The Expression of Apoptosis-Related Genes Bcl-2 and Bax Protein and Apoptosis Positivity in Cervical Carcinoma during Irradiation

To evaluate the apoptosis positivity, the expression of Bcl-2, bax proteinsin 30 patients with squamous cell cervix carcinoma before and after radiotherapy. Methods: By usingimmuno-histochemical and TDT-dUTP nick end labelling techniques, 30 cases of squamous cell cervicalcarcinoma were analyzed. Results: The apoptosis positivity before and after irradiation was 76.7%and 100% respectively, with the difference being significant (P 【 0.05); The positive rates of Bcl-2protein before and after irradiation were 73.3% and 46.7% respectively, with the difference beingsignificant (P 【 0.05); The positive rates of bax protein before and after irradiation were 86% and100% respectively, with the difference being significant (P 【 0.05). Conclusion: bax and Bcl-2protein play an important role in apoptosis induced by fractionated radiation therapy. Apoptosisinduced by irradiation is contributed to upregulation of bax protein or downregulation of Bcl-2protein.

Signal transduction mediated by Bid,a pro-death Bcl-2 family proteins, connects the death receptor and mitochondria apoptosis pathways

Two major apoptosis pathways have been defined in mammalian cells, the Fas/TNF-R1 death receptor pathway and the mitochondria pathway. The Bcl-2 family proteins consist of both anti-apoptosis and pro- apoptosis members that regulate apoptosis, mainly by controlling the release of cytochrome c and other mitochondrial apoptotic events. However, death signals mediated by Fas/TNF-R1 receptors can usually activate caspases directly, bypassing the need for mitochondria and escaping the regulation by Bcl-2 family proteins. Bid is a novel pro-apoptosis Bcl-2 family protein that is activated by caspase 8 in response to Fas/TNF-R1 death receptor signals. Activated Bid is translocated to mitochondria and induces cytochrome c release, which in turn activates downstream caspases. Such a connection between the two apoptosis pathways could be important for induction of apoptosis in certain types of cells and responsible for the pathogenesis of a number of human diseases.

Effects of Ethyl Pyruvate on Myocardial Apoptosis and Expression of Bcl-2 and Bax Proteins after Ischemia-reperfusion in Rats

In order to study the effects of ethyl pyruvate on cardiomyocyte apoptosis following ischemia/reperfusion （I/R） in vitro and the expression of Bcl-2 and Bax proteins, isolated rat hearts were perfused in a Langendorff model. Twenty-four rats were randomly divided into 3 groups （n=8 in each group）： control group was perfused for 120 min. In the I/R group, after 30 min stabilization the injury was induced by 30 min global ischemia followed by 60 min reperfusion. Ethyl pyruvate （EP） group was set up with the same protocol as I/R group except that it was supplied with 2 mmol/L EP 15 rain before ischemia and throughout reperfusion. Myocardial malonaldehyde （MDA） content was measured. Myocardial apoptotic index （AI） was tested by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling （TUNEL） method. The expression of anti-apoptotic protein Bcl-2 and pro-apoptotic protein Bax in cardiac myocytes was detected by immunohistochemistry. As compared with control group, the content of MDA, myocardial AI and the expression of Bcl-2, Bax proteins were increased significantly in I/R group, but the content of MDA, myocardial AI and the expression of Bax protein were decreased obviously and the expression of Bcl-2 protein was up-regulated in EP group （P〈0.05）. These results demonstrate that EP could inhibit apoptosis of cardiac myocytes possibly via alleviating oxidative stress, up-regulating Bcl-2 and down-regulating Bax proteins.

Dioscin-induced Apoptosis of Human LNCaP Prostate Carcinoma Cells through Activation of Caspase-3 and Modulation of Bcl-2 Protein Family

Dioscin is a natural steroid saponin derived from several plants, showing potent anti-cancer effect against a variety of tumor cell lines. In the present study, we investigated the anti-cancer activity of dioscin against human LNCaP cells, and evaluated the possible mechanism involved in its antineoplastic action. It was found that dioscin（1, 2 and 4 μmol/L） could significantly inhibit the viability of LNCaP cells in a time- and concentration-dependent manner. Flow cytometry revealed that the apoptosis rate was increased after treatment of LNCaP cells with dioscin for 24 h, indicating that apoptosis was an important mechanism by which dioscin inhibited cancer. Western blotting was employed to detect the expression of caspase-3, Bcl-2 and Bax in LNCaP cells. The expression of cleaved caspase-3 was significantly increased, and meanwhile procaspase-3 was markedly decreased. The expression of anti-apoptotic protein Bcl-2 was down-regulated, whereas the pro-apoptotic protein Bax was up-regulated. Moreover, the Bcl-2/Bax ratio was drastically decreased. These results suggested that dioscin possessed potential anti-tumor activity in human LNCaP cells through the apoptosis pathway, which might be associated with caspase-3 and Bcl-2 protein family.

Influence of Tanshinone lla on heat shock protein 70,Bcl-2 and Bax expression in rats with spinal ischemia/reperfusion injury

Tanshinone lla is an effective monomer component of Danshen, which is a traditional Chinese medicine for activating blood circulation to dissipate blood stasis. Tanshinone Ila can effectively improve brain tissue ischemia/hypoxia injury. The present study established a rat model of spinal cord ischemia/reperfusion injury and intraperitoneally injected Tanshinone lla, 0.5 hour prior to model establishment. Results showed that Tanshinone Ila promoted heat shock protein 70 and Bcl-2 protein expression, but inhibited Bax protein expression in the injured spinal cord after ischemia/reperfusion injury. Furthermore, Nissl staining indicated a reduction in nerve cell apoptosis and fewer pathological lesions in the presence of Tanshinone Ila, compared with positive control Danshen injection.

Pretreatment with low-frequency repetitive transcranial magnetic stimulation may influence neuronal Bcl-2 and Fas protein expression in the CA1 region of the hippocampus: A possible anti-epilepsy mechanism in a lithium-pilocarpine-induced epileptic rat mod

BAOKGROUND： Bcl-2 and Fas proteins are well known as anti-apoptotic and pro-apoptotic factors respectively. However, whether the anti-epileptic mechanism of low-frequency repetitive transcranial magnetic stimulation （rTMS） involves an anti-apoptotic effect via regulating Bcl-2 and Fas protein expression remains to be determined. OBJECTIVE： To verify the correlation between the anti-epileptic mechanism following pretreatment of low-frequency rTMS and anti-hippocampal apoptosis. DESIGN, TIME AND SETTING： A randomized controlled animal experiment was performed at Institute of Neurological Disorders, Affiliated Hospital of North Sichuan Medical College between September 2007 and March 2008. MATERIALS： Pilocarpine （053K13011） was provided by Sigma, USA; lithium was provided by Shanghai Biotechnology Co., Ltd., China; Dantec Maglite-r25 rTMS instrument was provided by Dundee, Denmark. METHODS： A total of 21 adult male Wistar rats were randomly divided into control （n = 6）, rTMS pretreatment （n = 9）, and sham-stimulation （n = 6） groups. The rTMS pretreatment group was pretreated with low-frequency rTMS （0.5 Hz, 75% threshold intensity, 20 times/bundle, and 5 bundles/day）, while the sham-stimulation group was sham-stimulated with a similar sound for 7 successive days to establish lithium-pilocarpine-induced epileptic state models. MAIN OUTCOME MEASURES： Epileptic stroke latency; neuronal morphology was observed using hematoxylin and eosin staining; mean positive-reactive cell number and mean absorbance of Bcl-2 and Fas protein in the hippocampal CA1 region was observed using immunohistochemistry. RESULTS： Epileptic latency in the rTMS pretreatment group was significantly enhanced （P 〈 0.01）, and a number of degenerated neurons were observed to be apoptotic. Bcl-2 protein expression increased at each time point, but Fas protein expression decreased （P 〈 0.01）. CONCLUSION： Low-frequency rTMS has an anti-epileptic effect, which may be via regulation of Bcl-2 and Fas protein expression in the hippocampal region.

THE EXPERIMENTAL STUDY ON THE CELL APOPTOSIS AND EXPRESSION OF BCL-2 PROTEIN IN INTRACEREBRAL HEMORRHAGE IN MODEL OF RATS

Objective To study whether there is the apoptosis of neural cells and the expression of Bcl-2 protein in intracerebral hemorrhage (ICH) in model of rats, for the further understanding the mechanism of the delayed damage of the neural cells around the hematoma after ICH. Methods Fifty SD rats were randomly divided into 5 groups, ten in each. With the Group A as the control, the rest 40 were used to set up intracerebral hemorrhage model. The brains were taken out at 12 th , 24 th , 48 th and 72 th hours, respectively. Apoptosis cells were detected with terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL), and the expression of Bcl-2 protein was detected with immunochemical stainging methed (SP). Results In the control group, no apoptosis cells and Bc1-2 protein were detected. In rest groups, the apoptosis cells and Bc1-2 protein were expressed in different degree. Apoptosis rates verified and corresponded with the time after ICH, with the peak at 48 th -72 th hour after hemorrhage. The peak rate of apoptosis cells was (24.50±2.69)% and Bcl-2 protein expression was (20.76±1.97)% . There was significant difference between the experimental groups and control (P<0.05), and no linear relationship between the apoptosis rate and the expression of Bcl-2 protein. Conclusion Apoptosis may be an important factor in the secondary trauma of ICH. There is a time leg after hemorrhage. All this is instructive to clinical treatment in time. Bcl-2 protein keeps increasing in a certain time after hemorrhage, but not synchronize with the cell apoptosis. This indicates that bcl-2 has the effect to reduce the apoptosis of neural cells.

Regulatory Effect of Bcl-2 Family Proteins in CPB-induced Cardiomyocyte Apoptosis in Dog Hearts

Summary: Whether conventional hypothermic CPB induces myocyte apoptosis in dog hearts and modulation of bcl-2, bcl-xl, bax, bad, and caspase-3 pathways in this setting was investigated. Ten healthy adult dogs were randomized into sham-operated and CPB groups. Samples of left ventricle were obtained before, during and 3 h after CPB. In situ TUNEL was used to detect apoptotic myocytes. Immunohistochemistry and flow cytometry were employed for detection of expressions of bcl-2, bcl-xl, bax and bad proteins. Z-DEVD-AMC substrate cleavage and TBARS methods were used to measure the activity of caspase-3 and the content of lipid peroxide in LV myocardium, respectively. After CPB, the number of apoptotic myocytes in CPB group was significantly increased. The results of immunohistichemistry demonstrated that bcl-2, bcl-xl, bax and bad proteins were constitutionally present on the sarcolemma of the LV myocytes. FACS results showed that, after CPB, expressions of bax and bad in CPB group were significantly upregulated, while the expressions of bcl-2 and bcl-xl were not significantly changed in both groups. The activity of caspase-3 and the content of lipid peroxide in LV myocardium in CPB group were also significantly increased after CPB. The present study shows that there exists myocardiocyte apoptosis in dog hearts undergoing conventional hypothermic CPB and the myocyte apoptosis is initiated by ischemia and performed during reperfusion. Moreover, the CPB-induced myocyte apoptosis was associated with upregulation of expressions of bax and bad proteins, activation of caspase-3 and increase of oxidative stress.

TRAIL、bcl-2在卵巢癌组织中的表达及其相关性探讨

目的:探讨TRAIL和bcl-2在卵巢癌组织中的表达及相关性。方法:用免疫组化SP法检测10例正常卵巢,20例良性卵巢肿瘤,60例卵巢癌组织中TRAIL蛋白和bcl-2蛋白表达情况,并进行二者间相关性分析。结果:(1)正常卵巢组织、良性卵巢肿瘤、卵巢癌中TRAIL蛋白的表达率分别为90.0%、80.0%、38.3%;bcl-2蛋白的表达率分别为0%、20.0%、55.0%。两者间比较:在正常卵巢,良性卵巢肿瘤中TRAIL蛋白、bcl-2蛋白的表达无差异(P>0.05);在良性、恶性卵巢肿瘤中TRAIL蛋白、bcl-2蛋白的表达有差异(P<0.05)。(2)在卵巢癌中TRAIL蛋白表达与组织学类型、病理分级无关(P>0.05),与临床分期期别密切相关(P<0.05);bcl-2蛋白的表达与组织学类型无关(P>0.05),与病理分级、临床分期期别密切相关(P<0.05)。(3)TRAIL蛋白表达和bcl-2蛋白的表达呈负相关(P<0.05)。结论:TRAIL蛋白和bcl-2蛋白可能共同参与了卵巢癌的发生、发展过程。并且可能通过减少TRAIL蛋白表达,升高bcl-2蛋白表达,起到协同抑制肿瘤细胞凋亡作用,从而促进了卵巢癌的发生、发展。

THE QUANTITATIVE MEASUREMENT OF BCL-2, P53 PROTEIN AND PCNA EXPRESSION IN BREAST CARCINOMA AND THEIR CORRELATION WITH PROGNOSIS

To study quantitative index of bci-2, P53, Nroliferating cell nuclear antigen (PCNA),ER and PR in breast carcinoma and their correiation and their relatiousbip with prognosis, the ex expression of bcl-2, P53 and PCNA were studied by immunohistochemical technique. The measurementof ER and PR used enzyme linked affinuity histochemical methods. The quantitative index was analyzed by image technique. All analyses were hased on 60 breast carcinomas. The results were as follows:the more bcl-2 protein, the lower histological graded the longer survival term and the highersurvival rate (P< 0. 05). The quautitative measurement of bcl-2, P53 and PCNA expression were ofvalue in evaluating the degree of differentiation and prognosis in breast carcinoma. The quantitativeand qualitative measurement or p53 protein expression showed a Ⅰwerful evidence in evaluatingprognosis of bcl-2 were more significant in evaluating poor prognosis of breast carcinoma. A relationship between bcl-2 and ER, PR showed a better value for response to endocrine therapy in breastcarcinoma patients.

缺氧诱导因子-1α和BCL-2/腺病毒E1B19 kDa相关蛋白3在中耳胆脂瘤表达及意义

目的探讨缺氧诱导因子-1α(hypoxia inducible factor-1,HIF-1α)和BCL-2/腺病毒E1B19KDa相关蛋白3(Bcl2/adenovirus E1B 19 kD interacting protein 3,BNIP3)在中耳胆脂瘤中的表达及胆脂瘤上皮的凋亡情况。方法采用免疫组织化学方法检测30例中耳胆脂瘤标本与18例外耳道皮肤标本中HIF-1α和BNIP3蛋白的表达情况,使用末端脱氧核苷酸转移酶介导的dUTP缺口末端标记(terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling,Tunel)检测20例中耳胆脂瘤标本和18例外耳道皮肤标本的凋亡情况。使用Pearson相关分析检验HIF-1α和BNIP3蛋白之间的相关性。结果 HIF-1α在胆脂瘤组和对照组的平均光密度分别为0.16±0.07和0.08±0.03,两组比较差异有统计学意义(t=4.279,P<0.01);BNIP3在胆脂瘤组和对照组的平均光密度分别为0.16±0.08和0.11±0.06,两组比较差异有统计学意义(t=2.463,P=0.0185);经pearson相关分析,在胆脂瘤上皮中,HIF-1α和BNIP3之间呈正相关(r=0.418,P=0.003);Tunel染色中,凋亡指数在胆脂瘤组和对照组分别为(52.8±12.5)%和(9.99±2.97)%,两组比较差异有统计学意义(t=14.166,P<0.01)。结论 HIF-1α和BNIP3在中耳胆脂瘤中的异常表达可能与胆脂瘤的高凋亡特性有关。

Specific COX-2 inhibitor NS398 induces apoptosis in human liver cancer cell line HepG2 through BCL-2

AIM: To evaluate the effects of NS-398, a cyclooxygenase-2 (COX-2) inhibitor, on the proliferation and apoptosis of HepG2 cells. METHODS: The effects of NS-398 on the proliferation of HepG2 cells were evaluated by MTT. DNA fragmentation gel analysis was used to analyze the apoptotic cells. DNA ploidy and apoptotic cell percentage were calculated by flow cytornetry. The expression of COX-2 and Bcl-2 mRNA was identified by competitive RT-PCR. Furthermore, expression level of Bcl-2 was detected using Western blot in HepG2 after treated with NS-398. RESULTS: NS-398 inhibited cell proliferation and induced apoptosis of HepG2 cells in a concentration-dependent manner. DNA ploidy analysis showed that S phase cells were significantly decreased with increase of NS-398 concentration. The quiescent GO/G1 phase was accumulated with decrease of Bcl-2 mRNA. Whereas NS-398 had no effect on the expression of COX-2 mRNA, and no correlations were found between COX-2 mRNA and HepG2 cell proliferation and apoptosis induced by NS-398 (r=0.056 and r=0.119, respectively). Bcl-2 protein level was inhibited after treated with NS-398. CONCLUSION: NS-398 significantly inhibits the proliferation and induces apoptosis of HepG2 cells. Mechanisms involved may be accumulation of quiescent GO/G1 phase and decrease of Bcl-2 expression.

THE EXPRESSION AND CLINICAL VALUE OF APOPTOSIS CONTROL GENE Bcl-2 AND Bax IN BREAST CANCER

Objective: To study the expression and clinical value of apoptosis control gene bcl-2 and bax in breast cancer. Methods: Protein bax and bcl-2 in 41 breast cancers obtained from operations in our hospital in 1996 were detected using ABC immunohistochemical stain assay and compared with 10 cases with normal breast tissues. Results: The positive rate of bax in normal breast tissue was 90% and in breast cancer was 59%, with a significant statistical difference between them (P<0.05), but there was no statistical difference in bcl-2 protein expression. Among the 41 breast cancer, the group with lymph node metastasis (21 cases) had obviously low bax expression (43%) and high bcl-2 expression (76%), showing significant difference to the group without lymph node metastasis (P<0.05). Conclusion: The antiapoptosis function of bcl-2 was stronger than bax in breast cancer. Protein bax and bcl-2 assay may be useful in understanding the biological behaviors of breast cancer.

THE OVEREXPRESSION OF APOPTOSIS-RELATED GENES OF P_53 AND BCL-2 IN CERVICAL CARCINOMA

Objective To investigate the significance of overexpression of p5s and bcl-2 protein in carcinogene- sis of cervix. Methods 10 cases of cervical intraepithelial neoplasis(CIN) and 57 cases of invasive cancer were in- vestigated with immunohistochemistry technique. Results The overexpresion or P53 protein ir CIN and cervical can- cer was significantly higher than that or control, respectively (P<0.01). But there was no significant difference be- tween CIN and cervical cancer(P>0.05). The immunoreactivity of bcl-2 in CIN was much more higher than that of control (P<0.05). The positive rate and immunoreactivity of bcl-2 in cervical carcinoma were both remarkably high- er than those of control (P<0.0l),but there was no significant difference between CIN and cervical carcinoma (P> 0.05). It was also found that there was a remarkably positive correlation between the overexpression of bcl-2 and P53 (P<0.01). Conclusion Because of the loss of wtP53 function,the expression of bcl-2 can not be down-reguated, which is associated with the pathogenesis and development of cervical carcinoma.

Harmine induces apoptosis in HepG2 cells via mitochondrial signaling pathway

BACKGROUND:Harmine has antitumor and antinociceptive effects,and inhibits human DNA topoisomerase.However no detailed data are available on the mechanisms of action of harmine in hepatocellular carcinoma.This study aimed to investigate the effects of harmine on proliferation and apoptosis and the underlying mechanisms in the human hepatocellular carcinoma cell line HepG2.METHODS:The proliferation of HepG2 cells was determined by the cell counting kit-8 (CCK-8) assay and the clone formation test.The morphology of HepG2 cells was examined using fluorescence microscopy after Hoechst 33258 staining Annexin V/propidium iodide (PI) was used to analyze apoptosis and PI to analyze the cell cycle.Western blotting was used to assess expression of the apoptosis-regulated genes Bcl-2,Bax,Bcl-xl,Mcl-1,caspase-3,and caspase-9 Mitochondrial transmembrane potential (Ψ m) was determined using JC-1.RESULTS:Harmine inhibited the proliferation of HepG2 cells in a dose-dependent manner.Hoechst 33258 staining revealed nuclear fragmentation and chromosomal condensation,cell shrinkage,and attachment loss in HepG2 cells treated with harmine.The percentage of the sub/G1 fraction was increased in a concentration-dependent manner,indicating apoptotic cell death.PI staining showed that harmine changed the cell cycle distribution,by decreasing the proportion of cells inG0/G1 and increasing the proportion in S and G2/M.Harmine induced apoptosis in a concentration-dependent manner,with rates of 20.0%,32.7% and 64.9%,respectively.JC-1 revealed a decrease in Ψ m.Apoptosis of HepG2 cells was associated with caspase-3 and caspase-9 activation,down-regulation of Bcl-2,Mcl-1,and Bcl-xl,and no change in Bax.CONCLUSIONS:Harmine had an anti-proliferative effect in HepG2 cells by inducing apoptosis.Mitochondrial signal pathways were involved in the apoptosis.The cancer-specific selectivity shown in this study suggested that harmine is a promising novel drug for human hepatocellular carcinoma.

Abrogation of heat-shock protein (HSP)70 expression induced cell growth inhibition and apoptosis in human androgen-independent prostate cancer cell line PC-3m

Aim: To investigate the effect of abrogating heat shock protein (HSP) 70 expression by antisense HSP70 oligonucleotides treatment on human androgen-independent prostate cancer cell line PC-3m growth. Methods: PC-3m cells were treated with 0-16 μmol/L antisense HSP70 oligomers for 0-100 hr. Cell growth inhibition was analyzed using a trypan blue dye exclusion test. Apoptotic cells were detected and confirmed by flow cytometric analysis and DNA fragmentation analysis. The protein expression of HSP70 and bcl-2 affected by antisense HSP70 oligomers were determined using Western blot. Results: Antisense HSP70 oligomer induced apoptosis and then inhibited proliferation of PC-3m cells in a dose- and time-dependent manner. Ladder-like patterns of DNA fragments were observed in PC-3m cells treated with 10 μmol/L antisense HSP70 oligomer for 48 hr or 8 μmol/L for 72 hr on agarose gel electrophoresis. Antisense HSP70 oligomer pretreatment enhanced the subsequent induction of apoptosis by heat shock in PC-3m cells. In addition, undetectable HSP70 expression was observed at a concentration of 10 μmol/L antisense HSP70 oligomer treatment for 48 hr or 8 μmol/L for 72 hr in Western blot, which was paralleled by decreased expression levels of anti-apoptotic protein bcl-2. Conclusion: HSP70 antisense oligomer treatment abrogates the expression of HSP70, which may disrupt HSP70-bcl-2-interactions and further down-regulate bcl-2 expression, in turn inducing apoptosis and inhibiting cell growth in PC-3m cells.

Effect of heparin on apoptosis in human nasopharyngeal carcinoma CNE2 cells

In order to study the mechanism of the effect of heparin on apoptosis in carcinoma cells, the nasopharyngeal carcinoma cell line CNE2 was used to identify the effect of heparin on apoptosis associated with the expression of c-myc, bax, bcl-2 proteins by use of Hoechst 33258 staining, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), agarose gel electrophoresis, and flow cytometry, as well as Western blot analysis. The results showed that heparin induced apoptosis of CNE2 cells including the morphologic changes such as reduction in the volume, and the nuclear chromatin condensation, as well as the 'ladder pattern' revealed by agarose gel electrophoresis of DNA in a concentration-dependent manner. The number of TUNEL-positive cells was dramatically increased to 33.6+/-1.2% from 2.8+/-0.3% by treatment with heparin in different concentrations (10 to approximately 40 kU/L). The apoptotic index was increased to 32.5% from 3.5% by detecting SubG1 peaks on flow cytometry. Western blot analysis showed that levels of bcl-2, bax and c-myc were significantly overexpressed by treatment with the increase of heparin concentrations. These results suggest that heparin induces apoptosis of CNE2 cells, which may be regulated by differential expression of apoptosis-related genes.

Mechanical stretch induces mitochondria-dependent apoptosis in neonatal rat cardiomyocytes and G_(2)/M accumulation in cardiac fibroblasts

Heart remodeling is associated with the loss of cardiomyocytes and increase of fibrous tissue owing to abnormal mechanical load in a number of heart disease conditions. In present study, a well-described in vitro sustained stretch model was employed to study mechanical stretch-induced responses in both neonatal cardiomyocytes and cardiac fibroblasts. Cardiomyocytes, but not cardiac fibroblasts, underwent mitochondria-dependent apoptosis as evidenced by cytochrome c (cyto c) and Smac/DIABLO release from mitochondria into cytosol accompanied by mitochondrial membrane potential (△ψ_m) reduction, indicative of mitochondrial permeability transition pore (PTP) opening. Cyclosporin A, an inhibitor of PTP, inhibited stretch-induced cyto c release, △ψ_m reduction and apoptosis, suggesting an important role of mitochondrial PTP in stretch-induced apoptosis. The stretch also resulted in increased expression of the pro-apoptotic Bcl-2 family proteins, including Bax and Bad, in cardiomyocytes, but not in fibroblasts. Bax was accumulated in mitochondria following stretch. Cell permeable Bid-BH3 peptide could induce and facilitate stretch-induced apoptosis and △ψ_m reduction in cardiomyocytes. These results suggest that Bcl-2 family proteins play an important role in coupling stretch signaling to mitochondrial death machinery, probably by targeting to PTP. Interestingly, the levels of p53 were increased at 12 h after stretch although we observed that Bax upregulation and apoptosis occurred as early as 1 h. Adenovirus delivered dominant negative p53 blocked Bax upregulation in cardiomyocytes but showed partial effect on preventing stretch-induced apoptosis, suggesting that p53 was only partially involved in mediating stretch-induced apoptosis. Furthermore, we showed that p21 was upregulated and cyclin B1 was downregulated only in cardiac fibroblasts, which may be associated with G_2/M accumulation in response to mechanical stretch.

JTE-522-induced apoptosis in human gastric adenocarinoma cell line AGS cells by caspase activation accompanying cytochrome C release,membrane translocation of Bax and loss of mitochondrial membrane potential

AIM: To investigate the role of the mitochondrial pathway in JTE-522-induced apoptosis and to investigate the relationship between cytochrome C release, caspase activity and loss of mitochondrial membrane potential (Deltapsim). METHODS: Cell culture, cell counting, ELISA assay, TUNEL, flow cytometry, Western blot and fluorometric assay were employed to investigate the effect of JTE-522 on cell proliferation and apoptosis in AGS cells and related molecular mechanism. RESULTS: JTE-522 inhibited the growth of AGS cells and induced the apoptosis. Caspases 8 and 9 were activated during apoptosis as judged by the appearance of cleavage products from procaspase and the caspase activities to cleave specific fluorogenic substrates. To elucidate whether the activation of caspases 8 and 9 was required for the apoptosis induction, we examined the effect of caspase-specific inhibitors on apoptosis. The results showed that caspase inhibitors significantly inhibited the apoptosis induced by JTE-522. In addition, the membrane translocation of Bax and cytosolic release of cytochrome C accompanying with the decrease of the uptake of Rhodamin 123, were detected at an early stage of apoptosis. Furthermore, Bax translocation, cytochrome C release, and caspase 9 activation were blocked by Z-VAD.fmk and Z-IETD-CHO. CONCLUSION: The present data indicate a crucial association between activation of caspases 8, 9, cytochrome C release, membrane translocation of Bax, loss of Deltapsim and JTE-522-induced apoptosis in AGS cells.