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.