Effect of inhibited ubiquitin-proteasome pathway on growth and activity of telomerase in esophageal carcinoma cells

AIM: To investigate the effect on growth and activity of telomerase in esophageal carcinoma cells by inhibiting ubiquitin-proteasome pathway(UPP). METHODS: The esophageal carcinoma cell strain Eca9706 was treated with MG-132 to inhibit its UPP specially. The effect of growth suppression on cells was evaluated with MTT assay, morphologic changes of cells were observed under microscope, cell cycle and apoptosis were detected by flow cytometry (FCM). DNA fragment analysis was used to confirm the presence of apoptosis. The activity of telomerase was detected. RESULTS: MG-132 had obvious inhibitory effect on the growth of Eca9706 cells in a dose and time-dependent manner. Obvious pathologic change of cells were observed under microscope, cells became round, small and exfoliating. The FCM analysis showed that the ratio of esophageal carcinoma cells of G₁ phase increased and a obviously apoptotic sub-G₁ peak was found. Agarose electrophoresis showed marked ladder. The activity of telomerase was obviously inhibited. CONCLUSIONS: MG-132 significantly inhibits the growth and the activity of telomerase of Eca 9706 cells. These findings indicate that inhibiting UPP is a new strategy for the treatment of esophageal carcinoma.     

Effect of salidroside on mitochondrial membrane potential during injury induced by hypoxia/hypoglycemia in cultured SH-SY5Y cells

AIM: To investigate the effects of salidroside on intracellular free calcium concentration [Ca²⁺]i, apoptosis, mitochondrial membrane potential (MMP) and activity during injury induced by hypoxia/hypoglycemia in cultured SH-SY5Y cells. METHODS: Mitochondrial activity was measured by methylthiazolyl tetrazolium test. MMP,[Ca²⁺]i and apoptosis were measured by flow cytometry. RESULTS: SH-SY5Y cells were cultured in a hypoxia/hypoglycemia condition for 2, 4, 6 and 12 h,[Ca²⁺]i and apoptosis rate significantly increased compared with control group (P<0.01). After hypoxia /hypoglycemia cultures, MMP and mitochondrial activity declined 29.17% (P<0.01) and 38.80% (P<0.01) at 2 h, 56.72% (P<0.01) and 63.58% (P<0.01) at 12 h, were lower than that in control group (P<0.01). Salidroside significantly decreased [Ca²⁺]i and apoptosis rate, and increased MMP and mitochondrial activity in hypoxia /hypoglycemia-treated SH-SY5Y cells. CONCLUSIONS: Salidroside might inhibit the decline in MMP and mitochondrial activity induced by hypoxia /hypoglycemia, and has an inhibitory effects on neuronal apoptosis. The mechanism might be related to inhibiting intracellular calcium overload.     

Influence of energetic metabolism alteration on cardiac myocyte apoptosis

Many studies indicate that apoptosis is involved in the progression of congestive heart failure. At present, mechanisms that mitochondria regulates cell apoptosis is widely accepted.Cardiac myocytes have abundant mitochondria, which plays an important role in maintenance of cell physiological function. Recent studies find that cardiac energy metabolic shifts occur as a normal response to diverse physiologic and dietary conditions and as a component of the pathophysiologic processes which accompany cardiac hypertrophy, heart failure, and myocardial ischemia.Both clinical and experimental studies show that cardiac function can be improved and apoptosis is inhibited by intervention in energetic metabolism of myocytes.     

Fibronectin supports endotoxemia mice survival

AIM:To study the preventive effect of fibronectin on hepatic failure induced by endotoxin in mice.METHODS:The survival rate was observed in endotoxemia mice injected with fibronectin from human plasma. The tissue damage and expression of TNFα, IL-1β, IL-6 mRNA in hepatocyte were detected by the methods of histology, ultrastructure, DNA fragementation and RT-PCR.RESULTS:①Fibronectin obviously reduced the mortality of endotoxemia mice sensitized by D-galactosamine(GalN). ②Histopathology showed that less necrosis occurred on the hepatocyte of endotoxemia mice injected with fibronectin, compared with saline control. ③Ultrastructure and DNA fragmentation showed fibronectin suppressed hepatocyte apoptosis induced by LPS. ④Fibronectin down-regulated the overexpression of TNFα, IL-1β, IL-6 mRNA on hepatocyte induced by LPS.CONCLUSION:Fibronectin supports endotoxemia mice surrival by down-regulating the expression of TNFα, IL-β, IL-6, it may be a potent therapy for endotoxemia.     

Protective effects of adenosine on cultured rat hippocampal neurons after oxygen-glucose deprivation

AIM:To investigate the protective effects of adenosine on cultured rat hippocampal neurons after oxygen-glucose deprivation.METHODS:The control and adenosine-treated hippocampal neurons cultured for 12 d were exposed to oxygen-glucose deprivation environment for 0.5-4 h and then cultured with original medium in normoxia for 24 h. The soma area, survival rate, effluxes of lactate dehydrogenase (LDH)and apoptosis of neurons were observed.RESULTS:The soma area, effluxes of lactate dehydrogenase from neurons and apoptosis were increased while survival rate of neurons was decreased after oxygen-glucose deprivation compared with those pre-oxygen-glucose deprivation. Compared with the control, after oxygen-glucose deprivation the soma area, effluxes of lactate dehydrogenase from neurons and apoptosis were decreased, however, the survival rate of neurons was increased in the adenosine group.CONCLUSION:Oxygen-glucose deprivation can lead to the severe damage of cultured hippocampal neurons, and adenosine can reduce neuronal injury induced by oxygen-glucose deprivation.     

Factors involved in regulation of polymorphonuclear neutrophils apoptosisin vitro

AIM:This study aimed at elucidated the possibility that prevent tissue from secondary injury by regulating polymorphonuclear neutrophil (PMN) apoptosisin vitro. METHODS:Neutrophils, isolated from peripheral blood, were incubated with sodium arsenite (Ars), tumor necrosis factor (TNF-α), interleukin-6 (IL-6), burned serum and traumatic serum, respectively. Apoptosis rate, expression of CD11b, respiratory burst and concentration of Ca²⁺ were then measured. RESULTS:The elevation of PMN apoptosis rate was Ars concentration dependent, but activated PMN became insensitive to Ars. IL-6 delayed PMN apoptosis (compared with control at 24 h,P＜0.05), inhibited CD11b expression. Burned and traumatic serum had more significant effects on PMN compared with IL-6. CONCLUSION:PMN was observed for the first time to resist spontaneous apoptosis when activated by LPS/TNF, and became insensitive to apoptosis-inducing substance Ars. IL-6, burned serum and traumatic serum could delay PMN apoptosis and recover PMN functions partly.     

Poly(ADP-ribose) polymerase and cell injury

Poly(ADP-ribose) polymerase (PARP) is a protein-modifying and nucleotide-polymerizing enzyme. As a critical element in DNA repair, PARP can be activated by DNA strand breaks. Excessive activation of PARP, however, can deplete NAD⁺and ATP, leads to cell death. Cleavage of PARP by activated caspase-3 play an important role in cell apoptosis.     

Advances in apoptosis induced by natural drugs

Apoptosis, a form of cell death, has generated considerable interest in recent years. Much progress has been made on the apoptosis induced by natural drgus, including component or mixture of plant, animal, mineral or marine materials. This review discusses some of the natural drugs that induce apoptosis and the possible mechanisms.