Effects of minocycline on apoptosis and angiogenesis-related protein expression in a rat model of intracerebral hemorrhage

In the present study, a rat model of non-traumatic intracerebral hemorrhage was established by type IV collagenase injection into the right globus pallidus. Bax and Bcl-2 expression in tissues surrounding hematomas was significantly increased within 14 days after injury, and it then gradually decreased. Vascular endothelial growth factor, Flk-1 and Flt-1 mRNA expression gradually increased over time. After intraperitoneal injection with minocycline, Bax expression was decreased 1 day after intracerebral hemorrhage. Flk-1 and Flt-1 mRNA expression was decreased after minocycline injection, but Bcl-2 expression was increased, and vascular endothelial growth factor mRNA expression was decreased between 4-14 days. These results indicated that protective effects of minocycline on nerve tissues were associated with increased Bcl-2 expression and decreased Bax expression in the early stage after intracerebral hemorrhage. In the late stage, minocycline downregulated vascular endothelial growth factor and its receptor expression to inhibit brain tissue self-repair.

Neuroprotective effects of total saponins from Rubus parvifolius L. on cerebral ischemia/reperfusion injury in rats

This study examines the neuroprotective effects and mechanisms of action of total saponins from Rubus parvifolius L. (TSRP) on focal cerebral ischemia and reperfusion injury in rats. Focal cerebral ischemia and reperfusion injury was performed in rats using the suture method. The results indicate that intragastric injection of TSRP, at 5, 10 and 20 mg/kg, could decrease neurological impairment, reduce cerebral infarct volume, diminish pathological changes, and significantly inhibit the apoptosis of neurons surrounding the ischemic area. In addition, TSRP upregulated the expression of the anti-apoptotic factor Bcl-2, at the protein and mRNA levels, and it downregulated the expression of the pro-apoptotic factor Bax, at the protein and mRNA levels. These findings indicate that TSRP protects against cerebral ischemia/reperfusion injury, and that it may do so by regulating the expression of Bcl-2 and Bax.

Evaluation of Bcl-2 Family Gene Expression in Hippocampus of 3, 4-methylenedioxymethamphetamine Treated Rats

OBJECTIVE

3,4-methylenedioxymethamphetamine (MDMA) is an illicit, recreational drug that causes cellular death and neurotoxicity. This study evaluates the effects of different doses of MDMA on the expression of apoptosis-related proteins and genes in the hippocampus of adult rats.

MATERIALS AND METHODS

In this expremental study,a total of 20 male Sprague Dawley rats (200-250 g ) were treated with MDMA (0, 5, 10, 20 mg/kg i.p. twice daily) for 7 days. Seven days after the last administration of MDMA, the rats were killed. Bax and Bcl-2 genes in addition to protein expressions were detected by western blot and reverse transcriptionpolymerase chain reaction (RT-PCR).Results were analyzed using one-way ANOVA and p≤0.05 was considered statistically significant.

RESULTS

Our results showed that MDMA caused dose dependent up-regulation of Bax and down-regulation of Bcl-2 in the hippocampus. There was a significant alteration in bcl-2 and bax genes density.

CONCLUSION

Changes in apoptosis-related proteins and respective genes relating to Bax and Bcl-2 might be involved in the molecular mechanism of MDMA-induced apoptosis.

Pro- and antiapoptotic markers in upper tract urothelial carcinoma associated with Balkan endemic nephropathy

The role of aristolochic acid in the etiology of Balkan endemic nephropathy (BEN) and associated upper-tract urothelial carcinoma (UTUC) has been recently confirmed. The aim of this study was to determine apoptosis-related marker(s) specific for BEN-associated UTUC. Present investigation included 105 patients with UTUC, 44 from BEN region and 61 control tumors. Altered expression of Survivin was more often present in BEN UTUC with high grade and solid growth (P < 0.005; P < 0.05) than in control tumors. Significantly lower expression of proapoptotic marker Bax was found in BEN tumors with high grade, high stage, necrosis, and without metaplastic change (P < 0.05; 0.05; 0.05; 0.05) compared to control tumors with the same features. Group (BEN-related/control), stage, growth pattern, and caspase 3 activity were significantly associated with the expression of Bax (P = 0.002, 0.034, 0.047, 0.028, resp.,). This investigation identifies Bax as specific marker of BEN-associated UTUC. Decrease of pro-apoptotic protein Bax together with alteration of Survivin may be indicative for specific disturbances of intrinsic apoptotic pathway in UTUC arising in endemic areas.

Antitumor activity of active components alignment isolated from Stellera chamaejasme L. in nude mice bearing subcutaneous BEL-7402 hepatoma

AIM: To assess the antitumor activity of the effective extracts of S. chamaejasme L. (ScL) in a murine model of hepatocellular carcinoma and to explore the possible mechanisms involved.

METHODS: A tumor transplantation model was generated in nude mice to study the antitumor activity of the active components alignment Zp1111 in vivo. Immunohistochemistry (IHC) was employed to investigate the expression of Bcl-2 and Bax in tumor tissue.

RESULTS: Zp1111 exhibited strong antitumor activity in BEL7402-bearing nude mice, with the relative tumor proliferation rate (T/C) less than 60% at a dose of 187.5 or 250 mg/kg. Treatment with Zp1111 up-regulated Bax expression and slightly down-regulated Bcl-2 expression in tumor tissue.

CONCLUSION: The active components alignment of ScL significantly reduces BEL-7402 proliferation in a dose-dependent manner in vivo possibly by up-regulating Bax expression to induce cell apoptosis.

Effect of Lecithin on d-Galactosamine Induced Hepatotoxicity Through Mitochondrial Pathway Involving Bcl-2 and Bax

Twenty four Wistar strain albino rats were used for the investigations. Lecithin 50 and 100 mg/kg b wt was administered for 1 week by oral route. Liver damage was induced by intra peritoneal administration of 400 mg/kg b wt d-galactosamine on the last day. At the end of the study animals were sacrificed and liver enzyme levels, histopathology, mitochondrial integrity, expression of p53, Bax and Bcl-2 mRNA levels were studied. Increases in the liver enzyme levels by d-GalN were significantly inhibited by pretreatment with lecithin. Histopathological observation further confirmed the hepatoprotective effect of lecithin. In addition, the disruption of mitochondrial membrane, up regulation of Bax and down regulation of Bcl-2 mRNA levels in the liver of d-GalN intoxicated rats were effectively prevented by pretreatment with lecithin. The results of the present study validate our conviction that d-GalN causes hepatic damage via mitochondrial pathway involving Bax and Bcl-2.

Network modeling of CDF treated pancreatic cancer cells reveals a novel c-myc-p73 dependent apoptotic mechanism

Systems biology and molecular network modeling are important tools that are finding application in anti-cancer drug discovery. These technologies can be utilized to map and evaluate the entire set of pathways modulated by drugs in cancer cells without loosing key details. Such integrated approaches are especially useful in understanding the mechanism of action of agents that do not have a defined target. Our novel compound CDF (a synthetic analogue of curcumin), is one such multi-targeted agent with proven anti-cancer activity in vitro and in vivo. However, its mechanism of action is not fully understood, and thus a thorough analysis of key pathways targeted by CDF would be important for developing targeted and tailored therapy in the future. Applying Ingenuity Pathway Analysis (IPA), we have mapped the pathways altered by CDF treatment of BxPC-3 pancreatic cancer (PC) cells. Illumina HT-12 microar-rays were performed on RNA extracted from CDF treated cells. IPA analysis of gene expression at early time point (24 hrs) revealed deregulation of genes in the c-Myc hub. Western blot analysis validated the activation of c-Myc, p73 and its downstream pro-apoptotic effector Bax with simultaneous down-regulation of Bcl-2 in two distinct pancreatic cancer cell lines (BxPC-3 and Colo-357). In order to further delineate the role of c-Myc in inducing apoptosis, siRNA silencing technology was used. As expected, c-Myc siRNA knockdown resulted in abrogation of the growth inhibitory and apoptotic potential of CDF. In conclusion, our results demonstrate a novel c-Myc driven apoptotic network activated by CDF in PC cells that is independent of wild-type p53, and thus warrants further investigation on the clinical utility of CDF.

Curcumin Induces Apoptosis in EJ Bladder Cancer Cells via Modulating C-Myc and PI3K/Akt Signaling Pathway

Background

Cancer chemopreventive agent curcumin has been shown to possess cell growth inhibition and apoptosis induction properties in several types of cancer. However, the detailed molecular mechanisms of the compound remain far from clear in EJ bladder cancer cells.

Methods

The effect of curcumin on EJ cell growth and apoptosis was detected by MTT assays and flow cytometry. The phosphorylation levels of PTEN, PDK1, Akt, GSK-3β, c-Raf, and Bad and the expression levels of c-myc, Bax, Bcl-2, caspase-9, caspase-7, caspase-3, and PARP following curcumin administration were examined by immunoblots.

Results

Curcumin suppressed the growth of EJ cells in a time and concentration dependent manner. Immunoblot showed that curcumin increased expression levels of c-myc and inhibited the activation of PI3K/Akt pathway in a time-dependent manner in EJ cells. Activation of PTEN, GSK-3β, c-Raf, caspase-9, caspase-7, and caspase-3, cleavage of PARP, upregulation of Bad and Bax, and downregulation of Akt and Bcl-2 were also found in curcumin-treated EJ cells.

Conclusions

These findings establish a mechanistic linkup or interaction between c-myc, Bax, Bad, Bcl-2, caspase cascades, PI3K/Akt pathway and curcumin- induced apoptosis of EJ cells, suggesting that c-myc and PI3K/Akt signaling pathway play important roles in curcumin-induced apoptosis of EJ bladder cancer cells.

Differential expression of Bcl-2 and Bax during gastric ischemia-reperfusion of rats

AIM: To investigate expression of Bcl-2 and Bax in gastric ischemia-reperfusion (GI-R) and involvement of extracellular signal-regulated kinase (ERK) 1/2 activation.

METHODS: The GI-R model was established by ligature of the celiac artery for 30 min and reperfusion in Sprague-Dawley rats. Rats were assigned to groups in accordance with their evaluation period: control, 0, 0.5, 1, 3, 6, 24, 48, and 72 h. Expression and distribution of Bcl-2 and Bax proteins were analyzed by immunohistochemistry and western blotting in gastric tissue samples after sacrifice.

RESULTS: Compared with controls, the percentage of positive cells and protein levels of Bcl-2 decreased in the early phases of reperfusion, reached its minimum at 1 h (P < 0.05); it then increased, reaching its peak at 24 h of reperfusion (P < 0.05). The pattern of Bax expression was opposite to that of Bcl-2. Bax expression increased after reperfusion, with its peak at 1 h of reperfusion (P < 0.05), and then it decreased gradually to a minimum at 24 h after reperfusion (P < 0.05). On the other hand, inhibition of activation of ERK1/2 induced by PD98059, a specific upstream MEK inhibitor, had significant effects on Bcl-2 and Bax in GI-R. Compared with GI-R treatment only at 3 h of reperfusion, PD98059 reduced the number of Bcl-2 positive cells (0.58% of R3h group, P < 0.05) and Bcl-2 protein level (74% of R3h group, P < 0.05) but increased the number of Bax-positive cells (1.33-fold vs R3h group, P < 0.05) and Bax protein level (1.35-fold of R3h group, P < 0.05).

CONCLUSION: These results indicated that the Bcl-2 and Bax played a pivotal role in the gastric mucosal I-R injury and repair by activation of ERK1/2.

Effects of plumbagin on apoptosis and expression of apoptosis-related proteins in human hepatic stellate cells

AIM: To investigate the effects of plumbagin on leptin-induced apoptosis and expression of apoptosis-related protein in human hepatic satellite cells (HSC-LX2) and to explore the anti-fibrotic mechanism of plumbagin.

METHODS: After HSC-LX2 cells were cultured in vitro, stimulated with leptin for 24 h, and treated with different concentrations of plumbagin for 24 h, cell apoptosis was detected by flow cytometry; cell ultrastructure was observed by transmission electron microscopy; and the protein expression of P53, Bax, and Bcl-2 was determined by immunocytochemistry.

RESULTS: HSC-LX2 cells were divided into 6 groups: untreated cells (blank control group), those treated with 100 μg/L leptin (leptin control group), those treated with both leptin and colchicin (colchicin group), those treated with both leptin and 2, 8 or 16 μmol/L plumbagin (2, 8, 16 μmol/L plumbagin group). The apoptosis rate of HSC-LX2 cells was significantly increased in plumbagin groups. The apoptosis rates of cells treated with 8 or 16 µmol/L plumbagin or colchicine were significantly higher than those of the blank control group and leptin group (5.21% ± 0.41%, 8.10% ± 0.63%, 10.1% ± 1.08% vs 1.40% ± 0.13%, 2.85% ± 0.21%, all P < 0.01). Transmission electron microscopy revealed varying degrees of apoptosis in the leptin group or plumbagin groups. Immunocytochemistry analysis showed that the protein expression levels of P53 and Bax were higher and that of Bcl-2 was lower in plumbagin groups than in the leptin group (Bax: 85.24 ± 1.08, 86.35 ± 1.12, 91.13 ± 1.13 vs 56.63 ± 0.94; P53: 25.32 ± 0.6, 38.14 ± 0.71, 41.19 ± 0.72 vs 19.25 ± 0.46; Bcl-2: 32.12 ± 0.43, 27.71 ± 0.38, 21.46 ± 0.46 vs 44.51 ± 0.56, all P < 0.05 or 0.01).

CONCLUSION: Plumbagin can significantly accelerate leptin-induced apoptosis of HSC-LX2 cells possibly by up-regulating P53 and Bax expression and down-regulating Bcl-2 expression.

Expression of ErbB4 in the apoptotic neurons of Alzheimer's disease brain

Neuregulin-1 (NRG1) signaling participates in the synaptic plasticity, maintenance or regulation of adult brain. Although ErbB4, a key NRG1 receptor, is expressed in multiple regions in the adult animal brain, little is known about its localization in Alzheimer's disease (AD) brains. We previously reported that ErbB4 immunoreactivity showed regional difference in the hippocampus of age-matched control. In the present paper, immunohistochemical characterization of the distribution of ErbB4 receptor in the hippocampus relative to pathology staging were performed in age-matched control (Braak stage 0, n=6) and AD (Braak stage I/V, n=10). Here, we found that ErbB4 immunoreactivity was significantly increased in apoptotic hippocampal pyramidal neurons in the brains of AD patients, compared to those of age-matched control subjects. In AD brains, ErbB4 immunoreactivity was demonstrated to colocalize with the apoptotic signal Bax in apoptotic hippocampal pyramidal neurons. These results suggest that up-regulation of ErbB4 immunoreactivity in apoptotic neuron may involve in the progression of pathology of AD.

The neuroprotective effect of recombinant human erythropoietin via an antiapoptotic mechanism on hypoxic-ischemic brain injury in neonatal rats

PURPOSE

The neuroprotective effects of erythropoietin (EPO) have been recently shown in many animal models of brain injury, including hypoxic-ischemic (HI) encephalopathy, trauma, and excitotoxicity; however, limited data are available for such effects during the neonatal periods. Therefore, we investigated whether recombinant human EPO (rHuEPO) can protect against perinatal HI brain injury via an antiapoptotic mechanism.

METHODS

The left carotid artery was ligated in 7-day-old Sprague-Dawley (SD) rat pups (in vivo model). The animals were divided into 6 groups: normoxia control (NC), normoxia sham-operated (NS), hypoxia only (H), hypoxia+vehicle (HV), hypoxia+rHuEPO before a hypoxic insult (HE-B), and hypoxia+rHuEPO after a hypoxic insult (HE-A). Embryonic cortical neuronal cell culture of SD rats at 18 days gestation (in vitro model) was performed. The cultured cells were divided into 5 groups: normoxia (N), hypoxia (H), and 1, 10, and 100 IU/mL rHuEPO-treated groups.

RESULTS

In the in vivo model, Bcl-2 expressions in the H and HV groups were lower than those in the NC and NS groups, whereas those in the HE-A and HE-B groups were greater than those of the H and HV groups. The expressions of Bax and caspase-3 and the ratio of Bax/Bcl-2 were in contrast to those of Bcl-2. In the in vitro model, the patterns of Bcl-2, Bax, and caspase-3 expression and Bax/Bcl-2 ratio were similar to the results obtained in the in vivo model.

CONCLUSION

rHuEPO exerts neuroprotective effect against perinatal HI brain injury via an antiapoptotic mechanism.

Induction of hypoxia-inducible factor-1α inhibits drug-induced apoptosis in the human leukemic cell line HL-60

BACKGROUND

Leukemic cells originate from hypoxic bone marrow, which protects them from anti-cancer drugs. Although many factors that cause drug resistance in leukemic cells have been studied, the effect of hypoxia on drug-induced apoptosis is still poorly understood.

METHODS

In this study, we examined the effect of hypoxia on anti-leukemic drug resistance in leukemic cell lines treated with cobalt chloride (CoCl(2)), a hypoxia-mimetic agent. Cellular proliferation was evaluated using the methyl thiazolyl tetrazolium (MTT) assay. Flow cytometry analysis and western blots were performed to investigate apoptosis-related proteins.

RESULTS

Unlike its previously known apoptotic effect, the expression of HIF-1α increased the survival rate of human promyelocytic leukemia HL-60 cells when these cells were exposed to anti-leukemic drugs; these effects were mediated by heat-shock protein HSP70 and the pro-apoptotic protein Bax.

CONCLUSION

These findings may provide new insights for understanding the mechanisms underlying hypoxia and for designing new therapeutic strategies for acute myeloid leukemia.

Protective Role of Catechin on d-Galactosamine Induced Hepatotoxicity Through a p53 Dependent Pathway

Objective of this study was to obtain a better understanding of the mechanism responsible for the d-galactosamine (d-GalN) induced hepatotoxicity and to study the effect of catechin against d-GalN induced hepatotoxicity. Catechin 50 and 100 mg/kg b.wt was administered for 1 week by oral route. Liver damage was induced by intra-peritoneal administration of 400 mg/kg b.wt d-galactosamine on the last day of catechin treatment. At the end of treatment all animals were killed and liver enzyme levels were estimated. Dissected hepatic samples were used for histopathology, RNA isolation, expression studies of Bax, Bcl-2 and p53 mRNA levels and mitochondrial membrane potential studies. We found that increases in the liver enzyme activity and decrease in antioxidant enzyme activity by d-GalN were significantly restricted by oral pretreatment with catechin. Disruption of mitochondrial membrane potential, up regulation of p53, Bax and down regulation of Bcl-2 mRNA levels in the liver of d-GalN intoxicated rats were effectively prevented by pretreatment with catechin.

Antitumor effect of matrine in human hepatoma G2 cells by inducing apoptosis and autophagy

AIM: To study the antitumor effect of matrine in human hepatoma G2 (HepG2) cells and its molecular mechanism involved in antineoplastic activities.

METHODS: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect viability of HepG2 cells. The effect of matrine on cell cycle was detected by flow cytometry. Annexin-V-FITC/PI double staining assay was used to detect cellular apoptosis. Cellular morphological changes were observed under an inverted phase contrast microscope. Transmission electron microscopy was performed to further examine ultrastructural structure of the cells treated with matrine. Monodansylcadaverine (MDC) staining was used to detect autophagy. Whether autophagy is blocked by 3-methyladenine (3-MA), an autophagy inhibitor, was evaluated. Expression levels of Bax and Beclin 1 in HepG2 cells were measured by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: Matrine significantly inhibited the proliferation of HepG2 cells in a dose- and time-dependent manner, and induced G1-phase cell cycle arrest and apoptosis of HepG2 cells in a dose-dependent manner. The total apoptosis rate was 0.14% for HepG2 cells not treated with matrine. In contrast, the apoptosis rate was 28.91%, 34.36% and 38.80%, respectively, for HepG2 cells treated with matrine at the concentration of 0.5, 1.0 and 2.0 mg/mL. The remarkable morphological changes were observed under an inverted phase contrast microscope. Abundant cytoplasmic vacuoles with varying sizes were observed in HepG2 cells treated with matrine. Furthermore, vacuolization in cytoplasm progressively became larger and denser when the concentration of matrine was increased. Electron microscopy demonstrated formation of abundant autophagic vacuoles in HepG2 cells after matrine treatment. When the specific autophagic inhibitor, 3-MA, was applied, the number of autophagic vacuoles greatly decreased. MDC staining showed that the fluorescent density was higher and the number of MDC-labeled particles in HepG2 cells was greater in matrine treatment group than in control group. Fewer autophagic vacuoles were observed in the combined 3-MA and matrine treatment group when 3-MA was added before matrine treatment, indicating that both autophagy and apoptosis are activated when matrine-induced death of hepatoma G2 cells occurs. Real-time quantitative RT-PCR revealed that the expression levels of Bax gene, an apoptosis-related molecule, and Beclin 1 gene which plays a key role in autophagy were higher in matrine treatment group than in control group, indicating that Beclin 1 is involved in matrine-induced autophagy and the pro-apoptotic mechanism of matrine may be related to its upregulation of Bax expression.

CONCLUSION: Matrine has potent antitumor activities in HepG2 cells and may be used as a novel effective reagent in treatment of hepatocellular carcinoma.

A single nucleotide polymorphism in the Bax gene promoter affects transcription and influences retinal ganglion cell death

Pro-apoptotic Bax is essential for RGC (retinal ganglion cell) death. Gene dosage experiments in mice, yielding a single wild-type Bax allele, indicated that genetic background was able to influence the cell death phenotype. DBA/2J^Bax+/− mice exhibited complete resistance to nerve damage after 2 weeks (similar to Bax^−/− mice), but 129B6^Bax+/− mice exhibited significant cell loss (similar to wild-type mice). The different cell death phenotype was associated with the level of Bax expression, where 129B6 neurons had twice the level of endogenous Bax mRNA and protein as DBA/2J neurons. Sequence analysis of the Bax promoters between these strains revealed a single nucleotide polymorphism (T^129B6 to C^DBA/2J) at position −515. A 1.5- to 2.5-fold increase in transcriptional activity was observed from the 129B6 promoter in transient transfection assays in a variety of cell types, including RGC5 cells derived from rat RGCs. Since this polymorphism occurred in a p53 half-site, we investigated the requirement of p53 for the differential transcriptional activity. Differential transcriptional activity from either 129B6 or DBA/2J Bax promoters were unaffected in p53^−/− cells, and addition of exogenous p53 had no further effect on this difference, thus a role for p53 was excluded. Competitive electrophoretic mobility-shift assays identified two DNA–protein complexes that interacted with the polymorphic region. Those forming Complex 1 bound with higher affinity to the 129B6 polymorphic site, suggesting that these proteins probably comprised a transcriptional activator complex. These studies implicated quantitative expression of the Bax gene as playing a possible role in neuronal susceptibility to damaging stimuli.

Effects of paeonol and 5-FU on the proliferation and apoptosis of human esophageal carcinoma EC9706 cells

AIM: To investigate the effects of paeonol alone or in combination with 5-fluorouracil (5-FU) on the proliferation and apoptosis of human esophageal carcinoma EC9706 cells.

METHODS: Six different concentrations of paeonol (7.81, 15.63, 31.25, 62.50, 125.00 and 250.00 mg/L, respectively), three different concentrations of 5-FU (12.50, 25.00 and 50.00 mg/L, respectively), and paeonol (31.25 mg/L) in combination with 5-FU (12.50 mg/L) were used to treat EC9706 cells for different durations (24, 48 and 72 h). Untreated EC9706 cells were used as the control group. The proliferation of EC9706 cells was detected by methyl thiazolyl tetrazolium (MTT) assay after treatment for different durations. After treatment of EC9706 cells with paeonol at concentrations of 31.25, 62.50, 125.00 and 250.00 mg/L for 72 hours, the cell cycle was analyzed by flow cytometry; cell morphological changes were observed using an inverted microscope; the morphology of apoptotic cells was observed by HE staining and light microscopy. The expression of apoptosis-associated proteins Bcl-2 and Bax was detected by immunocytochemistry after treatment of EC9706 cells with paeonol (31.25 mg/L) and 5-FU (12.50 mg/L), alone or in combination, for 48 hours.

RESULTS: Paeonol or 5-FU could significantly inhibit the proliferation of EC9706 cells in a concentration- and time-dependent manner (both P < 0.05). Paeonol in combination with 5-FU showed more significant inhibitory effects on the proliferation of EC9706 cells when compared with paeonol or 5-FU alone (both P < 0.05). Paeonol (125.00 mg/L) treatment altered the cell cycle distribution of EC9706 cells: the percentages of cells in G₀/G₁ and G₂/M phases decreased, while that of cells in S phase increased (G₀/G₁ phase: 21.18% ± 2.28% vs 62.17% ± 5.23%; G₂/M phase: 0.76% ± 0.54% vs 9.92% ± 3.10%; S phase 78.06% ± 2.82% vs 27.91% ± 2.13%; all P < 0.05). Typical apoptotic changes were observed in EC9706 cells treated with paeonol. Both paeonol and 5-FU down-regulated the expression of Bcl-2 and up-regulated the expression of Bax, which was especially prominent in the combination group (2.21 ± 0.14 vs 5.67 ± 0.30 and 4.22 ± 0.34; 8.55 ± 0.33 vs 3.90 ± 0.27 and 6.28 ± 0.26, all P < 0.05).

CONCLUSION: Paeonol can significantly inhibit the proliferation and induce the apoptosis of human esophageal carcinoma EC9706 cells. Paeonol in combination with 5-FU shows a synergistic effect in suppressing the proliferation and promoting the apoptosis of EC9706 cells.

Targeting of Helicobacter pylori VacA to mitochondria

One of the major virulence factors of Helicobacter pylori is the vacuolating toxin vaca. It has been known for a long time that the toxin enters host cells by endocytosis. On the other hand there is ample evidence that vaca is able to trigger apoptosis and this effect has been attributed in part to interactions with mitochondria. However, for 10 years it was difficult to reconcile the obvious accumulation of vaca in endosomes with mitochondrial targeting. The accessibility of the mitochondria to the toxin was enigmatic. In our new study, we investigated the activities of p34, the toxic subunit of vaca, in more detail. We found that the p34 N-terminus carries a unique targeting sequence for import into mitochondria and for insertion into the mitochondrial inner membrane. By forming an anion channel in this membrane, the toxin has the ability to interfere directly with mitochondrial functions. Taking into account additional results from independent studies, we discuss the implications of our findings with respect to intracellular traffic, the remarkable possibility of a direct transfer of VacA from endosomes to mitochondria and vaca-dependent cell death.

Knockdown of RCAN1.4 Increases Susceptibility to FAS-mediated and DNA-damage-induced Apoptosis by Upregulation of p53 Expression

Despite the potential importance of the human regulator of calcineurin 1 (RCAN-1) gene in the modulation of cell survival under stress, little is known about its role in death-inducing signal pathways. In this study, we addressed the effects of RCAN1.4 knockdown on cellular susceptibility to apoptosis and the activation of death pathway proteins. Transfection of siRNAs against RCAN1.4 resulted in enhanced Fas- and etoposide-induced apoptosis, which was associated with increased expression and translocation of Bax to mitochondria. Our results suggest that enhanced expression and activation of p53 was responsible for the upregulation of Bax and the increased sensitivity to apoptosis, which could be reversed by p53 knockdown. To explain the observed upregulation of p53, we propose a downregulation of the ubiquitin ligase HDM2, probably translationally. These findings show the importance of appropriate RCAN1.4 expression in the modulation of cell survival and reveal a link between RCAN1.4 and p53.

Celecoxib inhibits the growth of gastric cancer cells not expressing COX-2 in vitro

AIM: To investigate whether celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, can induce the apoptosis of human gastric cancer MGC-803 cells not expressing COX-2 and explore potential mechanisms involved.

METHODS: Cell proliferation was measured by methyl thiazolyl tetrazolium (MTT) assay. Cell cycle distribution was measured by flow cytometry. The expression of Bax and Bcl-2 proteins was detected by immunohistochemistry. The secretion of vascular endothelial growth factor (VEGF) protein was detected by enzyme-linked immunosorbant assay (ELISA). The expression of COX-2 and nuclear factor-κB (NF-κB) proteins was examined by Western blot.

RESULTS: The expression of COX-2 protein was not detected in MGC-803 cells. Celecoxib could inhibit the proliferation and induce the apoptosis of MGC-803 cells in a dose- and time-dependent manner. The reduced rates of growth in cells treated with celecoxib at concentrations of 25, 50, 75 and 100 μmol/L for 24 h were 48.4%, 54.9%, 58.69% and 63.80%, respectively. Flow cytometry analysis showed that the apoptotic rate of MGC-803 cells treated with celecoxib was 4%, and a sub-G1 cell peak was present. Celecoxib inhibited the secretion of VEGF protein in MGC-803 cells. With the prolongation of the duration of incubation with celecoxib, the level of secreted VEGF decreased. Celecoxib could also inhibit the secretion of NF-κB protein by inhibiting its expression in a time-dependent manner.

CONCLUSION: Celecoxib inhibits growth and induces apoptosis of MGC-803 cells in a COX-2-independent manner. Celecoxib exerts its antitumor effects possibly by inhibiting the expression of NF-κB protein.

Expression of Bcl-2 and Bax in hepatocytes in nonalcoholic fatty liver disease

AIM: To investigate the role of apoptosis-regulated proteins Bcl-2 and Bax in the progression of nonalcoholic fatty liver disease (NAFLD) in rats.

METHODS: An experimental rat model of NAFLD was established by feeding rats a fat-rich diet (NAFLD group). Control animals were fed a standard diet (control group). Hepatic steatosis, inflammation and fibrosis were graded by routine HE staining of liver sections. The expression levels of Bcl-2 and Bax proteins in the liver were determined by Western blot.

RESULTS: The NAFLD model rats exhibited mild steatosis at week 4, simple fatty liver at week 8, and severe steatohepatitis with fibrosis at week 12. Western blot analysis showed that hepatic expression of Bax protein in the NAFLD group was more pronounced from week 4, and continued to rise at weeks 8 and 12 when compared with the control group (0.61 ± 0.03, 0.78 ± 0.03 and 1.02 ± 0.03 vs 0.51 ± 0.03, respectively; all P < 0.01), while the expression of Bcl-2 decreased with the progression of fatty liver (0.39 ± 0.01, 0.28 ± 0.01 and 0.15 ± 0.01 vs 0.52 ± 0.01, respectively; all P < 0.01). Bcl-2/Bax ratio in the NAFLD group decreased in a time-dependent manner, particularly prominent at week 12.

CONCLUSION: NAFLD may cause increased hepatic expression of Bax but decreased expression of Bcl-2, and the decrease in Bcl-2/Bax ratio may accelerate hepatocyte apoptosis.

Changes in the balance between proliferation and apoptosis during the progression of malignancy in thyroid tumours

The aim of this study was to gain better insight into molecular changes which reflect disturbances in the balance between proliferation and apoptosis during progression of thyroid malignancy from papillary microcarcinoma (PMC) via clinically manifest papillary carcinoma (PTC) to anaplastic carcinoma (ATC). The apoptosis related molecules (Bcl-2, Bax) and proliferation related marker (PCNA) were analysed immunohistochemically in 120 archival cases comprising PMC (n=34), PTC (n=52) and ATC (n=34). In addition, in situ apoptotic cell death was analysed by the TUNEL method. The average Bcl-2 staining score did not differ between PMC and PTC (p>0.05), but was significantly lower in ATC (p<0.05).The Bax score was higher in PTCs and ATCs than in PMCs (p<0.05). Due to these changes, the Bcl-2/Bax ratio showed a marked decrease from PMC to ATC (p<0.05), while proliferation activity increased significantly from PTC to ATC (p<0.05). Despite high Bax expression, the rate of apoptotic cell death was low in the investigated carcinomas, especially in ATC, i.e. the increase in proliferative activity was not counterbalanced with appropriate cell death. Differences were found in the expression of apoptotic molecules (Bcl-2 and Bax), their ratio (Bcl-2 /Bax) and in the rate of apoptotic cell death and proliferative activity between PMC, PTC and ATC, indicating that disturbances in the balance between apoptosis and proliferation, in favour of the latter, occur gradually during the progression of malignancy in thyroid tumours.

Protective effect of Radix Astragali injection on immune organs of rats with obstructive jaundice and its mechanism

AIM: To observe the protective effect of Radix Astragali injection on immune organs (lymph nodes, spleen and thymus) of rats with obstructive jaundice (OJ) and its mechanism.

METHODS: SD rats were randomly divided into sham-operation group, model control group and Radix Astragali treatment group. On days 7, 14, 21 and 28 after operation, mortality rate of rats, pathological changes in immune organs, expression levels of Bax and nuclear factor (NF)-κB p65 proteins, apoptosis indexes and serum tumor necrosis factor (TNF)-α level in spleen and thymus were observed, respectively.

RESULTS: Compared to model control group, the number of dead OJ rats in Radix Astragali treatment group decreased (P > 0.05). The TNF-α level (27.62 ± 12.61 vs 29.55 ± 18.02, 24.61 ± 9.09 vs 31.52 ± 10.95) on days 7 and 21, the pathological severity score for spleen [0.0 (0.0) vs 0.0 (2.0) on days 7 and 14 and for lymph nodes [0.0 (1.0) vs 1.0 (2.0), 1.0 (0.0) vs 2.0 (1.0)] on days 21 and 28, the product staining intensity and positive rate of Bax protein in spleen [0.0 (0.0) vs 1.0 (2.0), 0.0 (1.0) vs 2.0 (1.5) and thymus [0.0 (0.0) vs 1.0 (2.0), 0.0 (1.0) vs 2.0 (1.5)] on days 14 and 28, the apoptotic indexes [0.0 (0.0) vs 0.0 (0.01)] in spleen and thymus [0.0 (0.0) vs 0.0 (0.01) on days 14 and 21 were significantly lower in Radix Astragali treatment group than in model control group (P < 0.05).

CONCLUSION: Radix Astragali has protective effects on immune organs of OJ rats by relieving the pathological changes in immune organs, reducing TNF-α level and inhibiting Bax expression and apoptosis in spleen and thymus.

Exogenous phosphatidylethanolamine induces apoptosis of human hepatoma HepG2 cells via the bcl-2/bax pathway

AIM: To investigate the signaling pathways implicated in phosphatidylethanolamine (PE)-induced apoptosis of human hepatoma HepG2 cells.

METHODS: Inhibitory effects of PE on human hepatoma HepG2 cells were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell cycle, apoptosis and mitochondrial transmembrane potential (ΔΨm) were analyzed by flow cytometry. Immunocytochemical assay and Western blotting were used to examine Bcl-2, Bax and caspase-3 protein levels in HepG2 cells treated with PE.

RESULTS: PE inhibited the growth of HepG2 cells in a dose- and time- dependent manner. It did not affect the cell cycle, but induced apoptosis. PE significantly decreased δΨm at 0.25, 0.5 and 1 mmol/L, respectively, suggesting that PE induces cell apoptosis by decreasing the mitochondrial transmembrane potential. The Bcl-2 expression level induced by different concentrations of PE was lower than that in control groups. However, the Bax expression level induced by PE was higher than that in the control group. Meanwhile, PE increased the caspase-3 expression in a dose- and time-dependent manner.

CONCLUSION: Exogenous PE induces apoptosis of human hepatoma HepG2 cells via the bcl-2/bax pathway.

Expression of apoptosis-related Bcl-2-family and P53 in human adenocarcinoma of the pancreas

AIM: To investigate the relationships between P53 and Bcl-2 family (Bcl-2, Bax, Bcl-xL, Bcl-xS) expression and apoptosis in human pancreatic carcinoma (PC).

METHODS: The immunohistochemical method was used to detect the expression of P53 protein in a total of 35 patients with PC. The patients were divided into two groups, group 1 with immunonegative P53 (18 cases) and group 2 with immunopositive (17 cases). The expressions of P53, Bcl-2, Bax, Bcl-xL, and Bcl-xS in both groups were detected by Western blot. The apoptosis index (AI) of group 1 was determined by terminal deoxynucleotidyltransferase-mediated UTP end-labeling (TUNEL).

RESULTS: Bcl-2 was remarkably up-regulated in group 2 but down-regulated in group 1 (P = 0.047). Expressions of both Bax and Bcl-xL proteins were up-regulated in those two groups (P = 0.274, 0.334). Bcl-xS was remarkably down-regulated in group 2 but up-regulated in group1 (P = 0.01). The AI of both groups were 12.1 ± 2.47 and 9.1 ± 1.48, respectively (P = 0.023), no correlations were found between AI and expression of Bcl-2 family members, but marked correlations were noted between AI and the Bcl-2/bax ratios (P < 0.01).

CONCLUSION: Bcl-2 family is a group of anti-apoptotic proteins, and Bcl-xS is a pro-apoptotic protein. Both of them are dependent on the regulation of P53 which modulates apoptosis mainly through modifying Bcl-2/Bax ratios.

Endothelin A receptor blockade influences apoptosis and cellular proliferation in the developing rat kidney

Endothelin systems are believed to play important roles in the emergence and maintenance of functions of various organs during perinatal development, including the kidney. The present study was designed to investigate the roles of endothelin systems on physiologic renal growth and development. Newborn rat pups were treated with either Bristol-Myers Squibb-182874 (30 mg/kg/day), a selective endothelin A receptor (ET(A)R) antagonist, or vehicle for 7 days. To identify cellular changes, kidneys were examined for apoptotic cells by terminal deoxynucleotide transferase-mediated nick-end labeling stain and proliferating cell nuclear antigen (PCNA) by immunohistochemical (IHC) stain. To clarify the molecular control of these processes, immunoblots and reverse transcriptase-polymerase chain reaction for Clusterin, Bcl-2, Bcl-X(L), Bax, and p53 were performed. ETAR antagonist treatment resulted in reduced kidney weights, decreased PCNA-positive proliferating cells, and increased apoptotic cells. The protein expressions of renal Bcl-X(L) and Bax in the ETAR antagonist-treated group were significantly decreased, whereas the mRNA expressions of these genes were not changed. There were no significant differences in the expressions of Clusterin, Bcl-2, and p53. In conclusion, inhibition of endogenous endothelins impairs renal growth, in which decreased cellular proliferation, increased apoptosis and decreased expressions of renal Bcl-X(L) and Bax are possibly implicated.

Ponicidin inhibits monocytic leukemia cell growth by induction of apoptosis

In this study two monocytic leukemia cell lines, U937 and THP-1 cells, were used to investigate the anti-proliferation effects caused by ponicidin. Cell viability was measured by an MTT assay. Cell apoptosis was assessed by flow cytometry as well as DNA fragmentation analysis. Cell morphology was observed using an inverted microscope and Hoechst 33258 staining. RT-PCR and Western blot analysis were used to detect survivin as well as Bax and Bcl-2 expressions after the cells were treated with different concentrations of ponicidin. The results revealed that ponicidin could inhibit the growth of U937 and THP-1 cells significantly by induction of apoptosis. The suppression was in both time- and dose-dependent manner. Marked morphological changes of cell apoptosis were observed clearly after the cells were treated with ponicidin for 48 approximately 72 h. RT-PCR and Western blot analysis demonstrated that both survivin and Bcl-2 expressions were down-regulated remarkably while Bax expression remained constant before and after apoptosis occurred. We therefore conclude that ponicidin has significant anti-proliferation effects by inducing apoptosis on leukemia cells in vitro, downregulation of survivin as well as Bcl-2 expressions may be the important apoptosis inducing mechanisms. The results suggest that ponicidin may serve as potential therapeutic agent for leukemia.

Effect of angiopoietin-1 on expression of Bcl-2 and Bax in human gastric cancer cells

AIM: To explore the possible mechanism underlying the inhibitory effect of angiopoietin-1 (Ang1) on apoptosis of human gastric cancer cells MGC-803.

METHODS: The human gastric cancer cells (MGC-803) were cultured with Ad-Ang1 and Ad-GFP at proper multiplicity of infection (MOI = 20) and the expression levels of bcl-2 mRNA, bax mRNA and Bcl-2 protein, Bax protein were determined using RT-PCR and Western blot, respectively.

RESULTS: The expression levels of Bcl-2 mRNA and its protein were higher in Ad-Ang1 transfected group than in Ad-GFP transfected group and control group (0.609 ± 0.01 vs 0.462 ± 0.02, 0.609 ± 0.01 vs 0.475 ± 0.02, both P < 0.05). There was no significant difference between Ad-GFP group and control group. However, compared with the other groups, the expression level of Bax mRNA and its protein in the MGC-803 cells treated with Ad-Ang1 were significantly down-regulated (0.313 ± 0.04vs 0.413 ± 0.02, 0.313 ± 0.04 vs 0.407 ± 0.03, both P < 0.05). Meanwhile, the ratio of Bcl-2 to Bax increased markedly in Ad-Ang-1 transfected group.

CONCLUSION: Ang1 gene can significantly up-regulate Bcl-2 expression and down-regulate Bax expression at both transcriptional and translational levels in vitro, which may be one of mechanisms underlying protection against serum starvation-induced apoptosis.

Effect of exogenous FHIT gene expression on vincristine-induced apoptosis of human gastric cancer cells MKN-28

AIM: To investigate effect of exogenous fragile histidine triad (FHIT) gene expression on gastric cancer cells MKN-28 apoptosis induced by vincristine as well as its molecular mechanism.

METHODS: The recombinant FHIT gene was transfected into human gastric cancer cells MKN-28 through liposomes. The expression of exogenous FHIT gene was detected using western blot. The MKN-28-pRcCMV-FHIT, MKN-28-pRcCMV and MKN-28 cells were treated with vincristine of different concentrations. After treatment with vincristine, the inhibition rates of the cells in 3 groups were examined using MTT assay. The apoptosis of cells was determined by flow cytometry. The expressions of Bcl-2 and Bax were measured using Western blot.

RESULTS: The expression of FHIT protein was detected in MKN-28 cells after transfection with FHIT gene. After being treated with vincristine for 48 h, the apoptosis rates of the cells transfected with FHIT gene, the cells transfected with empty vector and the non-transfected cells were 30.967% ± 2.122%, 11.033% ± 1.724% and 10.733% ± 1.021%, respectively. The apoptosis of the cells transfected with FHIT gene was more obvious (F = 142.045, P < 0.05). The expression of Bcl-2 was down-regulated and that of Bax was up-regulated after treatment with vincristine.

CONCLUSION: The expression of exogenous FHIT gene can enhance the vincristine-induced apoptosis in gastric cancer cells, which may be related to the expressions of apoptosis-related protein Bcl-2 and Bax.

Increased renal cell apoptosis and its mechanism in rats with biliary cirrhosis

AIM: To investigate the renal pathological changes, cell apoptosis and expression of Bcl-2 and Bax proteins in rats with hepatic cirrhosis induced by common bile duct ligation (CBDL).

METHODS: Hepatic cirrhosis was induced by CBDL in SD rats. Thirty rats were randomized to 3 groups: sham operation group, 2-wk CBDL group and 5-wk CBDL. Hepatic and renal tissues were collected for pathohistological observation under microscope; the creatinine clearance rate (Ccr) and renal malonaldehyde (MDA) content were measured by biochemical method and spectrophotometric method, respectively; the apoptosis of renal cells was detected by TUNEL method; finally, the levels of Bcl-2 and Bax protein expression were examined by immunohistochemistry.

RESULTS: Hepatic histological examination showed that hepatic fibrosis occurred in 2-wk CBDL group and biliary cirrhosis in 5-wk CBDL. In the 5-wk CBDL group, desquamation and necrosis of renal tubule epithelia were found by HE staining, and irregular thickening of glomerular basement membrane, mesangial expansion and fusion of epithelial foot processes were observed by electron microscopy. The Ccr significantly decreased (1.10 ± 0.03 vs 1.40 ± 0.03, 1.80 ± 0.02; P < 0.05 or 0.01) while MDA content increased (4.07 ± 0.51 vs 2.32 ± 0.85, 0.79 ± 0.37, both P < 0.01) in the 5-wk CBDL group in comparison with that in the 2-wk CBDL group or sham operation group. The apoptotic rate of renal cells was significantly higher in the 5-wk CBDL group than that in the 2-wk CBDL group or sham operation group (68.36% ± 8.71% vs 24.08% ± 2.59%, 11.43% ± 2.77%; both P < 0.01). Bcl-2 protein decreased while Bax protein increased by turns in sham operation group, 2-wk CBDL group and 5-wk CBDL group (P < 0.05).

CONCLUSION: There are renal histopathological changes and cell apoptosis in rats with CBDL-induced hepatic cirrhosis, and low expression of Bcl-2 protein and high expression of Bax protein play important roles in the renal injury induced by CBDL cirrhosis.

Apoptosis of human pancreatic cancer cells induced by Triptolide

AIM: To investigate apoptosis in human pancreatic cancer cells induced by Triptolide (TL), and the relationship between this apoptosis and expression of caspase-3’ bcl-2 and bax.

METHODS: Human pancreatic cancer cell line SW1990 was cultured in DMEM media for this study. MTT assay was used to determine the cell growth inhibitory rate in vitro. Flow cytometry and TUNEL assay were used to detect the apoptosis of human pancreatic cancer cells before and after TL treatment. RT-PCR was used to detect the expression of apoptosis-associated gene caspase-3’ bcl-2 and bax.

RESULTS: TL inhibited the growth of human pancreatic cancer cells in a dose-and time-dependent manner. TL induced human pancreatic cancer cells to undergo apoptosis with typically apoptotic characteristics. TUNEL assay showed that after the treatment of human pancreatic cancer cells with 40 ng/mL TL for 12 h and 24 h, the apoptotic rates of human pancreatic cancer cells increased significantly. RT-PCR demonstrated that caspase-3 and bax were significantly up-regulated in SW1990 cells treated with TL while bcl-2 mRNA was not.

CONCLUSION: TL is able to induce the apoptosis in human pancreatic cancer cells. This apoptosis may be mediated by up-regulating the expression of apoptosis-associated caspase-3 and bax gene.

Copper Induces Apoptosis of Neuroblastoma Cells Via Post-translational Regulation of the Expression of Bcl-2-family Proteins and the tx Mouse is a Better Model of Hepatic than Brain Cu Toxicity

The basic mechanism(s) by which altered Cu homeostasis is toxic to hepatocytes and neurons, the two major cell types affected in copper storage diseases such as Wilson's disease (WD), remain unclear. Using human M17 neuroblastoma cells as a model to examine Cu toxicity, we found that there was a time- and concentration-dependent induction of neuronal death, such that at 24 h there was a approximately 50 % reduction in viability with 25 muM Cu-glycine(2). Cu-glycine(2) (25:50 muM) treatment for 24 h significantly altered the expression of 296 genes, including 8 genes involved with apoptosis (BCL2-associated athanogene 3, BCL2/adenovirus E1B 19kDa interacting protein caspase 5, regulator of Fas-induced apoptosis, V-jun sarcoma virus 17 oncogene homolog, claudin 5, prostaglandin E receptor 3 and protein tyrosine phosphatase, non-receptor type 6). Surprisingly, changes in the expression of more 'traditional' apoptotic genes (Bcl-2, Bax, Bak and Bad) did not vary more than 20 %. To test whether the induction of apoptosis in neuroblastoma cells was via post-translational mechanisms, we measured the protein expression of these apoptotic markers in M17 neuroblastoma cells treated with Cu-glycine(2) (0-100 muM) for 24-48 h. Compared with glycine treated cells, Cu-glycine(2) reduced Bcl-2 expression by 50 %, but increased Bax and Bak expression by 130% and 400 %, respectively. To assess whether Cu also induced apoptotic cell death in a mouse model of WD, we measured the expression of these apoptotic markers in the liver and brain of mice expressing an ATP7b gene mutation (tx(J) mice) at 10 months of age (near the end of their lives when overt liver pathology is displayed). Changes in the liver expression of these apoptotic markers in tx(J) mice compared to background mice mirrored those of Cu treated neuroblastoma cells. In contrast, few changes in apoptotic protein expression were detected in the brain between tx(J) and background mice, indicating the tx(J) mouse is a good model of hepatic, but not brain, Cu toxicity. Our results indicate that Cu-induction of neuronal apoptosis does not require de novo synthesis or degradation of apoptotic genes, and that Cu accumulation in the aged tx(J) mouse brain is insufficient to induce apoptosis.

Novel effect of the expression of proapoptotic proteins Bad, Bax and Bid in non-alcoholic steatohepatitis

AIM: To explore the effects of expression of apoptosis-related proteins Bad, Bax and Bid on the progress of non-alcoholic steatohepatitis (NASH) in mice.

METHODS: Experimental NASH models were established by feeding mice with a high fat, methionine and choline deficient (MCD) diet (MCD group). Control animals were fed with a choline-methionine supplemented diet (control group). Hepatic steatosis, inflammation and fibrosis were graded by routine H&E staining of liver sections. The levels of proapoptotic-related proteins, such as Bad, Bax and Bid, were determined by Western blot.

RESULTS: Mice fed with the MCD diet exhibited mild steatosis on day 10, moderate steatohepatitis in week 3 and severe steatohepatitis in week 8, as detected by H&E staining, in parallel with a rise in the levels of transaminases. Hepatic expression of Bad and Bax proteins was more pronounced from day 10, and continued to rise until week 3 and 8 in the MCD group compared with the control group (P < 0.05, P < 0.01 and P < 0.05, respectively). Moreover, Bid was activated through hydrolyzation and up-regulated by day 10, week 3 and 8 (P < 0.01).

CONCLUSION: Combined expression of the proapoptotic proteins Bad, Bax and Bid may be involved in the progression of MCD-induced steatohepatitis.

Effects of paeonol on apoptosis and proliferation of HT-29 cells and its molecular mechanism

AIM: To investigate the effects of paeonol in inhibiting proliferation of human colorectal cancer cell line HT-29 and inducing their apoptosis, and the possible molecular mechanisms involved.

METHODS: The inhibitory effect of paeonol on HT-29 cell proliferation was detected by MTT assay. Induction of apoptosis of HT-29 cells was measured by fluorescence microscopy, transmission electron microscopy, TUNEL assay and flow cytometry (FCM). Expression of apoptosis-associated genes bcl-2, bax and P53 was observed by immunocytochemical staining.

RESULTS: Paeonol at a concentration of 7.81-250 mg/L inhibited the proliferation of HT-29 cells, with obvious concentration-and time-effect relationships. Typical apoptosis morphology of HT-29 cells was observed by fluorescence and transmission electron microscopy after treatment with paeonol. Paeonol induced apoptosis of HT-29 cells when it was applied at a concentration of 15.63, 62.5 or 250 mg/L after 48 h. TUNEL assay showed a concentration-effect relationship between paeonol and apoptosis index. By FCM, the apoptosis rate of HT-29 cells was 7.6%, 16.2% and 34.5% respectively, which showed an obvious concentration-effect relationship. Cell cycle distribution was altered simultaneously. The S phase of the cells was increased, while the G₀/G₁ and G₂/M phases were decreased after treatment with paeonol. Immunocytochemical staining showed that the expression of Bcl-2 and p53 was decreased significantly, while the expression of Bax protein was not significantly altered by paeonol.

CONCLUSION: Paeonol inhibits HT-29 cell proliferation and induces apoptosis. This may be mediated via changes in the cell cycle, down-regulation of the Bcl-2/Bax ratio, and expression of p53 protein.

Induction of apoptosis of human gastric carcinoma SGC-7901 cell line by 5, 7-dihydroxy-8-nitrochrysin in vitro

AIM: To investigate the effect of 5, 7-dihydroxy-8-nitrochrysin (NOChR) on apoptosis of human gastric carcinoma SGC-7901 cell line.

METHODS: SGC-7901 cells were cultured in vitro and the inhibitory effect of NOChR on proliferation of SGC-7901 cells was measured by using an MTT assay. NOChR-induced apoptosis rate of SGC-7901 cells was detected using flow cytometry (FCM) with PI staining. DNA ladder bands were observed by DNA agarose gel electrophoresis. The influence of NOChR on the proxisome proliferator-activated receptor-γ (PPARγ), Bcl-2 and Bax protein expression of SGC-7901 cells was analyzed by Western blot.

RESULTS: MTT assay showed that NOChR markedly inhibited proliferation of SGC-7901 cells in a dose-dependent manner, and when IC₅₀ was 4.14 μmol/L, the potency of NOChR was 10 times than that of lead compound, chrysin (ChR, IC₅₀ was 40.56 μmol/L), and was similar to 5-fluorouracil (5-FU, IC₅₀ was 4.51 μmol/L). FCM with propidium iodide (PI) staining demonstrated that the apoptosis rates of SGC-7901 cells treated with 1.25, 5.00 and 20.00 μmol/L NOChR for 48 h were 9.8% ± 0.2%, 36.8% ± 1.9% and 45.5% ± 3.5%, respectively, and were significantly higher when treated with 5.00 and 20.00 μmol/L NOChR than that with 20.00 μmol/L ChR (12.9% ± 1.5%). DNA agarose gel electrophoresis showed that treatment of SGC-7901 cells with 20.00 μmol/L NOChR for 48 h resulted in typical DNA ladder bands of DNA of SGC-7901 cells, which could be eliminated by treating with 10.00 μmol/L GW9662, a blocker of PPARγ. Western blot analysis revealed that after 24 h of treatment with 20.00 μmol/L NOChR, PPARgamma and Bax protein expression of SGC-7901 cells increased but Bcl-2 expression decreased; however, pre-incubation with 10.00 μmol/L GW9662 could efficiently antagonize and weaken the regulatory effect of 20.00 μmol/L NOChR on Bax and Bcl-2 protein expression of SGC-7901 cells.

CONCLUSION: NOChR induces apoptosis of SGC-7901 cell lines by activating PPARγ and decreasing ratio of Bcl-2 to Bax.

Apoptotic cell death and its relationship to gastric carcinogenesis

AIM: To investigate the apoptotic process of cells within the intestinal metaplasia areas co-localizing with chronic gastritis and gastric carcinomas and to analyze the involvement of proteins regulating apoptosis in the process of intestinal metaplasia related gastric carcinogenesis.

METHODS: Forty-two gastric carcinoma and seventeen chronic gastritis cases were included in this study. All cases were examined for the existence of intestinal metaplasia. Ten cases randomly selected from each group were processed for TUNEL assay. TUNEL positive cells within the intestinal metaplasia areas, co-localizing either to gastric carcinoma or chronic gastritis, were counted and converted to apoptotic indices. In addition, p53, bcl-2 and bax expression patterns within these tissues were analyzed on the basis of immunohistochemistry.

RESULTS: Twenty-eight of the cases were intestinal and 14 of the cases were diffuse type adenocarcinomas. 64% (27/42) of the gastric carcinoma cases had intestinal metaplasia. Intestinal metaplasia co-localized more with intestinal type carcinomas compared with diffuse type carcinomas [75% (21/28) vs 42% (6/14), respectively; P≤ 0.05]. The mean apoptotic index in tumor cells was 0.70 ± 0.08. The mean apoptotic index in intestinal metaplasias co-localizing to tumors was significantly higher than that of intestinal metaplasias co-localizing to chronic gastritis (0.70 ± 0.03 vs 0.09 ± 0.01, respectively; P≤ 0.05). p53 positivity was not observed in areas of intestinal metaplasia adjacent to tumors or chronic gastritis. Intestinal metaplasia areas adjacent to tumors showed lower cytoplasmic bcl-2 positivity compared to intestinal metaplasia areas adjacent to chronic gastritis [55.5% (15/27) vs 70.5% (12/17), respectively]. On the other hand, intestinal metaplasia areas adjacent to tumors showed significantly higher cytoplasmic bax positivity compared to intestinal metaplasia areas adjacent to chronic gastritis [44.4% (12/27) vs 11.7% (2/17), respectively; P≤ 0.05].

CONCLUSION: Existence of apoptotic cells on the basis of TUNEL positivity is shown in intestinal metaplasias co-localizing to both diffuse and intestinal type gastric cancers in this study. Our results also suggested bax expression dependent induction of apoptosis especially in intestinal metaplasia areas adjacent to tumors. These findings strongly support the involvement of apoptotic mechanisms in the process of gastric carcinogenesis especially in the transition from intestinal metaplasia to gastric cancer. It may be suggested that induction of apoptosis in intestinal metaplasia areas adjacent to tumors may involve different mechanisms than induction by chronic inflammation.

Role of acinar cell apoptosis and expression of Bax and Caspase-8 in rats with acute pancreatitis

AIM: To investigate the apoptosis of pancreatic acinar cells and the expression of apoptosis-regulated genes Bax and Caspase-8 in experi-mental acute pancreatitis and their correlations with the severity of the disease in rats.

METHODS: The models of acute edematous pancreatitis (AEP) and acute necrotizing pancreatitis (ANP) were established by retrograde injection of different concentrations of sodium deoxycholate into the common biliary and pancreatic duct, and then the rats were randomly divided into 3 groups (10 for each): sham operated group (control), AEP group (treated with 7.5 g/L sodium deoxycholate) and ANP group (treated with 15 g/L sodium deoxycholat). The apoptosis of acinar cells was determined by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay. The amounts of Bax and Caspase-8 mRNA expression in the pancreas were analyzed by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). The expression of Bax and Caspase-8 protein were detected by immunohistochemical method. The levels of serum amylase, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were also measured respectively.

RESULTS: The levels of serum amylase (63413 ± 6118, 1532134 ± 17654 nkat/L vs 15736 ± 483 nkat/L, P < 0.01), TNF-α (1.86 ± 0.13, 2.97 ± 0.14 mg/L vs 0.95 ± 0.08 mg/L, P < 0.01) and IL-6 (47.10 ± 7.05, 170.10 ± 7.59 ng/L vs 29.20 ± 4.47 ng/L, P < 0.01) in AEP and ANP group were significantly higher than those in control group, and there were also significant differences between ANP and AEP group (P < 0.05). The apoptotic index (AI) in both AEP and ANP group was obviously higher than that in control group (22.09 ± 3.71, 6.50 ± 1.58 vs 0.13 ± 0.05, P < 0.01), and there was also marked difference between ANP and than AEP group (P < 0.05). Meanwhile, in AEP and ANP group the expression of Bax (mRNA: 1.530 ± 0.501, 1.046 ± 0.337; protein: 453.7 ± 30.5, 339.4 ± 26.7) and Caspase-8 (mRNA: 0.595 ± 0.17, 0.505 ± 0.173; protein: 3606 ± 337, 3134 ± 231) were observably higher than those in control group (Bax mRNA: 0.613 ± 0.244, Bax protein: 245.2 ± 30.0; Caspase-8 mRNA: 0.357 ± 0.130, Caspase-8 protein: 2396 ± 266) (P < 0.01). Bax expression was also significantly different between ANP and AEP group both at mRNA and protein level, but not Caspase-8 mRNA and protein.

CONCLUSION: In acute pancreatitis, the apoptosis of pancreatic acinar cells is negatively correlated with the severity of pancreatitis. Bax and Caspase-8 may contribute to the acinar cell apoptosis and reduction of AP severity.

Early apoptosis and cell death induced by ATX-S10Na (II)-mediated photodynamic therapy are Bax- and p53-dependent in human colon cancer cells

AIM: To investigate the roles of Bax and p53 proteins in photosensitivity of human colon cancer cells by using lysosome-localizing photosensitizer, ATX-S10Na (II).

METHODS: HCT116 human colon cancer cells and Bax-null or p53-null isogenic derivatives were irradiated with a diode laser. Early apoptosis and cell death in response to photodynamic therapy were determined by MTT assays, annexin V assays, transmission electron microscopy assays, caspase assays and western blotting.

RESULTS: Induction of early apoptosis and cell death was Bax- and p53-dependent. Bax and p53 were required for caspase-dependent apoptosis. The levels of anti-apoptotic Bcl-2 family proteins, Bcl-2 and Bcl-x_L, were decreased in Bax- and p53-independent manner.

CONCLUSION: Our results indicate that early apoptosis and cell death of human colon cancer cells induced by photodynamic therapy with lysosome-localizing photosensitizer ATX-S10Na (II) are mediated by p53-Bax network and low levels of Bcl-2 and Bcl-x_L proteins. Our results might help in formulating new therapeutic approaches in photodynamic therapy.

Expression of p53, Bax and Bcl-2 proteins in hepatocytes in non-alcoholic fatty liver disease

AIM: To analyze the protein expression essential for apoptosis in liver steatosis.

METHODS: The expression of proapoptotic proteins p53, Bax, and antiapoptotic Bcl-2 in hepatocytes with steatosis (SH) and without steatosis (NSH) was evaluated in 84 patients at various stages of non-alcoholic fatty liver disease (NAFLD).

RESULTS: Immunohistochemical staining of liver tissue showed the activation of p53 protein in SH and NSH with increased liver steatosis, diminished Bcl-2 and slightly decreased Bax protein. Positive correlation was found between the stage of liver steatosis with p53 expression in SH (r = 0.54, P < 0.01) and NSH (r = 0.49, P < 0.01). The antiapoptotic protein Bcl-2 was diminished together with the advancement of liver steatosis, especially in non-steatosed hepatocytes (r =0.43, P < 001).

CONCLUSION: Apoptosis is one of the most important mechanisms leading to hepatocyte elimination in NAFLD. The intensification of inflammation in NAFLD induces proapoptotic protein p53 with the inhibition of antiapoptotic Bcl-2.

Involvement of P53 and Bax/Bad triggering apoptosis in thioacetamide-induced hepatic epithelial cells

AIM: Thioacetamide (TAA) has been used in studying liver fibrosis and cirrhosis, however, the mechanisms of TAA-induced apoptosis in liver are still unclear. The hepatic epithelial cell line clone 9 was cultured and treated with TAA to investigate the causes of cell death.

METHODS: The cell viability of TAA-induced clone 9 cells was determined using MTT assay. Total cellular GSH in TAA-induced clone 9 cells was measured using a slight modification of the Tietze assay. The activity of caspase 3 in TAA-induced clone 9 cells was monitored by the cleavage of DEVD-p-nitroanaline. TUNEL assay and flow cytometry were applied for the determination of DNA fragmentation and the proportion of apoptosis in TAA-induced clone 9 cells, respectively. The alterations of caspase 3, Bad, Bax and Phospho-P53 contents in TAA-induced clone 9 cells were measured by Western blot.

RESULTS: The experimental data indicated that TAA caused rat hepatic epithelial cell line clone 9 cell death in a dose-and time-dependent manner; 60% of the cells died (MTT assay) within 24 h after 100 mg/L TAA was applied. Apoptotic cell percentage (TUNEL assay) and caspase 3 activities were highest after 100 mg/L TAA was added for 8 h. The release of GSH and the elevation in caspase content after TAA treatment resulted in clone 9 cell apoptosis via oxidative stress and a caspase-dependent mechanism. The phospho-p53, Bax and Bad protein expressions in clone 9 cells were increased after TAA treatment.

CONCLUSION: These results reveal that TAA activates p53, increases caspase 3, Bax and Bad protein contents, perhaps causing the release of cytochrome c from mitochondria and the disintegration of membranes, leading to apoptosis of cells.

Clinicopathological and immunohistochemical analysis of gastrointestinal stromal tumor

AIM: To investigate the clinicopathological features of gastrointestinal stromal tumor (GIST) and to study the reference indexes for malignancy.

METHODS: Fifty-two cases of primary GIST were distinguished from a group of gastrointestinal mesenchymal tumors using a panel of antibodies such as CD117 and CD34 by immunohistochemical SP method. Their biological behaviors were analyzed using the expression of p21WAF1 and Bax in 52 cases of GIST.

RESULTS: Grossly, the tumor size was between 1.5 cm and 13 cm (mean: 5.5 cm). Focal areas of hemorrhage, necrosis, or small cyst formation could be seen. Microscopically, the tumor was composed of spindle cells (20 cases), epithelioid cells (20 cases) and mixed cells (12 cases). Immunohistochemically, CD117 and CD34 showed diffuse strong positive expressions, the positive rates were 98.1% and 92.3%. SMA, S-100, NSE, NF and MBP showed focal positive expressions, the positive rates were 48.1%, 28.8%, 25%, 21.2% and 42.3% respectively. Vimentins were all positive desmin and CgA were all negative. In normal adult stomach and intestine, the immunoreactive staining for CD117 and CD34 showed immunoreactive interstitial cells of Cajal in myenteric neuroplexus. Among the 52 cases of GIST, 27 were positive for p21WAF1 (51.9%), 29 for Bax (55.8%). The expression of p21WAF1 and Bax had no significent difference with the localization, size, histological subtype of GIST, but had a significent difference with the histological grade (P = 0.000, respectively). p21WAF1 expression had a positive correlation to Bax expression (r = 0.461, P = 0.001, κ = 0.459).

CONCLUSION: GIST has complicated arrangements and various cell types. Positivity of CD117 and CD34 is the most valuable factor in diagnosing GIST. Expression of p21WAF1 and Bax plays an important role in potential malignancy and malignancy rather than in benign GIST. p21WAF1 and Bax may be used as the markers in the assessment of GIST malignant potential.

Expression and significances of apoptosis gene, invasion-associated proteases and vascular epithelial growth factor in Lauren's classification of gastric carcinoma

AIM: To explore distinctive biological behavior in the intestinal-type gastric carcinoma and diffuse-type gastric carcinoma, according to the expression of Bcl-2, Bax, Cath-D and vascular epithelial growth factor (VEGF).

METHODS: Immunohistochemistry SP method was performed to detect the expression of Bcl-2, Bax, Cath-D and VEGF in 36 cases of intestinal-type gastric carcinoma, 38 cases of diffuse-type gastric carcinoma, and their corresponding normal gastric tissues.

RESULTS: The expression of Bcl-2, Bax, Cath-D and VEGF were significantly higher in gastric carcinoma than those in the normal controls (44.59% vs 27.30%; 58.11% vs 71.62%; 77.00% vs 21.60%; 71.62% vs 14.86%; all P < 0.05). The positive expression of Bcl-2 and Cath-D were markedly higher in diffuse-type gastric carcinoma than those in intestinal-type one (29.14 ± 24.70 vs 19.80 ± 27.37; 52.59 ± 33.76 vs 29.21 ± 39.67; both P < 0.05), while the expression of Bax was notably lower in the former (32.56 ± 35.55 vs 47.74 ± 27.43, P < 0.05). The positive rate of VEGF expression was closely correlated with the invasion depth (7.13 ± 15.81, 62.77 ± 44.37, and 40.82 ± 42.70 for mucosal or sub-mucosal invasion, muscular invasion, and serosa invasion, respectively) and lymph node metastasis (metastasis vs non-metastasis: 42.05 ± 42.61 vs 34.15 ± 42.52) of gastric carcinoma.

CONCLUSION: Bcl-2, Bax, Cath-D and VEGF are involved in the development and metastasis of gastric cancer. Due to the involvement of different genes, the intestinal-type or diffuse-type gastric carcinoma shows a distinctive biological behavior.

Effects of quercetin on proliferation and cell cycle of colon carcinoma cell Line HT-29

AIM: To investigate the effect of quercetin on the proliferation and apoptosis of colon carcinoma cell line HT-29 and its molecular mechanism.

METHODS: HT-29 cells were treated with different concentrations of quercetin (40×10^-6, 80×10^-6 and 160×10^-6 mol/L) for 72 h. HT-29 cells treated with DMSO vehicle were used as the controls. MTT assay, flow cytometry, immunocytochemistry and reverse transcription polymerase chain reaction (RT-PCR) was used to observe the changes of cell proliferation, cell cycle, Caspase-3 protein expression, and bax, bcl-2, and Caspase mRNA expression in HT-29 cells, respectively.

RESULTS: Quercetin at a concentration of 40×10^-6 mol/L promoted the proliferation of HT-29 cells (P < 0.05), while it significantly inhibited the proliferation of HT-29 cells at the concentrations of 80×10^-6 and 160×10^-6 mol/L (P < 0.05 or P < 0.01), showing a time-dependent manner. After treatment with 40×10^-6, 80×10^-6 and 160×10^-6 mol/L quercetin for 72 h, the proliferation ratio of HT-29 cells were 111.8% ± 9.6%, 64.6% ± 8.3% and 26.1% ± 5.7%, respectively; the percentages of HT-29 cells at period G₀/G₁ were 32.7% ± 5.4%, 58.1% ± 18.3% and 71.6% ± 20.8% respectively, and those of HT-29 cells at period S were 48.6% ± 17.5%, 27.4% ± 13.4% and 15.4% ± 10.1%, respectively; the apoptosis rates of HT-29 cells were 7.0% ± 1.3%, 15.6% ± 3.6% and 26.4% ± 6.2% respectively. 80×10^-6. 160×10^-6 mol/L quercetin acted on HT-29 cell, the cells at period G₀/G₁ and the apoptosis rates were significantly increased (P < 0.01), and the cells at period S were significantly decreased (P < 0.01) after 80×10^-6 and 160×10^-6 mol/L quercetin treatment. Quercetin at concentrations of 80×10^-6 and 160×10^-6 mol/L increased the expression of Caspase-3 and bax mRNA and Caspase-3 protein, but decreased the expression of bcl-2 mRNA. Quercetin at a concentration of 40×10^-6 mol/L increased Caspase-3 mRNA expression and the proliferation of HT-29 cells, but not Caspase-3 protein expression.

CONCLUSION: Quercetin at lower concentrations can promote the proliferation of colon carcinoma cell line HT-29 while it can inhibit the proliferation and induce apoptosis of HT-29 cells at higher concentrations. The mechanism may be associated with up-regulation of Caspase-3 and bax and down-regulation of bcl-2 expression.

Alanyl-glutamine dipeptide inhibits hepatic ischemia-reperfusion injury in rats

AIM: To investigate the protective effect and mechanism of alanyl-glutamine dipeptide (Ala-Gln) against hepatic ischemia-reperfusion injury in rats.

METHODS: Rats were divided into group C as normal control Group (n=16) and group G as alanyl-glutamine pretreatment (n=16). Rats were intravenously infused with 0.9% saline solution in group C and Ala-Gln -enriched (2% glutamine) 0.9% saline solution in group G via central venous catheter for three days. Then all rats underwent hepatic warm ischemia for 30 min followed by different periods of reperfusion. Changes in biochemical parameters, the content of glutathione (GSH) and the activity of superoxide dismutase (SOD) in liver tissue, Bcl-2 and Bax protein expression and morphological changes of liver tissue were compared between both groups.

RESULTS: One hour after reperfusion, the levels of liver enzymes in group G were significantly lower than those in group C (P<0.05). Twenty-four hours after reperfusion, the levels of liver enzymes in both groups were markedly recovered and the levels of liver enzyme in group G were also significantly lower than those in group C (P <0.01). One and 24 h after reperfusion, GSH content in group G was significantly higher than that in group C (P <0.05). There was no statistical difference in activities of SOD between the two groups. One and 24 h after reperfusion, the positive expression rate of Bcl-2 protein was higher in group G than in group C (P <0.05) and the positive expression rate of Bax protein was lower in group G than in group C (P < 0.05). Histological and ultrastructural changes of liver tissue were inhibited in group C compared to group G.

CONCLUSION: Our results suggest that Ala-Gln pretreatment provides the rat liver with significant tolerance to warm ischemia-reperfusion injury, which may be mediated partially by enhancing GSH content and regulating the expression of Bcl-2 and Bax proteins in the liver tissue.

Relationship between expression of gastrin, somatostatin mRNA and cell apoptosis and Bcl-2, Bax in large intestinal carcinoma

AIM: To explore the correlations the between expression of somatostatin (SS), gastrin (GAS) mRNA and cell apoptosis index (AI) and Bcl-2, Bax in large intestinal cancer.

METHODS: The expression of GAS and SS genes were detected in 62 colorectal cancer patients by nested reverse transcription polymerase chain reaction (RT-PCR), and the apoptosis of the cells was detected by TUNEL method. The protein expression of,Bcl-2, Bax, GAS, and SS were detected using immunohistochemical staining (S-P method).

RESULTS: The expression of GAS and SS mRNA and protein were basically consistent. The AI in SS high and moderate expression patients with large intestinal cancer was remarkably higher than that in SS low expression ones (q = 5.06, 3.95, both P < 0.01), while it was just opposite in GAS positive patients (q = 6.66, 6.33, P < 0.01). The positive rates of Bax and Bcl-2 expression had significant difference between SS (or GAS) high, moderate and low expression patients with large intestinal cancer (Bax: χ² = 9.24, 6.91, P < 0.05; Bcl-2: χ² = 7.17, 13.83, P < 0.05). The positive rate of Bax expression in SS high (80%, 8/10) and moderate (76.5%, 13/17) expression patients was notably higher than that in the low expression ones (40.0%, 14/35) (χ² = 5.24, 6.09, P < 0.05), but the rate of Bcl-2 expression was just opposite (χ² = 4.71, 4.70, P < 0.05). The positive rate of Bcl-2 expression in GAS high (90.9%,10/11) and moderate expression patients (86.7%,13/15) was markedly higher than that in the low expression ones (44.4%, 16/36) (χ² = 5.60, 7.69, P < 0.05), but the positive rate of Bax expression in GAS high expression patients (27.3%, 3/8) was obviously lower than that in the low expression ones (69.4%, 25/36) (χ² = 4.59, P < 0.05). Bax expression was not significantly different between moderate and low GAS positive patients. The value of GAS/SS was positively correlated with Bcl-2 expression (r = 0.34, P < 0.01), but negatively with the AI value and Bax expression (r = －0.546, P < 0.01; r = －0.299, P < 0.05).

CONCLUSION: GAS and SS play important roles in the regulation and control of cell apoptosis in large intestinal carcinoma, and the mechanism may be related to the aberrant expression of Bcl-2 and Bax.

Effects of glutamine on glutathione content and expression of Bcl-2 and Bax protein during hepatic ischemia and reperfusion injury in rats

AIM: To investigate the effect of alanyl-glutamine dipeptiven (Ala-Gln) on the content of glutathione (GSH) and the expression of Bcl-2 and Bax protein during hepatic ischemia and reperfusion injury (HIRI) in rats.

METHODS: A total of 48 Wistar rats were randomly divided into glutamine group (group G) and control group (group C), which were pretreated with Gln and normal saline, respectively. The liver was subjected to warm ischemia by Pringle method for 30 min, and then reperfused. The serum samples were colleted 1 and 24 h after the reperfusion, and the level of serum ALT was measured. The GSH content and histopathological changes were detected in the liver tissues. The expression of Bcl-2 and Bax protein in the liver tissues were detected by immunohistochemistry.

RESULTS: The level of serum ALT was significantly lower in group G than that in group C 1 and 24 h after the reperfusion (8.3 ± 2.0 mkat/L vs 13.7± 5.5 mkat/L, P < 0.05; 2.9 ± 2.5 mkat/L vs 9.1 ± 4.3 mkat/L, P < 0.01), but the GSH content was significantly higher in group G than that in group C (1216.09 ± 152.78 mg/g vs 856.68 ± 117.64 mg/g, P < 0.01; 899.73 ± 57.75 mg/g vs 800.50 ± 94.79 mg/g, P < 0.05). The histopathological changes were significantly slighter in group G than those in group C. One and twenty-four hours after the reperfusion, the positive rate of Bcl-2 protein expression was significantly higher in group G than that in group C (100.0% vs 37.5%, P < 0.05; 87.5% vs 25.0%, P < 0.05), while the positive rate of Bax protein expression was significantly lower in group G than that in group C (25.0% vs 87.5%, P < 0.05; 25.0% vs 87.5%, P < 0.05).

CONCLUSION: Ala-Gln (Gln) can protect rats against HIRI, and the mechanism may relate to the enhancement of GSH content and the regulation of Bcl-2, Bax protein expression.

Renal cells apoptosis and Bax, Bcl-2 expression in rats with severe acute pancreatitis

AIM: To explore the roles of renal cell apoptosis and expression of Bax and Bcl-2 in renal injury in rats with severe acute pancreatitis (SAP).

METHODS: Thirty rats were randomized into sham operation (SO, n = 15) and SAP group (n = 15). The model of SAP was established by retrograde injection of 50 g/L sodium taurocholate into the biliopancreatic duct in the rats. Serum creatinine (Cr) and blood urea nitrogen (BUN) were determined 6, 12, and 18 h after injection. The pathological changes were observed by light and electron microscopy. The apoptosis of renal cells was determined by TUNEL method, and the expression of Bax and Bcl-2 was detected by immunohistochemical staining (SABC assay).

RESULTS: As compared with those in SO group at the same phase, serum Cr and BUN in SAP group increased markedly. Significant injuries of renal tissue were observed under light and electron microscope.The apoptotic index of renal glomerular cells increased significantly 6, 12, 18 h after injection (3.2±1.1 vs 0.8±0.1, P <0.05; 3.9±1.8 vs 0.9±0.1, P <0.05; 4.8±1.7 vs 0.8±0.2, P <0.01, respectively). The apoptotic index of renal tubule cells also increased significantly (9.8±1.1 vs 1.3±0.5, P <0.01; 12.6±2.3 vs 1.2±0.3, P <0.01; 15.7±2.6 vs 1.3±0.3, P <0.01, respectively). The expression of Bax in renal glomerulus and tubule increased significantly at 6, 12, 18 h, respectively (glomerulus: 3.05±0.86 vs 1.01±0.04, P <0.05; 3.37±1.13 vs 1.06±0.05, P <0.05; 4.11±1.24 vs 1.09±0.03, P <0.05; tubule: 8.17±2.16 vs 1.53±0.07, P <0.01; 12.92±1.81 vs 1.61±0.05, P <0.01; 13.08±2.53 vs 1.59±0.05, P <0.01), and increased continuously. Bcl-2 was mainly expressed in the regions of renal tubule, and it also increased in SAP group at 6, 12, 18 h, respectively (3.38±1.07 vs 1.58±0.02, P <0.05; 4.26±1.13 vs 1.59±0.06, P <0.05; 7.21±1.04 vs 1.61±0.02, P <0.01). The level of Bcl-2 expression in renal glomerulus was higher in SAP group than that in SO group at 6, 12, 18 h, respectively (2.18±0.65 vs 1.04±0.02; 2.42±0.63 vs 1.03±0.05, P <0.05; 2.69±0.47 vs 1.08±0.04, P <0.05), but decreased with the duration of the injuries.

CONCLUSION: Renal cell apoptosis, which relates to the up-regulated expression of Bax and downed regulated expression of Bcl-2, may be involved in the pathogenesis of renal injury in patients with SAP.

Apoptosis and its pathway in X gene-transfected HepG2 cells

AIM: To investigate the effect of hepatitis B virus (HBV) X gene on apoptosis and expressions of apoptosis factors in X gene-transfected HepG₂ cells.

METHODS: The HBV X gene eukaryon expression vector pcDNA3-X was transiently transfected into HepG₂ cells by lipid-media transfection. Untransfected HepG₂ and HepG₂ transfected with pcDNA3 were used as controls. Expression of HBx in HepG₂ was identified by RT-PCR. MTT and TUNEL were employed to measure proliferation and apoptosis of cells in three groups. Semi-quantified RT-PCR was used to evaluate the expression levels of Fas/FasL, Bax/Bcl-xL, and c-myc in each group.

RESULTS: HBV X gene was transfected into HepG₂ cells successfully. RT-PCR showed that HBx was only expressed in HepG₂/pcDNA3-X cells, but not expressed in HepG₂ and HepG₂/pcDNA3 cells. Analyzed by MTT, cell proliferation capacity was obviously lower in HepG₂/pcDNA3-X cells (0.08910±0.003164) than in HepG₂ (0.14410±0.004927) and HepG₂/pcDNA3 cells (0.12150±0.007159) (P<0.05 and P<0.01). Analyzed by TUNEL, cell apoptosis was much more in HepG₂/pcDNA3-X cells (980/2 000) than HepG₂ (420/2 000), HepG₂/pcDNA3 cells (520/2 000) (P<0.05 and P<0.01). Evaluated by semi-quantified RT-PCR, the expression level of Fas/FasL was significantly higher in HepG₂ cells transfected with HBx than in HepG₂ and HepG₂/pcDNA3cells (P<0.05 and P<0.01). Bax/Bcl-xL expression level was also elevated in HepG₂/pcDNA3-X cells (P<0.05 and P<0.01). Expression of c-myc was markedly higher in HepG₂/pcDNA3-X cells than in HepG₂ and HepG₂/pcDNA3 cells (P<0.05 andP<0.01).

CONCLUSION: HBV X gene can impair cell proliferation capacity, improve cell apoptosis, and upregulate expression of apoptosis factors. The intervention of HBV X gene on the expression of apoptosis factors may be a possible mechanism responsible for the change in cell apoptosis and proliferation.

Overexpression of Bax induces apoptosis and enhances drug sensitivity of hepatocellular cancer-9204 cells

AIM: To investigate the role of overexpression of Bax in apoptotic pathways and the response of human hepatocellular cancer (HCC)-9204 cells to cell death induced by adriamycin.

METHODS: The whole length of Bax cDNA was transfected into human HCC-9204 cells by the method of lipofectamine transfection. An inducible MT-II regulatory system was constructed, which allowed controlled expression of protein upon addition of ZnSO₄ (100 μmol/L) as an external inducer. Stable transfecting inducible expression vector containing Bax gene was performed. Expression of Bax in protein was analyzed by immunohistochemistry and Western blotting. TUNEL and flow cytometry were used to assess the effect of Bax on apoptosis. Colony assay and tetrazolium blue (MTT) assay were used to evaluate the difference in drug sensitivity of HCC-9204 cells after Bax-transfection.

RESULTS: Immunohistochemistry and Western blotting demonstrated that the expression of Bax protein markedly increased in Bax-transfected cells 4 h after the addition of ZnSO₄. Bax positive signal was frequently found on the cytoplasm and perinuclear region of HCC-9404 cells, and there was ectopic expression in cells with marked condensation of chromatin and cytoplasm (apoptotic cells). Apoptotic index significantly increased in Bax-transfected HCC-9204/Bax cells (3.6 vs 27.2, 4.2 vs 32.3, P<0.05). Flow cytometry analysis showed a significant sub-G1 peak and apoptosis in 15.4% HCC-9204/Bax cells 24 h after treatment. Furthermore, colony survival rate decreased from 66% (HCC-9204/pMD) to 45% (HCC-9204/Bax) 2 d after ADR withdrawal. MTT assay result showed that the effects of Bax on cell viability following ADR exposure were significant as compared to the vehicle-transfected HCC-9204/pMD cells (21% vs 44%, P<0.01).

CONCLUSION: Overexpression of Bax not only induces apoptosis, but also sensitizes HCC-9204 cells to cell death induced by adriamycin.

Expression of PGE2, Bcl-2 and Bax in carcinogenesis of colorectal mucosa

AIM: To investigate the expression of PGE₂, Bcl-2 and Bax in the carcinogenesis of colorectal mucosa and the relationship between them.

METHODS: The expression of PGE₂, Bcl-2 and Bax were detected in 15 normal colorectal mucous membrane (NCM), 20 chronic colonitis (CHC), 30 colorectal adenoma (CAA), 50 colorectal cancer (CC)and 50 cancer adjacent (CAT) tissues by DAB immunohistochemical staining. The correlations among PGE₂, Bcl-2 and Bax expression as well as the clinical and pathological characteristics were analyzed.

RESULTS: The rates of PGE₂ expression in NCM, CHC, CAT, CAA and CC tissues were 6.67%, 10%, 40%, 56.7% and 90% respectively and manifested an ascending trend. The rates of Bcl-2 expression in the five groups were 6.67%, 10%, 38%, 46.7%, and 76% respectively and also showed an ascending trend. The rates of Bax expression in the five groups was 86.67%, 75%, 78%, 76.7% and 82% respectively and there was no significant difference among the five groups (P>0.05). However, the positive degree in NCM, CA and CC group exhibited a descending trend (P<0.05). The expressions of PGE₂, Bcl-2 and Bax in human CC were not associated with sex, age and the size of tumor (P>0.05). A positive correlation was noted between expression of PGE₂ and Bcl-2 in CC tissue (r = 0.532, P<0.05). The same correlation also existed between Bax and Bcl-2 (r = 0.653, P<0.05). The rates of PGE₂, Bcl-2 and Bax expression in highly and moderately differentiated CC were significantly higher than those in lowly differentiated one (100%, 88.9%, 85.2% vs 79.3%, 60.9%, 78.3%; P<0.05). The expression of Bcl-2 was significantly higher in Duke's A, B stage than that in Duke's C, D (90%, 77.8% vs 60%, 57.2%; P<0.05).

CONCLUSION: The expression of PGE₂ and Bcl-2 increases while that of Bax decreases with the occurrence and development of CC, which indicates that PGE₂ and Bcl-2 play important roles in the carcinogenesis and development of CC. At the same time, there is a positive relationship between PGE₂ and Bcl-2.