石蒜碱对结肠癌HT29细胞增殖、凋亡的影响及凋亡机制的初步探讨

目的研究石蒜碱(lycorine)对结肠癌HT29细胞增殖和凋亡的影响,探讨其可能的凋亡机制。方法选择人结肠癌HT29细胞株进行培养与处理,按石蒜碱干预浓度为0μmol/L(对照组)、1μmol/L、4μmol/L、16μmol/L分为四组,探讨不同浓度石蒜碱对HT29细胞增殖的抑制作用、对HT29细胞克隆形成率的影响、对HT29细胞凋亡的形态学及凋亡率的影响,以及对细胞凋亡相关蛋白、MAPK/ERK通路蛋白的影响。结果 MTT结果显示,与对照组比较,各浓度的石蒜碱诱导HT29细胞24 h、48h后HT29细胞的存活率均下降(均P 0.05)。HT29细胞接种7 d后肉眼可见细胞集落形成,以上四组细胞克隆形成率分别为(77.00±3.61)%、(64.17±2.02)%、(51.50±2.78)%、(26.67±1.61)%。Hoechst 33258染色结果示,对照组细胞呈均匀的淡蓝色荧光、细胞核无明显凋亡形态学特征,余各浓度的石蒜碱组呈现不同程度的核浓缩、核碎裂、核边集及细胞呈现蓝白色荧光等典型的凋亡改变。流式细胞术凋亡检测结果显示,HT29细胞凋亡率随着石蒜碱浓度的增加而升高(P 0.05)。与对照组相比,各浓度石蒜碱组的Bcl-2、p-ERK蛋白表达量均减少(均P 0.05),Bax、Caspase-3蛋白表达量均增加(均P 0.05)。结论石蒜碱可抑制结肠癌HT29细胞的增殖并诱导其凋亡,其凋亡机制可能与抑制MAPK/ERK信号通路有关。     

内源性大麻素诱导人肝癌细胞MHCC97H凋亡中Caspase-3的作用

目的 检测内源性大麻素(AEA)是否诱导人肝癌高转移细胞株MHCC97H细胞凋亡、以及Caspase-3在细胞凋亡过程中的作用.方法 分别于AEA(100 μmol/L)作用细胞前后,应用Annexin V Binding方法 、流式细胞仪检测细胞凋亡率;荧光活性检测试剂盒检测细胞Caspase-3活性;半定量逆转录-聚合酶链反应(RT-PCR)方法 ,检测Caspase-3、bcl-2及bax的mRNA表达.结果 AEA作用细胞3、6、12、24 h,细胞凋亡率分别为(14.13±2.17)%、(27.04±3.21)%、(34.98±7.74)%及(81.35±9.71)%,其中24 h的细胞凋亡率与对照组(12.72±0.44)%比较,差异有统计学意义(P<0.01).AEA作用细胞24 h,细胞的Caspase-3活性由142.0±5.8增加至226.0±6.4(P<0.01);Caspase-3 mRNA的表达由0.24±0.13升高至0.54±0.32(P<0.05);如预先加入Caspase-3抑制剂(Z-VAD-FMK)后再加入AEA,则细胞的Caspase-3活性不再升高90.0±4.3.RT-PCR方法 未检测到bcl-2 mRNA及bax mRNA的表达.结论 AEA对人肝癌高转移细胞MHCC97H具有凋亡诱导作用,Caspase-3参与了凋亡的调控.     

Stat3信号转导通路调控Survivin表达促进结肠癌细胞凋亡

目的 探讨Stat3/Survivn信号转导通路调控结肠癌细胞凋亡的作用机制.方法 用阳离子脂质体介导Stat3反义寡核苷酸(20 mol/L)转染人结肠癌HT29细胞,噻唑蓝(MTY)法检测细胞增殖状态;流式细胞术检测细胞周期与凋亡;Western blot检测Stat3、p-Stat3、Survivin与bcl-2凋亡家族成员bcl-2、bcl-Xl于bax的表达.结果 Stat3反义寡核苷酸作用HT29细胞72 h后,G1期细胞比率由61.4%上升至75.6%,S期细胞比率由19.4%下降至8.6%,细胞增殖受抑制.凋亡细胞百分比由5.6%增加至22.1%,促进细胞凋亡.Stat3、p-Stag、Cychn D1与Survivin表达下降,bcl-2、bcl-Xl与bax变化不明显.结论 阻断Stat3通路可以抑制靶基因Survivin表达并诱导结肠癌细胞凋亡.     

bcl-2高表达提高肾小管上皮细胞抗凋亡能力的研究

目的 观察凋亡相关基因bcl-2高表达抑制过氧化氢诱导肾小管上皮细胞凋亡的作用.方法 构建含有人bcl-2 cDNA的逆转录病毒真核表达载体PLXSN,脂质体法将重组质粒转染PA317细胞,G418筛选阳性克隆,鉴定后浓缩收集病毒上清,浓缩病毒液,感染人肾小管上皮细胞株HK-2,Western blot检测bcl-2 mRNA表达.5 mmol/L过氧化氢(HO2)诱导细胞凋亡后,流式细胞仪检测细胞凋亡发生变化.结果 流式细胞仪分析显示5 mmol/L H2O2:成功诱导肾小管上皮细胞凋亡,bel-2逆转录病毒感染肾小管上皮细胞后,bcl-2蛋白水平呈高表达,HK bcl-2组细胞凋亡数量(12.41±3.46)较HK-2组(19.62±4.20)显著减少(P<0.05).而转染空载体的对照组无明显变化(19.62±4.20,P<0.05).结论 bel-2蛋白高表达显著抑制氧化剂诱导的肾小管上皮细胞凋亡.     

胸苷激酶基因系统对膀胱癌细胞及凋亡基因的影响

目的 探讨单纯疱疹病毒胸苷激酶／丙氧鸟苷(HSV-TK／GCV)系统对膀胱癌细胞BIU87的杀伤作用及对凋亡基因的影响。方法 脂质体将TK基因成功转入BIU87。噻唑蓝(MTT)法、TUNEL法、流式细胞仪(FCM)分别检测GCV对其生长影响及凋亡率和细胞周期变化；逆转录一聚合酶链反应(RT-PCR)检测bcl-2、bax、bak、Caspase-3 mRNA表达变化．比色法测定Caspase．3活性变化。结果 作用5dlmg,／LGCV能杀死67％的细胞，100mg／，LGCV达到最大杀伤率杀死97％的细胞；GCV诱导细胞凋亡，细胞周期阻滞在S和G2期；bcl-2表达降低，bax表达升高，Caspase-3表达及活性升高。结论 HSV-TK／GCV系统可有效杀伤膀胱癌细胞并引起细胞凋亡，细胞周期阻滞、bcl-2和bax表达变化、Caspase-3活化是引起凋亡发生的重要因素。     

姜黄素对肝癌HepG2细胞和肝脏正常细胞L-02细胞的生长抑制作用及其机制

目的 观察姜黄素对肝癌HepG2细胞和肝脏正常L-02细胞的生长抑制作用,探讨其抗肿瘤的作用和机制.方法 贴壁法培养HepG2细胞和L-02细胞,噻唑蓝(MTT)比色法分析姜黄素对细胞生长的抑制率,流式细胞仪(FACS)检测细胞周期及凋亡,免疫细胞化学及Western blot技术检测半胱氨酸-天冬氨酸蛋白酶(Caspase)-3、Caspase-8、Caspase-9、死亡受体5(DR5)、B淋巴细胞/白血病-2(bcl-2)和bax蛋白的表达.结果 姜黄素在100 mg/L浓度下,对HepG2细胞生长抑制率可达84％,凋亡率为25.89％,而诱导正常L-02细胞的凋亡率为10.10％,阻滞HepG2细胞周期于G1期,此过程中Caspase-3、Caspase-9和Caspase-8被激活,DR5蛋白表达上升,bcl-2/bax蛋白表达比率下降.结论 姜黄素能够选择性杀伤HepG2细胞,并通过内源性和外源性两条通路促其凋亡.     

移植骨髓间充质干细胞对兔退变椎间盘髓核细胞凋亡的影响

目的 观察骨髓间充质干细胞(MSCs)移植对兔退变椎间盘髓核细胞凋亡的影响.方法 以各兔L2/3、L3/4、L4/5、L5/6节段分为正常组、退变组、成纤维细胞(SFs)移植对照组、MSCs移植治疗组.MSCs和SFs分别经绿色荧光蛋白(GFP)转染后,注射植入退变椎间盘的髓核.通过透射电镜观察退变椎间盘凋亡髓核细胞形态;用实时定量聚合酶链反应(PCR)检测退变组织中髓核细胞凋亡相关基因bcl-2和box mRNA的表达;免疫荧光法标记髓核细胞凋亡相关蛋白Caspase-3,并通过TUNEL法标记凋亡髓核细胞,激光共聚焦显微镜检测髓核细胞凋亡蛋白表达率和细胞凋亡比率.结果 透射电镜下,退变椎间盘中凋亡髓核细胞呈现出核染色质边集,空泡形成,核膜断裂,凋亡小体形成等变化.MSCs移植治疗组bcl-2 mRNA的表达量高于退变组和SFs移植对照组(P<0.05),bax mRNA的表达量与退变组差异无统计学意义(P>0.05).MSCs移植治疗组细胞凋亡率和Caspase-3表达率均高于正常组[细胞凋亡率分别为(16.75±2.14)%和(6.86±1.08)%;Caspase-3表达率分别为[(20.34±1.03)%和(6.09±0.77)%](P<0.05),低于退变组和SFs移植对照组[细胞凋亡率分别为(31.87±4.16)%和(29.02±2.16)%;Caspase-3表达率分别为(31.50±3.78)%和(30.20±4.93)%](P<0.05).结论 髓核细胞凋亡在椎间盘退变过程中起重要作用.MSCs移植能有效抑制椎间盘髓核细胞凋亡,延缓椎间盘退变过程.     

南瓜蛋白诱导人胰腺癌细胞凋亡的线粒体机制

目的 探讨南瓜蛋白(CUS)诱导人胰腺癌细胞(PANC)-1凋亡的线粒体机制.方法 0、2.5、10.0、40.0 mg/L的CUS处理胰腺癌PANC-1 72 h,荧光显微镜和流式细胞仪观察线粒体膜电位(△Ψm)的变化,Western blot检测胞质细胞色素C(Cyt-C)的含量变化和细胞半胱氨酰天冬氨酸特异性蛋白酶-9(Caspase-9)和Caspase-3、B细胞淋巴瘤/白血病-2(bcl-2)和B细胞淋巴瘤/白血病-2相关X蛋白(bax)蛋白的表达水平.结果 0、2.5、10.0、40.0 mg/L CUS处理PANC-1 72 h后,△Ψm逐渐下降,分别为167.23±8.27、123.56±7.26、83.25±5.36和40.45±5.87,差异有统计学意义(P＜0.05);Western blot结果显示线粒体Cyt-C释放到细胞质的量逐渐增加,灰度值分别为0.29±0.05、1.69±0.35、1.87±0.40、2.47±0.32(P＜0.05);Caspase-9、Caspase-3和bax蛋白的表达逐渐增强,且其作用呈剂量依赖性(Caspase-9灰度值分别为0.15±0.03、0.19±0.05、0.49±0.09、0.89±0.08,P＜0.05;Caspase-3灰度值分别为0.88±0.08、1.81±0.19、2.36±0.38、2.92±0.24,P ＜0.05;bax灰度值分别为0.79±0.18、1.66±0.31、2.61±0.41、3.67±0.24,P＜0.05);而bcl-2蛋白表达无明显变化(bcl-2灰度值分别为0.88±0.08、0.82±0.18、0.84±0.04、0.82±0.13,P＞0.05).结论 线粒体途径在CUS诱导胰腺癌细胞凋亡中起重要作用,其机制可能是CUS通过激活促凋亡蛋白bax表达增加,降低△Ψm,促进线粒体Cyt-C的释放,从而激活Caspase系列酶,诱导胰腺癌细胞凋亡.     

bcl-2 mRNA、baX mRNA表达在三氧化二砷诱导肝癌细胞凋亡中的意义

目的 分析三氧化二砷(As2O3)诱导肝癌细胞凋亡中凋亡相关基因bcl—2 mRNA、bax mRNA表达的意义。方法 采用电镜、流式细胞仪、电泳及半定量RT—PCR方法检测不同剂量三氧化二砷诱导人肝癌细胞株bel—7402后凋亡的出现及bcl-2mRNA、bax mRNA的表达。结果 0．5にmol/L As2O3处理肝癌细胞未见凋亡，8μmol/L As2O3诱导肝癌细胞出现明显凋亡。对照组和药物组未检测到bcl-2 mRNA的表达，随浓度增加，bax mRNA的表达上调。结论 As2O3通过诱导凋亡抑制肝癌细胞株bel-7402的增殖，凋亡诱导基因bax mRNA的表达上调与此过程有关。bcl—2mR—NA表达与此过程无关。     

3-甲基腺嘌呤促进吡柔比星诱导膀胱癌BIU-87细胞凋亡及机制

目的 探讨3-甲基腺嘌呤(3-MA)自噬抑制剂联合吡柔比星(THP)对膀胱癌BIU-87细胞杀伤作用及机制.方法 膀胱癌BIU-87细胞分为对照组、3-MA(10 mmol/L)组、THP(5 mg/L)组、3-MA(10 mmol/L)+ THP(5 mg/L)组.噻唑蓝(MTT)法检测细胞增殖;流式细胞术检测细胞凋亡;Western blot检测各组细胞中自噬蛋白微管相关蛋白1轻链3(LC3)-Ⅱ、Beclin-1以及凋亡蛋白半胱氨酰天冬氨酸特异性蛋白酶(Caspase)-3和Caspase-9的表达.结果 药物作用24h后,各组细胞增殖率分别为(86.64±3.09)％、(63.70±5.62)％、(58.43±3.89)％、(37.55±4.17)％,其中3-MA+THP组细胞增殖下降最明显(P ＜0.05);3-MA与THP联合应用后,自噬蛋白LC3-Ⅱ、Beclin-1的表达明显减弱,而凋亡蛋白Caspase-3和Caspase-9的表达在各组中最强(P＜0.05).结论 3-MA抑制膀胱癌BIU-87细胞对化疗药物保护性自噬反应,增加膀胱癌细胞对THP细胞毒杀伤作用的敏感性.     

硒对淋巴细胞杀伤大肠癌细胞过程中Fas/FasL表达的影响

目的　探讨硒对淋巴细胞抗大肠癌过程中凋亡相关基因Fas/FasL表达的影响。方法　以半胱氨酸硒作为影响因素,人T淋巴细胞为效应细胞及人结肠癌细胞（LoVo细胞株）为靶细胞,采用四甲基偶氮唑蓝(MTT)比色法、凋亡细胞荧光计数检测凋亡细胞的数量,逆转录-聚合酶链(RT-PCR)反应、原位杂交技术检测,硒对效应细胞杀伤肿瘤细胞过程中Fas/FasL表达的影响。结果　不同浓度的半胱氨酸硒（0.5、1.0　mg/L）作用48h后,可增强人T淋巴细胞抗肿瘤活性［分别为（25.12±3.91）%,（46.17±3.68）%,P＜0.05］,且肿瘤细胞的凋亡比例上升［分别为(18.6±4.1)%,（32.7±2.1）%,P＜0.05］;能使免疫效应细胞和肿瘤细胞表达FasL和Fas水平增高。结论　硒可提高淋巴细胞的抗肿瘤作用,可能通过Fas/FasL途径起作用。     

Analysis of the Fas system and Bcl-2 in rat liver allograft rejection.

BACKGROUND: Apoptosis is involved in the mechanism of cell death observed in liver allograft rejection. The liver cells are sensitive to Fas-mediated apoptosis; however, little is known about the involvement of the Fas system in liver allograft rejection. We used rat models to investigate the expression of Fas/Fas ligand and apoptosis-related proteins during liver allograft rejection. MATERIALS AND METHODS: DA rats to Lewis, and Lewis to Lewis orthotopic liver transplantation were performed; liver samples were collected on days 1, 3, 5, 7, and 9 postoperatively (each n = 3). Apoptosis was monitored by TUNEL and electron microscopy. The expression of Fas, FasL, bcl-2, and bax was examined at the mRNA level and by means of immunohistochemistry. RESULTS: The TUNEL index in the allografts and isografts on day 7 was 20.1 +/- 1.5 and 7.7 +/- 2.6/1000 cells, respectively. Fas and bax mRNA were constitutively expressed in both of the groups. The expression of Fas ligand mRNA in the allografts which rose on day 5 was 10 times stronger compared to that in the isografts. On the other hand, bcl-2 mRNA was generally expressed in the isografts while it decreased in the allografts. The immunohistochemical analysis also showed an increased reactivity of Fas ligand on day 5 in the allograft, which was observed both in parenchymal and nonparenchymal cells. CONCLUSIONS: These results strongly suggest that Fas/Fas ligand interaction mediates the liver injury during allograft rejection. In addition, other regulatory factors of apoptosis, such as bcl-2, might also be involved in this pathogenesis.     

Proapoptotic Fas ligand is expressed by normal kidney tubular epithelium and injured glomeruli

Fas ligand (FasL) is a cell membrane cytokine that can promote apoptosis through activation of Fas receptors. Fas receptor activation induces glomerular cell apoptosis in vivo and participates in tubular cell death during acute renal failure. However, there is little information on the expression of FasL in the kidney. This study reports that FasL mRNA and protein are present in normal mouse and rat kidney. In situ hybridization and immunohistochemistry showed that proximal tubular epithelium is the main site of FasL expression in the normal kidney. In addition, increased total kidney FasL mRNA and de novo FasL protein expression by glomerular cells were observed in two different models of glomerular injury : rat immune-complex proliferative glumerulonephritis and murine lupus nephritis. Both full-length and soluble FasL were increased in the kidneys of the mice with nephritis. Cultured murine proximal tubular epithelial MCT cells and primary cultures of murine tubular epithelial cells expressed FasL mRNA and protein. Tubular epithelium-derived FasL induced apoptosis in Fassensitive lymphoid cell lines but not in Fas-resistant lymphoid cell lines. By contrast, MCT cells grown in the presence of the survival factors of serum were resistant to FasL, and only became partially sensitive to apoptosis induced by high concentrations (100 ng/ml) of FasL upon serum deprivation. However, MCT cells stimulated with inflammatory mediators (tumor necrosis factor-alpha, interferon-gamma, and lipopolysaccharide) increased cell surface Fas expression and were sensitized to apoptosis induced by FasL (FasL 55 +/- 5% versus control 8.3 +/- 4.1% apoptotic cells at 24 h, P < 0.05). Cytokine-primed primary cultures of tubular epithelial cells also acquired sensitivity to FasL-induced apoptosis. These results suggest that FasL expression by intrinsic renal cells may play a role in cell homeostasis in the normal kidney and during renal injury.     

不同浓度地塞米松对人骨关节炎软骨细胞凋亡及Fas/FasL基因表达的影响

目的糖皮质激素会破坏软骨,通过观察地塞米松对人骨关节炎软骨细胞(human articular chondrocytes,HACs)凋亡及Fas/FasL基因表达的影响,探讨其促进HACs凋亡的作用机制。方法取行人工膝关节置换的膝骨关节炎患者自愿捐赠软骨组织,体外分离培养HACs,取第2代细胞进行实验。将HACs分别置于含浓度为0.125、1.25、12.5、25及50μg/mL地塞米松培养液中,培养48 h后采用MTT法选择地塞米松最佳工作浓度进行后续实验。将HACs分别采用最佳工作浓度地塞米松(实验组)及不含地塞米松培养液(对照组)培养,0、24、48 h后行TMRE/Hoechst/Annexin V-FITC/7-AAD四重染色检测细胞凋亡,48 h后行实时定量PCR检测Fas/FasL mRNA表达,0、24、48 h后行免疫组织化学染色检测Fas/FasL蛋白表达。结果 25μg/mL浓度组细胞抑制率显著高于50μg/mL浓度组,差异有统计学意义(P<0.05);与其他浓度组比较,差异亦有统计学意义(P<0.05);选择25μg/mL浓度作为后续实验工作浓度。培养0、24、48 h,实验组HACs凋亡细胞百分比分别为5.8%±0.3%、27.0%±2.6%、36.0%±3.1%,呈明显时间依赖性(P<0.05)。培养48 h后实验组及对照组Fas mRNA相对表达量分别为(8.93±1.12)×10—3及(3.31±0.37)×10—3,FasLmRNA相对表达量分别为(5.92±0.66)×10—3及(2.31±0.35)×10—3,两组比较差异均有统计学意义(P<0.05)。随培养时间延长,实验组Fas及FasL蛋白表达逐渐增加,且各时间点均显著高于对照组,差异均有统计学意义(P<0.05)。结论地塞米松可促进HACs细胞凋亡及上调凋亡基因Fas/FasL表达,为进一步探讨Fas/FasL信号通路在地塞米松促HACs凋亡中的作用提供了实验依据。     

芍药苷对椎间盘内紊乱兔Fas介导的凋亡通路的调节作用

目的 探讨芍药苷在兔椎间盘内紊乱（internal disc disruption,IDD）发生过程中,是否干预死亡受体介导的信号传导途径,影响髓核细胞的凋亡,及其发生的可能机制.方法 取新西兰大白兔96只,雌雄不限,体重（3.0±0.5） kg.随机分为4组,每组24只.其中3组行纤维环穿刺造模（分别在L3/L4,L4/L及L5/L6椎间盘进行穿刺）.造模后各组分别采用芍药苷高剂量每天120 mg/kg、低剂量每天30 mg/kg及生理盐水灌胃治疗,正常对照组采用生理盐水灌胃,分笼常规饲养.分别在术后的3周、6周和10周将各组大白兔处死取材,每个时间点8只,离断腰椎,分离椎间盘.免疫组化法检测Fas、FasL、Caspase-8的表达,流式细胞术检测细胞凋亡率.结果 造模组Fas、FasL、Caspase-8的表达较正常对照组升高（P＜0.05）.高、低剂量组Fas、FasL、Caspase-8的表达较生理盐水组降低（P＜0.05）.各造模组细胞凋亡率均高于正常对照组（P＜0.05）;高、低剂量组细胞凋亡率低于生理盐水组（P＜0.05）.结论 芍药苷可以抑制Fas表达,进而抑制Caspase-8的激活,最终起到抑制髓核细胞凋亡的作用.     

他莫昔芬与γ-干扰素联合抗人乳腺癌细胞株的作用及其机制研究

目的: 探讨他莫昔芬(TAM)与 γ-干扰素(γ-IFN)联合抗乳腺癌细胞株的作用及其机制。方法:在体外培养条件下，分别或联合应用γ-IFN,TAM或雌二醇（E2）作用于ER阳性的MCF-7人乳腺癌细胞株，用MTT比色法分析细胞生长抑制作用;用流式细胞仪（FCM）检测细胞周期分布、凋亡率及用药前后Bcl-2,Bax,Fas,FasL及Caspase-8蛋白的变化;荧光分光光度仪检测Caspase-3活性。结果:TAM能抑制ER阳性乳腺癌细胞的生长，阻滞细胞周期于G0/G1期，并可诱导细胞凋亡;同时，TAM能拮抗外源性雌激素对MCF-7细胞的促生长作用。γ-IFN预处理细胞24h后，TAM抗乳腺癌细胞的作用增强。联用γ-IFN与TAM后，细胞Bcl-2蛋白表达下调，Caspase-8表达上调;但药物处理前后，细胞Bax，Fas，FasL蛋白表达水平及Caspase-3活性未见明显变化。结论:体外条件下，TAM通过影响细胞周期、诱导细胞凋亡而发挥抗ER阳性乳腺癌细胞作用;γ-IFN能加强TAM的抗乳腺癌作用。两者作用机制可能系通过下调Bcl-2表达和上调Caspase-8的表达。     

Expression of bcl-2 homologue mRNAs in rat liver allograft: rejection-induced cell apoptosis is associated with upregulation of bax and bcl-xs expression

Abstract Apoptosis is considered to play an important role in rejection of organ transplants, although the precise mechanism has not been elucidated. In this study, we screened for the expression of bcl-2 homologues (bcl-2, bax, bcl-xl, and bcl-xs) and Fas ligand (FasL) by RT-PCR method in grafts during acute rejection in rats following liver transplantation. Both bax and bcl-xs (inducers of apoptosis) mRNA levels increased steadily in the allografted group from postoperative day (POD) 2 to 8, while no remarkable changes of bcl-2 and bcl-xl expression (inhibitors of apoptosis) were recognized. Significant induction of FasL gene expression was observed in the allografted group on POD 4 and expression gradually decreased thereafter, although minimal FasL mRNA expression was seen in isografts. Our results indicated, for the first time, that rejection-induced cell apoptosis is closely associated with upregulation of bax and bcl-xs expression besides FasL, but not with down-regulation of bcl-xl.     

Fas and Fas-ligand expression in human pancreatic cancer

OBJECTIVE: To investigate Fas and FasL expression in pancreatic tissues and cultured pancreatic cancer cell lines, and to assess the ability of anti-Fas antibodies to induce apoptosis. SUMMARY BACKGROUND DATA: Activation of the Fas receptor by Fas-ligand (FasL) results in apoptosis, and dysregulation of this pathway may contribute to abnormal cell proliferation. METHODS: Northern blotting and immunohistochemistry were used to compare Fas and FasL expression in normal and cancerous tissues. DNA 3'-OH end labeling was used to detect apoptotic cells. The effects of Fas activation on cell growth and signaling pathways were investigated in culture. RESULTS: Pancreatic cancers exhibited increased Fas RNA levels, whereas FasL mRNA levels were similar in both groups. Despite the colocalization of Fas and FasL in the cancer cells, an apoptotic signal was present in approximately 10% of these cells in only 2 of 16 cancer samples. Fas and FasL were coexpressed in all four cell lines, whereas Fas-associated phosphatase 1 was below the level of detection in all cell lines. Only COLO-357 cells underwent apoptosis after Fas activation. Apoptosis was associated with enhanced activation of jun kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). In the presence of actinomycin D, Fas antibody also induced apoptosis in the other three cell lines. CONCLUSIONS: These results suggest that pancreatic cancer cells are resistant to Fas-mediated apoptosis by mechanisms excluding receptor downregulation or Fas-associated phosphatase upregulation and raise the possibility that Fas-mediated apoptosis may be dependent on the activation of the JNK/p38 MAPK pathway in these cells.