Cyclooxygenase-2 Expression Is Related to the Epithelial-to-Mesenchymal Transition in Human Colon Cancers

Purpose

Down-regulation of E-cadherin is a hallmark of the epithelial-to-mesenchymal transition (EMT). EMT progression in cancer cells is associated with the loss of certain epithelial markers and the acquisition of a mesenchymal phenotype, as well as migratory activities. Cyclooxygenase-2 (COX-2) expression is associated with tumor invasion and metastasis in colon cancer. This study investigated the relationship between E-cadherin and COX-2 in colon cancer cells and human colon tumors.

Materials and Methods

Colon cancer cell lines and immunohistochemistry were used.

Results

E-cadherin expression was inversely related to the expressions of COX-2 and Snail in colon cancer cells. Ectopic expression of COX-2 or Snail reduced E-cadherin and induced a scattered, flattened phenotype with few intercellular contacts in colon cancer cells. Treatment of cancer cells with phorbol 12-myristate 13-acetate increased the expressions of COX-2 and Snail, decreased 15-hydroxyprostaglandin dehydrogenase expression, and increased the cells'' motility. In addition, exposure to prostaglandin E₂ increased Snail expression and cell motility, and decreased E-cadherin expression. Membranous E-cadherin expression was lower in adenomas and cancers than in the adjacent, non-neoplastic epithelium. In contrast, the expressions of Snail and COX-2 were higher in cancers than in normal tissues and adenomas. The expressions of COX-2 and Snail increased in areas with abnormal E-cadherin expression. Moreover, COX-2 expression was related to higher tumor stages and was significantly higher in nodal metastatic lesions than primary cancers.

Conclusion

This study suggests that COX-2 may have a role in tumor metastasis via EMT.     

Cyclooxygenase-2 is Upregulated in Copper-Deficient Rats

Copper deficiency inactivates Cu/Zn-SOD and promotes accumulation of reactive oxygen species. This process likely impairs nitric oxide (NO)-mediated relaxation as well as triggers vascular inflammation. The current study was designed to determine whether COX-2, a proinflammatory protein, expression and activity are upregulated in the oxidative environment associated with inadequate Cu. Weanling male Sprague Dawley rats were fed purified diets which were either Cu-adequate (Cu-A); Cu-marginal (Cu-M), Cu-deficient (Cu-D), or the Cu-D diet combined with the SOD mimetic Tempol (Cu-D/T; 1 mM in drinking water) for 4 weeks. COX-2 protein, PGE₂ (COX-2 metabolite) and isoprostanes (index of oxidative stress) were all higher in the Cu-D group vs Cu-A group, but no significant differences occurred between the Cu-M and Cu-A groups. Tempol protected against an attenuation of NO-mediated vasodilation in the Cu-D rats but did not prevent the elevation of PGE₂ or isoprostanes. Our data suggest a role for copper as a modulator of oxidative stress and inflammation independent of SOD activity or NO-derived oxidants.     

Clinical Trials of Cyclooxygenase-2 Inhibitors

Inflammation Research -     

Augmented Expression of Cyclooxygenase-2 in Human Atherosclerotic Lesions

Cyclooxygenase-1 (Cox-1) and Cox-2 convert arachidonic acid to prostaglandin H(2), the precursor of other prostaglandins and thromboxanes, eicosanoids important in vascular pathophysiology. However, knowledge of the expression of cyclooxygenases within atherosclerotic lesions is scant. This study tested the hypothesis that human atheroma and nonatherosclerotic arteries express the two Cox isoforms differentially. Cox-1 mRNA and protein localized on endothelial and medial smooth muscle cells of normal arteries (n = 5), whereas Cox-2 expression was not detectable. In contrast, atheromatous (n = 7) lesions contained both Cox-1 and Cox-2, colocalizing mainly with macrophages of the shoulder region and lipid core periphery, whereas smooth muscle cells showed lower levels, as demonstrated by immunohistochemical and in situ hybridization analysis. Furthermore, microvascular endothelium in plaques showed notable staining for both isoforms. In accord with immunohistochemical studies, Western blot analysis of protein extracts from normal arteries revealed constitutive Cox-1, but not Cox-2, expression. Extracts of atheromatous lesions, however, contained both Cox-1 and Cox-2 protein, detected as two immunoreactive proteins of approximately 70 and 50 kd. Macrophages expressed the short form of Cox-1/-2 constitutively after several days of in vitro culture, rather than the 70-kd protein. These results shed new light on the inflammatory pathways that operate in human atheroma. In particular, the expression of Cox-2 in atheromatous, but not in unaffected, arteries has therapeutic implications, given the advent of selective Cox-2 inhibitors.     

Cyclooxygenase-2 deficiency exacerbates bleomycin-induced lung dysfunction but not fibrosis

Cyclooxygenase (COX)-derived eicosanoids have been implicated in the pathogenesis of pulmonary fibrosis. Uncertainty regarding the influence of COX-2 on experimental pulmonary fibrosis prompted us to clarify the fibrotic and functional effects of intratracheal bleomycin administration in mice genetically deficient in COX-2. Further, the effects of airway-specific COX-1 overexpression on fibrotic and functional outcomes in wild-type and COX-2 knockout mice were assessed. Equivalent increases in airway cell influx, lung collagen content, and histopathologic evidence of fibrosis were observed in wild-type and COX-2 knockout mice 21 d after bleomycin treatment, suggesting that COX-2 deficiency did not alter the extent or severity of fibrosis in this model. However, bleomycin-induced alterations in respiratory mechanics were more severe in COX-2 knockout mice than in wild-type mice, as illustrated by a greater decrease in static compliance compared with genotype-matched, saline-treated control mice (26 +/- 3% versus 11 +/- 4% decreases for COX-2 knockout and wild-type mice, respectively; P < 0.05). The influence of COX-1 overexpression in airway Clara cells was also examined. Whereas the fibrotic effects of bleomycin were not altered in wild-type or COX-2 knockout mice overexpressing COX-1, the exaggerated lung function decrement in bleomycin-treated COX-2 knockout mice was prevented by COX-1 overexpression and coincided with decreased airway cysteinyl leukotriene levels. Collectively, these data suggest an important regulatory role for COX-2 in the maintenance of lung function in the setting of lung fibrosis, but not in the progression of the fibrotic process per se.     

Pulmonary fibrosis in Hermansky-Pudlak syndrome is not fully usual

A 55-year-old female patient with Hermansky-Pudlak syndrome (albinism, thrombopathia and ceroid accumulation) underwent a single lung transplantation for pulmonary fibrosis. Examination of explanted lung showed usual interstitial pneumonia pattern associated with two unusual lesions: presence of numerous macrophages containing ceroid pigments within fibrosis and characteristic foamy swelling of pneumocytes. This later lesion, which has only been recently described, seems related to the mechanism of the disease by defect of surfactant secretion. This lesion allows the histological individualization of pulmonary fibrosis associated with Hermansky-Pudlak syndrome from idiopathic usual interstitial pneumonia.     

Chronic Airways Obstruction in Pulmonary Sarcoidosis: Its Poor Response to Bronchodilators

Emphysema, chronic bronchitis, asthma, and cystic fibrosis are often cited as examples of chronic airways obstruction, while sarcoidosis is typically restrictive. Approximately 15 percent of sarcoidosis patients, however, have airways obstruction clinically characterized by wheezing with granulomatous involvement of airways. Since the majority have Stage IV disease by chest radiograph, their lungs usually have honey-combining with pulmonary fibrosis, adhesions, cavities, and mediastinal distortion.     

MAP2 Splicing is Altered in Huntington's Disease

Dendritic alteration of striatal medium spiny neurons is one of the earliest morphological abnormalities in Huntington's disease (HD). The main microtubule‐associated protein in dendrites is MAP2. The low‐molecular weight isoforms of MAP2 (LMW‐MAP2) are the juvenile forms resulting from exclusion of the sequence encoded by exons E7‐E9 and are downregulated after the early stages of neuronal development when E7‐E9 exon‐including high‐molecular weight isoforms (HMW‐MAP2) are favored. Splicing alteration has recently been proposed to contribute to HD in view of two pathogenic missplicing events resulting in a highly toxic N‐terminal version of mutant huntingtin and in a detrimental imbalance in MAP Tau isoforms with three or four tubulin‐binding repeats. Both splicing events are postulated targets of the SR splicing factor SRSF6 which has recently been reported to be dramatically altered in HD. SR proteins often regulate functionally related sets of genes and SRSF6 targets are enriched in genes involved in brain organogenesis including several actin‐and tubulin‐binding proteins. Here we hypothesized that MAP2 might be target of SRSF6 and altered in HD. By SRSF6 knockdown in neuroblastoma cells, we demonstrate that splicing of MAP2 E7‐E9 exons is affected by SRSF6. We then show a disbalance in LMW and HMW MAP2 mRNA isoforms in HD striatum in favor of the juvenile LMW forms together with a decrease in total MAP2 mRNA. This is accompanied by a global decrease in total MAP2 protein due to almost total disappearance of HMW‐MAP2 isoforms with preservation of LMW‐MAP2 isoforms. Accordingly, the predominant dendritic MAP2 staining in striatal neuropil of control subjects is absent in HD cases. In these, MAP2‐immunoreactivity is faint and restricted to neuronal cell bodies often showing a sharp boundary at the base of dendrites. Together, our results highlight the importance of splicing alteration in HD and suggest that MAP2 alteration contributes to dendritic atrophy.     

大鼠脊髓压迫损伤后COX-2基因和蛋白的表达

目的观察大鼠脊髓压迫损伤后COX-2mRNA和蛋白在脊髓组织内表达的时间特征,以及COX-2的空间分布特点。方法以压迫装置致脊髓损伤后,在伤后不同时间点(30min、3h、6h、24h、72h、1w)分别应用RT-PCR、Western blotting、免疫组化技术检测COX-2mRNA和蛋白表达和分布。结果RT-PCR和Western blotting显示,COX-2mRNA和蛋白伤后30min表达开始增加,于伤后6h达到峰值,伤后1w表达接近基础水平。免疫组化提示,COX-2蛋白在假手术组表达仅见于脊髓血管内皮细胞,伤后COX-2蛋白表达见于损伤区附近脊髓灰质内的神经元和血管内皮细胞,损伤中心部位COX-2免疫阳性细胞少见。结论脊髓压迫损伤早期可快速诱导COX-2基因的表达上调和蛋白的合成,伤后COX-2蛋白分布发生变化,主要位于脊髓神经元和血管内皮细胞。     

罗玲主任中医师辨治肺结节的经验

肺结节是单一孤立的肺部结节,边界清楚、影像不透明、直径≤30 mm、周围为含气肺组织所包绕,无肺不张、肺门增大或胸腔积液表现。其检出率高,病因未明,西医目前无有效治疗手段,以定期CT随访为主。如何改善患者症状,让肺结节缩小或消失已成为研究的重点。罗玲主任中医师在临床诊疗中,从痰瘀虚论治,采用扶正祛邪、豁痰化瘀散结法,获得满意疗效,本文对其经验进行总结。     

Survival of Patients with Glioblastoma Multiforme is not Influenced by Altered Expression of P16, P53, EGFR, MDM2 or Bcl-2 Genes

Deregulated expression of one or more growth control genes including p16, p53, EGF receptor (EGFR), MDM2 or Bcl-2 may contribute to the treatment resistance phenotype of GBM and generally poor patient survival. Clinically, GBM have been divided into two major groups defined by (1) histologic progression from a low grade tumor (“progressive” or “secondary” GBM) contrasted with (2) those which show initial clinical presentation without a prior history (“de novo” or “primary” GBM). Using molecular genetic analysis for p53 gene mutations together with immunophenotyping for overexpression of EGFR, up to four GBM variants can be distinguished, including the p53⁺/EGFR progressive or the p53^-/EGFR⁺de novo variant. We examined the survival of 80 adult patients diagnosed with astrocytic GBM stratified by age category (>40, 41–60 or 61–80) to determine whether alterations in any one given growth control gene or whether different genetic variants of GBM (progressive versus de novo) were associated with different survival outcomes. Survival testing using Kaplan-Meier plots for GBM patients with or without altered expression of p16, p53, EGFR, MDM2 or Bcl-2 showed no significant differences by age group or by gene expression indicating a lack of prognostic value for GBM. Also the clinical outcome among patients with GBM showed no significant differences within each age category for any GBM variant including the progressive and de novo GBM variants indicating similar biologic behavior despite different genotypes. Using a pair-wise comparison, one-third of the GBM with normal p16 expression showed accumulation of MDM2 protein and this association approached statistical significance (0.01 < P < 0.05) using the Bonferroni procedure. These GBM may represent a variant in which the p19^ARF/MDM2/p53 pathway may be deregulated rather than the p16/cyclin D-CDK4/Rb pathway.     

Cyclooxygenase-2 is involved in oxidative damage and alpha-synuclein accumulation in dopaminergic cells

Cyclooxygenase (COX) is the rate-limiting enzyme that catalyzes the formation of prostaglandins from arachidonic acid. The inducible isoform COX-2 is upregulated in the dopaminergic neurons of the substantia nigra of postmortem Parkinson's disease (PD) patients and in neurotoxin-induced Parkinsonism models. COX-2 has attracted significant attention as an important source of oxidative stress in dopaminergic neurons due to its potential to oxidize catechols including dopamine. However, the role of COX-2 in the pathogenesis of PD has not been fully evaluated. Here, we show that COX-2 induces dopamine oxidation, as evidenced by the findings that COX-2 can facilitate dopamine oxidation in a cell-free system and in COX-2-overexpressing SH-SY5Y cells, and that this can be completely abolished by the selective COX-2 inhibitor meloxicam. Increased COX-2 expression causes oxidative protein modification and α-synuclein accumulation in dopaminergic cells. These data suggest that an abnormal increase in COX-2 expression causes dopamine oxidation and contributes to the preferential vulnerability of dopaminergic cells as in PD.     

Cyclooxygenase-2 is involved in oxidative damage and alpha-synuclein accumulation in dopaminergic cells

Cyclooxygenase (COX) is the rate-limiting enzyme that catalyzes the formation of prostaglandins from arachidonic acid. The inducible isoform COX-2 is upregulated in the dopaminergic neurons of the substantia nigra of postmortem Parkinson's disease (PD) patients and in neurotoxin-induced Parkinsonism models. COX-2 has attracted significant attention as an important source of oxidative stress in dopaminergic neurons due to its potential to oxidize catechols including dopamine. However, the role of COX-2 in the pathogenesis of PD has not been fully evaluated. Here, we show that COX-2 induces dopamine oxidation, as evidenced by the findings that COX-2 can facilitate dopamine oxidation in a cell-free system and in COX-2-overexpressing SH-SY5Y cells, and that this can be completely abolished by the selective COX-2 inhibitor meloxicam. Increased COX-2 expression causes oxidative protein modification and alpha-synuclein accumulation in dopaminergic cells. These data suggest that an abnormal increase in COX-2 expression causes dopamine oxidation and contributes to the preferential vulnerability of dopaminergic cells as in PD.     

Masticatory HyperMuscularity is not Related to Reduced Cranial Volume in Myostatin‐Knockout Mice

It has been suggested recently that masticatory muscle size reduction in humans resulted in greater encephalization through decreased compressive forces on the cranial vault. Following this logic, if masticatory muscle size were increased, then a reduction in brain growth should also occur. This study was designed to test this hypothesis using a myostatin (GDF‐8) knockout mouse model. Myostatin is a negative regulator of skeletal muscle growth, and individuals lacking this gene show significant hypermuscularity. Sixty‐two [32 wild‐type (WT) and 30 GDF‐8 ‐/‐ knockout], 1, 28, 56, and 180‐day‐old CD‐1 mice were used. Body and masseter muscle weights were collected following dissection and standardized lateral and dorsoventral cephalographs were obtained. Cephalometric landmarks were identified on the radiographs and cranial volume was calculated. Mean differences were assessed using a two‐way ANOVA. KO mice had significantly greater body and masseter weights beginning at 28 days compared with WT controls. No significant differences in cranial volumes were noted between KO and WT. Muscle weight was not significantly correlated with cranial volume in 1, 28, or 180‐day‐old mice. Muscle weights exhibited a positive correlation with cranial volume at 56 days. Results demonstrate that masticatory hypermuscularity is not associated with reduced cranial volume. In contrast, there is abundant data demonstrating the opposite, brain growth determines cranial vault growth and masticatory apparatus only affects ectocranial morphology. The results presented here do not support the hypothesis that a reduction in masticatory musculature relaxed compressive forces on the cranial vault allowing for greater encephalization. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Cyclooxygenase-2 is expressed frequently and early in Barrett's oesophagus and associated adenocarcinoma

AIMS: To establish the prevalence of cyclooxygenase-2 (COX-2) expression in a large series of resected Barrett's adenocarcinoma and associated preneoplastic lesions and to correlate this expression with clinicopathological data and prognosis. METHODS: COX-2 expression was assessed by immunohistochemistry in resected surgical specimens of 66 Barrett's adenocarcinomas and 32 cases of Barrett's mucosa (with dysplasia in 17 cases). RESULTS: Epithelial expression of COX-2 protein was increased in Barrett's mucosa compared with normal oesophagus. Epithelial expression of COX-2 was found in 91% of Barrett's specialized mucosa negative for dysplasia, 94% of Barrett's mucosa with dysplasia, and 97% of Barrett's adenocarcinoma. COX-2 expression was significantly higher in the well-differentiated adenocarcinomas when compared with the poorly differentiated tumours. There was no significant correlation between COX-2 expression and the other pathological features of the tumours. Survival analysis showed no significant prognostic value for COX-2. CONCLUSION: Our results confirm up-regulation of COX-2 in Barrett's oesophagus-metaplastic and dysplastic-and in Barrett's adenocarcinoma. Increased COX-2 expression did not differ during the progression from Barrett's oesophagus negative for dysplasia to Barrett's adenocarcinoma and is related to adenocarcinoma whose histology is well differentiated. This suggests that enhanced expression of COX-2 may occur early during Barrett's-associated neoplastic transformation.     

Cyclooxygenase-2 expression in oligodendrocytes increases sensitivity to excitotoxic death

Background  

We previously found that cyclooxygenase 2 (COX-2) was expressed in dying oligodendrocytes at the onset of demyelination in the Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD) model of multiple sclerosis (MS) (Carlson et al. J.Neuroimmunology 2006, 149:40). This suggests that COX-2 may contribute to death of oligodendrocytes.