Ethanolic Neem (Azadirachta indica) Leaf Extract Induces Apoptosis in the Hamster Buccal Pouch Carcinogenesis Model by Modulation of Bcl-2, Bim,Caspase 8 and Caspase 3

Induction of apoptosis is one of the most active strategies in cancer chemoprevention and the ability of medicinal ‍plants in this regard has attracted major research interest. The present study was designed to investigate the apoptosis ‍inducing capacity of an ethanolic neem leaf extract (ENLE) during 7,12-dimethylbenz[a]anthracene (DMBA)-induced ‍hamster buccal pouch carcinogenesis using the apoptosis-associated proteins Bcl-2, Bim, caspase 8 and caspase 3 as ‍markers. Topical application of DMBA to the hamster cheek pouch for 14 weeks resulted in well developed squamous ‍cell carcinomas associated with increased expression of Bcl-2 and decreased expression of Bim, caspase 8 and caspase ‍3. Administration of ENLE inhibited DMBA-induced hamster buccal pouch (HBP) carcinogenesis, as revealed by ‍the absence of neoplasms, with induction of Bim and caspases 8 and 3 and inhibition of Bcl-2 expression. Our results ‍suggest that the chemopreventive effects of ENLE may be mediated by induction of apoptosis.     

西黄浸提液抑制胃癌SGC-7901 细胞增殖的可能机制

[摘要] 目的：探讨西黄浸提液对胃癌SGC-7901 细胞增殖的影响及其可能机制。方法：常规培养胃癌细胞株SGC-7901,用CCK-8 法和细胞流式细胞术检测不同质量浓度（3.2、6.4、12.8 和25.6 mg/ml）的西黄浸提液在不同时间点（24、48 和72 h）对SGC-7901 细胞增殖和凋亡的影响,用qPCR法检测不同质量浓度西黄浸提液对SGC-7901 细胞凋亡相关基因Bax 和Bcl-2 mRNA表达的影响,用Western blotting 检测西黄浸提液对凋亡相关蛋白caspase 3、caspase 9、Bax和Bcl-2 表达的影响。结果：3.2~25.6 mg/ml的西黄浸提液均能有效地抑制胃癌SGC-7901 细胞的增殖（P<0.05 或P<0.01）,并且随浓度增加SGC-7901 细胞凋亡率增加（P<0.01）。西黄浸提液能够显著上调SGC-7901 细胞Bax mRNA和下调Bcl-2 mRNA表达水平（P<0.05 或P<0.01）,并可增加caspase3、caspase 9 和Bax 蛋白表达、降低Bcl-2 蛋白表达（P<0.05 或P<0.01）。结论：西黄浸提液通过触发细胞凋亡抑制胃癌SGC-7901细胞的增殖,此可成为一个潜在的胃癌辅助治疗的方法。     

Immunohistochemical detection of apoptotic markers in gastric cancer

Apoptosis proteins may play a role in prognosis and therapy response; however, they have not been fully investigated in gastric cancer. We aimed to assess the expression of proteins in the Bcl-2 family. Immunohistochemistry was employed to examine the expression of the antiapoptotic proteins Bcl-2 and Bcl-XL and the proapoptotic proteins Bad, Bak, Bax, Bid, Bim, and p53 in 21 cases of gastric cancer. Immunopositivity was observed in 12/21 (57%) cases for p53, 16/21 (76%) cases for Bcl-XL, and 5/21 (23%) cases for Bcl-2. For the proapoptotic members of the Bcl family, loss of protein expression was observed: Bid (14/21 cases; 66%), Bad (13/21 cases; 61%), Bax (12/21 cases; 57%), Bak (9/21 cases; 42%), and Bim (4/21 cases; 19%). This study identified apoptosis proteins that exhibit heterogeneous expression between primary gastric carcinomas.     

小檗胺通过内质网应激通路诱导胃癌细胞A GS凋亡

目的:研究小檗胺对人胃癌细胞AGS增殖和凋亡的影响,并探讨其可能的作用机制.方法:应用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(MTT)法测定细胞活力;膜联蛋白V/碘化丙啶(An-nexin V/PI)细胞凋亡法测定细胞凋亡;Western blot法测定Bcl-2、Bax、chop、GRP78和cle...     

Identification and characterization of Bimgamma,a novel proapoptotic BH3-only splice variant of Bim

BH3 (Bcl-2 homology 3)-only proteins of the Bcl-2 family play an essential role in apoptosis. In this study, a novel human BH3-only protein, Bcl-2-interacting mediator (Bim)gamma, was identified during our study of regulation of prostate cancer cell death by Bcl-2 family proteins. Bimgamma shares the highest amino acid sequence homology to BimEL and BimL, two proapoptotic BH3-only Bcl-2 proteins derived from alternative mRNA splicing. Genomic studies indicate that Bimgamma is a novel splice variant of Bim and is generated as a result of the retention of a 126-bp intron of the bim gene. Bimgamma mRNA displays a tissue-specific expression pattern distinct from those of the other Bim isoforms. Subcellular fractionation studies indicate that Bimgamma is localized both in intracellular membranes and cytosol. Interestingly, Bimgamma mRNA, similar to the BimEL protein, is up-regulated in the majority of the prostate cancer cell lines studied, whereas several other proapoptotic Bcl-2 proteins, including Bax, Bak, and Bad, are down-regulated in prostate cancer cells. Functional studies indicate that Bimgamma inhibits clonal growth in prostate cancer cells and promotes apoptosis, which is inhibited by overexpressing Bcl-2. Because both Bimgamma and BimEL are proapoptotic BH3-only proteins and both are up-regulated in prostate cancer cells, they may play a unique role in prostate cancer development.     

Prevention of N-methyl-N'-nitro-N-nitrosoguanidine and saturated sodium chloride-induced gastric carcinogenesis in Wistar rats by lycopene.

We investigated "the "chemopreventive potential of lycopene against gastric carcinogenesis induced in male Wistar rats by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and saturated sodium chloride (S-NaCl). Administration of lycopene inhibited MNNG+S-NaCl-induced gastric carcinogenesis as revealed by the absence of carcinomas. Lipid peroxidation, reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR) were used to monitor the chemopreventive potential of lycopene. The extent of lipid peroxidation was significantly lower, whereas GSH, GPx, GST and GR were markedly enhanced in the gastric mucosa of tumour-bearing animals. Our data suggest that lycopene may exert its inhibitory effects by modulating the oxidant and antioxidant status in the gastric mucosa.     

Gab2基因在胃癌中的表达及对胃癌细胞增殖、凋亡、迁移及AKT、p-AKT、Bax、Bcl-2表达的影响研究

目的 探讨Gab2基因在胃癌中的表达及对胃癌细胞增殖、凋亡、迁移及对AKT、p-AKT、Bax、Bcl-2表达的影响.方法 采用RT-PCR及Western Blot检测胃癌组织和癌旁组织中Gab2的表达.培养人胃癌细胞株SGC-7901,分别用Gab2小干扰RNA(Gab2-siRNA)和阴性对照(siRNA-NC)转染细胞,以空脂质体转染的细胞作为对照组,各组细胞培养48 h.应用Western Blot检测细胞中Gab2、AKT、p-AKT、Bax、Bcl-2蛋白表达的变化,CCK-8检测细胞增殖情况,流式细胞仪检测细胞凋亡,Transwell小室检测细胞迁移能力.结果 胃癌组织中Gab2的mRNA及蛋白表达水平均明显高于癌旁组织(P﹤0.01);Gab2-siRNA组Gab2蛋白表达水平明显低于对照组(P﹤0.01);siRNA-NC组细胞的存活率、凋亡率、迁移数及AKT、p-AKT、Bax、Bcl-2蛋白表达与对照组比较,差异均无统计学意义(P﹥0.05);Gab2-siRNA组细胞的AKT蛋白表达与对照组比较,差异无统计学意义(P﹥0.05),细胞的存活率、迁移数及p-AKT、Bcl-2蛋白表达明显低于对照组(P﹤0.01),细胞凋亡率及Bax蛋白表达明显高于对照组(P﹤0.01).结论 Gab2在胃癌组织高表达,沉默Gab2的表达能显著抑制人胃癌细胞株SGC-7901的增殖和迁移,并通过调节Bax、Bcl-2蛋白表达促进细胞凋亡,其可能的机制与AKT信号通路的调控有关.     

S-benzyl-cysteine-mediated Cell Cycle Arrest and Apoptosis Involving Activation of Mitochondrial-dependent Caspase Cascade through the p53 Pathway in Human Gastric Cancer SGC-7901 Cells

S-benzyl-cysteine (SBC) is a structural analog of S-allylcysteine (SAC), which is one of the major watersolublecompounds in aged garlic extract. In this study, anticancer activities and the underlying mechanismsof SBC action were investigated and compared these with those of SAC using human gastric cancer SGC-7901cells. SBC significantly suppressed the survival rate of SGC-7901 cells in a concentration- and time-dependentmanner, and the inhibitory activities of SBC were stronger than those of SAC. Flow cytometry revealed that SBCinduced G2-phase arrest and apoptosis in SGC-7901 cells. Typical apoptotic morphological changes were observedby Hoechst 33258 dye assay. SBC-treatment dramatically induced the dissipation of mitochondrial membranepotential (ΔΨm), and enhanced the enzymatic activities of caspase-9 and caspase-3 whilst hardly affectingcaspase-8 activity. Furthermore, Western blotting indicated that SBC-induced apoptosis was accompanied byup-regulation of the expression of p53, Bax and the down-regulation of Bcl-2. Taken together, this study suggestedthat SBC exerts cytotoxic activity involving activation of mitochondrial-dependent apoptosis through p53 andBax/Bcl-2 pathways in human gastric cancer SGC-7901 cells.     

Expression of insulin-like growth factor-I receptor, estrogen receptor alpha, Bcl-2 and Bax proteins in human breast cancer

Disturbance in expression of estrogen receptors together with changing influence of growth factor receptors and apoptosis associated proteins plays a role in breast cancer development and progression. However, immunohistochemical detection and relationships among these proteins were not often considered in relation to breast cancer and a few evaluations of expression provided mismatching results and conclusions. Consequently, we examined by immunohistochemistry the expression of the insulin-like growth factor-I receptor (IGF-IR), estrogen receptor alpha (ERalpha) and apoptosis-associated proteins, Bcl-2 and Bax, in human primary breast cancer, as well as analyzing the relationships among these proteins. The positive immunostaining for IGF-IR, ERalpha, Bcl-2 and Bax was noted in 56, 63.8, 82.8 and 50% of tumors, respectively. We observed that IGF-IR negatively correlated with ERalpha in the group of all tumors and in axillary node negative cancer (p<0.03, p<0.05, respectively), but not in the subgroup of node positive cancer. Expression of ERalpha correlated positively with Bcl-2 and negatively with Bax proteins (p<0.0001, p<0.05, respectively). We did not note significant relationships between IGF-IR and Bcl-2, or IGF-IR and Bax proteins. We found that increased Bax expression was associated with positive lymph node status, pT2 stage and G3 grade of tumors. Knowledge about alterations in the IGF-IR expression and relations of the receptor to other biological factors could help in our understanding of breast cancer biology and the importance of the IGF-IR in cancer progression as well as in effective management of breast cancer.     

RNA干扰抑制RPS12基因表达对胃癌细胞凋亡的影响及分子机制探讨

目的: 探讨RPS12基因特异的RNA干扰对胃癌BGC823细胞凋亡的影响及机制。 方法: 设计并构建RPS12特异性shRNA表达载体(RPS12-shRNA),以Lipofectamine2000介导将RPS12特异性shRNA及Scram-ble-shRNA表达载体分别转染胃癌细胞。RT-PCR方法检测BGC823细胞中RPS12基因及凋亡相关基因Bcl-2和Bax mRNA的表达,流式细胞术(flow cytometry,FCM)分析RNA干扰对细胞凋亡的影响。 结果: RT-PCR结果显示,RPS12-shRNA表达载体转染第3、5、7天后,RPS12基因表达低于对照组,其中第5天下调最明显。RPS12特异性RNA干扰第5天、第7天后,Bcl-2 mRNA表达明显下调,BaxmRNA表达无明显改变。流式细胞术分析结果显示,RNA干扰RPS12基因第7天后,胃癌细胞凋亡率(17.84%)明显高于对照组(1.89%)。 结论: RNA干扰RPS12基因促进胃癌细胞凋亡作用可能是其作为上游基因通过下调Bcl-2基因表达而实现的。     

Effects of the proteasome inhibitor bortezomib alone and in combination with chemotherapeutic agents in gastric cancer cell lines

The proteasome plays a pivotal role in controlling cell proliferation, apoptosis, and differentiation in a variety of tumor cells. Bortezomib is a boronic acid dipeptide derivative, which is a selective and potent inhibitor of the proteasome and has prominent effects in vitro and in vivo against several solid tumors. We examined the anti-proliferative and apoptotic effects of bortezomib in three gastric cancer cell lines (SNU638, MUGC-3 and MKN-28), along with its antitumor combination effects with other chemotherapeutic agents. Tumor cell growth inhibition and apoptosis was measured by MTT assay and FACS analysis, respectively. Apoptosis- and cell cycle-associated protein expression levels were measured by Western blot assay. Bortezomib induced the suppression of tumor cell growth and apoptosis in a dose-dependent manner with an inhibitory dose (ID)50 of approximately 0.5 microg/ml in all gastric cancer cell lines tested. Further combination treatment with cisplatin and docetaxel, in particular with docetaxel displayed dramatically increased tumor cell growth suppression in all three gastric cancer cell lines, as compared to single drug treatment alone. This was concomitant with the induction patterns of apoptotic cells. Bortezomib treatment increased the Bax protein expression. Moreover, combination treatment of bortezomib plus docetaxel resulted in a dramatic increase in the Bax expression. In contrast, Bcl-2 expression was decreased by combination treatment with bortezomib plus docetaxel in SNU638 cells. Finally, bortezomib, docetaxel and to a greater degree bortezomib plus docetaxel increased the expression levels of p27 proteins even without influencing p53 expression levels. Bortezomib has profound effects on tumor cell growth inhibition and induction of apoptosis in human gastric cancer cells, suggesting that bortezomib may be an effective therapeutic drug for patients with gastric cancer. Further combination studies with other chemotherapeutic drugs, in particular docetaxel showing more tumor cell growth inhibition and apoptosis suggest that combining bortezomib with docetaxel might be more effective for displaying tumor cell growth inhibitory effects in gastric cancer cells through regulation of Bcl-2, Bax and p27 proteins in vitro.     

Finasteride induces apoptosis via Bcl-2, Bcl-xL, Bax and caspase-3 proteins in LNCaP human prostate cancer cell line

We investigated the effects of finasteride, a 5alpha-reductase inhibitor, on cell death machinery through the induction of apoptosis in an in vitro model for prostate cancer. Finasteride treatment of the LNCaP hormone-dependent human prostate cancer cell line caused the loss of cell viability and accelerated apoptosis in a concentration-dependent manner. The contents of immunoreactive procaspase-3 were examined by immunoblot analysis and the results suggest that the apoptosis induced by finasteride involves the increase of caspase-3 activity. Early cell changes that occur during apoptosis are associated with mitochondrial changes mediated by members of the Bcl-2 family of proteins. Therefore, Bcl-2, Bcl-xL and Bax were evaluated by the Western blot analysis. The immunoreactivity for pro-apoptotic Bax was markedly increased whereas antiapoptotic Bcl-2 and Bcl-xL expression was significantly reduced after incubation of cells with finasteride. These findings suggest that finasteride induces apoptosis in LNCaP cells via proteins of the Bcl-2 and caspase family.     

特异性环氧合酶-2抑制剂SC236诱导胃癌细胞株凋亡的实验研究

目的:探讨环氧合酶-2(COX-2)特异性抑制剂SC236诱导胃癌细胞株SGC7901凋亡的机制. 方法: SC236对人胃癌来源的SGC7901细胞进行凋亡诱导.以吖啶橙染色后荧光显微镜下观察凋亡细胞形态并计算凋亡指数.Western blot法检测凋亡调节蛋白Bcl-2、Bak、Bax与CED-9的表达情况.流式细胞仪检测细胞凋亡率.结果: SGC7901细胞经SC236作用后,细胞中凋亡促进因子Bak的表达水平明显增高、凋亡抑制因子Bcl-2的表达水平显著下降、而凋亡促进因子Bax和凋亡抑制因子CED-9表达水平无明显变化.细胞凋亡指数或凋亡率则随SC236浓度的增加和作用的时间延长而升高.结论: COX-2特异抑制剂SC236可通过上调凋亡促进因子Bak表达和下调凋亡抑制因子Bcl-2表达而诱导胃癌细胞株SGC7901的凋亡.     

Involvement of proapoptotic Bcl-2 family members in parthenolide-induced mitochondrial dysfunction and apoptosis

Parthenolide is a sesquiterpene lactone responsible for the bioactivities of Feverfew. Besides its potent anti-inflammatory effect, this compound has recently been reported to induce apoptosis in cancer cells, possibly through mitochondrial dysfunction. In the present study, we attempted to examine parthenolide-mediated cell death signaling pathway by focusing on the involvement of Bcl-2 family members. Using a human colorectal cancer cell line COLO205, we first demonstrated that parthenolide acted through the cell death receptor pathway to activate caspase 8. Following caspase 8 activation, Bid, a proapoptotic Bcl-2 member, was cleaved and this cleavage then triggered Bax conformational changes and Bax translocation from cytosol to mitochondrial membrane. Meanwhile, another proapoptotic protein, Bak, was up-regulated and oligomerized on the mitochondrial membrane. All these alterations were found to be prerequisite for the subsequent release of proapopototic mitochondrial proteins, including cytochrome c and Samc, in parthenolide-treated cells. Moreover, selective inhibition of caspase 8 activity by a synthetic caspase inhibitor (IETD-FMK) or overexpression of a viral protein (CrmA) suppressed the cleavage of Bid, conformational changes of Bax, cytochrome c release, and apoptosis. Therefore, the proapoptotic Bcl-2 family members are important mediators relaying the cell death signaling elicited by parthenolide from caspase 8 to downstream effector caspases such as caspase 3, and eventually to cell death.     

Ginsenoside-Rh2 Inhibits Proliferation and Induces Apoptosis of Human Gastric Cancer SGC-7901 Side Population Cells

Objectives: To observed the effects of ginsenoside -Rh2 (GS-Rh2) on proliferation and apoptosis of side population (SP) human gastric cancer SGC-7901 cells. Materials and Methods: SGC-7901 SP and Non-SP cells were sorted by flow cytometry and assessed using the cck-8 method. Expression of apoptosis-related proteins Bax and Bcl-2 of SP before and after the intervention was determined by Western-blotting. Results: It was found that the proliferation of SP was significantly faster than that of NSP (<0.05). In addition, GS-Rh2 inhibited proliferation of gastric cancer SP cells, induced cell cycle arrest and cell apoptosis, and changed the expression of BAX/Bcl-2 proteins in a time-dependent and concentration-dependent manner (<0.05). Conclusions: With increase of GS-Rh2 dose, GS-Rh2 gradually inhibit the proliferation of SGC-7901 SP cells, which have high proliferation rate, through G1/G0 phase arrest, followed by apoptosis which involves the up-regulation of Bax and the down-regulation of Bcl-2.     

Activation of mitochondrial voltage-dependent anion channel by apro-apoptotic BH3-only protein Bim

Bcl-2 family of proteins regulates apoptosis by controlling mitochondrial membrane permeability. We have previously shown that the voltage-dependent anion channel (VDAC) plays a crucial role in apoptotic changes of the mitochondria and its activity is directly regulated by some Bcl-2 family members, including Bcl-2/Bcl-x(L) and Bax/Bak but not Bid. Here, we showed that in isolated mitochondria, Bim induced loss of membrane potential and cytochrome c release like Bax/Bak, with these changes being inhibited by an anti-VDAC antibody. In addition, microinjection of the anti-VDAC antibody significantly reduced Bim-induced apoptosis. Study using purified proteins indicated that Bim directly interacts with the VDAC. Immunoprecipitation analysis revealed that Bim interacts with the VDAC and the interaction is remarkably enhanced during apoptosis. An experiment using liposomes indicated that Bim enhanced VDAC activity, as did Bax/Bak. Furthermore, Bim (but not tBid) was able to induce apoptotic changes of yeast mitochondria in a VDAC-dependent manner, and also induced the lysis of red blood cells, with this effect being inhibited by the anti-VDAC antibody. These results indicate that Bim has an ability to activate directly the VDAC, which plays an important role in apoptosis of mammalian cells.     

靶向SATB1基因的短发夹RNA诱导肺癌A549细胞凋亡

目的:探讨靶向SAT B1(special AT-rich sequence-binding protein-1)基因的短发夹RNA (short hairpinRNA,shRNA)对肺癌A549细胞凋亡的影响及其可能的机制.方法:构建靶向SATB1基因的shRNA重组质粒SATB1-shRNA,采用脂质体法将其转染至A549细胞;分别采用RT-PCR和蛋白质印迹法检测A549细胞中SATB1、Bcl-2、Bax mRNA和SATB1、Bcl-2、Bax、caspase 3蛋白的表达水平FCM检测A549细胞的凋亡率.结果:成功构建了SATB1-shRNA重组质粒;SATB1-shRNA转染A549细胞后,SATB1、Bcl-2 mRNA及其蛋白表达下调,Bax mRNA和Bax、caspase 3蛋白表达上调(p＜0.05).SATB1-shRNA转染组细胞凋亡率[(14.18±1.59)％]较对照组[(1.84±0.57)％]明显增加(P＜ 0.01).结论:SATB1-shRNA可显著下调肺癌A549细胞中SATB1基因的表达水平并诱导细胞凋亡,其机制可能与下调Bcl-2基因表达所引起的级联效应有关.     

2-deoxyglucose-induced toxicity is regulated by Bcl-2 family members and is enhanced by antagonizing Bcl-2 in lymphoma cell lines

Targeting altered cancer cell metabolism with the glycolysis inhibitor, 2-deoxyglucose (2DG), is a viable therapeutic strategy, but the effects of 2DG on lymphoma cells and the mechanism of action are unknown. Five T-cell lymphoma lines and two B-cell lymphoma lines were shown to be highly sensitive to 2DG. Examination of the cell death pathway demonstrated pro-apoptotic protein Bax 'activation' and caspase cleavage in 2DG-treated cells. However, Q-VD-OPh, a potent inhibitor of caspase activity provided minimal protection from death. In contrast, overexpressing the anti-apoptotic protein Bcl-2 dramatically enhanced the survival of 2DG-treated cells that was negated by a Bcl-2 antagonist. BH3-only members, Bim and Bmf, were upregulated by 2DG, and shRNAs targeting Bim protected from 2DG toxicity demonstrating that Bim is a critical mediator of 2DG toxicity. 2DG also induced GADD153/CHOP expression, a marker of endoplasmic reticulum (ER) stress and a known activator of Bim. Mannose, a reagent known to alleviate ER stress, transiently protected from 2DG-induced cell death. Examination of the effects of 2DG on energy metabolism showed a drop in ATP levels by 30 min that was not affected by either Bcl-2 or mannose. These results demonstrate that ER stress appears to be rate limiting in 2DG-induced cell death in lymphoma cells, and this cell killing is regulated by the Bcl-2 family of proteins. Bcl-2 inhibition combined with 2DG may be an effective therapeutic strategy for lymphoma.     

Magnolol, a natural compound, induces apoptosis of SGC-7901 human gastric adenocarcinoma cells via the mitochondrial and PI3K/Akt signaling pathways

Gastric cancer is the fourth most commonly diagnosed cancer with the second highest mortality rate worldwide. Surgery, chemotherapy and radiation therapy are generally used for the treatment of stomach cancer but only limited clinical response is shown by these therapies and still no effectual therapy for advanced gastric adenocarcinoma patients is available. Therefore, there is a need to identify other therapeutic agents against this life-threatening disease. Plants are considered as one of the most important sources for the development of anticancer drugs. Magnolol, a natural compound possesses anticancer properties. However, effects of Magnolol on human gastric cancer remain unexplored. The effects of Magnolol on the viability of SGC-7901 cells were determined by the MTT assay. Apoptosis, mitochondrial membrane potential and cell cycle were evaluated by flow cytometry. Protein expression of Bcl-2, Bax, caspase-3 and PI3K/Akt was analysed by Western blotting. Magnolol induced morphological changes in SGC-7901 cells and its cytotoxic effects were linked with DNA damage, apoptosis and S-phase arrest in a dose-dependent manner. Magnolol triggered the mitochondrial-mediated apoptosis pathway as shown by an increased ratio of Bax/Bcl-2, dissipation of mitochondrial membrane potential (ΔΨm), and sequential activation of caspase-3 and inhibition of PI3K/Akt. Additionally, Magnolol induced autophagy in SGC-7901 cells at high concentration but was not involved in cell death. Magnolol-induced apoptosis of SGC-7901 cells involves mitochondria and PI3K/Akt-dependent pathways. These findings provide evidence that Magnolol is a promising natural compound for the treatment of gastric cancer and may represent a candidate for in vivo studies of monotherapies or combination antitumor therapies.     

microRNA-21通过Bcl-2通路调节胃癌紫杉醇化疗耐药性

目的:研究miR-21在胃癌组织中的表达水平及对胃癌生物学行为的影响,探讨miR-21与紫杉醇化疗耐药性的关系及机制。方法:实时荧光定量（real-time quantitative polymerase chain reaction,RT-qPCR）比较25例胃癌组织和癌旁组织中miR-21的表达差异;细胞实验探讨miR-21对胃癌细胞增殖、凋亡能力的影响;MTT法测定紫杉醇对SGC-7901细胞的生长抑制率;Western blot验证Bcl-2、Bax、PTEN蛋白表达和miR-21的关系。结果:miR-21在胃癌组织中表达水平高于癌旁正常组织（P=0.015）;与NC组比较,转染miR-21模拟物的胃癌SGC-7901细胞增殖能力（P＜0.05）增强,下调miR-21表达水平可促进胃癌细胞凋亡(P＜0.05);转染miR-21 mimic组的紫杉醇对胃癌细胞的抑制率明显低于miR-21 inhibitor组;miR-21 inhibitor组较NC组中Bcl-2的蛋白水平下降（P=0.000）,而PTEN（P=0.039）、Bax（P=0.037）表达升高。结论:miR-21在胃癌组织中过表达,且过表达的miR-21可能通过升高Bcl-2表达并降低Bax、PTEN蛋白表达从而促进胃癌细胞增殖,抑制胃癌细胞凋亡,并增加紫杉醇化疗耐药性。