Techniques to assess the proliferative potential of brain tumors

Near-Infrared Perylenecarboximide Fluorophores for Live-Cell Super-Resolution Imaging

Organic near-infrared (NIR) photoblinking fluorophores are highly desirable for live-cell super-resolution imaging based on single-molecule localization microscopy (SMLM). Herein we introduce a novel small chromophore, PMIP, through the fusion of perylenecarboximide with 2,2-dimetheylpyrimidine. PMIP exhibits an emission maximum at 732 nm with a high fluorescence quantum yield of 60% in the wavelength range of 700-1000 nm and excellent photoblinking without any additives. With resorcinol-functionalized PMIP (PMIP-OH), NIR SMLM imaging of lysosomes is demonstrated for the first time in living mammalian cells under physiological conditions. Moreover, metabolically labeled nascent DNA is site-specifically detected using azido-functionalized PMIP (PMIP-N3) via click chemistry, thereby enabling the super-resolution imaging of nascent DNA in phosphate-buffered saline with a 9-fold improvement in spatial resolution. These results indicate the potential of PMIP-based NIR blinking fluorophores for biological applications of SMLM.

Prognostic Factors Independently Associated With Improved Progression-Free Survival After Surgical Resection in Patients With Spinal Cord Astrocytomas: An Institutional Case Series

BACKGROUND

Spinal astrocytomas are rare tumors in which the extent of resection and adjuvant therapy remain controversial. A number of new molecular markers are used, but their utility in spinal cord tumors remains unclear.

OBJECTIVE

To determine prognostic indicators of progression-free survival (PFS) in patients with spinal astrocytomas.

METHODS

A retrospective chart review identified all patients managed at a single institution for spinal cord astrocytomas between 1999 and 2019. Data collected included baseline demographics, presenting signs and symptoms, tumor size, operative outcomes, and adjuvant treatment. Pathological data including histopathological grade, proliferative index, and molecular profile were collected. Duration of follow-up, presence of tumor progression, and status at last follow-up were documented. Univariate and multivariate analyses were performed to determine predictors of PFS.

RESULTS

Seventy-five patients were included in our study with an average age of 42 ± 17 yr. The thoracic spine was the most commonly involved spinal segment (50 patients), and most patients had grade I or grade II tumors (50 patients). On univariate analysis, gross total resection (GTR), lower tumor grade, and low Ki-67 index were associated with lower tumor progression (P-values .01, .04, and .00013, respectively). On multivariate Cox regression analysis, GTR, adjuvant chemotherapy and radiation, and low Ki-67 index were independent predictors of PFS (P-values .009, .011, and .031, respectively).

CONCLUSION

In spinal astrocytomas, GTR, adjuvant therapy, and low Ki-67 are independently associated with improved PFS. These data may help guide management of these tumors and provide important prognosticating information.

Minimally invasive surgery of the anterior skull base: transorbital approaches

Minimally invasive approaches are becoming increasingly popular to access the anterior skull base. With interdisciplinary cooperation, in particular endonasal endoscopic approaches have seen an impressive expansion of indications over the past decades. The more recently described transorbital approaches represent minimally invasive alternatives with a differing spectrum of access corridors. The purpose of the present paper is to discuss transorbital approaches to the anterior skull base in the light of the current literature. The transorbital approaches allow excellent exposure of areas that are difficult to reach like the anterior and posterior wall of the frontal sinus; working angles may be more favorable and the paranasal sinus system can be preserved while exposing the skull base. Because of their minimal morbidity and the cosmetically excellent results, the transorbital approaches represent an important addition to established endonasal endoscopic and open approaches to the anterior skull base. Their execution requires an interdisciplinary team approach.

Novel Strategies for Breast Cancer Imaging: New Imaging Agents to Guide Treatment

The development of molecular therapies for cancer treatment has created a need to image biochemical and molecular processes to appropriately select tumors that express the drug target, thereby predicting a positive response to therapy. Biomarker-driven molecular imaging is complementary to pathologic analysis and offers a more direct measure of drug efficacy and treatment response, potentially providing early insight into therapeutic futility and allowing response-adapted treatment strategies. Imaging also allows a unique means of assessing the heterogeneity of both intra- and intertumoral targets as well as a mixed response to therapy; this information is important in the setting of metastatic disease. Here we review the development of novel molecular imaging probes and combinations of probes to guide therapy for two new targets and associated therapeutic agents: cyclin-dependent kinase inhibitors and poly(adenosine diphosphate-ribose) polymerase inhibitors.

PET Radiotracers for Imaging the Proliferative Status of Solid Tumors

Two different strategies have been developed for imaging the proliferative status of solid tumors with the functional imaging technique, Positron Emission Tomography (PET). The first strategy uses carbon-11 labeled thymidine and/or, more recently, fluorine-18 labeled thymidine analogs. These agents are a substrate for the enzyme thymidine kinase-1 (TK-1) and provide a pulse label of the number of cells in S phase. The second method for imaging the proliferative status of a tumor uses radiolabeled ligands that bind to the sigma-2 receptor which has a 10-fold higher density in proliferating (P) tumor cells versus quiescent (Q) tumor cells. This article compares and contrasts the two different strategies for imaging the proliferative status of solid tumors, and describes the strengths and weaknesses of each approach.

[A correlation between diffusion kurtosis imaging and the proliferative activity of brain glioma]

The aim of the study was to assess the capabilities of diffusion kurtosis imaging (DKI) in diagnosis of the glioma proliferative activity and to evaluate a relationship between the glioma proliferative activity index and diffusion parameters of the contralateral normal appearing white matter (CNAWM).

MATERIAL AND METHODS

The study included 47 patients with newly diagnosed brain gliomas (23 low grade, 13 grade III, and 11 grade IV gliomas). We determined a relationship between absolute and normalized parameters of the diffusion tensor (mean (MD), axial (AD), and radial (RD) diffusivities; fractional (FA) and relative (RA) anisotropies) and diffusion kurtosis (mean (MK), axial (AK), and radial (RK) kurtosis; kurtosis anisotropy (KA)) and the proliferative activity index in the most malignant glioma parts (p<0.05). We also established a relationship between the tensor and kurtosis parameters of CNAWM and the glioma proliferative activity index (p<0.05).

RESULTS

The correlation between all the absolute and normalized diffusion parameters and the glioma proliferative activity index, except absolute and normalized FA and RA values, was found to be statistically significant (p<0.05). Kurtosis (MK, AK, and RK) and anisotropy (KA, FA, RA) values increased, and diffusivity (MD, AD, RD) values decreased as the glioma proliferative activity index increased. A strong correlation between the proliferative activity index and absolute RK (r=0,71; p=0.000001) and normalized values of MK (r=0.8; p=0.000001), AK (r=0.71; p=0.000001), RK (r=0.81; p=0.000001), and RD (r=-0.71; p=0.000001) was found. A weak, but statistically significant correlation between the glioma proliferative activity index and diffusion values RK (r=-0.36; p=0.014), KA (r=-0.39; p=0.007), RD (r=0.35; p=0.017), FA (r=-0.42; p=0.003), and RA (r=-0.41; p=0.004) of CNAWM was found.

CONCLUSION

DKI has good capabilities to detect immunohistochemical changes in gliomas. DKI demonstrated a high sensitivity in detection of microstructural changes in the contralateral normal appearing white matter in patients with brain gliomas.

Phosphorylated 5-ethynyl-2'-deoxyuridine for advanced DNA labeling

The representative DNA-labeling agent 5-ethynyl-2'-deoxyuridine (EdU) was chemically modified to improve its function. Chemical monophosphorylation was expected to enhance the efficiency of the substrate in DNA polymerization by circumventing the enzymatic monophosphorylation step that consumes energy. In addition, to enhance cell permeability, the phosphates were protected with bis-pivaloyloxymethyl that is stable in buffer and plasma, and degradable inside various cell types. The phosphorylated EdU (PEdU) was less toxic than EdU, and had the same or a slightly higher DNA-labeling ability in vitro. PEdU was also successfully applied to DNA labeling in vivo. In conclusion, PEdU can be used as a less toxic DNA-labeling agent for studies that require long-term cell survival or very sensitive cell lines.

The emerging role of tumor-suppressive microRNA-218 in targeting glioblastoma stemness

Glioblastoma multiforme (GBM) is by far the most common and most aggressive malignant primary tumor in humans and has poor outcomes despite many advances in treatment using combinations of surgery, radiotherapy and chemotherapy. Recent studies demonstrate that GBM contains a subpopulation of cancer cells with stem cell characteristics, including self-renewal and multipotentiality, and that these cancer stem cells contribute to disease progression. MicroRNAs (miRNAs) are small non-coding regulatory RNA molecules that regulate a variety of cellular processes, including stem cell maintenance. An accumulating body of evidence shows that miR-218 may act as a tumor suppressor by inhibiting glioblastoma invasion, migration, proliferation and stemness through its different targets, indicating the great potential and relevance of miR-218 as a novel class of therapeutic target in glioblastoma.

Correlation of diffusion tensor, dynamic susceptibility contrast MRI and (99m)Tc-Tetrofosmin brain SPECT with tumour grade and Ki-67 immunohistochemistry in glioma

OBJECTIVE

Assessment of the grade and type of glioma is of paramount importance for prognosis. Tumour proliferative potentials may provide additional information on the behaviour of the tumour, its response to treatment and prognosis. The purpose of this study was to investigate the correlation between diffusion tensor imaging (DTI), dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) and (99m)Tc-Tetrofosmin brain single-photon emission computed tomography (SPECT), and the tumour grade and Ki-67 labelling index in newly diagnosed gliomas.

METHODS

Study was made of patients with suspected glioma on brain MRI between December 2010 and January 2012, by DTI, DSC MRI and (99m)Tc-Tetrofosmin brain SPECT. The proliferative activity of each tumour was measured by deriving the Ki-67 proliferation index from immunohistochemical staining of tumour specimens.

RESULTS

Glioma was newly diagnosed in 25 patients (17 men, 8 women, aged 19-79 years, median 55 years). The Ki-67 index ranged from 1% to 80% (mean 19.4%). On evaluation of the relationship between the (99m)Tc-Tetrofosmin tumour uptake by gliomas was found to be significantly correlated with cellular proliferation (rho=0.924, p<0.0001). Regarding DTI, significant negative correlation was demonstrated between the apparent diffusion coefficient (ADC) ratio and the Ki-67 index (rho=-0.545, p=0.0087). Significant correlation was also observed between the fractional anisotropy (FA) ratio and the Ki-67 index (rho=0.489, p=0.02). Strong correlation was found between relative cerebral blood volume (rCBV) and Ki-67 index (rho=0.853, p<0.0001), and between the (99m)Tc-Tetrofosmin lesion-to-normal (L/N) uptake ratio and rCBV (rho=0.808, p ≤ 0.0001). Significant negative correlation was demonstrated between the (99m)Tc-Tetrofosmin L/N ratio and ADC ratio (rho=-0.513, p=0.014). These imaging techniques were able to distinguish between low-grade and high-grade gliomas.

CONCLUSIONS

Findings on DSC MRI and brain SPECT with (99m)Tc-Tetrofosmin metrics were more closely correlated with glioma cellular proliferation.

The relationship between Cho/NAA and glioma metabolism: implementation for margin delineation of cerebral gliomas

Background

The marginal delineation of gliomas cannot be defined by conventional imaging due to their infiltrative growth pattern. Here we investigate the relationship between changes in glioma metabolism by proton magnetic resonance spectroscopic imaging (¹H-MRSI) and histopathological findings in order to determine an optimal threshold value of choline/N-acetyl-aspartate (Cho/NAA) that can be used to define the extent of glioma spread.

Method

Eighteen patients with different grades of glioma were examined using ¹H-MRSI. Needle biopsies were performed under the guidance of neuronavigation prior to craniotomy. Intraoperative magnetic resonance imaging (MRI) was performed to evaluate the accuracy of sampling. Haematoxylin and eosin, and immunohistochemical staining with IDH1, MIB-1, p53, CD34 and glial fibrillary acidic protein (GFAP) antibodies were performed on all samples. Logistic regression analysis was used to determine the relationship between Cho/NAA and MIB-1, p53, CD34, and the degree of tumour infiltration. The clinical threshold ratio distinguishing tumour tissue in high-grade (grades III and IV) glioma (HGG) and low-grade (grade II) glioma (LGG) was calculated.

Results

In HGG, higher Cho/NAA ratios were associated with a greater probability of higher MIB-1 counts, stronger CD34 expression, and tumour infiltration. Ratio threshold values of 0.5, 1.0, 1.5 and 2.0 appeared to predict the specimens containing the tumour with respective probabilities of 0.38, 0.60, 0.79, 0.90 in HGG and 0.16, 0.39, 0.67, 0.87 in LGG.

Conclusions

HGG and LGG exhibit different spectroscopic patterns. Using ¹H-MRSI to guide the extent of resection has the potential to improve the clinical outcome of glioma surgery.

Pineal parenchymal tumor of intermediate differentiation with marked elevation of MIB-1 labeling index

We report a case of pineal parenchymal tumor (PPT) in an 11-year-old girl. Brain magnetic resonance imaging (MRI) revealed a large tumor (48 mm) located in the pineal region with heterogeneous enhancement after gadolinium administration. The patient underwent tumor removal with craniotomy; only partial tumor resection could be performed because of massive intratumoral bleeding. Histopathological examination of the tumor showed lobular proliferation of round cells with moderate atypia. Cellularity varied by area, and focal Homer Wright rosettes were identified. Examination of tumor cells revealed a few mitoses (two mitotic figures per 10 high-powered fields), and immunohistochemical staining revealed positivity for synaptophysin, slight positivity for neurofilament protein (NFP) with antibody clone 2F11, and strong positivity for NFP with clone NF-M+H. The pathological diagnosis was pineal parenchymal tumor of intermediate differentiation grade II according to World Health Organization criteria despite a high (22%) MIB-1 labeling index (LI). The patient had a favorable clinical course after an intensified chemotherapy regimen designed for pineoblastoma and radiotherapy administered to the entire neuraxis, followed by stereotactic radiotherapy. In conclusion, MIB-1 LI could be a useful tool for deciding therapeutic strategies for PPT treatment when there is a discrepancy between clinical findings and pathological grading.

Krüppel-like factor 8 (KLF8) is expressed in gliomas of different WHO grades and is essential for tumor cell proliferation

Krüppel-like factor 8 (KLF8) has only recently been identified to be involved in tumor cell proliferation and invasion of several different tumor entities like renal cell carcinoma, hepatocellular carcinoma and breast cancer. In the present study, we show for the first time the expression of KLF8 in gliomas of different WHO grades and its functional impact on glioma cell proliferation. In order to get information about KLF8-mRNA regulation qPCR was performed and did not reveal any significant difference in samples (n = 10 each) of non-neoplastic brain (NNB), low-grade gliomas (LGG, WHO°II) and glioblastomas (GBM, WHO°IV). Immunohistochemistry of tissue samples (n = 7 LGG, 11 AA and 12 GBM) did not show any significant difference in the fraction of KLF8-immunopositive cells of all analyzed cells in LGG (87%), AA (80%) or GBM (89%). Tissue samples from cerebral breast cancer metastasis, meningiomas but also non-neoplastic brain demonstrated comparable relative cell counts as well. Moreover, there was no correlation between KLF8 expression and the expression pattern of the assumed proliferation marker Ki67, which showed high variability between different tumor grade (9% (LGG), 6% (AA) and 15% (GBM) of Ki67-immunopositive cells). Densitometric analysis of Western blotting revealed that the relative amount of KLF8-protein did also not differ between the highly aggressive and proliferative GBM (1.05) compared to LGG (0.93; p<0.05, studens t-test). As demonstrated for some other non-glial cancer entities, KLF8-knockdown by shRNA in U87-MG cells confirmed its functional relevance, leading to an almost complete loss of tumor cell proliferation. Selective blocking of KLF8 might represent a novel anti-proliferative treatment strategy for malignant gliomas. Yet, its simultaneous expression in non-proliferating tissues could hamper this approach.

Minichromosome maintenance (MCM) and AgNOR proteins expression in desmoid tumours: a tissue microarray analysis

In the present study, nuclear proliferative proteins: MCM2, MCM5, MCM7, Ki-67 and AgNORs expression was assessed in paraffin sections from sporadic desmoid tumours using a tissue microarray (TMA)-based immuno- and histochemistry, respectively. Nuclear expression of MCM7, where the percentage of positive cells was 0.87% (± 1.64) (range 0-5%), was found in 4/20 (20.0%) cases. In 32/32 (100%) of the examined desmoid cases no expression of nuclear proteins MCM2 and MCM5 was detected. Nuclear expression of Ki-67 was observed in 4/21 (19%) cases. Paraffin sections from 30 cases of desmoid tumours were silver-stained to visualize AgNORs. The following AgNOR parameters were calculated: mean AgNOR number per nucleus (N), mean AgNOR area per nucleus, mean AgNOR dot area per nucleus (A), and mean AgNOR content (C = N/A). In the investigated group the mean values of AgNOR parameters were the following number: 4.34 (± 0.11); area: 0.74 μm2 (± 0.19); dot area: 0.18 m2 (± 0.01), and AgNOR content: 23.73 (± 1.85). The mean AgNOR number per nucleus and mean AgNOR content in desmoid tumours were statistically significantly higher as compared to the controls (tonsil tissue) (p<0.001). This study observed low level of MCM7 and Ki-67 and lack of MCM2, MCM5 proteins expression which may explain commonly known low mitotic activity of desmoid tumour cells. The morphology of dots related to AgNORs (number, area) and their morphometric parameters point to elevated transcriptional activity of desmoid cells.

Prognostic significance of angiogenesis in relation to Ki-67, p-53, p-27, and bcl-2 expression in embryonal tumors

AIM

We investigated the angiogenesis and density of newly formed blood vessels in embryonal tumors in relation to Ki-67, bcl-2, p-53 and p-27 expression.

METHODS

Forty-five children with embryonal tumors were enrolled in the study. Forty patients had a medulloblastoma (MB) and 5 patients had atypical teratoid/rhabdoid tumor (AT/RT).

RESULTS

In MB, the 5-year PFS and OS was 62.5 and 70%, respectively. Patients with Ki-67 index >50%, bcl-2 index >30% and higher density of new vessels were associated with worse survival. In the multivariate analysis, Ki-67 index was identified as a factor with independent prognostic power. In AT/RTs, high density of new vessels (>25 HRF) was observed in 3 patients and Ki-67 index over 25% was found in 4 patients.

CONCLUSION

Increased Ki-67, bcl-2 and density of new vessels are of prognostic value for the disease outcome in MB.

Demonstration of disturbed activity of the lateral amygdaloid nucleus projection neurons in depressed patients by the AgNOR staining method

BACKGROUND

The aim to find a morphological biomarker of disturbed activity of the lateral amygdaloid nucleus in depression was approached by a karyometric analysis of projection neurons.

METHODS

The study was performed on paraffin-embedded brains from 19 depressed patients from both the major depressive disorder (MDD) and the bipolar disorder (BD) diagnostic groups, including 10 suicides, and 24 matched controls. The karyometric parameters of the lateral amygdaloid nucleus (La) projection neurons bilaterally were evaluated by the argyrophilic nucleolar organiser region (AgNOR) silver staining method.

RESULTS

An increased AgNOR number was found in the right La in suicides compared to controls. The intra-group comparisons between the hemispheres suggest a disturbed amygdaloid lateralisation in depressed patients. The effects were independent from psychotropic medication. There was a strong positive correlation between the nuclear area in La projection neurons and prefrontal limbic areas pyramidal neurons in the right hemisphere specific for suicide and MDD.

LIMITATIONS

A major limitation of this study is the relatively small number of cases. A further limitation is given by the lack of data on drug exposure across the entire lifespan.

CONCLUSION

The results suggest that depressed patients from both the MDD and BD diagnostic groups exhibit an increased activity of the La output neurons specific for suicidal patients. The distinctness of the diagnostic groups of mood disorders was accentuated in the correlation analysis. This putative hyperactivity was specific for the right hemisphere and psychotropic medication most likely did not counteract it.

Short-term sleep deprivation may alter the dynamics of hippocampal cell proliferation in adult rats

Long-term (>48 h) sleep deprivation (SD) reduces adult rat hippocampal cell proliferation and neurogenesis, yet reported effects of short-term (<24 h) SD are inconsistent. We systematically assessed the effects of various durations of SD on adult rat hippocampal cell proliferation. Rats were sleep-deprived for 6, 12, 24, 36 or 48 h and injected with 5-bromo-2'-deoxyuridine (BrdU) 2 h before the end of SD. Immunolabeling for BrdU in the hippocampal subgranular zone increased significantly after 12 h SD but tended to decrease after 48 h SD relative to respective Controls. Surprisingly, SD did not alter immunolabeling for Ki67 protein (Ki67) or proliferating cell nuclear antigen (PCNA), two intrinsic cell proliferation markers. SD did not affect BrdU or Ki67 labeling in the subventricular zone, nor did it affect serum corticosterone levels. Because immunoreactivity for Ki67 and PCNA can identify cells in all phases of the ∼25 h cell cycle in adult rat hippocampus, whereas BrdU labels only cells in S-phase (∼9.5 h), this discrepancy suggests that 12 h SD might have affected cell cycle dynamics. A separate group of rats were injected with BrdU 10 h before the end of 12 h SD, which would allow some time for labeled cells to divide; the results were consistent with an acceleration of the timing of hippocampal progenitor cell division during 12 h SD. These results suggest that short-term (12 h) SD transiently produces more hippocampal progenitor cells via cell cycle acceleration, and confirm the importance of using multiple cell cycle markers or BrdU injection paradigms to assess potential changes in cell proliferation.

Assessment of glioma proliferation using imaging modalities

The assessment of glioma proliferation rate is important to predict tumor behavior, response to therapy and prognosis. Various methods, largely involving immunohistological markers in tissue samples, have been proposed to this aim; however, they all require tissue removal through a biopsy or during a surgical procedure. Consequently, non-invasive imaging modalities that could reliably assess the proliferative potential of intracranial space-occupying lesions in vivo would be of obvious significance. In the present study we review the contribution of MRI, positron emission tomography and single-photon emission CT for the assessment of the proliferative potential of gliomas.

Gliomagenesis and the use of neural stem cells in brain tumor treatment

The role of neural stem cells (NSCs) in both the physiological and pathological processes in the brain has been refined through recent studies within the neuro-oncological field. Alterations in NSC regulatory mechanisms may be fundamental for the development and progression of malignant gliomas. A subpopulation of cells within the tumor known as brain tumor stem cells (BTSCs) have been shown to share key properties with NSCs. The BTSC hypothesis has significantly contributed to a potential understanding as to why brain tumors hold such dismal prognosis. On the other hand, the normal NSCs possess the capacity to migrate extensively towards the tumor bulk as well as to lingering neoplastic regions of the brain. The tropism of NSCs towards brain tumors may provide an additional tool for the treatment of brain cancer. The creation of potential therapies through the use of NSCs has been studied and includes the delivery of gene products to specific locations of the central nervous system selectively targeting malignant brain tumor cells and maximizing the efficiency of their delivery. Here, the proposed mechanisms of how brain tumors emerge, the molecular pathways interrupted in NSC pathogenesis and the most recent preclinical results in the use of NSCs for glioma treatment are reviewed.

Glioma diagnosis: immunohistochemistry and beyond

Clinicians and pathologists have been inundated by published reports of new and potentially interesting diagnostic, prognostic, and putative predictive "markers" whose expression (or loss) holds great promise for more enlightened diagnoses and ultimately better patient care. Although an understanding of therapeutically (and possibly diagnostically) relevant pathways of glioblastoma may be at hand, significant challenges remain. Many immunohistochemical and genetic tests have proven to be useful in the stratification of clinical trials, whereas the utility of many others for the day-to-day practice of pathology awaits further study and validation. The importance of critical literature review and careful consideration of practical issues such as test standardization, compliance, cost-effectiveness, and availability must all be considered before implementing any new diagnostic test. This review will focus on the role of immunohistochemistry in the routine diagnosis of astrocytic and oligodendrocytic tumors and in assisting with the diagnosis of some less common gliomas that have ependymal-like features. It will conclude with a summary of molecular and genetic studies, which not only hold great promise for improved diagnosis, but also reveal prognostic information on disease outcome and predict response to treatment or provide biologic targets for novel therapies.

Expression of PROX1 Is a common feature of high-grade malignant astrocytic gliomas

PROX1 is a prospero-related transcription factor that plays a critical role in the development of various organs including the mammalian lymphatic and central nervous systems; it controls cell proliferation and differentiation through different transcription pathwaysand has both oncogenic and tumor-suppressive functions. We investigated PROX1 expression patterns in 56 human astrocytic gliomas of different grades using immunohistochemistry. An average of 79% of cells in World Health Organization Grade IV (glioblastoma, n = 15) and 57% of cells in World Health Organization Grade III (anaplastic astrocytoma, n = 13) were strongly PROX1 positive; low-grade diffuse astrocytomas (Grade II, n = 13) had 21% of cells that were strongly positive; Grade I tumors (n = 15) had 1.5%; and non-neoplastic brain tissue (n = 15) had 3.7% of cells that were PROX1 positive. Double immunolabeling showed that PROX1+ cells in glioblastomas frequently coexpressed early neuronal proteins MAP2 and betaIII-tubulin but not the mature neuronal marker protein NeuN. Analyses of coexpression with proliferation markers suggest that PROX1+ cells have a marginally lower rate of proliferation than other tumor cells but are still mitotically active. We conclude that PROX1 may constitute a useful tool for the diagnosis and grading ofastrocytic gliomas and for distinguishing Grade III and Grade IV tumors from Grade I and Grade II tumors.

Reaching for the other side: generating sequence-dependent interstrand cross-links with 5-bromodeoxyuridine and gamma-rays

Interstrand cross-links impede critical cellular processes such as transcription and replication and are thus considered to be one of the most toxic types of DNA damage. Although several studies now point to the existence of gamma-radiation-induced cross-links in cellular DNA, little is known about the characteristics required for their creation. Recently, we reported the formation of interstrand cross-links that were specific for mismatched nucleotides within 5-bromo-2'-deoxyuridine-substituted DNA. Given the structural specificity for interstrand cross-link formation, it is likely that open or mismatched regions of DNA in cells may be particularly favorable for cross-link production. Herein, we investigated the effect of the local DNA sequence on the formation of interstrand cross-links, using 5-bromo-2'-deoxyuridine to generate radicals in a mismatched region of DNA. We investigated a total of 12 variations of bases in the mismatched region. The oligonucleotides were irradiated with gamma-rays, and interstrand cross-link formation was analyzed by denaturing gel electrophoresis. We found that the efficiency of cross-link formation was highly dependent on the nature of mismatched bases and, on the basis of electrophoretic mobility, observed several distinctive cross-link structures with specific DNA sequences. This study provides new insights into the reactivity of mismatched DNA and the mechanisms leading to interstrand cross-link formation. The potential application of 5-bromo-2'-deoxyuridine-induced interstrand cross-links to the field of DNA repair is discussed.

Imaging correlates of differential expression of indoleamine 2,3-dioxygenase in human brain tumors

BACKGROUND

Tryptophan catabolism via the kynurenine pathway, mediated by indoleamine 2,3-dioxygenase (IDO), is a mechanism involved in tumor immunoresistance. Positron emission tomography (PET) with alpha-[(11)C]methyl-L-tryptophan (AMT) can quantify transport and metabolism of tryptophan in infiltrating gliomas and glioneuronal tumors. In the present study, we investigated whether increased tryptophan metabolism in brain tumors measured by PET is related to expression of IDO in resected brain tumor specimens.

METHODS

IDO expression was assessed by immunohistochemistry in tumor specimens from 15 patients (median age, 34 years) with primary brain tumors who underwent AMT PET scanning before tumor resection. Patterns of IDO expression were compared between low- and high-grade tumors and also to AMT transport and metabolism measured on PET.

RESULTS

IDO immunoreactivity was seen in tumor cells in six of seven low-grade tumors but only in one of eight high-grade tumors (p = 0.01); three of these latter tumors showed endothelial staining only. Low-grade neoplasms showed lower transport rate (p < 0.01) but higher metabolic rate (p = 0.003) for AMT as compared to high-grade tumors. AMT metabolic rates were lower in tumor samples with no or minimal IDO expression as compared to those with widespread IDO staining (p = 0.017).

CONCLUSION

Low-grade tumors show widespread IDO expression, while IDO expression in high-grade brain tumors can be absent or largely confined to endothelial cells. AMT PET can be useful to identify brain tumors with different profiles of IDO expression, thus providing a useful imaging marker for emerging treatments targeting tumor IDO activity.

Cell proliferation in the presence of telomerase

Background

Telomerase, which is active early in development and later in stem and germline cells, is also active in the majority of human cancers. One of the known functions of telomerase is to extend the ends of linear chromosomes, countering their gradual shortening at each cell division due to the end replication problem and postreplication processing. Telomerase concentration levels vary between different cell types as well as between different tumors. In addition variable telomerase concentrations will exist in different cells in the same tumor when telomerase inhibitors are used, because of limitations of drug delivery in tissue. Telomerase extends short telomeres more frequently than long telomeres and the relation between the extension frequency and the telomere length is nonlinear.

Methodolgy/Principal Findings

Here, the biological data of the nonlinear telomerase-telomere dynamics is incorporated in a mathematical theory to relate the proliferative potential of a cell to the telomerase concentration in that cell. The main result of the paper is that the proliferative capacity of a cell grows exponentially with the telomerase concentration.

Conclusions/Significance

The theory presented here suggests that long term telomerase inhibition in every cancer progenitor or cancer stem cell is needed for successful telomere targeted cancer treatment. This theory also can be used to plan and asses the results of clinical trials targeting telomerase.

Cell proliferation index predicts relapse of brain metastases in non-irradiated patients

BACKGROUND

Brain metastasis is a common complication and a major cause of morbidity and mortality in human malignancies. We investigated whether the proliferating cell index of surgically treated single brain metastasis would predict the relapse at a location remote from the initial resection site within 2 months of the excision in patients with uncontrolled systemic disease and not subjected to adjuvant whole brain radio-therapy.

MATERIALS AND METHODS

Tissue biopsies derived from 25 patients with brain metastases specifically selected to be a single totally resected lesion and not treated subsequently by radiotherapy to the whole brain were stained by immunohistochemistry for the marker CDC47 and the proliferation index was calculated. The index was then analysed with respect to clinical parameters, including the incidence of brain relapse within 2 months of the first resection, the timing of diagnosis of brain metastasis as compared to the primary cancer diagnosis, and the perifocal brain oedema.

RESULTS

Statistical evaluation of the indexes in the patients with brain metastases relapsing within 2 months after the first craniotomy (n = 13) revealed significantly higher values as compared to the patients with lesions which had not relapsed or which had relapsed more than 2 months after first craniotomy (n = 12). The synchronous brain metastasis (that is, those occurring before or within 2 months of the primary cancer diagnosis) had a significantly higher proliferation index than the metachronous lesions (those occurring more than 2 months after primary cancer diagnosis).

CONCLUSIONS

The synchronous brain metastasis relapses within 2 months of primary resection and have a significantly higher proliferation index than the metachronous lesions which did not recur within 2 months. These results indicate that the estimation of the proliferation index of metastatic brain tumours may be helpful in predicting the course of disease progression.

Expression of cell adhesion proteins and proteins related to angiogenesis and fatty acid metabolism in benign, atypical, and anaplastic meningiomas

Most meningiomas are benign tumours of arachnoidal origin, although a small number have high proliferative rates and invasive properties which complicate complete surgical resection and are associated with increased recurrence rates. Few prognostic indicators exist for meningiomas and further research is necessary to identify factors that influence tumour invasion, oedema and recurrence. Paraffin sections from 25 intracranial meningiomas were analysed for expression of the proteins vascular endothelial growth factor (VEGF), VEGF receptors Flt1 and Flk1, E-cadherin, metalloproteinases 2 and 9 (MMP2, MMP9), CD44, receptor for hyaluronic acid-mediated motility (RHAMM), hyaluronic acid (HA), CD45, cyclooxygenase 2 (COX2), brain fatty acid binding protein (BFABP), Ki67, and proliferating cell nuclear antigen (PCNA). Correlations among protein expression were found for several markers of proliferation (Ki67, PCNA, MI) and microvessel density (MVD). COX2 expression increased with increasing with tumour grade and correlated with Ki67, PCNA, MI, MVD, and BFABP. BFABP expression also correlated with Ki67 and PCNA expression. Relationships were also identified among angiogenic factors (VEGF, Flt1, Flk1) and proliferation markers. Oedema was found to correlate with MMP9 expression and MMP9 also correlated with proliferation markers. No correlations were found for MMP2, E-cadherin, or CD44 in meningiomas. In conclusion Ki67, PCNA, MI, MVD, BFABP, and COX2 were significantly correlated with meningioma tumour grade and with each other. These findings, by correlating both intracellular fatty acid transport and eicosanoid metabolism with tumour proliferation, as determined by Ki67 labelling and mitotic index, suggest fatty acids are involved in the progression of meningiomas.

Intradural extracerebral choristoma. Case report and review of the literature

BACKGROUND

Intracranial extracerebral neuroglial choristoma is a very rare entity. A cleft palate or a nasopharyngeal teratoma has been described as accompanying choristoma, but there are no observations of both anomalies being simultaneously present and combined.

METHODS

An 8-month-old girl presented with seizures, without evidence of any other neurological abnormalities. Brain magnetic resonance imaging demonstrated a 2.0-cm-sized, round-shaped mass in the frontal midline. The T(1)- and T(2)-weighted images showed a well-circumscribed iso-signal intensity lesion with no gadolinium enhancement.

RESULTS

Surgical exploration revealed a yellowish tumor mass with whitish soft tissue material within the tumor, adherence to the surrounding blood vessels, and therefore subtotal removal was performed. Pathologic examination was neuroglial choristoma with 1.5% of MIB-1 labeling index. The patient also had a cleft palate with a pinkish palatal mass and underwent repair of the cleft palate, and excision of mass that was a mature cystic teratoma on pathologic examination. Follow-up at 18 months later showed that there was no evidence of tumor regrowth or neurological deficit, and the neurological development was normal.

CONCLUSION

The authors described a rare case of intracranial extracerebral neuroglial choristoma accompanied by both nasopharyngeal teratoma and cleft palate and suggested its benign nature from the low MIB-1 labeling index.

Review of meningioma histopathology

✓The histological appearance of a meningioma is an important predictor of tumor behavior and is frequently a factor in decisions concerning therapy. The relationship between histological features and prognosis is formalized in grading schemes such as those published by the World Health Organization (WHO), most recently in 2007. Although the latest edition is an improvement over previous grading schemes, the WHO scheme still fails to fully address a variety of important issues regarding the relationship between meningioma histological characteristics and behavior. In particular, routine histological examination fails to identify the subset of Grade I tumors that behave aggressively. Because of this, many additional prognostic markers that require immunohistochemical, cytogenetic, or molecular techniques to evaluate are under investigation. Only one, immunohistochemistry for the proliferation marker, Ki 67 (MIB-1), is used routinely and it has only limited utility. It is hoped that an understanding of the genetic changes that underlie tumor progression will improve healthcare professionals' ability to predict the behavior of meningiomas.

Molecular Neuroimaging: From Conventional to Emerging Techniques

The use of molecular imaging techniques in the central nervous system (CNS) has a rich history. Most of the important developments in imaging-such as computed tomography, magnetic resonance imaging, single photon emission computed tomography, and positron emission tomography-began with neuropsychiatric applications. These techniques and modalities were then found to be useful for imaging other organs involved with various disease processes. Molecular imaging of the CNS has enabled scientists and researchers to understand better the basic biology of brain function and the way in which various disease processes affect the brain. Unlike other organs, the brain is not easily accessible, and it has a highly selective barrier at the endothelial cell level known as the blood-brain barrier. Furthermore, the brain is the most complex cellular network known to exist. Various neurotransmitters act in either an excitatory or an inhibitory fashion on adjacent neurons through a multitude of mechanisms. The various neuronal systems and the myriad of neurotransmitter systems become altered in many diseases. Some of the most devastating diseases, including Alzheimer disease, Parkinson disease, brain tumors, psychiatric disease, and numerous degenerative neurologic diseases, affect only the brain. Molecular neuroimaging will be critical to the future understanding and treatment of these diseases. Molecular neuroimaging of the brain shows tremendous promise for clinical application. In this article, the current state and clinical applications of molecular neuroimaging will be reviewed.

Immunohistochemical expression of h-telomerase reverse transcriptase in canine and feline meningiomas

Telomere length maintenance is regarded as a fundamental step in tumorigenesis, as most human brain tumors, including meningiomas, stabilize the ends of their chromosomes using telomerase. This investigation represents an introduction to telomerase expression in canine and feline meningiomas. Twenty-five archived cases (14 dogs and 11 cats) were immunohistochemically tested for human-telomerase reverse transcriptase (h-TERT), scored, and quantified; furthermore, mitoses were counted on sections stained with a modified toluidine blue. The h-TERT antibody immunolabelled the nucleus and nucleolus of meningeal neoplastic cells, with an intensity ranging from mild to strong and a speckled distribution; a significantly higher expression in cats was noted, while no significant association between h-TERT immunolabelling and sex or histotype was evident in dogs or cats. The telomerase enzyme represents a fundamental parameter of potential malignant transformation, which may occur independently of the signal to proliferate, thereby supplying the cells with unlimited growth capabilities. Telomerase expression could be a prognostic indicator independent of the kinetic parameters, although this should be evaluated using a larger dataset with available clinical information.

Expression of Ki-67, Topoisomerase II? and c-MYC in astrocytic tumors: Correlation with the histopathological grade and proliferative status

Astrocytomas represent the most frequent primary tumors of the central nervous system. Recently, the determination of the proliferative index of astrocytic tumors by different methods has been proposed as a valuable tool for tumor grading and also as a prognostic marker. The aim of the present study was to evaluate the expression of cell proliferation-related proteins in human astrocytic tumors of different histopathological grades (WHO). An immunohistochemical study of the Ki-67, Topoisomerase IIalpha (Topo IIalpha) and c-MYC proteins using the avidin-biotin-peroxidase method was performed in 55 astrocytomas (13 grade I, 14 grade II, 7 grade III and 21 grade IV) and five samples of non-tumor brain tissue (control group). Ki-67, Topo IIalpha and c-MYC positive indices tended to increase according to malignant progression, were absent in non-tumor brain tissue and showed maximum values in high-grade astrocytomas (III and IV). A gradual increase in Ki-67 antigen expression was observed in agreement with mitotic index and histopathological classification. The same was not observed for Topo IIalpha and c-MYC. Ki-67 antigen detection in more than 8.0% of the tumor cells distinguished astrocytoma grade IV, while a labeling index between 1.5 and 8.0% characterized astrocytomas grade III and values below 1.5% discriminated low-grade tumors (I and II). These results indicate that Topo IIalpha and c-MYC expression is associated with cell proliferation in astrocytomas, although not in an exclusive way. Moreover, Ki-67 antigen was found to be the best marker of cellular proliferation, and its expression predicts the grade of astrocytic tumors.

Analysis of oncogenic signaling networks in glioblastoma identifies ASPM as a molecular target

Glioblastoma is the most common primary malignant brain tumor of adults and one of the most lethal of all cancers. Patients with this disease have a median survival of 15 months from the time of diagnosis despite surgery, radiation, and chemotherapy. New treatment approaches are needed. Recent works suggest that glioblastoma patients may benefit from molecularly targeted therapies. Here, we address the compelling need for identification of new molecular targets. Leveraging global gene expression data from two independent sets of clinical tumor samples (n = 55 and n = 65), we identify a gene coexpression module in glioblastoma that is also present in breast cancer and significantly overlaps with the "metasignature" for undifferentiated cancer. Studies in an isogenic model system demonstrate that this module is downstream of the mutant epidermal growth factor receptor, EGFRvIII, and that it can be inhibited by the epidermal growth factor receptor tyrosine kinase inhibitor Erlotinib. We identify ASPM (abnormal spindle-like microcephaly associated) as a key gene within this module and demonstrate its overexpression in glioblastoma relative to normal brain (or body tissues). Finally, we show that ASPM inhibition by siRNA-mediated knockdown inhibits tumor cell proliferation and neural stem cell proliferation, supporting ASPM as a potential molecular target in glioblastoma. Our weighted gene coexpression network analysis provides a blueprint for leveraging genomic data to identify key control networks and molecular targets for glioblastoma, and the principle eluted from our work can be applied to other cancers.

Metabolic alteration transients during paroxysmal activity in an epileptic patient with fixation-off sensitivity: a case study

The purpose of this study was to investigate short-time metabolic variations related to continuous epileptic activity elicited by fixation-off sensitivity (FOS). Time-resolved magnetic resonance spectroscopy was performed on a patient on whom previous clinical findings clearly indicated presence of FOS. The epileptic focus was localized with a simultaneous electroencephalographic and functional magnetic resonance imaging study. The results showed a linear increase of the sum of glutamate and glutamine with time of paroxysmal activity in epileptic focus and much greater concentration of choline-containing compounds in focus than in the contralateral side.