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Cancer stem cells are thought to be closely related to tumor progression and recurrence, making them attractive therapeutic targets. Stem cells of various tissues exist within niches maintaining their stemness. Glioblastoma stem cells ( GSCs) are located at tumor capillaries and the perivascular niche, which are considered to have an important role in maintaining GSCs. There were some extracellular matrices ( ECM) on the perivascular connective tissue, including type 1 collagen. We here evaluated whether type 1 collagen has a potential niche for GSCs. Imunohistochemical staining of type 1 collagen and CD133, one of the GSCs markers, on glioblastoma ( GBM) tissues showed CD133-positive cells were located in immediate proximity to type 1 collagen around tumor vessels. We cultured human GBM cell lines, U87MG and GBM cells obtained from fresh surgical tissues, T472 and T555, with serum-containing medium ( SCM) or serum-free medium with some growth factors ( SFM) and in non-coated (Non-coat) or type 1 collagen-coated plates ( Col). The RNA expression levels of CD133 and Nestin as stem cell markers in each condition were examined. The Col condition not only with SFM but SCM made GBM cells more enhanced in RNA expression of CD133, compared to Non-coat/ SCM. Semi-quantitative measurement of CD133-positive cells by immunocytochemistry showed a statistically significant increase of CD133-positive cells in Col/ SFM. In addition, T472 cell line cultured in the Col/ SFM had capabilities of sphere formation and tumorigenesis. Type 1 collagen was found in the perivascular area and showed a possibility to maintain GSCs. These findings suggest that type 1 collagen could be one important niche component for CD133-positive GSCs and maintain GSCs in adherent culture. [ABSTRACT FROM AUTHOR]

Temozolomide ( TMZ) is an oral alkylating agent which is widely used in the treatment of glioblastoma ( GBM) and is composed of astrocytic and/or oligodendroglial tumors, and the evaluation of O6-methylguanine DNA methyltransferase ( MGMT) expression is important to predict the response to TMZ therapy. In this study, we conducted immunohistochemical analysis of 117 cases of Japanese GBM including 19 cases of GBM with oligodendroglioma component ( GBMO), using a scoring system for quantitative evaluation of staining intensity and proportion of MGMT, and performed survival analysis of these patients. Immunohistochemically, 55 cases (47%) were positive for MGMT with various intensities and proportions (total score ( TS) ≥ 2), while 62 cases (53%) were negative ( TS = 0). The distribution of MGMT expression pattern was not affected by any clinicopathological parameters such as the histological subtype ( GBM vs. GBMO), age and gender. The survival analysis of these patients revealed that the minimal expression of MGMT ( TS ≥ 2) was a significant unfavorable prognostic factor ( P < 0.001) as well as resectability ( P = 0.004). Moreover, multivariate analysis showed that minimal MGMT expression in GBM was the most potent independent predictor for progression free survival ( P < 0.001) and also overall patient survival ( P < 0.001). This is the first report employing the scoring system for both staining intensity and proportion to evaluate immunohistochemical MGMT expression in GBM. In addition, our results emphases the clinicopathological values of the immunohistochemical approach for MGMT expression in glioma patients as a routine laboratory examination. [ABSTRACT FROM AUTHOR]

Oligodendrogliomas are defined by mutation in isocitrate dehydrogenase (NADP(+)) (IDH)1/2 genes and chromosome 1p/19q codeletion. World Health Organisation diagnosis endorses testing for 1p/19q codeletion to distinguish IDH mutant (Mut) oligodendrogliomas from astrocytomas because these gliomas require different treatments and they have different outcomes. Several methods have been used to identify 1p/19q status; however, these techniques are not routinely available and require substantial infrastructure investment. Two recent studies reported reduced immunostaining for trimethylation at lysine 27 on histone H3 (H3K27me3) in IDH Mut 1p/19q codeleted oligodendroglioma. However, the specificity of H3K27me3 immunostaining in this setting is controversial. Therefore, we developed an easy-to-implement immunohistochemical surrogate for IDH Mut glioma subclassification and evaluated a validated adult glioma cohort. We screened 145 adult glioma cases, consisting of 45 IDH Mut and 1p/19q codeleted oligodendrogliomas, 30 IDH Mut astrocytomas, 16 IDH wild-type (Wt) astrocytomas, and 54 IDH Wt glioblastomas (GBMs). We compared immunostaining with DNA sequencing and fluorescent in situ hybridization analysis and assessed differences in H3K27me3 staining between oligodendroglial and astrocytic lineages and between IDH1-R132H and non-canonical (non-R132H) IDH1/2 Mut oligodendroglioma. A loss of H3K27me3 was observed in 36/40 (90%) of IDH1-R132H Mut oligodendroglioma. In contrast, loss of H3K27me3 was never seen in IDH1-R132L or IDH2-mutated 1p/19q codeleted oligodendrogliomas. IDH Mut astrocytoma, IDH Wt astrocytoma and GBM showed preserved nuclear staining in 87%, 94%, and 91% of cases, respectively. A high recursive partitioning model predicted probability score (0.9835) indicated that the loss of H3K27me3 is frequent to IDH1-R132H Mut oligodendroglioma. Our results demonstrate H3K27me3 immunohistochemical evaluation to be a cost-effective and reliable method for defining 1p/19q codeletion along with IDH1-R132H and ATRX immunostaining, even in the absence of 1p/19q testing. [ABSTRACT FROM AUTHOR]

Purpose: 18F-fluoromisonidazole (18F-FMISO) is the most widely used positron emission tomography (PET) tracer for imaging tumor hypoxia. Previous reports suggested that the time from injection to the scan may affect the assessment of 18F-FMISO uptake. Herein, we directly compared the images at 2 h and 4 h after a single injection of 18F-FMISO. Methods: Twenty-three patients with or suspected of having a brain tumor were scanned twice at 2 and 4 h following an intravenous injection of 18F-FMISO. We estimated the mean standardized uptake value (SUV) of the gray matter and white matter and the gray-to-white matter ratio in the background brain tissue from the two scans. We also performed a semi-quantitative analysis using the SUVmax and maximum tumor-to-normal ratio (TNR) for the tumor. Results: At 2 h, the SUVmean of gray matter was significantly higher than that of white matter (median 1.23, interquartile range (IQR) 1.10–1.32 vs. 1.04, IQR 0.95–1.16, p < 0.0001), whereas at 4 h, it significantly decreased to approach that of the white matter (1.10, IQR 1.00–1.23 vs. 1.02, IQR 0.93–1.13, p = NS). The gray-to-white matter ratio thus significantly declined from 1.17 (IQR 1.14–1.19) to 1.09 (IQR 1.07–1.10) (p < 0.0001). All 7 patients with glioblastoma showed significant increases in the SUVmax (2.20, IQR 1.67–3.32 at 2 h vs. 2.65, IQR 1.74–4.41 at 4 h, p = 0.016) and the TNR (1.75, IQR 1.40–2.38 at 2 h vs. 2.34, IQR 1.67–3.60 at 4 h, p = 0.016). Conclusion: In the assessment of hypoxic tumors, 18F-FMISO PET for hypoxia imaging should be obtained at 4 h rather than 2 h after the injection. [ABSTRACT FROM AUTHOR]

Purpose: Metabolic activity and hypoxia are both important factors characterizing tumor aggressiveness. Here, we used F-18 fluoromisonidazole (FMISO) and F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) to define metabolically active hypoxic volume, and investigate its clinical significance in relation to progression free survival (PFS) and overall survival (OS) in glioblastoma patients. Experimental Design: Glioblastoma patients ( n = 32) underwent FMISO PET, FDG PET, and magnetic resonance imaging (MRI) before surgical intervention. FDG and FMISO PET images were coregistered with gadolinium-enhanced T1-weighted MR images. Volume of interest (VOI) of gross tumor volume (GTV) was manually created to enclose the entire gadolinium-positive areas. The FMISO tumor-to-normal region ratio (TNR) and FDG TNR were calculated in a voxel-by-voxel manner. For calculating TNR, standardized uptake value (SUV) was divided by averaged SUV of normal references. Contralateral frontal and parietal cortices were used as the reference region for FDG, whereas the cerebellar cortex was used as the reference region for FMISO. FDG-positive was defined as the FDG TNR ≥1.0, and FMISO-positive was defined as FMISO TNR ≥1.3. Hypoxia volume (HV) was defined as the volume of FMISO-positive and metabolic tumor volume in hypoxia (hMTV) was the volume of FMISO/FDG double-positive. The total lesion glycolysis in hypoxia (hTLG) was hMTV × FDG SUVmean. The extent of resection (EOR) involving cytoreduction surgery was volumetric change based on planimetry methods using MRI. These factors were tested for correlation with patient prognosis. Results: All tumor lesions were FMISO-positive and FDG-positive. Univariate analysis indicated that hMTV, hTLG, and EOR were significantly correlated with PFS ( p = 0.007, p = 0.04, and p = 0.01, respectively) and that hMTV, hTLG, and EOR were also significantly correlated with OS ( p = 0.0028, p = 0.037, and p = 0.014, respectively). In contrast, none of FDG TNR, FMISO TNR, GTV, HV, patients' age, or Karnofsky performance scale (KPS) was significantly correlated with PSF or OS. The hMTV and hTLG were found to be independent factors affecting PFS and OS on multivariate analysis. Conclusions: We introduced hMTV and hTLG using FDG and FMISO PET to define metabolically active hypoxic volume. Univariate and multivariate analyses demonstrated that both hMTV and hTLG are significant predictors for PFS and OS in glioblastoma patients. [ABSTRACT FROM AUTHOR]