FAM196B acts as oncogene and promotes proliferation of gastric cancer cells through AKT signaling pathway

Gastric cancer (GC) is the second leading cause of cancer-related deaths worldwide, but the mechanisms remain unknown. Here we report that family with sequence similarity 196 member B (FAM196B) is highly expressed in primary GC tissues and the expression level is correlated with the clinicopathologic characteristics of GC. In this experiment, knockdown of FAM196B suppressed GC cell proliferation and induced G1/G0 to S phase cell cycle arrest by regulating Cyclin D1, Cyclin A and CDK2 expressions. Furthermore, we investigated the molecular mechanism of FAM196B action in GC. The results showed that knockdown of FAM196B inhibited the activation of AKT signaling pathway. We further revealed that activating of AKT rescued the effect of FAM196B knockdown on cell proliferation and drove cell re-enter into the S phase of the cell cycle with SC79 (a AKT activator). Our findings demonstrated that FAM196B may promote GC cell proliferation by activating AKT signaling pathway. Taken together, this study provides a new evidence that FAM196B functions as a novel oncogene and could be a potential therapeutic target in therapy of GC.

Glutamate promotes neural stem cell proliferation by increasing the expression of vascular endothelial growth factor of astrocytes in vitro

The high levels of glutamate might involve in neurogenesis after brain injuries. However, the mechanisms are not fully understood. In this study, we investigated the effect of glutamate on the proliferation of rat embryonic neural stem/progenitor cells (NSCs) through regulating the vascular endothelial growth factor (VEGF) expression of astrocytes (ASTs) in vitro, and the cyclin D1 expression of NSCs. The results showed that glutamate promoted the expression and secretion of VEGF of rat astrocytes by activating group I mGluRs. Astrocyte conditioned medium-containing Glu [ACM (30%)] promoted the proliferation of embryonic NSCs compared with normal astrocyte conditioned medium+Glu [N-ACM (30%)+Glu (30 μM)] by increasing cell activity, diameter of neurospheres, bromodeoxyuridine (BrdU) incorporation and cell division; while ACM+VEGF neutralizing antibody [ACM (30%)+VEGF NAb (15 μg/ml)] significantly inhibited the proliferation of embryonic NSCs compared with ACM (30%). ACM (30%) increased the expressions of cyclin D1 and decreased cell death compared with N-ACM (30%)+Glu (30 μM). ACM (30%)+VEGF NAb (15 μg/ml) decreased the expressions of cyclin D1 and increased cell death compared with ACM (30%). These results demonstrated that glutamate could also indirectly promote the proliferation of rat embryonic NSCs through inducing the VEGF expression of ASTs in vitro, and VEGF may increase the expression of cyclin D1. These finding suggest that glutamate may be a major molecule for regulating embryonic NSC proliferation and facilitate neural repair in the process of NSC transplants after brain injuries.

The decreased self-renewal potential of NPCs during human embryonic brain development with reduced activity of MAPKs

Study of neural progenitor cells (NPCs) is important for treatment of degerative diseases in central nervous system. One of the key questions in NPCs transplantation therapy is about the understanding of which stage of the NPCs in brain development is ideal. Herein we investigated survival, proliferation and apoptosis of NPCs from 12 w, 16 w and 20 w human embryonic brain, meanwhile, the phosphorylation of mitogen-activated protein kinases (MAPKs) signaling were analyzed. The results showed that the survival, proliferation and cell division of 16 w and 20 w human NPCs significantly decreased comparing with 12 w human NPCs in vitro; and the NPCs apoptosis remarkably increased. Phosphorylation of ERK1/2 of 16 w and 20 w NPCs significantly decreased comparing with 12 w human NPCs, however phosphorylation of p38 MAPK increased. NPCs proliferation increase when ERK1/2 signaling is activated by PMA. The results demonstrated that self-renewal potential of NPCs decreased in culture during human embryonic brain development, the activity of ERK signaling pathway were decreased, and suggest NPCs from 12-week fetuses might be better donor for cell transplantation during the period of 12-20 weeks because of their advantage on survival and proliferation.

Computational molecular phenotyping of retinal sheet transplants to rats with retinal degeneration

Retinal progenitor sheet transplants have been shown to extend neuronal processes into a degenerating host retina and to restore visual responses in the brain. The aim of this study was to identify cells involved in transplant signals to retinal degenerate hosts using computational molecular phenotyping (CMP). S334ter line 3 rats received fetal retinal sheet transplants at the age of 24-40 days. Donor tissues were incubated with slow-releasing microspheres containing brain-derived neurotrophic factor or glial cell-derived neurotrophic factor. Up to 265 days after surgery, eyes of selected rats were vibratome-sectioned through the transplant area (some slices stained for donor marker human placental alkaline phosphatase), dehydrated and embedded in Eponate, sectioned into serial ultrathin datasets and probed for rhodopsin, cone opsin, CRALBP (cellular retinaldehyde binding protein), l-glutamate, l-glutamine, glutathione, glycine, taurine, γ-aminobutyric acid (GABA) and DAPI (4',6-diamidino-2-phenylindole). In large transplant areas, photoreceptor outer segments in contact with host retinal pigment epithelium revealed rod and cone opsin immunoreactivity whereas no such staining was found in the degenerate host retina. Transplant photoreceptor layers contained high taurine levels. Glutamate levels in the transplants were higher than in the host retina whereas GABA levels were similar. The transplant inner nuclear layer showed some loss of neurons, but amacrine cells and horizontal cells were not reduced. In many areas, glial hypertrophy between the host and transplant was absent and host and transplant neuropil appeared to intermingle. CMP data indicate that horizontal cells and both glycinergic and GABAergic amacrine cells are involved in a novel circuit between transplant and host, generating alternative signal pathways between transplant and degenerating host retina.

Adolescent rat circadian activity is modulated by psychostimulants

Circadian pattern of activity regulates many aspects of mammalian physiology and behavior to particular times of the day by entraining the circadian clocks to external environmental signals. Since circadian rhythms are sensitive to many pharmacological agents, it is important to understand if the repetitive use of psychostimulants such as amphetamine will alter the circadian rhythm behavioral activity pattern. The present study uses male Sprague-Dawley rats to study the long-term effects of amphetamine on the locomotor circadian rhythm activity pattern. Rats were randomly assigned to a testing cage that recorded their locomotor activity nonstop for eleven days using the open field assay, as follows: one day of baseline activity was recorded and then the experimental group was injected with amphetamine (0.6mg/kg) for 6days, no treatment for 3days (i.e., washout days) and then re-challenged with amphetamine for one more day while the control group was treated similarly with saline. The Cosine Curve Statistical Analysis (CCSA) test was used to fit a 24-hour curve to activity pattern. Results indicate that repetitive daily amphetamine injections cause behavioral sensitization and a significant change of circadian rhythm of locomotor activity pattern, and elicit behavioral expectation to receive the drug or expression of withdrawal during the washout days. The results suggest that either changes in circadian rhythm caused sensitization and withdrawal or sensitization and withdrawal caused the change in circadian rhythm activity.

Methylphenidate and amphetamine modulate differently the NMDA and AMPA glutamatergic transmission of dopaminergic neurons in the ventral tegmental area

Behavioral and neurochemical studies suggest that the induction of behavioral sensitization to psychostimulants involves transient changes at the synapses of the ventral tegmental area's dopaminergic neurons (VTA-DA). Differences in the behavioral response to amphetamine (Amph) and methylphenidate (MPD) were observed. In an attempt to understand these behavioral differences at the neuronal level, the dose-response characteristics of these two psychostimulants on electrophysiologically identified VTA-DA neurons at the glutamatergic synapse were investigated. Miniature excitatory post-synaptic currents (mEPSCs) and electrically induced EPSCs were recorded from horizontal midbrain slices of rats that had been pretreated intraperitoneally (i.p.) with saline (control), Amph (2.5, 5.0, 10.0 or 20.0 mg/kg), or MPD (2.5, 5.0, 10.0 or 20.0 mg/kg) 24 h before the recording. Perfusion of Amph through the bath (2.5, 5.0, 10.0 or 20.0 microM) increased the frequency (p<0.01) and the amplitude (p<0.05) of mEPSCs in dose-response characteristics, while MPD perfusion through the bath (2.5, 5.0, 10.0, or 20.0 microM) increased only the frequency (p<0.05) of the mEPSC. Both psychostimulants increased the prefrontal cortex's (PFC) glutamatergic EPSC in the VTA-DA neurons. However, only the higher doses of MPD induced significant effects (p<0.05) on the N-methyl-D-aspartate (NMDA) receptor-mediated EPSC but had no effects on the EPSC mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA/kainate) receptors. Contrarily, Amph increased both kinds of mediated EPSC, but mainly the EPSC mediated by AMPA/kainate receptors (p<0.01). These electrophysiological differences could represent the underlying mechanism responsible for the differences of behavioral effects, such as behavioral sensitization, elicited by MPD and Amph.

Dopaminergic ventral tegmental neurons modulated by methylphenidate

Treatment of psychostimulants leads to the development of behavioral sensitization, an augmented behavioral response to drug re-administration. The induction of behavioral sensitization to psychostimulants such as amphetamine and cocaine occurs at the ventral tegmental area's dopaminergic neurons (VTA-DA). Currently, there is limited experimental data about the physiological properties of methylphenidate (MPD) on VTA-DA neurons. Behavioral and electrophysiological experiments using male rats were performed before and after MPD treatment. The behavioral experiment included dose-response (0.6, 2.5, and 10.0 mg/kg MPD) study to select the most effective dose for the electrophysiological study. Methylphenidate increased locomotion in typical dose response characteristics. Based on this experiment, the 10.0 mg/kg MPD was used in two types of electrophysiological recordings: 1) intracellular recording of neuronal activity performed on horizontal 275-300 microm brain slices and 2) whole-cell patch clamping before and after electrical stimulation to study post-synaptic currents on neurophysiologically identified VTA-DA neurons. Methylphenidate suppressed the neuronal activity of these neurons for 210 +/- 30 sec. Stimulation of the prefrontal cortex afferent fibers to these VTA-DA neurons in the presence of TTX, saclofen, and picrotoxin led to the conclusion that this input is mediated via NMDA and kainate/AMPA receptors and may participate to induce behavioral sensitization to psychostimulants.