戊地昔布对人结肠癌HT-29细胞凋亡的影响

目的 观察戊地昔布（Valdecoxib）对COX-2高表达的人结肠癌HT-29细胞凋亡的影响。方法 将体外培养HT-29细胞分为正常组（C）、药物处理组（V）及溶剂对照组（S）。采用流式细胞术检测细胞凋亡,Western blot检测COX-2、caspase-3、cleaved caspase-3、Bcl-2、p38 MAPK、p-p38MAPK。结果 与正常组相比,药物处理组细胞凋亡明显增加(P<0.05),cleaved caspase-3和p-p38MAPK表达增高,Bax/Bcl-2比率明显升高(P<0.05)。Valdecoxib干预能够显著促进HT-29细胞凋亡,上调cleaved caspase-3和p-p38 MAPK的表达,增加Bax/Bcl-2比率。 结论 COX-2选择性抑制剂Valdecoxib能够促进HT-29细胞凋亡部分可能是通过激活p38MAPK信号通路而实现的。     

乳腺癌细胞耐药过程中p38MAPK活性与细胞凋亡的关系

目的研究乳腺癌细胞耐药过程中p38MAPK活性与细胞凋亡的关系,探讨p38MAPK信号转导途径在其中的作用。方法 以p38MAPK特异性抑制剂SB203580处理乳腺癌耐药细胞MCF-7／ADM,采用流式细胞技术分析对细胞凋亡的影响;MTT检测MCF-7／ADM细胞对阿霉素的半数药物抑制浓度（IC50）;Western blot检测SB203580处理MCF-7／ADM和MCF-7两株细胞后p38MAPK蛋白表达水平;RT—PCR检测细胞内MDR-1 mRNA水平。结果SB203580（10μmol／L）干预24h后MCF-7／ADM细胞的凋亡率为（26．73±4．90）％,与未干预组和对照组凋亡率相比差异有显著统计学意义（F=143．80,P〈0．001）;MCF-7／ADM细胞对阿霉素的敏感性明显提高（F=148927．10,P〈0．001）,相对逆转率达68．45％;与对照组和未干预组相比,干预组的MDR1 mRNA（F=9139．24,P〈0．001）及p38MAPK（F=685．42,P〈0．001）蛋白表达水平明显降低。结论p38MAPK信号转导途径与乳腺癌耐药密切相关,其可能机制为p38MAPK保护人乳腺癌耐药细胞（MCF-7／ADM）逃避凋亡,阻断该通路可增强乳腺癌耐药细胞发生凋亡。     

p38MAPK在EGCG诱导人胃癌MGC803细胞凋亡中的作用

目的：探讨p38丝裂原活化蛋白激酶（p38 mitogen—activaced protein kinase，v38MAPK）在表没食子儿茶素没食子酸酯（epigallocatechin-3-gallate，EGCG）诱导人胃癌MGC803细胞凋亡中的作用。方法：采用MTT法检测MGC803细胞的存活率，荧光显微镜观察和碘化丙啶染色FCM检测MGC803细胞凋亡率，Western印迹法检测MGC803细胞中p38MAPK蛋白及磷酸化p38MAPK蛋白的表达。结果：EGCG可诱导MGC803细胞凋亡，且p38MAPK被激活。用p38MAPK特异性抑制剂SB203580干预后，EGCG抑制MGC803细胞生长的作用明显减弱，细胞凋亡率下降，p38MAPK活性显著下降。结论：EGCG可诱导MGC803细胞凋亡，该作用可被SB203580显著抑制，提示EGCG可能通过激活D38MAPK使部分MGCR03细胞凋亡。     

p38丝裂原活化蛋白激酶阻滞剂SB203580对白血病K562细胞周期的作用及机制

 目的　研究p38丝裂原活化蛋白激酶（MAPK）阻滞剂SB203580对K562细胞周期的作用及机制。方法　以反转录-聚合酶链反应（RT-PCR ）和Western blotting方法检测SB203580处理K562细胞后p38、Cyclin D2、Cyclin E、p27 mRNA和蛋白的表达并以流式细胞术（FCM）检测其细胞周期的变化。结果　SB203580处理后K562细胞 p38、Cyclin D2、Cyclin E mRNA和蛋白表达降低;p27 mRNA和蛋白表达增高。G0／G1期细胞增多,S期细胞减少,与用药前相比差异均有统计学意义。结论　SB203580可能通过p38途径,影响细胞周期调控蛋白,最终抑制K562细胞的增生。     

AQP-5基因沉默对结肠癌细胞增殖及信号转导通路的影响

背景与目的:水通道蛋白-5(aquaporin 5,AQP-5)在人结肠癌组织中表达增高,与结肠癌的发生、发展及转移过程有关。但AQP-5影响的信号转导通路及对结肠癌细胞的具体影响尚不明确。本研究通过抑制结肠癌细胞株HT-29内源性AQP-5的表达,探讨AQP-5对HT-29细胞丝氨酸/苏氨酸蛋白激酶(AKT)、细胞外调节激酶细胞外调节激酶(ERK)、c-jun氨基末端激酶(JNK)和p38丝裂原活化蛋白激酶(p38MAPK)信号转导通路的影响。方法:体外常规培养人结肠癌HT-29细胞,取对数生长期的细胞用于实验。蛋白质印迹法(Western blot)检测AQP-5-siRNA转染效率;采用噻唑蓝(MTT)法检测各组细胞增殖抑制率;流式细胞术检测细胞凋亡率;Western blot检测转染AQP-5 siRNA的HT-29细胞AKT、ERK、JNK和p38蛋白的磷酸化形式及总蛋白的表达水平。结果:AQP-5-siRNA转染使HT-29细胞AQP-5基因表达下调的效率达90%。MTT分析结果显示,转染了AQP-5-siRNA的HT-29细胞增殖抑制率显著增高(P<0.05),流式细胞术发现转染了AQP-5-siRNA的HT-29细胞凋亡率显著增加(P<0.05)。Western blot结果显示,与转染NS-siRNA的阴性对照组相比较,转染了AQP-5-siRNA的HT-29细胞磷酸化的AKT、ERK和JNK蛋白磷酸化形式表达量与总蛋白表达量的改变两者差异无统计学意义(P>0.05)。而转染了AQP-5-siRNA的HT-29细胞磷酸化p38与总的p38蛋白比值下降(P<0.05)。结论:针对AQP-5的si-RNA具有促进HT-29细胞凋亡、抑制细胞增殖的作用,该作用可能与抑制p38MAPK蛋白的磷酸化活化有关。     

p38 MAPK在喹乙醇诱导HepG2细胞凋亡中的作用

目的:研究p38 MAPK信号通路在喹乙醇诱导的HepG2细胞凋亡中的作用。方法:分别用不同浓度(0、200、400、800μg/ml)的喹乙醇染毒HepG2细胞24 h和800μg/ml喹乙醇染毒HepG2细胞不同时间(0、0.5、1、2、4、6、12、24 h)后,采用Westernblot法检测细胞内磷酸化p38蛋白和p38总蛋白的表达情况,以p38 MAPK磷酸化水平反映p38 MAPK信号通路的活性。分别采用0、10、20μmol/L的p38 MAPK特异性抑制剂SB203580预处理HepG2细胞1 h后,再用800μg/ml喹乙醇染毒24 h,采用Annexin VFITC/PI法检测细胞凋亡。结果:随着喹乙醇染毒浓度和时间的增加,HepG2细胞的p38磷酸化蛋白表达量逐步增加,其中800μg/ml喹乙醇染毒细胞24 h的实验组与对照组相比,p38磷酸化蛋白的表达量明显上调(P0.01)。10、20μmol/L的SB203580对喹乙醇诱导细胞凋亡有促进作用,细胞的凋亡率分别为35.4%±2.83%、40.2%±3.98%,较喹乙醇对照组(23.1%±3.59%)明显升高(P0.05)。结论:喹乙醇能激活p38 MAPK信号通路,且p38 MAPK信号通路的激活参与抑制喹乙醇介导的HepG2细胞凋亡的过程。     

罗格列酮诱导人肝癌HepG2细胞凋亡中p38MAPK通路的作用北大核心CSCD

目的研究罗格列酮对人肝癌HepG2细胞增殖与凋亡的影响,探讨p38丝裂原活化蛋白激酶(p38MAPK)通路相关蛋白在其中发挥的作用。方法 MTT法检测罗格列酮对人肝癌HepG2细胞的增殖抑制率,流式细胞术检测细胞凋亡率,透射电子显微镜观察细胞凋亡形态变化,Western blot检测p38MAPK通路相关蛋白表达变化。结果罗格列酮可抑制HepG2细胞的增殖,诱导细胞凋亡(P<0.05);电子显微镜下可观察到典型的HepG2细胞凋亡表现。Western blot结果显示罗格列酮可激活p38MAPK通路,上调HepG2细胞中磷酸化p53及Bax蛋白的表达,下调Bcl-2蛋白的表达(P<0.05);而细胞外信号调节激酶ERK1/2的磷酸化程度没有明显改变。p38MAPK通路抑制剂SB203580可显著降低罗格列酮诱导的HepG2细胞的凋亡率;并且SB203580可部分逆转由罗格列酮引发的磷酸化p53、Bax及Bcl-2蛋白的表达变化。结论罗格列酮可通过激活p38MAPK通路诱导人肝癌HepG2细胞凋亡,其机制可能与p38MAPK通路参与磷酸化p53、Bax及Bcl-2蛋白的调控有关。     

Effects of p38 MAPK signaling pathway on apoptosis stimulated by olaquindox in human hepatoma G2 cells

目的:研究p38 MAPK信号通路在喹乙醇诱导的HepG2细胞凋亡中的作用.方法:分别用不同浓度(0、200、400、800μg/ml)的喹乙醇染毒HepG2细胞24h和800μg/ml喹乙醇染毒HepG2细胞不同时间(0、0.5、1、2、4、6、12、24 h)后,采用Western blot法检测细胞内磷酸化p38蛋白和p38总蛋白的表达情况,以p38 MAPK磷酸化水平反映p38 MAPK信号通路的活性.分别采用0、10、20μmol/L的p38 MAPK特异性抑制剂SB203580预处理HepG2细胞1h后,再用800μg/ml喹乙醇染毒24h,采用Annexin VFITC/PI法检测细胞凋亡.结果:随着喹乙醇染毒浓度和时间的增加,HepG2细胞的p38磷酸化蛋白表达量逐步增加,其中800μg/ml喹乙醇染毒细胞24h的实验组与对照组相比,p38磷酸化蛋白的表达量明显上调(P＜0.01).10、20μmol/L的SB203580对喹乙醇诱导细胞凋亡有促进作用,细胞的凋亡率分别为35.4％±2.83％、40.2％±3.98％,较喹乙醇对照组(23.1％±3.59％)明显升高(P＜0.05).结论:喹乙醇能激活p38 MAPK信号通路,且p38 MAPK信号通路的激活参与抑制喹乙醇介导的HepG2细胞凋亡的过程.     

幽门螺杆菌诱导人胃癌MKN45细胞COX-2表达的信号转导研究

目的:探讨p38丝裂原活化蛋白激酶(p38 mitogen-activated protein kinase,p38MAPK)信号转导对幽门螺杆菌(Helicobacter pylori,Hp)感染的胃上皮细胞MKN45中环氧合酶(cyclooxygenase-2,COX-2)表达的调控作用,揭示Hp感染引发胃癌的部分机制.方法:采用实时荧光定量-PCR(real-time fluorogentic quantitative-PCR,RFQ-PCR)检测Hp标准株NCTC11637感染对MKN45 细胞中COX-2 mRNA表达的影响,Western 印迹法检测Hp 感染MKN45细胞后p38MAPK信号通路的激活情况;运用p38MAPK特异性抑制剂SB203580阻断p38MAPK信号通路后,观察Hp对MKN45细胞COX-2 mRNA表达的影响.结果:Hp感染MKN45细胞后COX-2 mRNA水平明显上调,Hp感染后3、6、9和12 h时COX-2 mRNA 的表达量分别为正常值的3.0、7.2、5.1和4.3倍,各时间组COX-2 mRNA表达均明显高于对照组(P<0.01).Hp作用MNK45细胞20 min后p38MAPK 信号通路被激活,60 min时达峰值;而采用p38MAPK特异性抑制剂SB203580阻断p38MAPK信号转导通路后,Hp诱导的COX-2 mRNA表达明显降低(P<0.01).结论:Hp感染能激活p38MAPK信号通路,通过p38MAPK信号转导上调COX-2的表达,这可能是Hp感染引发胃癌的重要机制之一.     

虫草素抑制食管癌细胞Eca-109增殖、迁移和侵袭的作用及机制研究

目的:探讨虫草素对食管癌细胞Eca-109的作用及其潜在的机制。方法:不同浓度（35、70、140、280 μg/mL）虫草素分别处理Eca-109细胞24 h、48 h、72 h和96 h,CCK-8检测细胞活力,筛选虫草素最佳作用浓度（70 μg/mL）和时间（24 h）。实验分为4组:对照组、虫草素组（70 μg/mL虫草素）、SB203580组（10 μg/mL SB203580）和虫草素+SB203580组（70 μg/mL虫草素+10 μg/mL SB203580）。培养24 h后,CCK-8检测细胞增殖能力;流式细胞术检测细胞周期和凋亡;Transwell小室检测细胞迁移和侵袭能力;qRT-PCR和Western blot分别检测细胞周期相关、凋亡相关和p38 MAPK信号通路相关基因和蛋白的表达。结果:与对照组相比,虫草素组、SB203580组和虫草素+SB203580组细胞增殖、迁移和侵袭能力显著降低（P＜0.05）,细胞发生G2期阻滞,凋亡率显著升高（P＜0.05）,cyclinB1、CDK4、p-p38、ERK1和ERK2的表达下调（P＜0.05）,CKI和Caspase-3的表达上调（P＜0.05）。结论:虫草素可抑制食管癌细胞Eca-109增殖、迁移和侵袭,促进细胞凋亡,其作用机制与p38 MAPK信号通路有关。     

Antitumor and anti-metastatic effects of cyclooxygenase-2 inhibition by celecoxib on human colorectal carcinoma xenografts in nude mouse rectum

We examined the effects of the preferential cyclooxygenase-2 (COX-2) inhibitor celecoxib on tumorigenesis, angiogenesis, apoptosis, vascular endothelial growth factor (VEGF) protein expression and metastasis in HT-29 human colorectal carcinoma cell xenografts in nude mouse rectum. COX-2 mRNA expression was examined in the xenograft and metastatic sites. The antitumor effect of celecoxib in the xenografts was evaluated by measuring the weight of the peri-ano-rectal tumor. The anti-metastatic effect of celecoxib was assessed by quantification of lymph node and lung metastases by amplification of a cancer-related human DNA by TaqMan PCR. The effects of celecoxib on angiogenesis, apoptosis, prostaglandin E2 (PGE2) production and VEGF protein expression in the xenografts were evaluated by means of microvessel density (MVD) counting, terminal deoxynucleotidyl transferase-mediated nick end labeling assay, quantitative enzyme-linked immunosorbent assay and western blotting, respectively. The rectal xenograft model showed lymph node and lung metastases with enhanced expression of COX-2 mRNA in each organ. Celecoxib inhibited rectal xenograft growth in a dose-dependent manner as follows: 150?ppm, 33.0% (p=0.000220); 750?ppm, 46.4% (p=0.0000292); 1500?ppm, 63.4% (p=0.0000109). Celecoxib inhibited lymph node metastasis in a dose-dependent manner as follows: 150?ppm, 86.7% (p=0.0263); 750?ppm, 90.3% (p=0.00638); 1500?ppm, 96.0% (p=0.000894). Celecoxib also inhibited lung metastasis as follows: 750?ppm, 53.3% (p=0.0107); 1500?ppm, 78.3% (p=0.00022). Celecoxib (1500?ppm) significantly inhibited PGE2 production by 68.4% (p=0.000157) and MVD counting by 48.2% (p=1.3x10-12) and induced apoptosis 2.5-fold (p=3.0x10-14) in the rectal xenograft. Celecoxib suppressed VEGF protein expression in the rectal xenograft. These studies demonstrate that celecoxib reduces the growth and metastatic potential of colorectal carcinoma in mice through COX-2 inhibition, anti-angiogenesis and apoptosis induction. The studies using HT-29 human colorectal carcinoma cell xenografts in nude mouse rectum also provide important information that supports that the COX-2 inhibitor celecoxib has a high potential for use as a clinical agent for inhibition of hematological and lymphatic metastases of colorectal cancer.     

Celecoxib inhibits phorbol ester-induced expression of COX-2 and activation of AP-1 and p38 MAP kinase in mouse skin

Celecoxib, the first US FDA-approved selective cyclooxygenase-2 (COX-2) inhibitor initially developed for the treatment of adult rheumatoid arthritis and osteoarthritis, was reported to reduce the polyp burden in patients with familial adenomatous polyposis. This specific COX-2 inhibitor also protects against experimentally induced carcinogenesis, but molecular mechanisms underlying its chemopreventive activities remain largely unresolved. In the present work, we found that celecoxib inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced expression of COX-2 in female ICR mouse skin when applied topically 30 min prior to TPA as determined by both immunoblot and immunohistochemical analyses. In another study, celecoxib attenuated the DNA binding activity of activator protein 1 (AP-1) through suppression of c-Jun and c-Fos expression in TPA-treated mouse skin. In addition, celecoxib inhibited both the catalytic activity and phosphorylation of p38 mitogen-activated protein (MAP) kinase. In the same animal model, TPA treatment resulted in rapid activation via phosphorylation of extracellular signal-regulated protein kinase (ERK)1/2 and p38 MAP kinase, which are upstream of AP-1 in mouse skin. In order to clarify the roles of p38 and ERK in TPA-induced AP-1 activation, we utilized the pharmacologic inhibitors of these enzymes. The p38 inhibitor SB203580 blocked TPA-mediated AP-1 activation, while the MEK1/2 inhibitor U0126 was not inhibitory despite suppression of c-Fos expression in mouse skin. Furthermore, SB203580 markedly inhibited COX-2 expression induced by TPA. Taken together, these findings suggest that celecoxib down-regulates COX-2 by blocking activation of p38 MAP kinase and AP-1, which may represent molecular mechanisms underlying antitumor promoting effects of this drug on mouse skin tumorigenesis.     

蛋白酶体抑制剂诱导甲状腺癌细胞凋亡机制的探讨

目的:探讨p38MAPK信号转导通路参与蛋白酶体抑制剂诱导甲状腺癌细胞凋亡的作用机制。方法:选取甲状腺癌细胞系,利用丝裂原活化蛋白激酶(MAPK)的三种抑制剂抑制磷酸化途径,利用微小RNA干扰技术转染细胞,封闭p38MAPK。用蛋白质印迹法检测红系衍生的核因子2相关因子2(Nrf2)及p38MAPK的表达,实时定量PCR检测细胞内GCLC mRNA的表达,测定还原型谷胱甘肽的含量,流式细胞仪法检测甲状腺癌细胞凋亡率。结果:在甲状腺癌细胞系8305C细胞中,与对照组相比,p38MAPK的抑制剂SB203580和sip38MAPK均能够抑制蛋白酶体抑制剂诱导的Nrf2细胞核易位(P<0.01),并使随后的GCLC mRNA表达减少、GSH含量减少(P<0.01),显著提高蛋白酶体抑制剂诱导的甲状腺癌细胞凋亡率(P<0.01),而其他2种抑制剂和随机序列核酸siRNA无上述作用。结论:蛋白酶体抑制剂通过p38MAPK途径激活Nrf2的细胞核易位,进而导致GCLC的诱导作用和谷胱甘肽生成的连锁反应,成为蛋白酶体抑制剂在甲状腺癌细胞中的一种抗凋亡机制。     

Diosgenin induces death receptor-5 through activation of p38 pathway and promotes TRAIL-induced apoptosis in colon cancer cells

Previously, we demonstrated that diosgenin induced apoptosis in colorectal cancer cell lines HCT-116 and HT-29. HT-29 cells have been reported to be one of the most resistant colorectal cancer cell lines to TRAIL-induced apoptosis. In this study, we investigated the effect of diosgenin on TRAIL-induced apoptosis in HT-29 cells. We showed that diosgenin sensitizes HT-29 cells to TRAIL-induced apoptosis. Mechanisms underlying this sensitization mainly involved diosgenin-induced p38 MAPK pathway activation and subsequent DR5 overexpression. Furthermore, we showed that diosgenin alone, TRAIL alone or combination treatment increased COX-2 expression and that the use of a COX-2 inhibitor further increased apoptosis induction.     

滋肾固髓汤通过调控p38MAPK/p53信号通路诱导结直肠癌HCT-116细胞凋亡

目的:探讨滋肾固髓汤对结直肠癌HCT-116细胞凋亡的影响及其分子机制。方法:制备滋肾固髓汤含药血清,首先采用不同体积分数滋肾固髓汤含药血清处理HCT-116细胞,噻唑蓝(MTT)检测细胞增殖活性;再将HCT-116细胞分为空白组、滋肾固髓汤低、中、高剂量组、SB203580(p38MAPK抑制剂)组和高剂量滋肾固髓汤+SB203580组,分别加入相应药物进行干预后,Hoechst 33258染色观察细胞凋亡的形态学变化;Annexin V-FITC流式细胞术检测细胞的凋亡水平;Western blot检测细胞中p38MAPK、磷酸化(p)-p38MAPK(Thr180/Tyr182)、鼠双微染色体2(MDM2)、p53、Cleaved caspase-3、Bax和Bcl-2等蛋白表达水平。结果:滋肾固髓汤可抑制HCT-116细胞增殖活性,并呈时间和浓度依赖性。不同浓度滋肾固髓汤处理可诱导HCT-116细胞呈现核聚集、皱缩或碎裂等凋亡形态变化,促进细胞凋亡,上调p-p38MAPK、p53、Bax和Cleaved caspase-3等蛋白表达水平,下调MDM2和Bcl-2蛋白表达水平。S...     

The roles of p38MAPK and caspase-3 in DADS-induced apoptosis in human HepG2 cells

Objectives

To explore the function of p38MAPK and caspase-3 in DADS-induced apoptosis in human HepG2 cells, and discuss the signal transduetion mechanism of HepG2 cells in the apoptosis process induced by DADS by using the inhibitors of p38MAPK (SB203580) and caspase-3 (Z-DEVD-FMK).

Methods

After the human HepG2 cells had been treated with the DADS and inhibitors for 24 h, cell viability was determined by the MTT method, apoptosis was evaluated by flow cytometry (FCM) and the expressions of p38MAPK and caspase-3 were measured by western-blot.

Results

Our results indicated that DADS activities the p38MAPK and caspase-3, but the inhibitors, SB203580 and Z-DEVD-FMK (for p38MAPKand for caspase-3, respectively), both have the effect of inhibitory activity on P38MAPK and caspase-3. Furthermore, a combination treatment with both DADS and inhibitor (SB203580 or Z-DEVD-FMK) decreases the inhibitory and apoptotic activity of HepG2 cells increased compared with DADS-treated.

Conclusions

Our data indicate that p38MAPK and caspase-3 are involved in the process of DADS-induced apoptosis in human HepG2 cells and interact with each other.     

白细胞介素-33对急性髓系白血病细胞株HL-60、NB4凋亡和周期的调控作用及机制研究

目的  探讨白细胞介素-33（interleukin-33,IL-33）对急性髓系白血病细胞凋亡的影响及其可能的机制。方法 急性髓系白血病细胞株HL-60、NB4经外源性IL-33以及p38丝裂原活化蛋白激酶（p38 mitogen-activated protein kinase,p38 MAPK）特异抑制剂（SB203580）处理72 h后,采用Annexin V/DAPI双染色流式细胞术检测细胞凋亡率,细胞周期检测试剂盒检测细胞周期,Western blot 检测细胞周期蛋白依赖性激酶1（cyclin-dependent kinases 1,CDK1）蛋白表达以及p38 MAPK的磷酸化水平。结果 与对照组相比,IL-33组的HL-60和NB4细胞经IL-33作用后,细胞凋亡水平降低（P<0.05）,细胞周期中S期比例升高（P<0.001）;而SB+IL-33组细胞经SB203580和IL-33联合处理后,细胞凋亡水平高于IL-33组（P<0.05）,S期细胞的百分比低于IL-33组（P<0.05）;Western blot检测结果表明,与对照组相比,IL-33组细胞的p38 MAPK磷酸化（p-p38 MAPK） 水平和CDK1蛋白表达水平均显著增高（均P<0.05）,而SB+IL-33组的p-p38 MAPK水平以及CDK1水平较IL-33组显著下降（均P<0.05）。 结论 IL-33可通过激活p38 MAPK,抑制急性髓系白血病细胞株HL-60、NB4细胞的凋亡,抑制细胞周期停滞。     

Lidamycin induces marked G2 cell cycle arrest in human colon carcinoma HT-29 cells through activation of p38 MAPK pathway

Lidamycin (LDM), a member of the enediyne antibiotic family, is presently undergoing phase I clinical trials in P.R. China. In this study, we investigated the mechanisms of LDM-induced cell cycle arrest in order to support its use in clinical cancer therapy. Using human colon carcinoma HT-29 cells, we observed that LDM induced G2 cell cycle arrest in a time- and dose-dependent manner. LDM-induced G2 arrest was associated with increasing phosphorylation of Chk1, Chk2, Cdc25C, Cdc2 and expression of Cdc2 and cyclin B1. In addition, cytoplasmic localization of cyclin B1 was also involved in LDM-induced G2 arrest. Moreover, we found that p38 MAPK pathway contributed to LDM-induced G2 arrest. Inhibition of p38 MAPK by its inhibitor SB203580 not only attenuated LDM-induced G2 arrest but also potentiated LDM-induced apoptosis, which was accompanied by decreasing phosphorylation of Cdc2 and increasing expression of FasL and phosphorylation of JNK. Finally, we demonstrated that cells at G1 phase were more sensitive to LDM. Together, our findings suggest that p38 MAPK signaling pathway is involved in LDM-induced G2 arrest, at least partly, and a combination of LDM with p38 MAPK inhibitor may represent a new strategy for human colon cancer therapy.