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.