Nicotinic acid inhibits glioma invasion by facilitating Snail1 degradation.

Malignant glioma is a formidable disease that commonly leads to death, mainly due to the invasion of tumor cells into neighboring tissues. Therefore, inhibition of tumor cell invasion may provide an effective therapy for malignant glioma. Here we report that nicotinic acid (NA), an essential vitamin, inhibits glioma cell invasion in vitro and in vivo. Treatment of the U251 glioma cells with NA in vitro results in reduced invasion, which is accompanied by a loss of mesenchymal phenotype and an increase in cell-cell adhesion. At the molecular level, transcription of the adherens junction protein E-cadherin is upregulated, leading to accumulation of E-cadherin protein at the cell-cell boundary. This can be attributed to NA's ability to facilitate the ubiquitination and degradation of Snail1, a transcription factor that represses E-cadherin expression. Similarly, NA transiently inhibits neural crest migration in Xenopus embryos in a Snail1-dependent manner, indicating that the mechanism of action for NA in cell migration is evolutionarily conserved. We further show that NA injection blocks the infiltration of tumor cells into the adjacent brain tissues and improves animal survival in a rat model of glioma. These results suggest that NA treatment may be developed into a potential therapy for malignant glioma.

Alzheimer's disease and methanol toxicity (part 1): chronic methanol feeding led to memory impairments and tau hyperphosphorylation in mice.

Although methanol toxicity is well known for acute neurological sequelae leading to blindness or death, there is a new impetus to investigate the chronic effects of methanol exposure. These include a recently established link between formaldehyde, a methanol metabolite, and Alzheimer's disease (AD) pathology. In the present study, mice were fed with methanol to revisit the chronic effects of methanol toxicity, especially as it pertains to AD progression. Three groups of mice (n = 9) were given either water as a control or a methanol solution (concentrations of 2% or 3.8%) over a 6-week period. The methanol-fed mice were found to have impaired spatial recognition and olfactory memory in Y-maze and olfactory memory paradigms. Immunohistochemical analysis of the mouse brains found increased neuronal tau phosphorylation in the hippocampus and an increased cellular apoptotic marker in hippocampal CA1 neurons (~10% of neurons displayed chromatin condensation) in the methanol-fed groups. Two additional in vitro experiments in mouse embryonic cerebral cortex neurons and mouse neuroblastoma N2a cells found that formaldehyde, but not methanol or the methanol end product formic acid, induced microtubule disintegration and tau protein hyperphosphorylation. The findings of the behavioral tests and immunohistochemical analysis suggested that the methanol-fed mice presented with partial AD-like symptoms. The in vitro experiments suggested that formaldehyde was most likely the detrimental component of methanol toxicity related to hippocampal tau phosphorylation and the subsequent impaired memory in the mice. These findings add to a growing body of evidence that links formaldehyde to AD pathology.

Effects of visual working memory on brain information processing of irrelevant auditory stimuli.

Selective attention has traditionally been viewed as a sensory processing modulator that promotes cognitive processing efficiency by favoring relevant stimuli while inhibiting irrelevant stimuli. However, the cross-modal processing of irrelevant information during working memory (WM) has been rarely investigated. In this study, the modulation of irrelevant auditory information by the brain during a visual WM task was investigated. The N100 auditory evoked potential (N100-AEP) following an auditory click was used to evaluate the selective attention to auditory stimulus during WM processing and at rest. N100-AEP amplitudes were found to be significantly affected in the left-prefrontal, mid-prefrontal, right-prefrontal, left-frontal, and mid-frontal regions while performing a high WM load task. In contrast, no significant differences were found between N100-AEP amplitudes in WM states and rest states under a low WM load task in all recorded brain regions. Furthermore, no differences were found between the time latencies of N100-AEP troughs in WM states and rest states while performing either the high or low WM load task. These findings suggested that the prefrontal cortex (PFC) may integrate information from different sensory channels to protect perceptual integrity during cognitive processing.

Establishment and partial characterization of a human tumor cell line, GBM-HSF, from a glioblastoma multiforme.

This paper outlines the establishment of a new and stable cell line, designated GBM-HSF, from a malignant glioblastoma multiforme (GBM) removed from a 65-year-old Chinese woman. This cell line has been grown for 1 year without disruption and has been passaged over 50 times. The cells were adherently cultured in RPMI-1640 media with 10% fetal bovine serum supplementation. Cells displayed spindle and polygonal morphology, and displayed multi-layered growth without evidence of contact inhibition. The cell line had a high growth rate with a doubling time of 51 h. The cells were able to grow without adhering to the culture plates, and 4.5% of the total cells formed colonies in soft agar. The cell line has also been found to form tumors in nude mice and to be of a highly invasive nature. The cells were also partially characterized with RT-PCR. The RT-PCR revealed that Nestin, ß-tubulin III, Map2, Klf4, Oct4, Sox2, Nanog, and CD26 were positively transcribed, whereas GFAP, Rex1, and CD133 were negatively transcribed in this cell line. These results suggest that the GBM-HSF cell line will provide a good model to study the properties of cancer stem cells and metastasis. It will also facilitate more detailed molecular and cellular studies of GBM cell division and pathology.

Melatonin treatment increases the transcription of cell proliferation-related genes prior to inducing cell death in C6 glioma cells in vitro.

A number of studies have suggested that melatonin possesses anticancer properties. However, conflicting data exists with regard to the role of melatonin in the treatment of cancer. In the present study, the effects of melatonin on the transcriptional regulation of three genes associated with cell proliferation (Nestin, Bmi-1 and Sox2), and on C6 glioma cell survival and viability, were investigated in vitro to evaluate the use of melatonin in cancer therapy. Melatonin was shown to increase the mRNA levels of Nestin, Bmi-1 and Sox2 in a similar pattern, with the highest mRNA levels noted at a concentration of 3 mM. At higher concentrations of melatonin (5 mM), the mRNA levels of Nestin, Bmi-1 and Sox2 were reduced from their peak levels, and were correlated with changes observed in immunofluorescence morphology studies, cell viability and survival assays. Immunofluorescence studies of Nestin-stained cells demonstrated that treatment with a higher concentration of melatonin (3 and 5 mM) led to the Nestin filaments condensing and rearranging around the cell nuclei, and an alteration in the cell morphology. C6 cell viability was also significantly decreased at 3 mM melatonin, and cell death was observed at 5 and 10 mM melatonin. These results suggested that Nestin, Bmi-1 and Sox2 were strongly correlated with the survival of C6 cells following treatment with melatonin, and that high therapeutic concentrations of melatonin (>5 mM) were required to induce cell death. These findings suggested that the implementation of melatonin in the treatment of glioma and other types of cancer may be inhibited by conflicting cell growth signals in cells. Therefore, adjunct therapy is required to improve the efficacy of melatonin in the treatment of cancer.

[Rhesus monkey embryonic stem cells differentiation, proliferation and allotransplantation].

To investigate the characteristics of rhesus monkey embryonic stem cells and to promote their clinical application, the differentiation and proliferation of rosettes neural stem cells from GFP marked rhesus monkey embryonic stem cells were studied The results showed that: 1) A stable and high-efficient neural differentiation system was established. More than 95% of the embryonic stem cells were differentiated into neural stem cells on the 12(th) days of differentiation; 2) the rosettes neural stem cells differentiated from the rhesus monkey embryonic stem cells could maintain their rosettes-shape by proliferating with bFGF/EGF; 3) the neural stem cells could differentiate into neurons after transplanted into the rhesus monkey brain. In conclusion, the rosettes neural stem cells differentiated from rhesus monkey embryonic stem cells could maintain their characteristics after proliferation with bFGF/EGF and they could survive and differentiate into neurons after transplanted into the rhesus monkey brain, which strongly supports the clinical application of neural stem cells in the future.

[Differences in morphine-induced and food-induced conditioned place preference between adolescent and adult mice].

In the present study, the differences between addictive memory and ordinary memory were investigated by morphine-induced and food-induced conditioned place preference (CPP) in adolescent and adult mice. The result showed that: 1) morphine-induced CPP could be established in adult mice but not in adolescent mice. 2) food-induced CPP could be established both in adolescent and adult mice. This study indicated that between adolescent and adult mice, there was no difference in ordinary memory, but for addictive memory, they were quite different. Our data suggested that the development of addictive memory and ordinary memory system in mouse brain might not be paralleled.

[A traumatic brain injury model for distinguishing between transplanted neural cells and host cells in vivo].

To perform electrophysiological recording and other investigations on transplanted neural cells in vivo, we used mechanical damage to establish a special traumatic brain injury model that could distinguish transplanted cells from host cells. The morphology of the trauma-induced holes in the cortex of the rat brain was regular. The model was stable and repeatable. Neural stem cells were transplanted into the trauma-induced hole, and were able to survive for a long time. Most of the transplanted cells differentiated into neurons, and only a small amount turned into glia cells. There was a clear boundary between the host cells and the transplanted cells. Single cell electrophysiological recording on transplanted neural cells were detected in vivo. This study established a stable and repeatable traumatic brain injury model, which could be used to conduct in vivo electrophysiological recording research on transplanted neural cells.