选择性环氧合酶-2抑制剂塞来昔布抑制胃癌多药耐药基因表达的实验研究

目的:探讨选择性环氧合酶(COX-2)抑制剂塞来昔布对胃癌细胞株BGC823多药耐药(mdr)1表达的影响.方法:胃癌细胞株BGC823经浓度分别为0、10、100μ mol/L的塞来昔布处理后,酶联免疫吸附试验检测塞来昔布对胃癌细胞前列腺素E2(PGE2)分泌的影响,24、48 h后用RT-PCR检测多药耐药(mdr)1 mRNA表达,48 h后用免疫细胞化学染色法检测P-gp表达.结果:塞来昔布可显著抑制胃癌细胞株BGC823 PGE2分泌.并呈浓度依赖性(P<0.05).不同浓度塞来昔布作用于细胞后,胃癌细胞株BGC823的mdrl/P-gp表达受不同程度抑制,100μ mol/L的塞来昔布对mdrl mRNA表达抑制作用强于10μ mol/L(P<0.01).不同浓度药物与测量时间为交互作用,作用48h与24h相比,塞来昔布对mdrl mRNA表达的抑制作用更强(P<0.01).结论:塞来昔布可抑制BGC823的mdrl/P-gp表达,且呈剂量效应关系.塞来昔布可能通过抑制COX-2活性,抑制COX-2下游产物PGE2表达,从而抑制P-gp表达.选择性COX-2抑制剂可能有助于减轻肿瘤细胞对化疗药物的耐药性.     

姜黄素通过MAPK信号通路诱导人肝癌SMMC-7721细胞凋亡

本文阐述了姜黄素(Curcumin)对体外培养的人肝癌SMMC-7721细胞增殖和凋亡的影响,并探讨了其诱导凋亡的信号转导机制。采用MTT法和细胞计数法检测不同浓度姜黄素对人肝癌细胞株SMMC-7721增殖的影响,利用流式细胞术检测姜黄素对人肝癌SMMC-7721细胞凋亡的影响,通过RT-PCR及Western blot检测姜黄素对人肝癌SMMC-7721细胞中凋亡相关蛋白Caspase-3、Survivin、Bcl-2和Bax表达的影响,最后通过检测MAPK的磷酸化水平分析姜黄素诱导SMMC-7721细胞凋亡的信号转导机制,通过MAPK抑制剂实验进一步证实诱导凋亡的分子机制。研究结果显示,姜黄素呈时间和剂量依赖性抑制人肝癌SMMC-7721细胞的增殖,其中40μmol/L姜黄素可明显诱导SMMC-7721细胞的凋亡,并呈时间依赖性上调促凋亡蛋白Caspase-3和Bax的表达、下调抗凋亡蛋白Survivin和Bcl-2的表达,姜黄素对凋亡相关蛋白表达的调节及诱导凋亡可以通过激活JNK、抑制ERK和p38 MAPK信号通路实现。表明姜黄素可诱导人肝癌SMMC-7721细胞凋亡,其机制与姜黄素激活JNK、抑制ERK和p38 MAPK信号通路从而上调Caspase-3和Bax的表达,下调Survivin和Bcl-2的表达有关。     

塞来昔布诱导HCT-116结肠癌细胞G2/M阻滞

目的:研究选择性COX-2抑制剂塞来昔布诱导结肠癌细胞株HCT-116细胞周期阻滞的作用及其可能的机制。方法:应用流式细胞仪检测塞来昔布对HCT-116细胞周期的影响,定量PCR检测细胞周期素cyclinB1及COX-2 mRNA表达水平,Western-Blot检测细胞周期素cyclinB1的蛋白水平。结果:塞来昔布诱导HCT-116细胞G2/M阻滞的作用呈剂量依赖性,塞来昔布在mRNA及蛋白水平下调HCT-116细胞的cyclinB1。结论:塞来昔布能在体外抑制HCT-116细胞的增殖,诱导G2/M的阻滞,其作用与下调细胞周期素cyclinB1有关。     

MAPK和JAK—STAT途径中酪氨酸蛋白激酶在肝癌组织中的表达及意义

目的观察MAPK途径和JAK—STAT途径中重要酪氨酸蛋白激酶ERK、P38、C-Jun、JAK、STAT3、STAT5在肝癌组织中的表达及其相互关系,探讨蛋白激酶表达与肝癌患者临床病理特征之间的关系。方法收集原发性肝癌手术切除标本30例,制作组织芯片,酪氨酸蛋白激酶在不同组织中的表达检测采用免疫组化SP法。结果ERK、P38、C-Jun、JAK、STAT3、STAT5在肝癌组织中的表达平均光密度值显著高于肝硬化组（P〈0．01）。ERK与C-Jun、JAK、STAT3、STAT5在肝癌组织中的表达呈显著正相关,与P38呈显著负相关。JAK的过度表达与肝癌组织的分化程度有关,在低分化肝癌组织中表达率显著高于高中分化肝癌组织。结论MAPK和JAK—STAT通路的过度活化在肝癌发生发展过程中起重要作用,细胞信号转导系统失去正常的协调平衡可能是导致肿瘤发生的重要原因。     

URI基因稳定表达对肝癌SMMC-7721细胞增殖能力的影响

目的:瞬转以及筛选出能够稳定表达URI(RPB5-mediating protein)基因的SMMC-7721细胞株,以其为模型研究URI基因对人肝癌SMMC-7721细胞增殖的影响.方法:首先,抽提URI的重组质粒并转染到SMMC-7721细胞中,在G418药物的筛选下选出能够稳定表达URI基因的细胞株,RT-PCR法和酶切检测该稳定细胞中URI基因的表达效率以确认URI是否稳定表达,MTT法和克隆形成实验检测URI基因对SMMC-7721细胞增殖的影响.结果:成功建立URI基因过表达的稳定细胞株.与SMMC-7721细胞对照组比较,其URI mRNA表达水平显著上调,能稳定表达URI细胞株的增殖,克隆形成率明显升高.结论:pFLAG-CMV-4-URI重组质粒能使URI在肝癌SMMC-7721细胞内稳定表达,过表达URI基因有可能帮助细胞通过G2/M期检验点来提高肝癌细胞SMMC-7721的增殖能力.     

不同剂量的塞来昔布对C57BL/6小鼠移植瘤微淋巴管密度抑制作用的研究(英文)

目的:观察不同剂量的塞来昔布对C57BL/6小鼠肺癌移植瘤生长、COX-2表达和微淋巴管密度影响,探讨塞来昔布对C57BL/6小鼠肺癌移植瘤淋巴管生成可能作用机制及量效关系。方法:将Lewis肺癌细胞株接种于C57BL/6小鼠左侧腹股沟皮下建立移植瘤模型,随机分为4组:对照组、塞来昔布低剂量、中剂量、高剂量组。观察荷瘤小鼠生存状态,瘤体积变化,种瘤42天后牺牲小鼠,western blot半定量检测COX-2表达及微淋巴管密度。结果:Western blot半定量显示:塞来昔布高、中剂量组COX-2的表达水平及免疫组织化学染色微淋巴管密度计数均明显减低,差异有统计学意义(P0.05),低剂量组略有减低但差异无统计学意义(P0.05)。抑制程度呈明显的剂量依赖性。结论:塞来昔布抑制Lewis肺癌移植瘤的生长及淋巴转移,可能与下调COX-2的表达,阻遏了淋巴管生成的信号通路,抑制微淋巴管生成有关,该抑制作用呈一定的剂量相关性。     

Notch信号通路对肝癌细胞迁移能力及E-cadherin，COX-2表达的影响

目的:探讨Notch信号通路对肝癌细胞迁移能力及钙粘附蛋白E(E-cadherin)、环氧化酶-2(COX-2)表达的影响。方法:体外培养肝癌细胞系(SMMC-7721、MHCC97H)、正常非肿瘤肝细胞系(HL-7702),Transwell小室用于测定细胞的迁移侵袭能力,Western blot蛋白印迹法用于测定Notch1、E-cadherin、COX-2蛋白的表达水平,并采用DAPT阻断Notch信号通路,比较肝癌细胞系与正常非肿瘤肝细胞系的迁移侵袭能力及肝癌细胞中E-cadherin、COX-2蛋白的表达水平的改变。结果:SMMC-7721细胞、MHCC97H细胞的迁移能力强于HL-7702细胞,差异有统计学意义(P0.05);相比于HL-7702细胞,MHCC97H细胞、SMMC-7721细胞中的Notch1、COX-2表达水平均显著升高,E-cadherin的表达水平明显降低(P0.05);DAPT处理后,SMMC-7721细胞、MHCC97H细胞发生迁移的能力均弱于对照组,差异有统计意义(P0.05);DAPT处理后,SMMC-7721细胞、MHCC97H细胞内COX-2、Notch1的表达量明显降低,而E-cadherin的表达水平升高(P0.05)。结论:Notch信号通路参与肝癌细胞迁移过程,其机制可能与E-cadherin、COX-2的表达相关。     

连香树精油对人肝癌SMMC-7721细胞抗肿瘤机制的研究

为探讨连香树精油的体外抗肿瘤活性。以人肝癌SMMC-7721细胞为受试细胞株,利用MTT法、流式细胞术、JC-1法和Western blot法评价连香树精油的体外抗肿瘤活性。结果表明:连香树精油处理24 h后可降低SMMC-7721细胞存活率;细胞中G0/G1期的比例下降,G2/M期的比例升高;细胞线粒体膜电位降低;自噬相关蛋白LC3-Ⅱ、Beclin-1表达上升,加入自噬抑制剂氯喹后LC3-Ⅱ蛋白与Bcl-2抗凋亡蛋白表达下降。综上说明连香树精油能抑制SMMC-7721细胞的增殖活性,通过阻滞G2/M期抑制细胞分裂,通过降低线粒体膜电位诱导SMMC-7721细胞凋亡,而自噬在SMMC-7721细胞凋亡过程中作为一种保护机制而存在。     

塞来昔布对直肠癌HCA-7 细胞放射敏感性的实验研究

目的:观察环氧合酶-2(COX-2)抑制剂塞来昔布对直肠癌HCA-7细胞株的放射敏感性及探讨其机制。方法:采用MTT法检测塞来昔布作用不同时间对直肠癌HCA-7细胞株增殖的影响,计算出塞来昔布的半数抑制浓度IC50;HCA-7细胞克隆形成实验用于检测塞来昔布对HCA-7细胞的放射敏感性,并绘制存活曲线;流式细胞仪(FCM)测定塞来昔布对HCA-7的细胞周期的影响。结果:塞来昔布对HCA-7细胞株的抑制率随时间的延长而升高,48h的IC50是40.19μmol/L;照射组+药物组的SF2、D0、Dq、SER较单纯照射组均有所下降。塞来昔布使HCA-7细胞发生G2和M期阻滞,并抑制S期的比例。结论:塞来昔布能增加直肠癌HCA-7细胞的放射敏感性。     

Leptin介导JAK/STAT信号通路对猪皮下前脂肪细胞脂类代谢调控的研究

以猪原代皮下前脂肪细胞为研究材料,检测Leptin介导JAK/STAT信号通路中基因表达水平,旨在阐明Leptin介导JAK/STAT信号通路对脂肪代谢的分子机制。用0和100 ng/mL Leptin分别处理脂肪细胞48 h,油红O染色鉴定脂肪细胞,试剂盒测定细胞中甘油三酯和游离脂肪酸含量,Real-time PCR方法检测皮下前脂肪细胞中JAK/STAT信号通路中基因表达水平。研究结果表明:皮下前脂肪细胞中,Leptin组甘油三酯含量均显著低于对照组(P<0.05),脂肪酸含量均低于对照组;JAK/STAT信号通路中LepR、JAK2、STAT3、CPT-1、ACOX1和PGC-1α基因的表达量均显著高于对照组(P<0.05);LepR、JAK2、STAT3、CPT-1、ACOX1和PGC-1α基因表达量均与甘油三酯和游离脂肪酸含量呈显著负相关(P<0.05)。该研究结果表明,Leptin激活皮下前脂肪细胞中JAK/STAT信号通路,上调通路相关基因的表达,促进甘油三酯分解及脂肪酸氧化,降低细胞中甘油三酯和游离脂肪酸含量。     

Role of cyclooxygenases COX-1 and COX-2 in modulating adipogenesis in 3T3-L1 cells

Cyclooxygenase (COX) catalyses the rate-limiting step of prostanoid biosynthesis. Two COX isoforms have been identified, COX-1, the constitutive form, and COX-2, the inducible form. While COX-2 has been implicated in body fat regulation, the underlying cellular mechanism remains to be elucidated. The present study was undertaken to examine the potential role of COX in modulating adipogenesis and to dissect the relative contribution of the two isoenzymes in this process. COX-2 was found to be expressed in undifferentiated 3T3-L1 cells and down-regulated during differentiation, whereas the cellular level of COX-1 remained relatively constant. Abrogating the activity of either of these two isoenzymes by selective COX inhibitors accelerated cellular differentiation, suggesting that both COX isoenzymes negatively influenced differentiation. Tumor necrosis factor-alpha (TNFalpha) significantly up-regulated COX-2 expression ( approximately 2-fold) in differentiating 3T3-L1 cells, whereas similar effect was not observed with COX-1 expression. Abrogating the induced COX-2 activity reversed the TNFalpha-induced inhibition of differentiation by approximately 70%, implying a role for COX-2 in mediating TNFalpha signaling. Hence, both COX isoforms were involved in the negative modulation of adipocyte differentiation. COX-2 appeared to be the main isoform mediating at least part of the negative effects of TNFalpha.     

Cyclooxygenase-1 and an alternatively spliced mRNA in the rat stomach: effects of aging and ulcers

Prostaglandins play a critical role in gastric mucosal cytoprotection and decrease progressively with age. Cyclooxygenase (COX), the rate-limiting enzyme for prostaglandin synthesis, exists in two isoforms, COX-1 and COX-2. The rat COX-1 gene expresses an alternatively spliced mRNA COX-1 splice variant (SV) that may, at best, code for a truncated COX-1 protein. With the use of competitive PCR, we determined whether COX gene expression was altered in the stomach with increasing age and after gastric ulcer induction. COX-1 mRNA was significantly reduced in the aged, and COX-1SV mRNA was significantly higher in the adults compared with the young and aged stomach. Levels of COX-1 and COX-2 were similarly expressed in the normal stomach. In acute gastric ulcers, only COX-2 mRNA levels were significantly elevated. When ulcers were undergoing healing and repair, COX-1 and COX-2 mRNA levels were significantly elevated. Age-related changes in COX-1 and COX-1SV but not COX-2 mRNA may alter gastric mucosal cytoprotection. Furthermore, COX-1 and COX-2 may both contribute to the healing of a gastric ulcer.     

Resistance exercise and cyclooxygenase (COX) expression in human skeletal muscle: implications for COX-inhibiting drugs and protein synthesis

We have shown that ibuprofen and acetaminophen block cyclooxygenase (COX) synthesis of prostaglandin PGF(2alpha) and the muscle protein synthesis increase following resistance exercise. Confusingly, these two drugs are purported to work through different mechanisms, with acetaminophen apparently unable to block COX and ibuprofen able to nonspecifically block COX-1 and COX-2. A recently discovered intron-retaining COX, now known to have three variants, has been shown to be sensitive to both drugs. We measured the expression patterns and levels of the intron 1-retaining COX-1 variants (-1b1, -1b2, and -1b3), COX-1, and COX-2 at rest and following resistance exercise to help elucidate the COX through which PGF(2alpha), ibuprofen, and acetaminophen regulate muscle protein synthesis. Skeletal muscle biopsy samples were taken from 16 individuals (8M, 8F) before, 4, and 24 h after a bout of resistance exercise and analyzed using real-time RT-PCR. Relatively few individuals expressed the intron 1-retaining COX-1b variants (COX-1b1, -1b2, and -1b3) at any time point, and when expressed, these variants were in very low abundance. COX-1 was the most abundant COX mRNA before exercise and remained unchanged (P > 0.05) following exercise. COX-2 was not expressed before exercise, but increased significantly (P < 0.05) at 4 and 24 h after exercise. The inconsistent and low levels of expression of the intron 1-retaining COX-1 variants suggest that these variants are not likely responsible for the inhibition of PGF(2alpha) production and skeletal muscle protein synthesis after resistance exercise by ibuprofen and acetaminophen. Skeletal muscle-specific inhibition of COX-1 or COX-2 by these drugs should be considered.     

Role of the different isoforms of cyclooxygenase and nitric oxide synthase during gastric ulcer healing in cyclooxygenase-1 and -2 knockout mice

Traditional NSAIDs, selective cyclooxygenase (COX)-2 inhibitors, and inhibitors of nitric oxide synthase (NOS) impair the healing of preexisting gastric ulcers. However, the role of COX-1 (with or without impairment of COX-2) and the interaction between COX and NOS isoforms during healing are less clear. Thus we investigated healing and regulation of COX and NOS isoforms during ulcer healing in COX-1 and COX-2 deficiency and inhibition mouse models. In this study, female wild-type COX-1(-/-) and COX-2(-/-) mice with gastric ulcers induced by cryoprobe were treated intragastrically with vehicle, selective COX-1 (SC-560), COX-2 (celecoxib, rofecoxib, and valdedoxib), and unselective COX (piroxicam) inhibitors. Ulcer healing parameters, mRNA expression, and activity of COX and NOS were quantified. Gene disruption or inhibition of COX-1 did not impair ulcer healing. In contrast, COX-2 gene disruption and COX-2 inhibitors moderately impaired wound healing. More severe healing impairment was found in dual (SC-560 + rofecoxib) and unselective (piroxicam) COX inhibition and combined COX impairment (in COX-1(-/-) mice with COX-2 inhibition and COX-2(-/-) mice with COX-1 inhibition). In the ulcerated repair tissue, COX-2 mRNA in COX-1(-/-) mice, COX-1 mRNA in COX-2(-/-) mice, and, remarkably, NOS-2 and NOS-3 mRNA in COX-impaired mice were more upregulated than in wild-type mice. This study demonstrates that COX-2 is a key mediator in gastric wound healing. In contrast, COX-1 has no significant role in healing when COX-2 is unimpaired but becomes important when COX-2 is impaired. As counterregulatory mechanisms, mRNA of COX and NOS isoforms were increased during healing in COX-impaired mice.     

Effects of selective and non-selective COX inhibitors on antigen-induced release of prostanoid mediators and bronchoconstriction in the isolated perfused and ventilated guinea pig lung

The contribution of cycloxygenase (COX)-1 and COX-2 in antigen-induced release of mediators and ensuing bronchoconstriction was investigated in the isolated perfused guinea pig lung (IPL). Antigen challenge with ovalbumin (OVA) of lungs from actively sensitised animals induced release of thromboxane (TX)A(2), prostaglandin (PG)D(2), PGF(2)(alpha), PGI(2) and PGE(2), measured in the lung effluent as immunoreactive TXB(2), PGD(2)-MOX, PGF(2)(alpha), 6-keto PGF(1)(alpha) and PGE(2), respectively. This release was abolished by the non-selective COX inhibitor flurbiprofen (10 microM). In contrast, neither the selective COX-1 inhibitor FR122047 nor the selective COX-2 inhibitor celecoxib (10 microM each) significantly inhibited the OVA-induced bronchoconstriction or release of COX products, except for PGD(2). Another non-selective COX inhibitor, diclofenac (10 microM) also significantly inhibited antigen-induced bronchoconstriction. The data suggest that both COX isoenzymes, COX-1 and COX-2 contribute to the immediate antigen-induced generation of prostanoids in IPL and that the COX-1 and COX-2 activities are not associated with different profiles of prostanoid end products.     

Synthesis and biological evaluation of methanesulfonamide analogues of rofecoxib: Replacement of methanesulfonyl by methanesulfonamido decreases cyclooxygenase-2 selectivity

A new group of 3-(4-substituted-phenyl)-4-(4-methylsulfonamidophenyl)-2(5H)furanones in which the methylsulfonyl (MeSO(2)) COX-2 pharmacophore present in rofecoxib was replaced by a methanesulfonamido (MeSO(2)NH) moiety, and where the substituent at the para-position of the C-3 phenyl ring was simultaneously varied (H, F, Cl, Br, Me, OMe), were evaluated to determine the combined effects of steric and electronic substituent properties upon COX-1 and COX-2 inhibitory potency and COX isozyme selectivity. Structure-activity relationship (SAR) studies showed that compounds having a neutral (H), or electronegative halogen (F, Cl, Br), substituent at the para-position of the C-3 phenyl ring inhibited both COX-1 and COX-2 with COX-2 selectivity indexes in the 3.1-39.4 range. In contrast, compounds having an electron-donating Me or OMe substituent were selective inhibitors of COX-2 (COX-1 IC(50)>100 microM). These SAR data indicate the 3-aryl-4-(4-methylsulfonamidophenyl)-2(5H)furanone scaffold provides a suitable template to design COX inhibitors with variable COX-2 selectivity indexes.     

Cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) selectivity of COX inhibitors

In vitro evaluations of the selectivity of COX inhibitors are based on a great variety of experimental protocols. As a result, data available on cyclooxygenase (COX)-1/COX-2/5- lipoxygenase (LOX) selectivity of COX inhibitors lack consistency. We, therefore, performed a systematic analysis of the COX-1/COX-2/5-LOX selectivity of 14 compounds with selective COX inhibitory activity (Coxibs). The compounds belonged to different structural classes and were analyzed employing the well-recognized whole-blood assay. 5-LOX activity was also tested on isolated human polymorphonuclear leukocytes. Among COX inhibitors, celecoxib and ML-3000 (licofelone) inhibited 5-LOX in human neutrophils at micromolar ranges. Surprisingly, ML-3000 had no effect on 5-LOX product synthesis in whole-blood assay. In addition, we could show that inhibition of COX pathways did not increase the transformation of arachidonic acid by the 5-LOX pathway.     

Quantitative structure-activity relationship study of orally active cyclooxygenase-2 (COX-2) inhibitors of derivatives of 3-phenoxypyran-4-one

The cyclooxygenase (COX) inhibition activities of the derivatives of 3-phenoxypyran-4-one were analyzed through multiple-regression analysis (MRA). Appropriate physicochemical parameters, identified for the substitutents of phenyl ring, attached to 3-phenoxypyran-4-one moiety were quantitatively correlated with COX-2 and COX-1 inhibition activities of these compounds. The derived significant correlation equation for COX-2 inhibition suggested that the ortho-substituent with negative resonance parameter, the para-substituent with lower dipole moment and the meta-substituent having higher resonance parameter were advantageous for the activity. The derived correlation equation for COX-1 inhibition suggested the significance of resonance effect for ortho-substituents and electron-donating effect for para-substituent. A few potential congeners were also suggested for further synthesis.