Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A workshop, "Chemopreventive properties of nonsteroidal anti-inflammatory drugs (NSAIDs): Role of COX-dependent and -independent mechanisms," sponsored by the Chemical and Physical Carcinogenesis Branch, Division of Cancer Biology of the National Cancer Institute, was held in Rockville, Maryland, on January 8, 2001. The workshop was composed of two parts: oral presentations by a series of speakers, and a group discussion of preselected topics.
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PMID:National Cancer Institute workshop on chemopreventive properties of nonsteroidal anti-inflammatory drugs: role of COX-dependent and -independent mechanisms. 1189 63

Understanding the mechanisms underlying carcinogenesis provides insights that are necessary for the development of therapeutic strategies to prevent cancer. Chemoprevention--the use of drugs or natural substances to inhibit carcinogenesis - is an important and rapidly evolving aspect of cancer research. We discuss evidence that cyclooxygenase 2 (COX 2), an inducible form of the enzyme, is a potential pharmacological target to prevent cancer. Key data implicating a causal relation between increased activity of COX 2 and carcinogenesis and possible mechanisms of action of COX 2 in this context are covered. Importantly, selective COX 2 inhibitors appear to be safe enough in human beings to allow large-scale clinical testing in healthy people. Several chemoprevention trials using selective COX 2 inhibitors are underway.
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PMID:Cyclo-oxygenase 2: a pharmacological target for the prevention of cancer. 1190 9

Cyclooxygenase-2 (COX-2), the inducible cyclooxygenase isozyme involved in the conversion of arachidonic acid (AA) to biologically active prostanoids, has become the subject of intense interest during the last few years. The recent surge of interest stems from seminal studies that correlated elevated expression of COX-2 with tumor induction and progression, and epidemiological studies that correlated reduced risk of developing certain types of cancers with chronic use of non-steroidal anti-inflammatory agents (NSAIDs). Although these observations were first reported with colorectal cancer (CRC), similar findings have subsequently been made with other types of cancers. A wide spectrum of studies continue to be undertaken in both laboratory and clinical settings to elucidate the mechanisms underlying these anti-tumor effects of COX-2 for potential translation into cancer chemoprevention and therapy. The aim of this article is to present a review of COX genes, the prostaglandin-cyclooxygenase relationship, the role of COX-2 in carcinogenesis and the rationale for targeting COX-2 with NSAIDs for cancer chemoprevention. Special emphasis is given to the role of COX-2 expression in the genesis and progression of colorectal neoplasia, and its correlation with other pathological characteristics of CRC. Preliminary observations on COX-2 expression in inflammatory bowel disease (IBD)-related colorectal neoplasia are also presented.
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PMID:COX-2, NSAIDs and human neoplasia. Part I: Colorectal neoplasms. 1249 94

The cyclooxygenase-2 (COX-2) inhibitor celecoxib and the ornithine decarboxylase (ODC) inhibitor difluoromethylornithine (DFMO) were each previously shown to prevent skin tumor development when administered throughout the course of UV irradiation. This raised the question of whether maintenance or continued growth of existing tumors required prostaglandins, the product of COX, or polyamines, the product of ODC. To address this question, SKH hairless mice were irradiated 3 times/week with 90 mJ/cm(2); this dose was increased 10% weekly to a maximum of 175 mJ/cm(2). UV was stopped at 27 weeks, at which time there were an average of 5 papillomas/mouse. The mice were then placed in one of four treatment groups: group 1, no treatment; group 2, 0.4% DFMO in the drinking water; group 3, 500 p.p.m. celecoxib in the diet (AIN76); group 4, both DFMO and celecoxib. The control group continued to produce new tumors in a nearly linear manner such that by week 31 the tumor number had nearly doubled, i.e. approximately 10 tumors/mouse. The group receiving DFMO showed significant tumor regression, losing an average of 1 tumor/mouse/week, such that 50% of the tumors remained at week 31. The celecoxib group showed a 25% reduction in tumor number. The group receiving the combination of celecoxib and DFMO showed the greatest regression, with an 89% reduction in tumor number compared with the control group. There was also a corresponding reduction in the size of the tumors. To determine whether tumor regression was permanent or required continued treatment, all treatments were stopped at 31 weeks. Over the next 4 weeks, tumors reappeared at the same rate in all treatment groups. It is concluded that the combination of celecoxib and DFMO are potent therapeutic agents for skin cancer, although the benefits are lost with the cessation of treatment.
Carcinogenesis 2003 May
PMID:Celecoxib and difluoromethylornithine in combination have strong therapeutic activity against UV-induced skin tumors in mice. 1277 Oct 40

It is clear that COX-2 plays an important role in tumor and endothelial cell biology. Increased expression of COX-2 occurs in multiple cells within the tumor microenvironment that can impact on angiogenesis. COX-2 appears to: (a) play a key role in the release and activity of proangiogenic proteins; (b) result in the production of eicosanoid products TXA2, PGI2, PGE2 that directly stimulate endothelial cell migration and angiogenesis in vivo, and (c) result in enhanced tumor cell, and possibly, vascular endothelial cell survival by upregulation of the antiapoptotic proteins Bcl-2 and/or activation of PI3K-Akt. Selective pharmacologic inhibition of COX-2 represents a viable therapeutic option for the treatment of malignancies. Agents that selectively inhibit COX-2 appear to be safe, and well tolerated suggesting that chronic treatment for angiogenesis inhibition is feasible [107-110]. Because these agents inhibit angiogenesis, they should have at least additive benefit in combination with standard chemotherapy [111] and radiation therapy [24, 112]. In preclinical models, a selective inhibitor of COX-2 was shown to potentiate the beneficial antitumor effects of ionizing radiation with no increase in normal tissue cytotoxicity [113-115]. More recently, metronomic dosing regimens of standard chemotherapeutic agents without extended rest periods were shown to target the microvasculature in experimental animal models and result in significant antitumor activity [116-118]. This antiangiogenic chemotherapy regimen could be enhanced by the concurrent administration of an angiogenesis inhibitor [116-119]. Trials that will evaluate continuous low dose cyclophosphamide in combination with celecoxib are underway in patients with metastatic renal cancer, and non-Hodgkin's lymphoma [120]. Given the safety and tolerability of the selective COX-2 inhibitors, and the potent antiangiogenic properties of these agents, the combination of antiangiogenic chemotherapy with a COX-2 inhibitor warrants clinical evaluation [118, 121, 122]. The effects of selective COX-2 inhibitors on angiogenesis may also be due, in part, to COX-independent mechanisms [123-125]. Several reports have confirmed COX-independent effects of celecoxib, at relatively high concentrations (50 microM), where apoptosis is stimulated in cells that lack both COX-1 and COX-2 [126]. More recently, Song et al. [127] described structural modifications to celecoxib that revealed no association between the COX-2 inhibitory and proapoptotic activities of celecoxib [125]. Some of the COX-independent mechanisms for NSAIDs and selective COX-2 inhibitors include activation of protein kinase G, inhibition of NF-kappa B activation, downregulation of the antiapoptotic protein Bcl-XL, inhibition of PPAR delta, and activation of PPAR gamma. One or more of these COX-independent effects could contribute to the antiangiogenic properties of NSAIDs and selective COX-2 inhibitors. In order to take advantage of both the COX-dependent and COX-independent benefits of NSAIDs and selective COX-2 inhibitors, will require evaluation of these agents in neoplastic disease settings, using cancer-specific biomarkers. In conclusion, the contribution of COX-2 at multiple points in the angiogenic cascade makes it an ideal target for pharmacologic inhibition. The reported success of selective COX-2 inhibitors in cancer prevention could be related to angiogenesis inhibition [109]. As premalignant lesions progress towards malignancy, there is a switch to the angiogenic phenotype that is subsequently followed by rapid tumor growth [128, 129]. Intervention with angiogenesis inhibitors at this early stage of carcinogenesis has been shown to attenuate tumor growth in transgenic mouse models [130, 131]. The continued dependence on angiogenesis for later stages of tumorigenesis suggests that COX-2 inhibitors also will have clinical utility in the management of advanced cancers.
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PMID:Therapeutic potential of selective cyclooxygenase-2 inhibitors in the management of tumor angiogenesis. 1279 55

The purpose of this study was to determine whether cyclooxygenase-2 (COX-2) was overexpressed in head and neck squamous cell carcinoma (HNSCC) in relation to vascular endothelial growth factor (VEGF) expression and lymph node metastasis. COX-2 has an important role in the promotion of carcinogenesis, tumor invasiveness and angiogenesis. VEGF is a proangiogenic factor that is up-regulated in various tumors. VEGF has been shown to interact with COX-derived prostaglandins in angiogenesis. To better understand the roles of these genes in HNSCC, we evaluated the immunohistochemical expression pattern of COX-2 and VEGF in relationship with histologic differentiation, clinical stage, and nodal status in 146 HNSCC. The COX-2/VEGF double immunofluorescein staining was evaluated with confocal scanning laser microscope. A positive expression was seen in 96% (140/146: 98 strong positive, 42 weakly positive) for COX-2 and in 98% (143/146: 63 strong positive, 80 weakly positive) for VEGF in HNSCC. A correlation was present in the positive expression of COX-2 with histologic differentiation, clinical stage, and nodal status. VEGF expression was also correlated with nodal status. A significant relation was observed between COX-2 and VEGF expressions. The simultaneous expression of COX-2 and VEGF was statistically significant (p<0.05). These results indicate that elevated COX-2 or VEGF expression is more common in HNSCC with poor prognostic characteristics. The present findings support the efforts to initiate clinical trials on the efficacy of COX-2 inhibitors in adjuvant treatment of HNSCC.
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PMID:Correlation of cyclooxygenase-2 pathway and VEGF expression in head and neck squamous cell carcinoma. 1288 61

Cyclooxygenase-2 (COX-2) has an important role in the promotion of carcinogenesis, tumor invasion and angiogenesis. Vascular endothelial growth factor (VEGF) is a proangiogenic factor that is up-regulated in various tumors. VEGF has been shown to interact with COX-derived prostaglandins in angiogenesis. Cyclin D1 gene overexpression and amplification have been shown to play a role as prognostic factors in many human cancers. To better understand the roles of these genes in mammary carcinoma, the immunohistochemical expression patterns of COX-2 and VEGF were evaluated in relationship with cyclin D1 overexpression, tumor stage, clinicopathologic parameters and patient survival in 128 mammary infiltrating duct carcinomas. The expressions of COX-2/VEGF, COX-2/cyclin D1, and VEGF/cyclin D1 were evaluated using double immunofluorescein staining with a confocal scanning laser microscope. A positive expression was seen in 41% for COX-2, 47% for VEGF, and 66% for cyclin D1 in the cases with breast cancer. There was correlation in positive expression of COX-2 or VEGF with histologic grade, lymph node metastasis, and tumor size. Conversely, a significant inverse relation was observed between VEGF and patient age. There was a correlation in overexpression of cyclin D1 with lymph node metastasis, survival rate and survival length. Significant correlations were observed between COX-2 and VEGF as well as COX-2 and cyclin D1. Co-expression of only COX-2 and VEGF was detected with significance. These results indicate that elevated COX-2 or VEGF expression or cyclin D1 overexpression is more common in breast cancer patients with poor prognostic characteristics and is partly associated with an unfavorable outcome. The present findings support the efforts to initiate clinical trials on the efficacy of COX-2 inhibitors in adjuvant treatment of breast cancer.
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PMID:Role of COX-2, VEGF and cyclin D1 in mammary infiltrating duct carcinoma. 1288 88

A series of epidemiological, experimental and preliminary clinical trials strongly suggest that mesalazine or 5-aminosalicyclic acid (5-ASA) may have antineoplastic and potentially prophylactic chemopreventive properties. It is assumed that mesalazine may have similar genetic and molecular targets as nonsteroidal anti-inflammatory drugs (NSAIDs), which is further supported by its close similarity with aspirin, differing only in its structure by the presence of an amino group at position 5 of the benzene ring. The putative chemopreventive actions include the inhibition of inflammatory cascades and/or reactions involved in cell growth and proliferation, such as cyclo-oxygenase (COX-1 and COX-2), which regulate cell proliferation through the formation of prostaglandins; lipoxygenase; nuclear factor kappaB (NFkappaB), responsible for the subsequent expression of pro-inflammatory molecules; MAP kinases and Bcl-2, as well as the activation of apoptotic processes, such as the stimulation of intestinal sphingomyelinase. The peroxisome-proliferator-activated receptor delta (PPARdelta), which also regulates gene transcription, is thought to play a role in both inflammatory and non-inflammatory driven carcinogenesis. This may be another significant target. It is hypothesized that 5-ASAs may prevent the enhancing effect of prostaglandins on PPARdelta binding to DNA by its COX inhibitory properties, decreasing proliferation of colorectal mucosal cells in non-inflammatory bowel disease patients with sporadic polyps of the large bowel.
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PMID:Review article: mechanisms of action of mesalazine in preventing colorectal carcinoma in inflammatory bowel disease. 1295 Apr 15

Several lines of evidence suggest that the cyclooxygenase enzymes (specifically COX-2) might be an important molecular target for the intervention of cancer at both early and late stages of some cancers, providing an opportunity for both cancer prevention and therapy. COX-2 is overexpressed during carcinogenesis, and appears to have a role in both tumour initiation and promotion and is amenable to intervention. This review discusses the importance of COX modulation via non-specific, as well as COX-2 specific COX inhibitors (NSAIDs and COX-2 selective inhibitors [COXIB]). A brief discussion on the pharmacoeconomic considerations of NSAID and COXIB use and safety issues that have recently been the focus of debate, will be presented.
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PMID:Cyclooxygenase inhibition in cancer prevention and treatment. 1464 Sep 18

Cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF), and microvessel density (MVD) have been reported to be significantly related to carcinogenesis and to tumoral progression. The aim of the study was to analyse immunohistochemically the overexpression of COX-2 and VEGF, and the MVD between one another, and also in relation with clinical outcome in ovarian carcinoma. We selected 52 patients with ovarian carcinoma homogeneous by stage, type and histological grade, surgical and chemotherapeutic treatment. Of these, 28 patients had died of progression of their disease within 2 years of their primary surgical treatment, while 24 patients were alive with no evident disease at 5 years from the primary surgical treatment. The differences of the COX-2 status, the MVD and the VEGF expression in the two groups of ovarian carcinoma patients with low and high survival rate, respectively, were calculated according to the Fisher's exact test and the logistic regression. The shift in location of MVD in the two groups of patients was calculated according to the Wilcoxon Mann-Whitney test. MVD was correlated with COX-2 and VEGF overexpression (P=0.009 and P=0.003, respectively), COX-2 and VEGF were correlated to one another (P=0.044). In logistic regression analysis, COX-2, VEGF, and MVD were significant (P=0.017, P=0.008, P<0.0005, respectively). In the cases with low survival rate, the average MVD was 102, while in the cases with high survival rate the average MVD was 40.5 (P<0.0005). The evaluation of the COX-2, the VEGF and the MVD may give additional prognostic information for first-line chemotherapy and clinical outcome of patients with ovarian carcinoma and may encourage selection of more tailored therapies. Angiogenesis inhibitors or COX-inhibitors probably can have synergistic effects with chemotherapy.
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PMID:COX-2 status in relation to tumor microvessel density and VEGF expression: analysis in ovarian carcinoma patients with low versus high survival rates. 1471 60


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