bcl-2家族BH3-only蛋白在依托泊苷诱导胃腺癌细胞凋亡中的作用

目的研究bcl-2家族BH3-only蛋白Noxa、Bim和PUMA在依托泊苷诱导胃腺癌细胞凋亡中的作用。方法Annexin V-FITC染色,流式细胞仪(FCM)检测细胞凋亡率,半定量RT-PCR检测细胞中BH3-only蛋白的mRNA表达量。结果依托泊苷诱导胃腺癌细胞凋亡具有剂量、时间依赖性,SGC-7901细胞系比BGC-823更加敏感,100μM的依托泊苷作用48小时后SGC-7901的凋亡率达到50%,而BGC-823的凋亡率只有20%。BH3-only蛋白Noxa的mRNA表达明显上调,Bim少量上调与依托泊苷诱导的细胞凋亡有关系;相反,PUMA的mRNA表达量在依托泊苷治疗前后没有变化。结论依托泊苷诱导的胃腺癌细胞凋亡与BH3-only蛋白Noxa和Bim表达上调有关联。     

放射诱导胃癌细胞的凋亡及其相关基因的研究

目的观察放射诱导人胃癌细胞株SGC-7901凋亡的作用，并进一步研究bcl-2基因及家族、bax基因、p53基因在此过程中的作用。方法用不同剂量的9 MeV β线照射SGC-7901细胞，观察细胞在受照后的不同时间生长情况。电子透射电镜下观察细胞形态变化。琼脂糖凝胶电泳检测DNA条带变化。流式细胞仪检测受照前后细胞周期及凋亡率的变化。免疫细胞化学法检测受照前后bcl-2、bax、p53基因的表达水平。结果单次剂量照射后，SGC-7901细胞凋亡率与时间、剂量有相关性。在放射诱导SGC-7901细胞凋亡的过程中，bcl-2基因表达水平下降，bax基因表达水平升高，而p53基因表达水平无变化。结论放射能够诱导胃癌细胞株SGC-7901凋亡，凋亡率在72h达高峰。bcl-2及bax基因参与了放射诱导凋亡的调控。细胞凋亡主要是通过p53基因非依赖途径。     

下调Beclin1 抑制卵巢癌A2780/DDP细胞对顺铂的耐药性

目的：探究敲减Beclin1 表达对卵巢癌细胞A2780 对顺铂耐药的影响及其相关机制。方法：以Western blotting 及qPCR 检测卵巢癌细胞株A2780 及耐药细胞株A2780/DDP 中Beclin1 的表达情况；A2780/DDP 细胞转染Beclin1 siRNA 后，用MTT法检测细胞对顺铂敏感性的变化，克隆形成实验检测各组细胞的克隆形成情况，流式细胞术检测各组细胞的凋亡，MDC荧光染色检测细胞的自噬情况，Western blotting 检测自噬相关蛋白、溶酶体相关膜蛋白Lamp-2 以及组织蛋白酶Cathepsin B的表达情况。结果：顺铂耐药细胞株A2780/DDP 中Beclin1 mRNA及蛋白的表达水平均明显高于A2780 细胞株（均P<0.05），在A2780细胞中加入顺铂刺激后Beclin1 蛋白的表达水平显著升高（P<0.05）。敲减Beclin1 表达可促进顺铂诱导的A2780/DDP 细胞的凋亡（P<0.05）、抑制细胞自噬的发生（P<0.05）、减少细胞克隆形成（P<0.05）和增加细胞对顺铂的敏感性（P<0.05）；Western blotting结果显示，敲减Beclin1 可上调A2780/DDP 细胞中cleaved-caspase 3 和Cathepsin B的蛋白水平，下调Atg3、Atg7、LC3Ⅱ/Ⅰ、Lamp-2的表达水平（均P<0.05）。结论：敲减Beclin1 表达可提高A2780/DDP细胞对顺铂的敏感性，其机制可能与调节自噬相关蛋白表达抑制细胞保护性自噬和影响溶酶体功能，从而促进顺铂诱导耐药细胞凋亡有关。     

丹参酮Ⅰ对人胃腺癌细胞SGC-7901增殖、凋亡的影响

目的：研究丹参酮I（Tan I）对SGC-7901人胃腺癌细胞增殖、凋亡的影响。方法：体外培养SGC-7901细胞,实验分为对照组,5-FU250μg/ml,Tan I 0.5μg/ml,Tan I 1μg/ml,Tan I 2μg/ml,Tan I 4μg/ml。MTT法检测SCG-7901细胞增殖情况;Hoechst33258/PI双荧光活染法观察凋亡细胞核形态学改变;流式细胞仪检测细胞周期分布,免疫细胞化学SABC法检测SGC-7901人胃腺癌细胞中Bcl-2的表达。结果：Tan I对胃腺癌细胞的生长有明显的抑制作用;Tan I作用后胃腺癌细胞表现为凋亡特征性的形态改变;Tan I可浓度依赖性引起G1期细胞数量增多,S期细胞减少;Tan I作用组胃腺癌细胞Bcl-2表达明显减少。结论：TanI对体外培养的SGC-7901人胃腺癌细胞的生长有明显的抑制作用,可通过促进其凋亡、影响细胞周期分布及抑制SGC-7901人胃腺癌细胞Bcl-2的表达发挥其抗肿瘤作用。     

Ad-PTEN体外对SGC-7901胃癌细胞生长的抑制作用

目的：探讨腺病毒介导的PTEN基因表达体外对SGC-7901胃癌细胞生长抑制作用及其分子机制。方法：将携有PTEN基因的复制缺陷型腺病毒载体（Ad-PTEN）感染SGC-7901胃癌细胞,用RT-PCR法检测Ad-PTEN在细胞中的表达,光学显微镜及荧光显微镜下观察Ad-PTEN感染细胞前后形态的变化,MTT法检测Ad-PTEN对SGC-7901胃癌细胞生长的抑制作用,用流式细胞术（FCM）检测SGC-7901胃癌细胞凋亡率。RT-PCR分析Bax、Bcl-2、p53、Survivin细胞凋亡相关基因的表达。结果：Ad-PTEN基因组感染SGC-7901胃癌细胞后,RT-PCR结果显示PTEN目的基因能在SGC-7901胃癌细胞中转录,其表达可明显抑制该胃癌细胞的生长,并诱导细胞凋亡。其凋亡机制可能与Bax/Bcl-2比值、p53基因表达上调、Survivin下调有关。结论：重组腺病毒Ad-PTEN具有抑制SGC-7901胃癌细胞生长和诱导细胞凋亡的作用。     

丹参酮Ⅰ对人胃腺癌细胞SGC-7901增殖、凋亡的影响

目的:研究丹参酮I(Tan I)对SGC-7901人胃腺癌细胞增殖、凋亡的影响。方法:体外培养SGC-7901细胞,实验分为对照组,5-FU250μg/ml,Tan I 0.5μg/ml,Tan I 1μg/ml,Tan I 2μg/ml,Tan I 4μg/ml。MTT法检测SCG-7901细胞增殖情况;Hoechst33258/PI双荧光活染法观察凋亡细胞核形态学改变;流式细胞仪检测细胞周期分布,免疫细胞化学SABC法检测SGC-7901人胃腺癌细胞中Bcl-2的表达。结果:Tan I对胃腺癌细胞的生长有明显的抑制作用;Tan I作用后胃腺癌细胞表现为凋亡特征性的形态改变;Tan I可浓度依赖性引起G1期细胞数量增多,S期细胞减少;Tan I作用组胃腺癌细胞Bcl-2表达明显减少。结论:TanI对体外培养的SGC-7901人胃腺癌细胞的生长有明显的抑制作用,可通过促进其凋亡、影响细胞周期分布及抑制SGC-7901人胃腺癌细胞Bcl-2的表达发挥其抗肿瘤作用。     

铂类药物对胃癌细胞生物学行为和MDR1表达的影响

目的 研究顺铂（CDDP）和奥沙利铂（L-OHP）对人胃癌细胞株生长的抑制作用,进而分析两种铂类不同的作用机制。方法 用不同浓度（IC10、IC30、IC50）的CDDP和L-OHP分别作用胃癌细胞株（BGC-823和SGC-7901）24、48、72h,应用MTT比色法检测细胞的增殖抑制率;采用RT-PCR法检测MDR1基因表达量。IC30浓度的两种铂类药物作用于胃癌细胞48h后,用流式细胞术分析细胞凋亡,细胞划痕实验评价细胞迁移能力。结果 两种铂类药物作用后,胃癌细胞BGC-823和SGC-7901的增殖受到抑制,呈时间和剂量依赖,L-OHP的量效变化更明显。两种铂类药物作用后,MDR1呈上升趋势,随着浓度增加和（或）时间的延长,表达增强。BGC-823细胞的凋亡率增加较SGC-7901细胞明显,L-OHP组的细胞凋亡率高于CDDP组;BGC-823细胞的增殖迁移较SGC-7901细胞慢而距离短,CDDP作用后细胞的增殖迁移较L-OHP作用后快而距离长。结论 L-OHP诱导胃癌细胞凋亡及抑制细胞迁移侵袭的能力均强于CDDP。胃癌对两种铂类药的耐药机制可能与其诱导MDR1表达上调有关。     

光辉霉素对胃癌细胞周期、凋亡的影响及可能机制

目的 探讨光辉霉素（MTM）对胃癌细胞周期、凋亡的影响及可能的机制。方法 体外培养胃癌BGC-823、SGC-7901、MKN-28、AGS和正常胃黏膜GES-1细胞，采用实时荧光定量（QPCR） 和Western blotting检测SP1 mRNA和蛋白表达。0、25、50、100 nmol／L MTM处理BGC-823细胞24 h，QPCR和Western blotting检测SP1、p53、p21 mRNA和蛋白表达。流式细胞术检测50 nmol／L MTM处理BGC-823细胞周期和凋亡的变化。结果 QPCR检测胃癌BGC-823、 SGC-7901、MKN-28、AGS细胞系中SP1 mRNA表达量为6.12±0.15，5.42±0.24，3.33±0.21，3.01±0.12，均显著高于GES-1细胞（P＜0.05）；Western blotting检测SP1 蛋白表达与mRNA表达一致。0、25、50、100 nmol／L MTM处理BGC-823细胞，SP1 mRNA和蛋白表达逐渐降低， p53、p21 mRNA和蛋白表达逐渐升高。50 nmol／L MTM组SP1表达量最低（mRNA：0.48±0.12；蛋白：0.28±0.09）， p53表达量最高（mRNA：5.37±0.45；蛋白：1.29±0.20）；100 nmol／L MTM组p21表达量最高（mRNA：4.92±0.53；蛋白：0.86±0.15）；与0 nmol／L MTM组比较，差异具有统计学意义（P＜0.05）。流式细胞术结果显示，50 nmol／L MTM组BGC-823细胞G0／G1比例为（63.71±2.14）％和凋亡率为（24.68±1.09）％，均明显高于0 nmol／L MTM组［（57.39±1.83）％和（9.23±0.75）％］，差异具有统计学意义（P＜0.05）。结论 MTM通过降低SP1、上调p53、p21表达水平来增加胃癌细胞周期阻滞，诱导凋亡。     

RNA干扰STMN1基因表达通过Notch信号通路诱导胃癌细胞凋亡及增强化疗敏感性的研究

摘 要：［目的］ 探讨RNA干扰微管不稳定性蛋白(STMN1)基因表达通过Notch信号通路对胃癌细胞凋亡及化疗敏感性的影响。［方法］ RT-PCR及Western blotting分别检测人胃黏膜上皮细胞GES-1和人胃癌细胞MKN28、SGC7901、BGC823中STMN1 mRNA及蛋白表达;STMN1-siRNA转染BGC823细胞,同时设定对照组和阴性对照组,转染48h后RT-PCR及Western blotting分别检测STMN1 mRNA及蛋白表达;后续实验分为对照组、STMN1-siRNA组、顺铂组、STMN1-siRNA+顺铂组,细胞培养48h后,CCK8及流式细胞仪分别检测细胞增殖及凋亡情况;Western blotting检测活化的含半胱氨酸的天冬氨酸蛋白水解酶3（Cleaved Caspase-3）、Notch1、Hes1蛋白表达。［结果］ STMN1在MKN28、BGC823、SGC7901胃癌细胞中的mRNA及蛋白表达均显著高于在GES-1细胞中的表达（P<0.05）,选择BGC823细胞作为研究对象;转染STMN1-siRNA后BGC823细胞中STMN1的mRNA及蛋白表达均显著低于对照组（P<0.05）;STMN1-siRNA组、顺铂组、STMN1-siRNA+顺铂组OD值及Notch1、Hes1蛋白表达均显著低于对照组,细胞凋亡率及Cleaved caspase3蛋白表达均显著高于对照组（P<0.05）,STMN1-siRNA+顺铂组OD值及Notch1、Hes1蛋白表达均显著低于STMN1-siRNA组和顺铂组,细胞凋亡率及Cleaved caspase3蛋白表达均显著高于STMN1-siRNA组和顺铂组（P<0.05）。［结论］ RNA干扰STMN1表达可通过抑制Notch信号通路增强顺铂对胃癌细胞增殖的抑制及凋亡的促进作用。     

氯喹促进顺铂诱导胃癌SGC7901细胞凋亡及其机制

  目的  研究自噬对顺铂（cisplatin,DDP）诱导的胃癌SGC7901细胞凋亡的影响,并初步探讨其可能机制。  方法  DDP和（或）氯喹处理胃癌SGC7901细胞,MTT法检测细胞增殖,流式细胞术检测细胞凋亡,MDC染色后荧光显微镜观察自噬囊泡,West. ern Blot检测自噬和凋亡相关蛋白。  结果  5 mg/L的顺铂作用于胃癌SGC7901细胞24 h,细胞凋亡率为21.07%±2.12%,同时观测到自噬囊泡增多和LC3-Ⅱ蛋白表达升高;氯喹特异性抑制自噬活性后,提高了顺铂诱导的细胞凋亡率（30.16%±3.54%,P < 0.05）;检测到凋亡相关蛋白Caspase-3和P53表达增加,Bcl-2蛋白表达下降。  结论  自噬在顺铂诱导胃癌SGC7901细胞凋亡的过程中起保护作用,氯喹抑制自噬后,可能通过激活P53蛋白及灭活Bcl-2蛋白的表达来促进细胞凋亡,联合应用顺铂和氯喹有望成为胃癌治疗的新策略。      

Anticancer therapy targeting the apoptotic pathway

Apoptosis, or programmed cell death, has an essential role in controlling cell number in many developmental and physiological settings and in chemotherapy-induced tumour-cell killing. It is a genetically regulated biological process, guided by the ratio of proapoptotic and antiapoptotic proteins. Recently, inducers of apoptosis have been used in cancer therapy. Several studies have attempted to induce apoptosis by triggering the tumour-necrosis-factor-related apoptosis-inducing ligand receptor and the BCL2 family of proteins, and others have targeted the caspases, and proteins that inhibit apoptosis. Most of these therapies are still in preclinical development because of their low efficacy and susceptibility to drug resistance, but some of them have shown promising results. In this article, we review the development and clinical efficacy of proapoptotic drugs that have shown promise.     

ATP-dependent steps in apoptotic signal transduction

Apoptotic changes of the nucleus induced by Fas (Apo1/CD95) stimulation are completely blocked by reducing intracellular ATP level. In this study, we examined the ATP-dependent step(s) of Fas-mediated apoptotic signal transduction using two cell lines. In SKW6.4 (type I) cells characterized by rapid formation of the death-inducing signaling complex on Fas treatment, the activation of caspases 8, 9, and 3, cleavage of DFF45 (ICAD), and release of cytochrome c from the mitochondria to the cytoplasm were not affected by reduction of intracellular ATP, although chromatin condensation and nuclear fragmentation were inhibited. On the other hand, in the Fas-mediated apoptosis of Jurkat (type II) cells, which is characterized by involvement of mitochondria and, thus, shares signal transduction mechanisms with apoptosis induced by other stimuli such as genotoxins, activation of the three caspases, cleavage of DFF45 (ICAD), and nuclear changes were blocked by reduction of intracellular ATP, whereas release of cytochrome c was not affected. These results suggested that the ATP-dependent step(s) of Fas-mediated apoptotic signal transduction in type I cells are only located downstream of caspase 3 activation, whereas the activation of caspase 9 by released cytochrome c is the most upstream ATP-dependent step in type II cells. These observations also confirm the existence of two pathways for Fas-mediated apoptotic signal transduction and suggest that the Apaf-1 (Ced-4 homologue) system for caspase 9 activation operates in an ATP-dependent manner in vivo.     

PKC-delta is an apoptotic lamin kinase

Protein kinase C-delta is activated during apoptosis, following proteolytic cleavage by caspase 3. Furthermore, overexpression of the catalytic kinase fragment of PKC-delta induces the nuclear phenotype associated with apoptosis, though the molecular basis of this effect has not been determined. In these studies we have examined the role of PKC-delta in the disassembly of the nuclear lamina at apoptosis. The nuclear lamina is disassembled during mitosis and apoptosis and mitotic disassembly involves hyperphosphorylation of lamin proteins by mitotic lamin kinases. During apoptosis, lamin proteins are degraded by caspase 6 and the contribution made by phosphorylation has not been proven. We show here that protein kinase C-delta co-localized with lamin B during apoptosis and activation of PKC-delta by caspase 3 was concomitant with lamin B phosphorylation and proteolysis. Inhibition of PKC-delta delayed lamin proteolysis, even in the presence of active caspase 6, whilst inhibitors of mitotic lamin kinases were without effect. In addition recombinant human PKC-delta was able to phosphorylate lamin B in vitro suggesting that its actions are direct and not via an intermediary kinase. We propose that PKC-delta is an apoptotic lamin kinase and that efficient lamina disassembly at apoptosis requires both lamin hyperphosphorylation and caspase mediated proteolysis.     

Cyclooxygenase-2 overexpression reduces apoptotic susceptibility by inhibiting the cytochrome c-dependent apoptotic pathway in human colon cancer cells

The cyclooxygenase-2 (COX-2) gene encodes an inducible enzyme that converts arachidonic acid to prostaglandins and is up-regulated in colorectal neoplasms. Evidence indicates that COX-2 may regulate apoptosis and can influence the malignant phenotype. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit COX enzymes and induce apoptosis in colorectal cancer cell lines, which may contribute to their antitumor effects. To determine whether forced COX-2 expression modulates susceptibility to drug-induced apoptosis, HCT-15 colon carcinoma cells were stably transfected with the COX-2 cDNA, and two clones overexpressing COX-2 were isolated. Selective COX-2 (NS398) and nonselective (sulindac sulfide) COX inhibitors, as well as 5-fluorouracil (5-FU), induced apoptosis (terminal deoxynucleotidyl transferase-mediated nick end labeling in a dosage-dependent manner. Forced COX-2 expression significantly attenuated induction of apoptosis by all three of the drugs compared with parental HCT-15 cells. NSAIDs and 5-FU induced the mitochondrial release of cytochrome c as well as caspase-3 and -9 activation, and to a much lesser extent, caspase-8. COX-2-overexpressing cells showed reduced cytochrome c and caspase activation, relative to parental cells. A specific inhibitor of caspase-3 restored cell survival after drug treatment. COX-2 transfectants were found to overexpress the antiapoptotic Bcl-2 mRNA and protein relative to parental cells. In conclusion, forced COX-2 expression significantly attenuates apoptosis induction by NSAIDs and 5-FU through predominant inhibition of the cytochrome c-dependent apoptotic pathway. COX-2-mediated up-regulation of Bcl-2 suggests a potential mechanism for reduced apoptotic susceptibility.     

Increased expression of apoptotic markers in melanoma

Extensive labelling for the apoptotic markers calcium channel receptor P2X(7) and caspase-3 and telomerase activity was co-localized at a similar intensity in areas affected by superficial spreading melanoma obtained from 80 patients. Labelling for each of these markers also extended 2 microm from the melanoma into the keratinocyte layer of the adjacent normal epidermis. Conversely, the calcium-regulating receptors P2X(1-3) and P2Y(2) (found in normal but not neoplastic skin) were fully de-expressed within 2 microm of the melanoma but fully expressed beyond that distance. The cell adhesion protein E-cadherin (also only present in normal skin) was progressively de-expressed from a point 2 microm from the melanoma until full de-expression within the lesion. These results show that telomerase-induced proliferation and defensive apoptosis are co-localized and simultaneous processes in melanoma tissue. Melanoma cell proliferation appears to overwhelm the apoptotic defence, perhaps due to the anti-apoptotic effects of telomerase. In addition, keratinocyte regulation of the epidermis and dermis is severely compromised by the loss of E-cadherin and P2X(1-3) and P2Y(2) receptors, resulting in a lesion that is aggressive and malignant.