Cancer stem cells.
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Cell Transformation, Neoplastic↗
Biomedical subjects
François Berger
Publications and source records attributed to François Berger.
Direct-tissue SELDI-TOF mass spectrometry analysis: a new application for clinical proteomics.
BACKGROUND: New molecular profiling technologies can aid in analysis of small pathologic samples obtained by minimally invasive biopsy and may enable the discovery of key biomarkers synergistic with anatomopathologic analysis related to prognosis, therapeutic response, and innovative target validation. Thus proteomic analysis at the histologic level in healthy and pathologic settings is a major issue in the field of clinical proteomics. METHODS: We used surface-enhanced laser desorption ionization-time-of-flight mass spectrometry (SELDI-TOF MS) technology with surface chromatographic subproteome enrichment and preservation of the spatial distribution of proteomic patterns to detect discrete modifications of protein expression. We performed in situ proteomic profiling of mouse tissue and samples of human cancer tissue, including brain and lung cancer. RESULTS: This approach permitted the discrimination of glioblastomas from oligodendrogliomas and led to the identification of 3 potential markers. CONCLUSION: Direct tissue proteomic analysis is an original application of SELDI-TOF MS technology that can expand the use of clinical proteomics as a complement to the anatomopathological diagnosis.
Animals↗
Functional neuronal differentiation of bone marrow-derived mesenchymal stem cells.
Recent results have shown the ability of bone marrow cells to migrate in the brain and to acquire neuronal or glial characteristics. In vitro, bone marrow-derived MSCs can be induced by chemical compounds to express markers of these lineages. In an effort to set up a mouse model of such differentiation, we addressed the neuronal potentiality of mouse MSCs (mMSCs) that we recently purified. These cells expressed nestin, a specific marker of neural progenitors. Under differentiating conditions, mMSCs display a distinct neuronal shape and express neuronal markers NF-L (neurofilament-light, or neurofilament 70 kDa) and class III beta-tubulin. Moreover, differentiated mMSCs acquire neuron-like functions characterized by a cytosolic calcium rise in response to various specific neuronal activators. Finally, we further demonstrated for the first time that clonal mMSCs and their progeny are competent to differentiate along the neuronal pathway, demonstrating that these bone marrow-derived stem cells share characteristics of widely multipotent stem cells unrestricted to mesenchymal differentiation pathways.
Animals↗
Glioma, melatonin, and radiotherapy.
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Animals↗
Resistance to phorbol ester-induced differentiation in human myeloid leukemia cells: a hypothetic role for the mRNA stabilization process.
UM384 cells, derived from the human myeloid leukemia U937 cell line, fail to differentiate in response to 12-O-tetradecanoylphorbol-13-acetate (TPA). Using cDNA microarray and real-time quantitative PCR (RT-QPCR) approaches, we observed a difference in the response to TPA treatment: all the genes from U937 cells were continuously modulated from 2 to 24h. In UM384 cells, 60% of the genes were transiently modulated at 2h, then returned to control levels at 24h. Moreover, HuR, an AU-rich element-binding protein (ARE-BP), was differentially located in the two cell lines. Therefore, a defect of mRNA stabilization could be responsible for the resistance of UM384 cells to TPA-induced differentiation, suggesting a possible role for the post-transcriptional regulation in the leukemogenesis.
Cell Cycle Proteins↗
Undetectable levels of N6-methyl adenine in mouse DNA: Cloning and analysis of PRED28, a gene coding for a putative mammalian DNA adenine methyltransferase.
Three methylated bases, 5-methylcytosine, N4-methylcytosine and N6-methyladenine (m6A), can be found in DNA. However, to date, only 5-methylcytosine has been detected in mammalian genomes. To reinvestigate the presence of m6A in mammalian DNA, we used a highly sensitive method capable of detecting one N6-methyldeoxyadenosine per million nucleosides. Our results suggest that the total mouse genome contains, if any, less than 10(3) m6A. Experiments were next performed on PRED28, a putative mammalian N6-DNA methyltransferase. The murine PRED28 encodes two alternatively spliced RNA. However, although recombinant PRED28 proteins are found in the nucleus, no evidence for an adenine-methyltransferase activity was detected.
Adenine↗
N6-methyladenine: the other methylated base of DNA.
Contrary to mammalian DNA, which is thought to contain only 5-methylcytosine (m5C), bacterial DNA contains two additional methylated bases, namely N6-methyladenine (m6A), and N4-methylcytosine (m4C). However, if the main function of m5C and m4C in bacteria is protection against restriction enzymes, the roles of m6A are multiple and include, for example, the regulation of virulence and the control of many bacterial DNA functions such as the replication, repair, expression and transposition of DNA. Interestingly, even if adenine methylation is usually considered a bacterial DNA feature, the presence of m6A has been found in protist and plant DNAs. Furthermore, indirect evidence suggests the presence of m6A in mammal DNA, raising the possibility that this base has remained undetected due to the low sensitivity of the analytical methods used. This highlights the importance of considering m6A as the sixth element of DNA.
Adenine↗
In vitro tumoral progression of human bladder carcinoma: role for TGFbeta.
OBJECTIVE: Investigating whether extracellular factors are possible actors in tumoral progression in bladder carcinoma. METHODS: RT112/G2 bladder tumour cells were grown in presence of TGFbeta and analysed by immunological and cDNA microarray techniques. RESULTS: TGFbeta inhibited cell proliferation, reduced TNFalpha- and IFNgamma-induced apoptosis by decreasing TNFalpha-RI and IFNgamma-R antigen expression. It also inhibited cleaved caspase 8 and 9 expression, decreased E-cadherin, and increased BclxL and cyclooxygenase-2 expression. The cDNA microarray approach showed that TGFbeta up-regulated the expression of genes with defined roles in tumoral progression sometimes associated with poor outcome in bladder cancer. CONCLUSION: These results suggest that a part of the bladder tumoral progression process may be related to the action of exogenous TGFbeta confirming the possible role for the microenvironment.
Apoptosis↗
Should we control the pineal status of patients following brain radiotherapy?
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Brain Neoplasms↗
Therapeutic electrical stimulation of the central nervous system.
The electrical effects on the nervous system have been known for long. The excitatory effect has been used for diagnostic purposes or even for therapeutic applications, like in pain using low-frequency stimulation of the spinal cord or of the thalamus. The discovery that High-Frequency Stimulation (HFS) mimics the effect of lesioning has opened a new field of therapeutic application of electrical stimulation in all places where lesion of neuronal structures, such as nuclei of the basal ganglia, had proven some therapeutic efficiency. This was first applied to the thalamus to mimic thalamotomy for the treatment of tremor, then to the subthalamic nucleus and the pallidum to treat some advanced forms of Parkinson's disease and control not only the tremor but also akinesia, rigidity and dyskinesias. The field of application is increasingly growing, currently encompassing dystonias, epilepsy, obsessive compulsive disease, cluster headaches, and experimental approaches are being made in the field of obesity and food intake control. Although the effects of stimulation are clear-cut and the therapeutic benefit is clearly recognized, the mechanism of action of HFS is not yet understood. The similarity between HFS and the effect of lesions in several places of the brain suggests that this might induce an inhibition-like process, which is difficult to explain with the classical concept of physiology where electrical stimulation means excitation of neural elements. The current data coming from either clinical or experimental observations are providing elements to shape a beginning of an understanding. Intra-cerebral recordings in human patients with artefact suppression tend to show the arrest of electrical firing in the recorded places. Animal experiments, either in vitro or in vivo, show complex patterns mixing inhibitory effects and frequency stimulation induced bursting activity, which would suggest that the mechanism is based upon the jamming of the neuronal message, which is by this way functionally suppressed. More recent data from in vitro biological studies show that HFS profoundly affects the cellular functioning and particularly the protein synthesis, suggesting that it could alter the synaptic transmission by reducing the production of neurotransmitters. It is now clear that this method has a larger field of application than currently known and that its therapeutical applications will benefit to several diseases of the nervous system. The understanding of the mechanism has opened a new field of research, which will call for reappraisal of the basic effects of electricity on the living tissues.
Animals↗
Coordinated and spatial upregulation of arc in striatonigral neurons correlates with L-dopa-induced behavioral sensitization in dyskinetic rats.
Although oral administration of L-Dopa remains the best therapy for Parkinson disease, its long-term administration causes the appearance of abnormal involuntary movements such as dyskinesia. Although persistent striatal induction of some genes has already been associated with such pathologic profiles in hemiparkinsonian rats, molecular and cellular mechanisms underlying such long-term adaptations remain to be elucidated. In this study, using a rat model of L-Dopa-induced dyskinesia, we report that activity regulated cytoskeletal (Arc)-associated protein is strongly upregulated in the lesioned striatum and that the extent of its induction further varies according to the occurrence or absence of locomotor sensitization. Moreover, Arc is preferentially induced, along with FosB, nur77, and homer-1a, in striatonigral neurons, which express mRNA encoding the precursor of dynorphin. Given the likely importance of Arc in the regulation of cytoskeleton during synaptic plasticity, its upregulation supports the hypothesis that a relationship exists between cytoskeletal modifications and the longlasting action of chronically administrated L-Dopa.
3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
A putative generalized model of the effects and mechanism of action of high frequency electrical stimulation of the central nervous system.
High-frequency stimulation (HFS) of neural structures has been used since 1997 as an alternative to lesions in functional neurosurgery of movement disorders, and more recently, it has been applied to the treatment of epilepsies, obsessive-compulsive disorders, cluster headaches, and has other applications in experimental models, particularly for obesity. Although their clinical efficacy is not questioned, and that the effects most of the time parallel those of ablative techniques, leading to the concept of functional inhibition, the intimate mechanisms by which HFS induces excitation within fiber bundles and seems to inhibit cellular nuclei is still strongly debated. Principally due to the observation of long-term clinical effects over a period up to 15 years, it is clear that the mechanism is not due to a progressive lesion, as at every moment the interruption of stimulation reverses totally the effects. There is no current proof that long-term HFS is able to reset neural networks, or to induce profound modifications of the functional organization or of the synaptic connectivity. To understand what is responsible for the immediate, reversible and adaptable effects of HFS, several mechanisms must be considered, which might be involved simultaneously or in sequence: i) Jamming of neural transmission through stimulated nuclei is one possibility, based on the principle that the regular imposed activity might drive the neurons to fire in a regular pattern, making it impossible to transmit more subtle messages, either normal or abnormal. Although it is difficult to prove this type of mechanism, it might account for the reports of increased activity following HFS in various structures. ii) Direct inhibition of spike initiation at the level of the membrane could be due to activation of inhibitory terminals, particularly gaba-ergic, or by a blockade of the voltage gated ion channels. iii) Recent data show that HFS decreases the production and release of low molecular weight proteic neurotransmitters, which could account for the functional inhibition while the efferent axon is still excited by the electrical stimulus. iv) Retrograde activation of upstream neuronal structures, as reported in the external pallidum during stimulation of STN, might be responsible of additional jamming-like effects due to collisions with descending spikes.
Animals↗
Gene expression profiling of human adrenocortical tumors using complementary deoxyribonucleic Acid microarrays identifies several candidate genes as markers of malignancy.
The aim of this study was to identify predictor sets of genes whose over- or underexpression in human sporadic adrenocortical tumors would help to identify malignant vs. benign tumors and to predict postsurgical metastatic recurrence. For this, we analyzed the expression of 230 candidate genes using cDNA microarrays in a series of 57 well-characterized human sporadic adrenocortical tumors (33 adenomas and 24 carcinomas). We identified two clusters of genes (the IGF-II cluster containing eight genes, including IGF-II, and the steroidogenesis cluster containing six genes encoding steroidogenic enzymes plus eight other genes) whose combined levels of expression appeared to be good predictors of malignancy. This predictive value was as strong as that of the pathological score of Weiss. The analysis of the population of carcinomas (13 tumors) for genes whose expression would be strongly different between recurring and nonrecurring tumors allowed identification of 14 genes meeting these criteria. Among these genes, there are probably new markers of tumor evolution that will deserve additional validation on a larger scale. Taken together, these results show that the parallel analysis of the expression levels of a selected group of genes on microgram quantities of tumor RNA (a quantity that can be obtained from fine needle aspirations) appears as a complementary method to histopathology for the diagnosis and prognosis of evolution of adrenocortical carcinomas.
Adolescent↗
Isolation and characterisation of mesenchymal stem cells from adult mouse bone marrow.
The future use of adult mesenchymal stem cells (MSCs) for human therapies depends on the establishment of preclinical studies with other mammals such as mouse. Surprisingly, purification and characterisation of murine MSCs were only poorly documented. The aim of this study was to purify mouse MSCs from adult bone marrow and to functionally characterise their abilities to differentiate along diverse lineages. Adherent cells from adult C57Bl/6J mouse bone marrow were depleted of granulo-monocytic cells and subsequently allowed to grow on fibronectin-coated dishes in presence of fetal bovine serum and growth factors. The growing fibroblastoid cell population primarily consisted of spindle- and star-shaped cells with significant renewal capacity as they were cultured until 30 passages (about 60 doubling population). We fully demonstrated the MSC phenotype of these cells by inducing them to differentiate along osteoblastic, adipocytic, and chondrocytic pathways. Mouse MSCs (mMSCs) sharing the same morphological and functional characteristics as human MSCs can be successfully isolated from adult bone marrow without previous mouse or bone marrow treatment. Therefore, mMSCs will be an important tool to study the in vivo behaviour and fate of this cell type after grafting in mouse pathology models.
Adipocytes↗
Expression of the thrombospondin 1 fragment 167-569 in C6 glioma cells stimulates tumorigenicity despite reduced neovascularization.
Gliomas are among the most malignant and most highly vascularized human tumors. We studied the therapeutic action of an angiostatic fragment of human thrombospondin 1 (named TSP1ang) on experimental glioma tumor growth. TSP1ang (enclosing amino acids 167-569) comprised the procollagen-homology domain and the three type I repeats of the original molecule. C6 glioma cells that stably express TSP1ang were generated, and their rate of in vitro growth did not appear to differ from that of C6 cells transfected with an empty plasmid. TSP1ang-expressing C6 cells were then injected either subcutaneously or intracerebrally into nude mice. The resulting tumors appeared to be less vascularized, but unexpectedly started to grow earlier and had a much more invasive phenotype than tumors derived from control C6 cells. They were also much more aggressive, since the mice bearing intracerebral TSP1ang-expressing tumor cells died before day 19 post-implantation, whereas all mice bearing control C6 tumors were alive at this time point. These results indicate that careful attention should be paid at designing smaller fragments from the multimodular angiostatic molecule TSP1 since, as observed in this study, it may unmask protumorigenic properties that counteract its antiangiogenic activity.
Animals↗
N(6)-Methyldeoxyadenosine, a nucleoside commonly found in prokaryotes, induces C2C12 myogenic differentiation.
N(6)-methyl-2(')-deoxyadenosine (MedAdo) is a nucleoside naturally found in prokaryotic DNA. Interestingly, the N(6)-methylation of adenine in DNA seems to have been counter-selected during the course of evolution since MedAdo has not been detected in mammalian DNA until now. We show here that treatment with MedAdo induces myogenesis in C2C12 myoblasts. The presence of MedAdo in C2C12 DNA was investigated using a method based on HPLC coupled to electrospray ionization tandem mass spectrometry which is several thousand fold more sensitive than assays used previously. By this procedure, MedAdo is detected in the DNA from MedAdo-treated cells but remains undetectable in the DNA from control cells. Furthermore, MedAdo regulates the expression of p21, myogenin, mTOR, and MHC. Interestingly, in the pluripotent C2C12 cell line, MedAdo drives the differentiation towards myogenesis only. Thus, the biological effect of MedAdo is suppressed in the presence of BMP-2 which transdifferentiates C2C12 from myogenic into osteogenic lineage cells. Taken together these results point to MedAdo as a novel inducer of myogenesis and further extends the differentiation potentialities of this methylated nucleoside. Furthermore, these data raise the intriguing possibility that the biological effects of MedAdo on cell differentiation may have led to its counter-selection in eukaryotes.
Adenine↗
Infection of human astrocytes and glioblastoma cells with Toxoplasma gondii: monocyte chemotactic protein-1 secretion and chemokine expression in vitro.
In immunocompromised hosts, disruption of toxoplasmic cysts and conversion from bradyzoites to tachyzoites occur in brain. In these areas, infiltrates of mononuclear cells are observed. In the murine toxoplasmosis model, recent data suggest that chemokines may play a role in leukocyte recruitment in the central nervous system (CNS). This study analyzed the monocyte chemotactic protein-1 (MCP-1) secretion and chemokine expression after Toxoplasma gondii infection of human astrocytes, glioblastoma cells (U373) and fibroblasts (MRC5) in vitro. T. gondii infection of these CNS cells, astrocytes and glioblastoma cells significantly increased MCP-1 secretion, particularly for astrocytes. In our cellular models, the pattern of chemokine gene expression is dominated by MCP-1 expression. MCP-1 mRNAs were also quantified by real-time-PCR (LightCycler). The behavior of cells studied after T. gondii infection was different (invasion and growth) and the cell mechanisms of chemokine regulation could be dependent on the type of cells infected, while MCP-1 may contribute to the cell recruitment during human cerebral reactivation of T. gondii.
Animals↗
Development of gliomas: potential role of asymmetrical cell division of neural stem cells.
Asymmetrical cell division is a mechanism that gives rise to two daughter cells with different proliferative and differentiative fates. It occurs mainly during development and in adult stem cells. Accumulating evidence suggests that tumour cells arise from the transformation of normal stem cells. Here, we propose that the asymmetrical mitosis potential of stem cells is associated with the generation of migrating tumour progenitors. Application of this speculative model to glioma proposes that the sites where tumour-initiating stem cells reside are indolent and distinct from the tumour mass, and implies that the tumour mass is continuously replenished with new migrating tumour cells from these clinically silent regions. This hypothesis offers explanations for our inability to cure glioblastoma and points to asymmetrical division as a new potential therapeutic target.
Brain Neoplasms↗