The mitochondrial translocator protein in human gliomas

The translocator protein (TSPO) is an 18 kDa molecule spanning the outer mitochondrial membrane. Structural predictions, reported physical interactions and experimental data from diverse models suggest that TSPO is involved in apoptosis, proliferation and steroidogenesis. TSPO is up-regulated in several human cancers and its high levels are frequently associated with advanced disease and poor outcome. TSPO was shown to be up-regulated in astrocytomas and this was correlated with high tumour grade and shorter patient survival. Here it is confirmed that TSPO is highly expressed in astrocytomas and this is correlated with tumour grade. TSPO expression is significantly higher in astrocytic tumours than in oligodendrogliomas and this differential expression is epigenetically driven. Low TSPO expression in oligodendrogliomas is associated with frequent promoter methylation, whereas in astrocytomas, where TSPO is expressed at high levels, the promoter typically remains unmethylated. As oligodendrogliomas and astrocytomas have very different biology and prognosis, and several TSPO ligands, including those enabling positron emission tomography (PET) scanning, are in development, we propose pre-operative PET imaging to differentiate these two histotypes. TSPO is not an independent prognostic factor in our patient population. The main cell population expressing TSPO within the tumour bulk are neoplastic cells. Consistent with no evidence for TSPO as a strong prognostic factor in gliomas, no alteration in proliferation, cell cycle progression and baseline or induced apoptosis following TSPO siRNA knock-down in an in vitro astrocytoma model is demonstrated. Furthermore, there was no evidence of cortisol production by several astrocytoma cell lines in vitro despite TSPO protein expression. Out of the examined MPTP-related binding and functional partners of TSPO (VDAC1, ANT, HK I and II) only HKII up-regulation appears be reproducibly related to patient outcome in gliomas. Consistently, targeting hexokinases in vitro in a glioma model inhibited proliferation and increased apoptosis

Supratentorial neurenteric cyst—A case report

Supratentorial neurenteric cyst is a rare congenital lesion. We report here a case of a 33-year-old female who presented with seizures. A multicystic lesion in the left premotor cortex with moderate contrast enhancement was demonstrated with MRI. Microscopically, the lesion showed small cystic structures filled with a proteinaceous fluid. The wall of the cysts was lined with a single layer of ciliated columnar or cuboidal epithelium on a basement membrane. Glandular structures resembling gastrointestinal glands were also present. The cells of the cyst lining and glandular structures revealed strongly positive immunoreactions for epithelial markers (cytokeratin and epithelial membrane antigen)

The role of histone protein modifications and mutations in histone modifiers in pediatric b-cell progenitor acute lymphoblastic leukemia

While cancer has been long recognized as a disease of the genome, the importance of epigenetic mechanisms in neoplasia was acknowledged more recently. The most active epigenetic marks are DNA methylation and histone protein modifications and they are involved in basic biological phenomena in every cell. Their role in tumorigenesis is stressed by recent unbiased large-scale studies providing evidence that several epigenetic modifiers are recurrently mutated or frequently dysregulated in multiple cancers. The interest in epigenetic marks is especially due to the fact that they are potentially reversible and thus druggable. In B-cell progenitor acute lymphoblastic leukemia (BCP-ALL) there is a relative paucity of reports on the role of histone protein modifications (acetylation, methylation, phosphorylation) as compared to acute myeloid leukemia, T-cell ALL, or other hematologic cancers, and in this setting chromatin modifications are relatively less well studied and reviewed than DNA methylation. In this paper, we discuss the biomarker associations and evidence for a driver role of dysregulated global and loci-specific histone marks, as well as mutations in epigenetic modifiers in BCP-ALL. Examples of chromatin modifiers recurrently mutated/disrupted in BCP-ALL and associated with disease outcomes include MLL1, CREBBP, NSD2, and SETD2. Altered histone marks and histone modifiers and readers may play a particular role in disease chemoresistance and relapse. We also suggest that epigenetic regulation of B-cell differentiation may have parallel roles in leukemogenesis

Mycobacterium tuberculosis-infected human monocytes down-regulate microglial MMP-2 secretion in CNS tuberculosis via TNFα, NFκB, p38 and caspase 8 dependent pathways

Tuberculosis (TB) of the central nervous system (CNS) is a deadly disease characterized by extensive tissue destruction, driven by molecules such as Matrix Metalloproteinase-2 (MMP-2) which targets CNS-specific substrates. In a simplified cellular model of CNS TB, we demonstrated that conditioned medium from Mycobacterium tuberculosis-infected primary human monocytes (CoMTb), but not direct infection, unexpectedly down-regulates constitutive microglial MMP-2 gene expression and secretion by 72.8% at 24 hours, sustained up to 96 hours (P < 0.01), dependent upon TNF-α. In human CNS TB brain biopsies but not controls the p38 pathway was activated in microglia/macrophages. Inhibition of the p38 MAP kinase pathway resulted in a 228% increase in MMP-2 secretion (P < 0.01). In contrast ERK MAP kinase inhibition further decreased MMP-2 secretion by 76.6% (P < 0.05). Inhibition of the NFκB pathway resulted in 301% higher MMP-2 secretion than CoMTb alone (P < 0.01). Caspase 8 restored MMP-2 secretion to basal levels. However, this caspase-dependent regulation of MMP-2 was independent of p38 and NFκB pathways; p38 phosphorylation was increased and p50/p65 NFκB nuclear trafficking unaffected by caspase 8 inhibition. In summary, suppression of microglial MMP-2 secretion by M.tb-infected monocyte-dependent networks paradoxically involves the pro-inflammatory mediators TNF-α, p38 MAP kinase and NFκB in addition to a novel caspase 8-dependent pathway

Preserved global histone H4 acetylation linked to ETV6-RUNX1 fusion and PAX5 deletions is associated with favorable outcome in pediatric B-cell progenitor acute lymphoblastic leukemia.

Epigenetic dysregulation is a hallmark of cancer executed by a number of complex processes the most important of which converge on DNA methylation and histone protein modifications. Epigenetic marks are potentially reversible and thus promising drug targets. In the setting of acute lymphoblastic leukemia (ALL) they have been associated with clinicopathological features including risk of relapse or molecular subgroups of the disease. Here, using immunocytochemistry of bone marrow smears from diagnosis, we studied global histone H4 acetylation, whose loss was previously linked to treatment failure in adults with ALL, in pediatric patients. We demonstrate that preserved global histone H4 acetylation is significantly associated with favorable outcome (RFS, EFS, OS) in children with B cell progenitor (BCP) ALL, recapitulating the findings from adult populations. Further, for the first time we demonstrate differential histone H4 acetylation in molecular subclasses of BCP-ALL including cases with ETV6-RUNX1 fusion gene or PAX5 deletion or deletions in genes linked to B cell development. We conclude global histone H4 acetylation is a prognostic marker and a potential therapeutic target in ALL

The 18-kDa Mitochondrial Translocator Protein in Human Gliomas: An 11C-(R)PK11195 PET Imaging and Neuropathology Study.

The 18-kDa mitochondrial translocator protein (TSPO) is up-regulated in high grade astrocytomas and can be imaged by positron emission tomography (PET) using the selective radiotracer 11C-(R)PK11195. We investigated 11C-(R)PK11195 binding in human gliomas and its relationship with TSPO expression in tumor tissue and glioma associated microglia/macrophages within the tumors. METHODS: Twenty-two glioma patients underwent dynamic 11C-(R)PK11195 PET scans and perfusion MRI acquisition. Parametric maps of 11C-(R)PK11195 binding potential (BPND) were generated. Co-registered MR/PET images were used to guide tumor biopsy. The tumor tissue was quantitatively assessed for TSPO expression and infiltration of glioma associated microglia/macrophages (GAMs) using immunohistochemistry and double immunofluorescence. The imaging and histopathologic parameters were compared among different histotypes and grades, and correlated with each other. RESULTS: BPND of 11C-(R)PK11195 in high-grade gliomas were significantly higher than in low-grade astrocytomas and low-grade oligodendrogliomas. TSPO in gliomas was expressed predominantly by neoplastic cells, and its expression correlated positively with BPND in the tumors. Glioma associated microglia/macrophages only partially contributed to the overall TSPO expression within the tumors, and TSPO expression in GAMs did not correlate with tumor BPND. CONCLUSION: PET with 11C-(R)PK11195 in human gliomas predominantly reflects TSPO expression in tumor cells. It therefore has the potential to effectively stratify patients that are suitable for TSPO targeted treatment