NeuN expression correlates with reduced mitotic index of neoplastic cells in central neurocytomas.
ABSTRACT In the developing brain, neuronal differentiation is associated with permanent exit from the mitotic cycle. This raises the possibility that neuronal differentiation may suppress proliferative activity, even in neoplastic cells. As a first step towards understanding the relation between neuronal differentiation and mitotic cycling in brain tumours, we studied the expression of NeuN (a neuronal marker) and Ki-67 (a mitotic marker) by double-labelling immuno-fluorescence in 16 brain tumours with neuronal differentiation. The tumours included a series of 11 central neurocytomas, and five single cases of other tumour types. In the central neurocytomas, NeuN(+) cells had a 15-fold lower Ki-67 labelling index, on average, than did NeuN(-) cells (P < 0.01). In the other tumours (one extraventricular neurocytoma, one desmoplastic medulloblastoma, one olfactory neuroblastoma, one ganglioglioma and one anaplastic ganglioglioma), the Ki-67 labelling index was always at least fourfold lower in NeuN(+) cells than in NeuN(-) cells. These results indicate that neuronal differentiation is associated with a substantial decrease of proliferative activity in neoplastic cells of central neurocytomas, and suggest that the same may be true across diverse types of brain tumours. However, tumours with extensive neuronal differentiation may nevertheless have a high overall Ki-67 labelling index, if the mitotic activity of NeuN(-) cells is high. The correlation between NeuN expression and reduced mitotic activity in neurocytoma cells is consistent with the hypothesis that neuronal differentiation suppresses proliferation, but further studies will be necessary to determine causality and investigate underlying mechanisms.
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ABSTRACT: The herpes simplex virus type 1 (HSV-1) latency-associated transcript (LAT) is expressed abundantly in latently infected sensory neurons. LAT-deletion-mutant virus strains have reduced-reactivation phenotypes in small animal models of infection, demonstrating that LAT plays an important role in the latency-reactivation cycle of HSV-1. Previous studies demonstrated that the anti-apoptosis functions of LAT are important for regulating the latency-reactivation cycle because three different anti-apoptosis genes can substitute for LAT. Although LAT inhibits caspase 3 activation, the signalling pathway by which LAT inhibits caspase 3 activation was not identified. In this study, we analysed mouse neuroblastoma cells (C1300) that express LAT stably (DC-LAT6 cells) following serum starvation. As expected, DC-LAT6 cells were resistant to apoptosis following serum withdrawal. Levels of total and phosphorylated AKT (protein kinase B), a serine/threonine protein kinase that promotes cell survival, were higher in DC-LAT6 cells after serum withdrawal than in C1300 cells or a cell line stably transfected with a LAT promoter mutant (DC-DeltaLAT311). A specific AKT inhibitor reduced the anti-apoptosis functions of LAT and phosphorylated AKT levels. After serum withdrawal, more DC-LAT6 cells sprouted neurites and exhibited a differentiated morphology. NeuN (neuronal nuclei), a neuron-specific nuclear protein, was expressed abundantly in DC-LAT6 cells, but not C1300 cells, after serum withdrawal, further supporting the concept that LAT enhanced neuronal-like morphology. Collectively, these studies suggested that LAT, directly or indirectly, maintained total and phosphorylated AKT levels, which correlated with increased cell survival and mature neuronal-like morphology.Journal of General Virology 12/2009; 91(Pt 4):858-66. DOI:10.1099/vir.0.015719-0
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ABSTRACT: The advantages of homodyne receivers and the problems that must be to overcome in order to realize the required performance are reviewed. Some examples of our recent and homodyne technologies are introduced as applied to pagers, wireless remote control equipment, and radio systems using reflected signalsSignals, Systems, and Electronics, 1995. ISSSE '95, Proceedings., 1995 URSI International Symposium on; 11/1995
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ABSTRACT: This paper proposes a new approach of Kriging Estimation (KE) to the problem of probability density estimation, which is critical during the registration of medical images using Mutual Information (MI). The author proposed that the linear coefficients of Kriging Interpolation have "probability character" which makes them appropriate to be utilized in probability estimation. KE is a complement of existent probability estimation methods, the experiments provided have proved its efficacy.Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2005; 3:3097-9. DOI:10.1109/IEMBS.2005.1617130