue was obtained from subareas showing the positive Met uptake. Immunohistochemistry was performed to examine the tumor proliferative activity and existence of GSCs. In all patients, the volume of Met uptake area at TNR ≦ 1.4 was larger than that of the Gd-enhanced area. The Met uptake area at TNR 1.4 beyond the Gd-enhanced tumor was much wider in high invasiveness-type GBMs than in those of low invasiveness type, and survival was much shorter in the former than the latter types. Immunohistochemistry revealed the existence of GSCs in the area showing Met uptake at TNR 1.4 and no Gd enhancement. Areas at TNR > 1.4 included active tumor cells with relatively high Ki-67 labeling index. In addition, it was demonstrated that GSCs could exist beyond the border of Gd-enhanced tumor. Therefore, to obtain maximum resection of GBMs, including infiltrating GSCs, aggressive surgical excision that includes the Met-positive area at TNR 1.4 should be considered.

Intracranial anaplastic solitary fibrous tumor/hemangiopericytoma: immunohistochemical markers for definitive diagnosis.

Intracranial anaplastic hemangiopericytoma (AHPC) is a rare and malignant subset of solitary fibrous tumor/hemangiopericytoma (SFT/HPC) as per the WHO 2016 Classification of Tumors of the Central Nervous System. AHPC portends a poor prognosis and is associated with higher rates of recurrence/metastasis in comparison with SFT/HPC. Accordingly, it is critical to continue to define the clinical course of patients with AHPC and in so doing further refine clinicopathologic/immunohistochemical (IHC) criteria needed for definitive diagnosis. Herein, we describe clinical/histological characteristics of six patients with AHPC. In addition, we reviewed and analyzed the expression of various IHC markers reported within the literature (i.e., a total of 354 intracranial SFT/HPCs and 460 meningiomas). Histologically, tumors from our six patients were characterized by a staghorn-like vascular pattern, mitotic cells, and strong nuclear atypia. Immunohistochemically, all tumors displayed positive nuclear staining for STAT6; other markers, including CD34 and Bcl-2, were expressed only in three patients. Analysis of IHC expression patterns for SFT/HPC and meningioma within the literature revealed that nuclear expression of STAT6 had the highest specificity (100%) for SFT/HPC, followed by ALDH1 (97.2%) and CD34 (93.6%). Of note, SSTR2A (95.2%) and EMA (85%) displayed a high specificity for meningioma. Anaplastic SFT/HPC is a tumor with poor prognosis that is associated with higher rates of recurrence and metastasis in comparison with SFT/HPC. Given that anaplastic SFT/HPC requires more aggressive treatment than meningioma despite of a similar presentation on imaging, it is crucial to be able to distinguish between these tumors.

Tricks and traps of ICG endoscopy for effectively applying endoscopic transsphenoidal surgery to pituitary adenoma.

Differentiating tumor from normal pituitary gland is very important for achieving complete resection without complications in endoscopic endonasal transsphenoidal surgery (ETSS) for pituitary adenoma. To facilitate such surgery, we investigated the utility of indocyanine green (ICG) fluorescence endoscopy as a tool in ETSS. Twenty-four patients with pituitary adenoma were enrolled in the study and underwent ETSS using ICG endoscopy. After administering 12.5 mg of ICG twice an operation with an interval > 30 min, times from ICG administration to appearance of fluorescence on vital structures besides the tumor were measured. ICG endoscopy identified vital structures by the phasic appearance of fluorescent signals emitted at specific consecutive elapsed times. Elapsed times for internal carotid arteries did not differ according to tumor size. Conversely, as tumor size increased, elapsed times for normal pituitary gland were prolonged but those for the tumor were reduced. ICG endoscopy revealed a clear boundary between tumors and normal pituitary gland and enabled confirmation of no more tumor. ICG endoscopy could provide a useful tool for differentiating tumor from normal pituitary gland by evaluating elapsed times to fluorescence in each structure. This method enabled identification of the boundary between tumor and normal pituitary gland under conditions of a low-fluorescence background, resulting in complete tumor resection with ETSS. ICG endoscopy will contribute to improve the resection rate while preserving endocrinological functions in ETSS for pituitary adenoma.

Clinical features and endoscopic findings of granular cell tumor of the sellar region: A case report and review of the literature.

BACKGROUND: Granular cell tumor (GCT) of the sellar region is a rare tumor of the sellar and suprasellar regions that originate from the neurohypophysis. This tumor is very difficult to differentiate from other pituitary neoplasms, such as pituitary adenoma, pituicytoma, and spindle cell oncocytoma. We report a rare case of GCT arising from the posterior pituitary of the sellar region and suggest a useful indicator for accurate diagnosis and pitfalls for surgical procedures. CASE DESCRIPTION: A 42-year-old woman was admitted to our hospital with bitemporal hemianopsia. Neuroimaging showed a large pituitary tumor in the sellar and suprasellar regions with a hypointense part on T2-weighted magnetic resonance imaging, and the enhanced anterior pituitary gland was displaced anteriorly. Laboratory findings showed mild hyperprolactinemia. Subtotal resection of the tumor was achieved using an endoscopic endonasal transsphenoidal approach. Histological findings showed round or polygonal cells with abundant granular eosinophilic cytoplasm staining strongly for thyroid transcription factor 1. The tumor was, therefore, diagnosed as a GCT of the sellar region, belonging to tumors of the posterior pituitary. After surgery, visual impairment and anterior pituitary function were improved. Follow-up neuroimaging after 1 year showed no signs of recurrence. CONCLUSION: GCT of the sellar region is difficult to diagnose on routine neuroimaging. Therefore, accurate diagnosis requires careful identification of clinical signs, magnetic resonance imaging including hypointensity on T2-weighted imaging, and analysis of combined morphological and immunohistochemical studies.

Clinical utility of new three-dimensional model using a zero-echo-time sequence in endoscopic endonasal transsphenoidal surgery.

OBJECTIVES: Recognizing the anatomical orientation surrounding the sellar floor is crucial in endoscopic endonasal transsphenoidal surgery (ETSS). Zero-echo-time (ZTE) sequences were recently suggested for a new bone identification technique on magnetic resonance imaging (MRI). This study aimed to evaluate the clinical usefulness of three-dimensional (3D)-ZTE-based MRI models in providing anatomical guidance for ETSS. PATIENTS AND METHODS: ZTE-based MRI and magnetic resonance angiography (MRA) data from 15 consecutive patients with pituitary tumor treated between September 2018 and May 2019 were used to create 3D-MRI models. From these, the architecture surrounding the sellar floor, particularly anatomical relationships between tumors and internal carotid arteries (ICAs), was visualized to preoperatively plan surgical procedures. In addition, 3D-ZTE-based MRI models were compared to actual surgical views during ETSS to evaluate model applicability. RESULTS: These 3D-ZTE-based MRI models clearly demonstrated the morphology of the sellar floor and matched well with intraoperative views, including pituitary tumor, by successively eliminating sphenoidal structures. The models also permitted determination of the maximum marginal line of the opening of the sellar floor by presenting vital structures such as ICAs and tumors. With such 3D-MRI models, the surgeon could access the intracranial area through the sellar floor more safely, and resect the pituitary tumor maximally without complications. CONCLUSION: Our 3D-MRI models based on ZTE sequences allowed distinct visualization of vital structures and pituitary tumor around the sellar floor. This new method using 3D-ZTE-based MRI models showed low invasiveness for patients and was useful in preoperative planning for ETSS, facilitating maximum tumor resection without complications.