Selective inhibition of cyclooxygenase-2 suppresses the growth of pancreatic cancer cells in vitro and in vivo

Cyclooxygenase-2 (COX-2), a prostaglandin synthetase, is involved in development of certain tumors. We therefore analyzed COX-2 expression in pancreatic cancer tissues (53 samples) and Panc-1 human pancreatic cancer cells by immunohistochemistry, RT-PCR and western-blotting analyses. Also, immunohistochemistry of proliferating cell nuclear antigen (PCNA) was performed. We found expression of COX-2 was dramatically upregulated in 36 of 53 cases (67.9%) and the expression of COX-2 was associated with the diameter (> 3 cm) of the tumors (p < 0.05), but not with the age, gender, tumor location, differentiation, lymph-node metastases and TNM stage. The positivity rate of PCNA expression in the pancreatic cancer cells of the COX-2 positive group (32.88 +/- 13.26%) was significantly higher than that in the COX-2 negative group (24.56 +/- 11.51%) (p < 0.05). Then we investigated the effect of selective inhibitors of COX-2 (NS398 and celecoxib) on proliferation of Panc-1 cells by 3-(4,5 dimethyl-2-thiazolyl)-2.5-diphenyl-2H-tetrazolium bromide (MTT) assay. Either NS398 or celecoxib suppressed proliferation of Panc-1 cells dose-dependently in vitro. Furthermore, Panc-1 cells were implanted into nude mice, and celecoxib was administrated orally with feed. The volume of the tumor xenografted into nude mice was decreased by 51.6% in the celecoxib group (p < 0.01). In conclusion, the increased expression of COX-2 may be responsible for rapid proliferation of pancreatic cancer, and specific inhibition of COX-2 suppresses proliferation of Panc-1 cells in vitro and in nude mice. The selective inhibitor of COX-2 may be an effectual agent for pancreatic cancer chemoprevention.     

Host prostaglandin E(2)-EP3 signaling regulates tumor-associated angiogenesis and tumor growth

Nonsteroidal antiinflammatories are known to suppress incidence and progression of malignancies including colorectal cancers. However, the precise mechanism of this action remains unknown. Using prostaglandin (PG) receptor knockout mice, we have evaluated a role of PGs in tumor-associated angiogenesis and tumor growth, and identified PG receptors involved. Sarcoma-180 cells implanted in wild-type (WT) mice formed a tumor with extensive angiogenesis, which was greatly suppressed by specific inhibitors for cyclooxygenase (COX)-2 but not for COX-1. Angiogenesis in sponge implantation model, which can mimic tumor-stromal angiogenesis, was markedly suppressed in mice lacking EP3 (EP3(-/-)) with reduced expression of vascular endothelial growth factor (VEGF) around the sponge implants. Further, implanted tumor growth (sarcoma-180, Lewis lung carcinoma) was markedly suppressed in EP3(-/-), in which tumor-associated angiogenesis was also reduced. Immunohistochemical analysis revealed that major VEGF-expressing cells in the stroma were CD3/Mac-1 double-negative fibroblasts, and that VEGF-expression in the stroma was markedly reduced in EP3(-/-), compared with WT. Application of an EP3 receptor antagonist inhibited tumor growth and angiogenesis in WT, but not in EP3(-/-). These results demonstrate significance of host stromal PGE(2)-EP3 receptor signaling in tumor development and angiogenesis. An EP3 receptor antagonist may be a candidate of chemopreventive agents effective for malignant tumors.     

环氧化酶-2在垂体瘤中的表达及其与血管形成的关系

目的:探讨环氧化酶-2在垂体瘤中的表达,探讨环氧化酶-2与血管形成的关系.方法:采用免疫组化方法检测84例垂体瘤组织和4例正常垂体组织中环氧化酶-2的表达,计量组织内微血管密度,并联系血管内皮生长因子的表达情况,分析其相关性.结果:环氧化酶-2和血管内皮生长因子表达与微血管密度均相关;环氧化酶-2在垂体瘤组织中的表达高于正常垂体组织(P<0.05),环氧化酶-2在无功能腺瘤的表达高于功能性腺瘤(P<0.05).结论:环氧化酶-2与垂体瘤血管生成有关.选择性环氧化酶-2抑制剂有望为垂体瘤的预防和治疗提供新途径.     

胰腺β细胞分化的信号通路调控

细胞替代治疗给糖尿病的根治带来了新希望.文章综述了近年来干细胞向胰岛细胞定向分化的分子研究进展,综合分析细胞信号通路在β细胞分化发育过程中所发挥的作用.其中Wnts信号是通过阻止β-Catenin分解从而激活Tcf/Lef介导的转录,促进干细胞向内胚层分化;Notch及其配体Delta或Jagged也对干细胞分化有重要影响,当Notch活性被抑制时,干细胞进入分化程序,发育为功能细胞;Hedgehog信号转导对许多发育过程是必须的,其主要以浓度依赖方式控制细胞的增殖、分化和组织的形成,这些信号通路按一定的顺序上调或下调,以启动PDX1等β细胞分化相关的转录因子的表达,从而调控着β细胞的分化发育.因此深入分析并通过调控这些信号通路为以后进行相关细胞定向分化,获取发育成熟、功能完整的β细胞,进行细胞治疗糖尿病奠定基础.     

环氧化酶2与血管生成性疾病及其对血管生成的调控

目的:环氧化酶2与肿瘤等血管生成性疾病关系密切,其抑制剂能抑制血管生成。本文就环氧化酶2及其抑制剂与血管生成性疾病的研究进展作一综述。资料来源:应用计算机检索PUBMED1999-05/2005-12期间的相关文章,检索词为“cyclooxygenase-2,COX-2”,并限定文章语言种类为English。同时计算机检索万方数据库1977-12/2005-12期间的相关文章,检索词为“环氧化酶,血管生成”,并限定文章语言种类为中文。资料选择:对资料进行初审,并查看每篇文献后的引文。纳入标准:文章所述内容应与环氧化酶2及其抑制剂与血管生成性疾病研究相关。排除标准:重复研究或Meta分析类文章。资料提炼:共收集到423篇相关文献,16篇文献符合纳入标准,排除的407篇文献为内容陈旧或重复。符合纳入标准的16篇文献中,16篇涉及环氧合酶系统,8篇涉及环氧化酶2与血管生成性疾病研究,8篇涉及环氧化酶2调节血管生成的机制与信号通路,2篇涉及对环氧化酶2的展望。资料综合:环氧化酶2是炎症调节因子,与炎症、溃疡、脑卒中、神经变性疾病等关系密切。最近研究表明环氧化酶2是一个调控血管内皮生长因子表达的新基因,其下游产物PGI2与内皮收缩、血小板聚集有关,另一产物前列腺素E2是调控血管生成的开关。环氧化酶2抑制剂出现的心血管副作用更加表明重新评价环氧化酶2的重要性。结论:环氧化酶2及其抑制剂不仅与炎症性疾病有关,还与血管生成性疾病关系密切,靶向介导环氧化酶2下游通路的治疗策略将更有前途。     

环氧化酶2与血管生成性疾病及其对血管生成的调控

目的：环氧化酶2与肿瘤等血管生成性疾病关系密切，其抑制剂能抑制血管生成。本文就环氧化酶2及其抑制剂与血管生成性疾病的研究进展作一综述。资料来源：应用计算机检索PUBMED 1999-05／2005-12期间的相关文章，检索词为“cyclooxygenase-2，COX-2”，并限定文章语言种类为English。同时计算机检索万方数据库1977—12／2005—12期间的相关文章，检索词为“环氧化酶，血管生成”，并限定文章语言种类为中文。资料选择：对资料进行初审，并查看每篇文献后的引文。纳入标准：文章所述内容应与环氧化酶2及其抑制剂与血管生成性疾病研究相关。排除标准：重复研究或Meta分析类文章。资料提炼：共收集到423篇相关文献，16篇文献符合纳入标准，排除的407篇文献为内容陈旧或重复。符合纳入标准的16篇文献中，16篇涉及环氧合酶系统，8篇涉及环氧化酶2与血管生成性疾病研究，8篇涉及环氧化酶2调节血管生成的机制与信号通路，2篇涉及对环氧化酶2的展望。资料综合：环氧化酶2是炎症调节因子，与炎症、溃疡、脑卒中、神经变性疾病等关系密切。最近研究表明环氧化酶2是一个调控血管内皮生长因子表达的新基因，其下游产物PGI2与内皮收缩、血小板聚集有关，另一产物前列腺素E2是调控血管生成的开关。环氧化酶2抑制剂出现的心血管副作用更加表明重新评价环氧化酶2的重要性。结论：环氧化酶2及其抑制剂不仅与炎症性疾病有关，还与血管生成性疾病关系密切，靶向介导环氧化酶2下游通路的治疗策略将更有前途。     

Inhibition of STAT3 signaling pathway by nitidine chloride suppressed the angiogenesis and growth of human gastric cancer

STAT3 has been strongly implicated in human malignancies, and constitutive activation of STAT3 serves a crucial role in cell survival, angiogenesis, immune evasion, and inflammation. In this study, we showed that nitidine chloride, a natural phytochemical alkaloid derived from Zanthoxylum nitidum (Roxb) DC, exerts potent anticancer activity through STAT3 signaling cascade. Nitidine chloride dose dependently suppressed VEGF-induced endothelial cell proliferation, migration, and tubular structure formation in vitro and dramatically reduced VEGF-triggered neovascularization in mouse cornea and Matrigel plugs in vivo. This angiogenesis inhibition mediated by nitidine chloride was well interpreted by the suppression of Janus kinase 2/STAT3 signaling and STAT3 DNA-binding activity in endothelial cells. Furthermore, nitidine chloride suppressed the constitutively activated STAT3 protein, its DNA-binding activity, and the expression of STAT3-dependent target genes, including cyclin D1, Bcl-xL, and VEGF in human gastric cancer cells. Consistent with the earlier findings, nitidine chloride inhibited gastric tumor cell growth and induced tumor cell apoptosis in vitro and effectively suppressed the volume, weight, and microvessel density of human SGC-7901 gastric solid tumors (n = 8) at a dosage of 7 mg/kg/d (intraperitoneal injection). Immunohistochemistry and Western blot analysis further revealed that the expression of STAT3, CD31, and VEGF protein in xenografts was remarkably decreased by the alkaloid. Taken together, we propose that nitidine chloride is a promising anticancer drug candidate as a potent STAT3 signaling inhibitor.     

环氧合酶-2在卵巢癌组织中的表达

目的:探讨环氧合酶-2(cyclooxygenase-2,COX-2)在卵巢癌组织中的表达及意义。方法:应用免疫组化和RT-PCR技术检测正常卵巢和卵巢癌组织中COX-2的表达情况。结果:检测的38例卵巢癌组织COX-2蛋白表达阳性23例,阳性表达率61%,33例表达COX-2mRNA,阳性表达率为87%;20例正常卵巢组织COX-2蛋白与COX-2mRNA均呈阴性表达。结论:COX-2在卵巢癌组织高表达,并在其发生发展中起重要作用。     

Connective tissue growth factor-specific antibody attenuates tumor growth, metastasis, and angiogenesis in an orthotopic mouse model of pancreatic cancer

Connective tissue growth factor (CTGF) plays an important role in fibrosis by modulating cell migration and cell growth but may also modify tumor growth and metastasis. Because CTGF is overexpressed in pancreatic ductal adenocarcinoma, we investigated the in vitro effects of CTGF on the proliferation and invasiveness of PANC-1 pancreatic cancer cells and examined the consequences of its in vivo inhibition on the growth and metastasis of these cells using a fully human CTGF-specific monoclonal antibody (FG-3019) in an orthotopic nude mouse model. Although PANC-1 cells expressed relatively high levels of endogenous CTGF mRNA, the addition of CTGF to conditioned medium increased the proliferation and invasiveness of PANC-1 cells. Moreover, transforming growth factor-beta1 caused a further increase in CTGF expression in these cells. In vivo, the twice weekly i.p. administration of FG-3019 decreased tumor growth and metastasis and attenuated tumor angiogenesis and cancer cell proliferation. FG-3019 did not enhance apoptosis and did not attenuate the inhibitory effects of gemcitabine on tumor growth and metastasis. These findings suggest that CTGF may contribute to aberrant autocrine and paracrine pathways that promote pancreatic cancer cell growth, invasion, metastasis, and angiogenesis. Therefore, blocking CTGF actions with FG-3019 may represent a novel therapeutic approach in pancreatic ductal adenocarcinoma.     

Lipoxygenase inhibitors attenuate growth of human pancreatic cancer xenografts and induce apoptosis through the mitochondrial pathway

Several studies have suggested that high dietary fat intake, particularly essential fatty acids, is associated with pancreatic cancer development and growth. Our previous studies have demonstrated that blockade of either the 5-lipoxygenase (LOX) or 12-LOX pathway of arachidonic acid metabolism inhibited pancreatic cancer cell proliferation and induced apoptosis. This study investigated the underlying mechanisms for LOX inhibitor-induced apoptosis and the potential of LOX inhibitors as antipancreatic cancer agents using the athymic mice xenograft model. Apoptosis of pancreatic cancer cells induced by LOX inhibitors (including the nonselective LOX inhibitor nordihydroguaiaretic acid, the 5-LOX inhibitor Rev-5901, and the 12-LOX inhibitor baicalein) was confirmed by growth inhibition, annexin V binding, and terminal deoxynucleotidyl transferase-mediated nick end labeling assay in MiaPaCa-2 and AsPC-1 human pancreatic cancer cells. Expression of the antiapoptotic proteins Bcl-2 and Mcl-1 was significantly decreased after LOX inhibitor treatment while that of the proapoptotic protein bax was increased. LOX inhibitors also markedly induced the release of cytochrome c from mitochondria into the cytosol. Caspase-9, caspase-7, and caspase-3 but not caspase-8 were activated after treatment, concomitant with cleavage of the capase-3 substrate poly(ADP-ribose) polymerase. In vivo studies in the athymic mice xenograft model also confirmed the growth inhibitory effect and induction of apoptosis by these LOX inhibitors in pancreatic cancer. In conclusion, LOX inhibitors block pancreatic cancer cell proliferation and induce apoptosis through the mitochondrial pathway both in vivo and in vitro. LOX inhibitors are likely to be valuable for the treatment of human pancreatic cancer.     

TGF-beta signaling pathway in pancreatic cancer cells

TGF-beta is a multifunctional cytokine which regulates cell growth, extracellular matrix deposition, cell differentiation, and immunosuppression etc. The signal is mainly mediated through Smad pathway to inhibit epithelial cell growth. In 50% of pancreatic cancer, Smad4/DPC4 gene is deleted or mutated, which might cause pancreatic carcinogenesis and be associated with highly invasive and metastatic character of the disease. On the other hand, TGF-beta signal itself has recently been shown to act in favor of cancer cells, especially in the late phase of tumor progression. In Smad4-inactivated pancreatic cancer cells, TGF-beta signal regulates a number of genes involved in tumor suppression and progression. The regulated genes and signaling pathways of TGF-beta signal should be investigated to obtain an effective therapeutic target molecule for pancreatic cancer.     

三叶因子2和环氧合酶-2在胃癌组织中的表达

目的:研究三叶因子2(TFF2)和环氧合酶-2(COX-2)在正常胃黏膜组织、癌旁组织和胃癌组织中的表达情况,探讨TFF2表达与胃癌发生的关系。方法:采用SP免疫组化方法检测30例正常胃黏膜组织、50例癌旁组织和50例胃癌组织中TFF2和COX-2的表达。结果:正常胃黏膜组织→癌旁组织→胃癌组织中,TFF2表达呈逐渐减弱趋势(165.80±16.42,184.44±19.02和206.79±17.62,P<0.01),而COX-2的表达呈逐渐上升趋势(217.50±12.60,203.08±17.68和193.50±16.160,P<0.01),TFF2的表达强度与COX-2呈负相关(r=-0.761,P<0.01)。结论:COX-2的表达增加抑制TFF2的表达,细胞增殖与凋亡失衡,最终导致胃癌的发生。     

环氧合酶-2对非小细胞肺癌血管生成及预后的影响

目的研究环氧合酶-2（COX-2）在非小细胞肺癌（NSCLC）中的表达及其对血管生成和预后的影响。方法随访手术切除且临床资料完整的48例非小细胞肺癌患者,采用免疫组织化学技术检测活检标本中COX-2、血管内皮生长因子（VEGF）表达和微血管密度（MVD）。通过生存曲线法比较阳性组和阴性组患者的预后情况。结果COX-2在非小细胞肺癌组织中阳性表达率为66.7%（32/48）,与VEGF表达68.8%（33/48）呈显著正相关（r=0.687,P〈0.01）,COX-2与淋巴结转移、组织分型、肺癌分期及较短生存期具有相关性。MVD随COX-2、VEGF表达增强而增高。结论COX-2的高表达可使VEGF表达上调,促进肿瘤血管形成,增加微血管密度。COX-2在非小细胞肺癌组织中高表达与肿瘤血管生成密切相关,可作为预测非小细胞肺癌预后的一种有用指标。     

Inhibition of human colon cancer cell growth by selective inhibition of cyclooxygenase-2.

A considerable amount of evidence collected from several different experimental systems indicates that cyclooxygenase-2 (COX-2) may play a role in colorectal tumorigenesis. Large epidemiologic studies have shown a 40-50% reduction in mortality from colorectal cancer in persons taking aspirin or other nonsteroidal antiinflammatory drugs on a regular basis. One property shared by all of these drugs is their ability to inhibit COX, a key enzyme in the conversion of arachidonic acid to prostaglandins. Two isoforms of COX have been characterized, COX-1 and COX-2. COX-2 is expressed at high levels in intestinal tumors in humans and rodents. In this study, we selected two transformed human colon cancer cell lines for studies on the role of COX-2 in intestinal tumorigenesis. We evaluated HCA-7 cells which express high levels of COX-2 protein constitutively and HCT-116 cells which lack COX-2 protein. Treatment of nude mice implanted with HCA-7 cells with a selective COX-2 inhibitor (SC-58125), reduced tumor formation by 85-90%. SC-58125 also inhibited colony formation of cultured HCA-7 cells. Conversely, SC-58125 had no effect on HCT-116 implants in nude mice or colony formation in culture. Here we provide evidence that there may be a direct link between inhibition of intestinal cancer growth and selective inhibition of the COX-2 pathway.     

Redox regulation of pancreatic cancer cell growth: role of glutathione peroxidase in the suppression of the malignant phenotype

Pancreatic cancer has low levels of antioxidant enzymes including manganese superoxide dismutase (MnSOD), which converts superoxide radical (O(2)(*-)) into hydrogen peroxide (H(2)O(2)), and glutathione peroxidase (GPx), which converts H(2)O(2) into water. Recent studies have demonstrated that overexpression of MnSOD has a tumor-suppressive effect in pancreatic cancer. However, GPx overexpression has been shown to reverse the tumor cell growth inhibition caused by MnSOD overexpression in other types of cancer. Our aims were to determine if overexpression of GPx alters in vitro pancreatic cancer cell behavior and if delivering the GPx gene directly to tumor xenografts alters growth and survival. In vitro, AdGPx slowed tumor growth by 39% and AdMnSOD slowed tumor growth by 35%. AdGPx also decreased plating efficiency and growth in soft agar. The combination of AdGPx and AdMnSOD had the greatest effect on tumor cell growth suppression with a 71% reduction in cell growth compared to controls. In vivo, either AdGPx or AdMnSOD alone slowed tumor growth by 51% and 54%, respectively, while the combination of AdGPx and AdMnSOD potentiated tumor growth suppression by 81% of controls and increased animal survival. GPx may be a tumor suppressor gene in pancreatic cancer. Delivery of the GPx gene alone or in combination with the MnSOD gene may prove beneficial for treatment of pancreatic cancer.     

Epidermal growth factor-like domain 7 promotes cell invasion and angiogenesis in pancreatic carcinoma

Epidermal growth factor-like domain 7 (EGFL7), also known as vascular endothelial stain, was firstly identified as a modulator of smooth muscle cell migration. Though the expression of EGFL7 was reported to be up-regulated during tumorigenesis, the clinical and biological functions of EGFL7 in pancreatic carcinoma (PC) were still not fully elucidated. In this study, we found that the serum EGFL7 level in PC tissues was statistically higher than that in normal subjects (p < 0.001), and its level in non-resectable patients was also higher than that in resectable ones (p = 0.013). Among these resectable PC patients, the postoperative EGFL7 expression was significantly down-regulated when tumors were resected (p = 0.018). Using the immunohistochemistry method, our results demonstrated that the positive expression of EGFL7 was significantly associated with the TNM stage (p = 0.024), lymph node metastasis (p = 0.003) and local invasion (p = 0.022), and the EGFL7 expression closely correlated to the micro-vessel density (MVD) in PC tissues by Spearman analysis (r = 0.941, p = 0.000). In vitro, EGFL7 was silenced by the small interference RNA in PC cells, and our data indicated that down-regulation of EGFL7 did not influence the cycle progression, proliferation, colony formation and apoptosis of PC cells (p > 0.05), whereas inhibition of EGFL7 expression could decrease PaCa-2 cell invasion (p < 0.05). More interestingly, by tubular formation, Chick embryo chorioallantoic membrane (CAM) and ELISA assays, our results revealed that silencing EGFL7 expression represented a strong inhibiting effect on tubular formation of micro-vessels through down-regulating the protein levels of VEGF and Ang-2 (p < 0.05). Our results raised the possibility of using EGFL7 as a potential prognostic biomarker and therapy target of PC, and down-regulation of EGFL7 might be considered to be a potentially important molecular treatment strategy for patients with PC.