3种选择性环氧合酶-2抑制剂对胰腺癌生长的影响

目的 比较3种不同选择性的环氧合酶-2(COX-2)抑制剂--美格昔康、塞来昔布、罗非昔布对人胰腺癌细胞生长及凋亡的影响，观察罗非昔布对人裸鼠胰腺癌移植瘤生长的抑制作用。方法采用3H-胞腺嘧啶核苷掺入，了解细胞DNA合成；用免疫组化检测增殖细胞核抗原(proliferating cell nuclear antigen，PCNA)及细胞COX-2的表达；用TUNEL染色法检测细胞凋亡。建立裸鼠胰腺癌移植瘤模型，给予罗非昔布8周，观察肿瘤大小、肿瘤组织的COX-2及PXNA的表达情况。结果 3种COX-2抑制剂均能抑制体外培养的胰腺癌细胞株BxPC-3的3H-胸腺嘧啶核苷掺入，其抑制效应与药物浓度呈显著正相关。COX-2抑制剂的选择性越高，对胰腺癌细胞生长的抑制作用越强。COX-2抑制剂均能诱导胰腺癌细胞的凋亡、降低胰腺癌细胞的COX-2、PCNA的表达。罗非昔布对裸鼠胰腺癌移植瘤的抑瘤率为87．7％；肿瘤组织的COX-2、PCNA表达均较对照组明显下降。结论 3种选择性COX-2抑制剂均能抑制人胰腺癌细胞的生长，并诱导其凋亡，对COX-2的选择性越高，对胰腺癌的抑制作用越强。罗非昔布可显著抑制裸鼠胰腺癌移植瘤的生长。     

NS398对胰腺癌细胞周期及其蛋白依赖性激酶抑制物p21Wafl/cipl、p27Kipl/pic2的影响

目的:观察选择性环氧合酶-2(COX-2)抑制剂NS398对胰腺癌细胞周期及细胞周期相关蛋白p21Wafl/cipl、p27Kipl/pic2转录和表达的影响,探讨NS398的抗胰腺癌机制.方法:以NS398和前列腺素E2(PGE2)处理SW1990人胰腺癌细胞,分别采用MTT法检测细胞活力,酶联免疫分析法(ELISA)检测细胞内PGE2含量,流式细胞仪(FCM)检测细胞周期变化,并以半定量逆转录聚合酶链式反应(RT-PCR)和Western印迹检测COX-2及细胞周期相关蛋白p21Wafl/cipl、p27Kipl/pic2的mRNA和蛋白水平.结果:NS398抑制胰腺癌细胞生长,并呈剂量依赖性减少细胞内PGE2的生成;NS398诱导细胞周期相关蛋白p21Wafl/cipl和p27Kipl/pic2转录和表达的升高并诱导部分细胞阻滞在G0/G1期(较对照组升高11%);10nmol/L的外源性PGE2可增加胰腺癌细胞的活力,但并不能拮抗NS398对细胞活力的抑制作用或细胞周期分布的改变,以及COX-2、p21Wafl/cipl、p27Kipl/pic2的转录和表达.结论:NS398可能通过增强p21Wafl/cipl和p27Kipl/pic2的表达而诱导细胞周期的阻滞,从而抑制胰腺癌细胞的生长活力.但NS398并非通过抑制COX-2的唯一机制,还可能存在其它非COX-2途径.     

寻找环氧合酶-2选择性抑制剂的新途径：对经典非甾体类抗炎药的结构改造

典型的环氧合酶-2(COX-2)选择性抑制剂对COX-2抑制选择性高，胃肠道副作用小，但在炎症组织分布选择性低，有心血管方面的副作用。本文分析了典型COX-2选择性抑制剂心血管危险性产生的机制，指出探索更安全的COX-2选择性抑制剂的一个有效途径是对经典非甾体类抗炎药(NSAID)结构的合理改造，保持药物分子在炎症组织分布的高选择性，提高对COX-2抑制的选择性；同时，对经典NSAID结构改造的研究进展进行了综述。     

选择性环氧合酶-2抑制剂体外筛选模型的建立

目的:建立选择性环氧合酶-2(COX-2)抑制剂筛选模型。方法:以脂多糖(LPS)为刺激剂刺激大鼠腹腔巨噬细胞产生前列腺素E2(PGE2),采用放免法确定最佳刺激浓度和时间,以选择性COX-2抑制剂戊地昔布和达布非隆(darbufelone)为阳性对照药验证实验模型。结果:达布非隆和戊地昔布对COX-2和COX-1的半数抑制浓度(IC50)的比值分别为3．175×10-4和3．576×10-3。结论:本实验建立的COX-2抑制剂筛选模型比较灵敏,可靠,可用于选择性COX-2抑制剂的筛选。     

NS398对胰腺癌细胞周期及其蛋白依赖性激酶抑制物p21^waf1/cip1、p27^Kip1/pic2的影响

目的：观察选择性环氧合酶-2（COX-2）抑制剂NS398对胰腺癌细胞周期及细胞周期相关蛋白p21^waf1/cip1、p27^Kip1／pic2转录和表达的影响，探讨NS398的抗胰腺癌机制。方法：以NS398和前列腺素E2（PGE2）处理SW1990人胰腺癌细胞，分别采用MTT法检测细胞活力，酶联免疫分析法（ELISA）检测细胞内PGE2含量，流式细胞仪（FCM）检测细胞周期变化，并以半定量逆转录聚合酶链式反应（RT-PCR）和Western印迹检测COX-2及细胞周期相关蛋白p21^waf1/cip1、p27^Kip1／pic2的mRNA和蛋白水平。结果：NS398抑制胰腺癌细胞生长，并呈剂量依赖性减少细胞内PGE2的生成；NS398诱导细胞周期相关蛋白p21^waf1/cip1和p27^Kip1／pic2转录和表达的升高并诱导部分细胞阻滞在G0/G1期（较对照组升高11％）；10nmol／L的外源性PGE2可增加胰腺癌细胞的活力，但并不能拮抗NS398对细胞活力的抑制作用或细胞周期分布的改变，以及COX-2、p21^waf1/cip1、p27^Kip1/pic2的转录和表达。结论：NS398可能通过增强p21^waf1/cip1和p27^Kip1/pic2的表达而诱导细胞周期的阻滞，从而抑制胰腺癌细胞的生长活力。但NS398并非通过抑制COX-2的唯一机制，还可能存在其它非COX-2途径。     

三环类环氧合酶-2选择性抑制剂的构效关系

按照中心环的结构分类综述三环类环氧合酶-2(COX-2)选择性抑制剂的构效关系。三环类COX-2选择性抑制剂是目前非甾体抗炎药中研究最多、也是最富有成果的一类化合物。     

最近发现的环氧合酶同工酶对非甾体类抗炎药研究的影响

两种环氧合酶 (COX)同工酶 COX- 1和 COX- 2的发现 ,对非甾体类抗炎药(NSAID)的研究有了新的认识。两种同工酶的结构、催化活性相同 ,但在分子水平上的调节各有其特异性。寻找选择性 COX抑制剂的主要目的是改进对 NSAID的耐受性 ,新的化合物对 COX- 2有很高的选择性 ,特别是非酸性的化合物 ,在消化道的耐受性较好。虽然这些化合物对于某些疾病 ,如结肠直肠癌和 Alzheimer型神经退化症可能有潜在的疗效 ,但也应该考虑其与肾有关的副作用。因此 ,需要进行临床试验 ,以验证 NSAID的选择性抑制剂的治疗效果和由于 COX- 2的可能引起的潜在副作用     

血小板衍生生长因子受体和COX-2与胃癌研究进展

血小板衍生生长因子受体(PDGFR)是Ⅲ型酪氨酸激酶受体家族,包括两种酪氨酸激酶受体即PDGFR-α、β,存在于细胞质中的血管生成因子,可以通过自分泌或旁分泌方式参与肿瘤间质血管生成的调节,促进细胞的增殖及迁移,影响着胃癌的发生、发展及预后。环氧合酶-2(COX-2)是花生四烯酸合成前列腺素的关键酶之一,属诱导性酶,COX-2的高表达在消化系肿瘤的发生、发展、浸润及转移中起重要作用。在胃癌中,PDGFR与COX-2均存在高表达,且二者具有协同作用,与促进胃癌血管形成及加速肿瘤细胞浸润、转移有关。     

环氧合酶-2抑制剂对K562白血病细胞增殖及凋亡的影响

目的:体外观察非甾体药物选择性环氧合酶-2(COX-2)抑制剂NS-398对白血病细胞株K562细胞增殖及凋亡影响。方法:采用噻唑蓝法观察NS-398对K562细胞增殖的影响,流式细胞仪检测细胞周期的改变及凋亡百分率的变化,DNA梯状电泳检测凋亡的发生。Western印迹法检测K562细胞半胱氨酸天冬氨酸特异性蛋白酶Caspa-se-3和COX-2的表达。结果:NS-398呈剂量依赖性的方式抑制K562细胞增殖,并诱导其凋亡。并呈浓度依赖性改变细胞周期的分布,一方面增高Go/G1期细胞比例,另一方面降低S期和G2/M期细胞比例,与对照组相比差异具显著性(P<0.05)。NS-398干预的K562细胞Caspase-3的蛋白表达均显著升高,而COX-2的蛋白表达降低,并呈浓度依赖性。结论:体外NS-398能有效的发挥抗K562细胞白血病效应,对白血病细胞增殖有抑制作用并诱导其凋亡,这可能与抑制COX-2表达及上调Caspase有关。     

环氧合酶-2和5-脂氧化酶双重抑制剂的研究进展

传统的非甾体抗炎药和选择性环氧合酶-2(COX-2)抑制剂在治疗炎症过程中引发胃肠道及肾脏不良反应,制约了其临床应用。COX-2和5-脂氧化酶(5-LOX)双重抑制剂同时抑制前列腺素(PGs)和炎症介质白三烯类(LTs)的生物合成,比单一的抑制剂抗炎效果好、安全性高,是一类有发展前景的新型非甾体抗炎药。笔者简要介绍COX-2/5-LOX双重抑制剂的研究进展,并讨论其作用机制及构效关系     

Intrathecally administered COX-2 but not COX-1 or COX-3 inhibitors attenuate streptozotocin-induced mechanical hyperalgesia in rats

Members of the cyclooxygenase (COX) family are known to catalyze the rate-limiting steps of prostaglandins synthesis and reported to be involved in neuropathic pain. Diabetic neuropathy is a type of neuropathic pain, though it is not clear if COX is relevant to the condition. Recently, spinal COX-2 protein was found to be increasing in streptozotocin-induced rats as compared to the constitutive expression. We attempted to determine which cyclooxygenase isoforms are involved in streptozotocin-induced mechanical hyperalgesia, which was induced by a single intraperitoneal injection of 75 mg/kg of streptozotocin. Intrathecal administrations of the COX-2 inhibitors SC-58125 (7-100 microg) and NS-398 (7-60 microg), as well as a high dose (100 microg) of the COX-1 inhibitor SC-560 attenuated hyperalgesia, whereas intrathecal administrations of a low dose (10 microg) of SC-560 and the COX-3 inhibitor acetaminophen (1-7 mg) did not. Further, intrathecal administration of SC-58125 (100 microg) did not produce an analgesic effect in normal rats. These results indicate that intrathecal administration of COX-2 inhibitors has an anti-hyperalgesic effect on streptozotocin-induced mechanical hyperalgesia and we concluded that spinal COX-2 is pivotal in streptozotocin-induced hyperalgesia.     

COX-1, COX-2 and the topical effect in NSAID-induced enteropathy

The side effects of NSAIDs are equally evident in the stomach and the small bowel. The latter is increasingly seen as being clinically significant, contributing substantially to the iron-deficiency anaemia that is so common in patients with rheumatoid arthritis. Furthermore, NSAID-enteropathy may be associated with life-threatening events. The pathogenesis of NSAID-enteropathy is uncertain but inhibition of COX-1 is believed to be of pivotal importance. However there is increasing evidence that COX-2 inhibition and the topical effect may have a synergistic detrimental action. We examined the role of COX-1, COX-2 and the so called topical effect of acidic NSAIDs. We found that COX-1 or COX-2 inhibition and the topical effect alone do not damage the GI tract. Dual inhibition of COX-1 and COX-2 results in intestinal inflammation similar to that caused by Indomethacin. The topical effect may act synergistically in this damage. The conventional view that the mechanism of gastrointestinal damage is principally caused by COX-1 inhibition needs to be revised in view of recent studies using selective inhibitors of the COX enzymes and COX knockout animals.     

Gastrointestinal effects of COX-2 inhibitors

The developing popularity of non-steroidal anti-inflammatory drugs (NSAIDs) over the last 100 years has been paralleled by an increase in associated complications, particularly affecting the gastrointestinal (GI) tract [1]. Over this period, there have been several attempts to develop less toxic NSAIDs, most of which have been unsuccessful. Since the discovery that the enzyme cyclooxygenase (COX) exists as two isoforms, the largely constitutive COX-1 and the mainly inducible COX-2, much interest has centred on the development of drugs capable of selectively inhibiting COX-2. Early studies that investigated specific COX-2 inhibitors (with no effect on the COX-1 isoform over the whole range of concentrations achieved in clinical usage) are encouraging, as they demonstrate that these drugs have fewer effects on gastroduodenal mucosa than standard NSAIDs given at equivalent doses. Further clinical experience with these agents outside trial settings and additional studies to assess the role of COX-2 when induced in the GI tract are needed, before such agents can be safely recommended for widespread prescribing.     

Therapeutic potential of COX-2 inhibitors in arthritis

Arthritis and related musculoskeletal conditions occur with great frequency in the population world wide, causing significant morbidity and, in some instances, increased mortality. Affecting both the young and the old, 15% of the population in the US was estimated in 1995 to have some form of arthritis with an increase to 18% projected by the year 2020 [1]. The economic impact of arthritis and related disorders in the US alone was estimated to be US $194.4 billion in 1992 and future costs are virtually certain to increase given the chronic nature of these diseases, their expanding prevalence and the considerable expense associated with newer therapies [2]. With no cure presently available, the aim of current treatment is to reduce inflammation, ameliorate symptoms and improve functional capacity. Non-steroidal anti-inflammatory drugs (NSAIDs), which suppress the formation of pro-inflammatory prostaglandins by antagonising the action of cyclooxygenase (COX), have been the mainstay of arthritis treatment for hundreds, if not, thousands of years. The clinical use of NSAIDs, however, has long been associated with significant toxicity. The recognition of two COX isoforms, cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), both suppressed by traditional NSAIDs, has led to an expanded hypothesis of NSAID action which consists of two postulates, namely, the efficacy of NSAIDs in the treatment of arthritis is due to the suppression of COX-2, while much of the toxicity associated with non-selective NSAIDs is the consequence of COX-1 suppression. The emergence of agents which selectively inhibit COX-2 has made it possible to clinically evaluate the validity of each of these postulates. In this report, the published experience with selective COX-2 inhibitors in the treatment of mechanical and inflammatory arthropathies is reviewed to examine the premise that isolated COX-2 suppression is comparable in efficacy to the dual COX-1/COX-2 suppression produced by non-selective NSAIDs.     

Evaluation of COX-1/COX-2 selectivity and potency of a new class of COX-2 inhibitors

A new class of selective cyclooxygenase-2 (COX-2) inhibitors has been identified by high throughput screening. Structurally distinct from previously described selective COX-2 inhibitors, these benzopyrans contain a carboxylic acid function and CF3 functionality. The compound SC-75,416 is a representative of this class. A range if in vitro and in vivo tests were employed to characterize its potency and selectivity. Using human recombinant enzymes, this compound displays a concentration that provides 50% inhibition (IC50) of 0.25 microM for COX-2 and 49.6 microM for COX-1. A mutation of the side pocket residues in COX-2 to COX-1 had little effect on potency suggesting that these inhibitors bind in a unique manner in COX-2 distinct from COX-2 inhibiting diaryl heterocycles. Using rheumatoid arthritic synovial cells stimulated with interleukin-1beta (IL-1beta) and washed platelets the compound displayed IC50 of 3 nM and 400 nM respectively. Potency and selectivity was maintained but predictably right shifted in whole blood with IC50 of 1.4 microM for lipopolysaccharide (LPS) stimulated induction of COX-2 and >200 microM for inhibition of platelet thromboxane production. SC-75,416 is 89% bioavailable and its in vivo half life is sufficient for once a day dosing. In the rat air pouch model of inflammation, the compound inhibited PGE2 production with an effective dose that provides 50% inhibition (ED50) of 0.4 mg/kg, while sparing gastric prostaglandin E2 (PGE2) production with an ED50 of 26.5 mg/kg. In a model of acute inflammation and pain caused by carrageenan injection into the rat paw, the compound reduced edema and hyperalgesia with ED50s of 2.7 and 4 mg/kg respectively. In a chronic model of arthritis the compound demonstrated an ED50 of 0.081 mg/kg and an ED(80) of 0.38 mg/kg. In a model of neuropathic pain, SC-75,416 had good efficacy. This compound's unique chemical structure and effect on COX enzyme binding and activity as well as its potency and selectivity may prove useful in treating pain and inflammation.     

Non-COX-2 targets and cancer: expanding the molecular target repertoire of chemoprevention

Chemoprevention represents a highly promising approach for the control of cancer. That nonsteroidal anti-inflammatory drugs (NSAIDs) prevent colon and other cancers has led to novel approaches to cancer prevention. The known inhibitory effect of NSAIDs on the eicosanoid pathway prompted mechanistic and drug development work focusing on cyclooxygenase (COX), culminating in clinical trials of cyclooxygenase 2 (COX-2) inhibitors for cancer prevention or treatment. However, two COX-2 inhibitors have been withdrawn due to side effects. Here we review several pathways of the eicosanoid cascade that are relevant to cancer; summarize the evidence regarding the role of COX-2 as a target for cancer prevention; and discuss several of the molecular targets that may mediate the chemopreventive effect of NSAIDs. The clinically modest results obtained to date with COX-2 specific inhibitors used in cancer prevention; the multiple COX-2-independent targets of both NSAIDs and COX-2 inhibitors; and the limitations of some COX-2 inhibitors indicate that exploiting these (non-COX-2) molecular targets will likely yield effective new approaches for cancer chemoprevention.     

COX-2 selective inhibitors: analysis of the renal effects

COX-2 selective inhibitors provide analgesia and blunt inflammation while also sparing the gastrointestinal tract from classic NSAID toxicity. Therapeutic effects are thought to result from inhibition of the inflammatory COX-2 isoform. Organ sparing is considered the result of preservation of homeostatic COX-1 enzyme function. Similar roles of the COX isoforms in the kidney would reduce NSAID-associated nephrotoxicity. However, human kidney tissue expresses COX-2 enzyme, suggesting a role for this isoform in maintenance of physiological renal processes. Available clinical data on the renal effects of COX-2 selective inhibitors in humans also demonstrate nephrotoxic potential.     

The search for new COX-2 inhibitors: a review of 2002 – 2008 patents

Background: Two COX isoenzymes are known, COX-1 and COX-2, for which the main inhibitors are the NSAIDs. The common anti-inflammatory drugs (such as aspirin, ibuprofen and naproxen) all act by blocking the action of both the COX-1 and COX-2 enzymes. The COX-2 inhibitors represent a new class of drugs that do not affect COX-1 but selectively block COX-2. This selective action provides the benefits of reducing inflammation without irritating the stomach and cardiovascular effects. Objective: This review focuses on patents published in the field during 2002 – 2008, paying particular attention to promising COX-2 inhibitors. Conclusion: Structural analogues of the COX-2 inhibitors celecoxib and valdecoxib, and novel potential pyridazine, triazole, indole and thione derivatives emerge as promising leads for the treatment of inflammation, pain and other diseases.     

胃癌组织中PTEN与COX-2基因表达及临床意义

目的检测PTEN、COX-2在胃癌组织中的表达情况,探讨其与胃癌发生发展的关系及作用机理。方法用免疫组化S-P法检测胃癌组织与非胃癌黏膜中PTEN与COX-2表达情况。结果 80例胃癌组织中42例PTEN蛋白表达明显下降或缺失,且与胃癌TNM分期、淋巴结转移相关(P<0.05)。COX-2在胃癌组织中的阳性率为67.5%,显著高于非胃癌黏膜组织(P<0.05),并相关于胃癌淋巴结转移、TNM分期。结论抑癌基因PTEN与凋亡抑制基因COX-2可能存在相互作用,共同参与了胃癌的发展、转移及浸润。     

Back to the future: COX-2 inhibitors for chemoprevention and cancer therapy

For more than a century, inhibition of prostaglandin biosynthesis via inhibition of the fatty acid cyclooxygenase (COX) has been achieved by non-steroidal anti-inflammatory drugs (NSAIDs), which targets both COX-1 and COX-2 and as such could be responsible for causing gastrointestinal (GI) toxicity. COX-2 is an inducible enzyme produced by many cell types in response to multiple stimuli. Recently, COX-2 over-expression has been found in several types of human cancers such as colon, breast, prostate and pancreas and appears to control many cellular processes. Because of its role in carcinogenesis, apoptosis, and angiogenesis, it is an excellent target for developing new drugs with selectivity for prevention and/or treatment of human cancers. Development of selective COX-2 inhibitors has been successfully documented and as such showed less toxicity to GI tract as compared to conventional NSAIDs. However, the long term use of COX-2 selective inhibitors showed cardiovascular toxicity, and thus their utilization for cancer prevention and therapy is currently questionable, suggesting that further development of novel COX-2 selective agents are needed. Among many solid tumors, pancreatic cancer has the worst prognosis, and inflammation has been identified as a significant factor in the development of pancreatic malignancy. Several cytokines, reactive oxygen species (ROS) and mediators of inflammatory pathway such as activation of nuclear factor-kappaB (NF-kappaB) and COX-2 leads to an increase in cell proliferation, survival, and inhibition of pro-apoptotic pathway, ultimately resulting in tumor angiogenesis, invasion and metastasis. In this brief review, we summarize the role of COX-2 and discuss some of the experimental data linking inflammation with the development of pancreatic cancer. In addition, we provide further evidence regarding the state of our knowledge toward the development of novel COX-2 targeting agents for the prevention and/or treatment of human cancers especially pancreatic cancer.