Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0009402 (colorectal cancer)
 53,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidemiological and experimental evidence indicates that aspirin can protect against colorectal cancer. Aspirin inhibits cyclooxygenase enzymes and blocks prostaglandin (PG) biosynthesis. Using rectal PGE(2) levels as a mucosal biomarker, we sought to determine the optimal aspirin dose that would significantly suppress PGE(2) levels for chemoprevention trials. We conducted a randomized, double-blinded study in 60 subjects with prior sporadic colorectal adenoma(s) and evaluated three aspirin doses (81, 325, and 650 mg) or placebo taken daily for 4 weeks. PGE(2) levels in rectal biopsies performed at baseline and week 4 were analyzed by competitive immunoassay. Plasma salicylate levels, pill counts, and subject calendars were used to assess compliance. The 81-mg aspirin dose significantly suppressed PGE(2) levels relative to placebo (P = 0.005) and did so to an equivalent extent as did higher doses (P > 0.4) in evaluable subjects (n = 55) over a 4-week treatment period. Serum salicylate levels were associated with aspirin dose (P = 0.0002). Pill counts and calendars indicated that >98% of doses were taken by all subjects. No adverse events occurred in this short-term study. The 81-mg daily aspirin dose suppressed PGE(2) levels to an equivalent extent as did the 650-mg dose and supports the use of this dose for chemoprevention trials.
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PMID:A dose-finding study of aspirin for chemoprevention utilizing rectal mucosal prostaglandin E(2) levels as a biomarker. 1189 77

Population-based studies have established that long-term intake of non-steroidal anti-inflammatory drugs (NSAIDs), compounds that inhibit the enzymatic activity of cyclooxygenase (COX), reduces the relative risk for developing colorectal cancer. These studies led to the identification of a molecular target, COX-2, that is involved in tumour promotion during colorectal cancer progression. Recent studies in humans indicate that therapy with specific COX-2 inhibitors might be an effective approach to colorectal cancer prevention and treatment.
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PMID:Colorectal cancer prevention and treatment by inhibition of cyclooxygenase-2. 1190 Feb 48

Although colorectal cancer is one of the most preventable forms of visceral cancer, it remains the second leading cause of cancer death in the United States. Most colorectal cancers are believed to arise from adenomatous polyps, premalignant mucosal masses that account for up to two thirds of colorectal polyps. Early identification and removal of adenomas prevent the development of colorectal cancer. Colonoscopy has emerged as the dominant method for evaluating symptomatic patients with colorectal cancer and for surveillance of patients with previous colon polyps or cancer. In the United States, fecal occult blood testing and flexible sigmoidoscopy are the most commonly used screening methods in average-risk persons, although there is an emerging trend toward the use of colonoscopy. For both screening and surveillance, the type of screening test used and the intervals at which it is performed are based on risk stratification, which also serves as the basis for selecting potential candidates for chemoprevention. Because colonoscopy, like most screening procedures, has several disadvantages, including risk of perforation and bleeding and an inherent "miss rate," alternative methods of prevention are being explored. A variety of agents with potential chemopreventive benefits have been identified, including cyclooxygenase (COX)-2-specific inhibitors (coxibs) even though these agents have not been approved for this use in the United States. COX-2 is overexpressed in colonic adenomas and cancers, and its inhibition has been shown to produce regression of polyps in familial adenomatous polyposis. Nonselective COX inhibition with nonsteroidal anti-inflammatory drugs (NSAIDs) has been consistently associated with reductions in the risk of mortality and the incidence of colorectal adenomas and cancers in case-control studies. Thus, selective COX-2 inhibition is a potential method of risk reduction in high-risk screening and surveillance groups, and large-scale trials of coxibs for the prevention of recurrence of adenomas after polypectomy are currently underway.
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PMID:Screening for colon cancer and evaluation of chemoprevention with coxibs. 1199 50

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used drugs for the treatment of inflammatory disease and have a chemopreventive effect on colorectal cancer. NSAIDs inhibit cyclooxygenase (COX)-1 and/or COX-2 activity, but the chemopreventive effect may be, in part, independent of prostaglandin inhibition. NSAID-activated gene (NAG-1) was previously identified as a gene induced by some NSAIDs in cells devoid of COX activity. NAG-1 has proapoptotic and antitumorigenic activity in vitro and in vivo. To determine whether the induction of NAG-1 by NSAIDs is influenced by COX expression, we developed COX-1- and COX-2-overexpressing HCT-116 cells. COX expression did not affect NSAID-induced NAG-1 expression as assessed by transient and stable transfection. Also, NAG-1 expression was not affected by PGE(2) and arachidonic acid, suggesting that NAG-1 induction by NSAIDs occurs by a prostanoid-independent manner. We also report that indomethacin increased NAG-1 expression in a number of cells from tissues other than colorectal. In conclusion, NSAIDs have dual function, induction of NAG-1 expression and inhibition of COX activity that occurs in a variety of cell lines.
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PMID:Dual function of nonsteroidal anti-inflammatory drugs (NSAIDs): inhibition of cyclooxygenase and induction of NSAID-activated gene. 1202 46

Future clinical applications of cyclooxygenase (COX)-2-selective inhibitors (coxibs) are likely to extend beyond their current use as oral analgesics in high-risk arthritis patients. The clinical utility of coxibs for the treatment of Alzheimer's disease (AD) is under investigation. Epidemiological surveys, preclinical studies, and preliminary clinical trials with nonsteroidal anti-inflammatory drugs (NSAIDs) have suggested that inflammatory mechanisms play a role in the neurodegeneration of AD. Clinical trials are currently being conducted to determine the effect of coxibs on the rate of AD progression. The use of coxibs as chemopreventive agents in colorectal cancer (CRC) is also under investigation. The chemopreventive benefits of coxibs to promote cell death (apoptosis) and inhibit angiogenesis in CRC have been shown in tumor cell lines and in animal and human models. In addition, palliative care clinicians and oncologists are increasingly including coxibs in their management of cancer pain. Coxibs are utilized for their opioid-sparing effect in the management of cancer pain, without impairing wound healing, or promoting bleeding diathesis (antiplatelet effects) or adverse gastrointestinal effects in patients receiving chemotherapy or radiation treatment.
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PMID:Emerging options with coxib therapy. 1208 98

Linoleic and alpha-linolenic acids, obtained from plant material in the diet are the precursors in tissues of two families with opposing effects which are referred to as "essential fatty acids" (EFA): arachidonic acid (AA) and pentaene (eicosapentaenoic acid: EPA) and hexaene (docosahexaenoic acid: DHA) acids. The role of EFA is crucial, without a source of AA or compounds which can be converted into AA, synthesis of prostaglandins (PGs) by a cyclooxygenase (COX) enzyme would be compromised, and this would seriously affect many normal metabolic processes. COX, also known as prostaglandin endoperoxide synthase (Pghs) or as prostaglandin G/H synthase, is a key membrane bound enzyme responsible for the oxidation of AA to PGs. Two COX isoforms have been identified, COX-1 and COX-2 that form PGH2, a common precursor for the biosynthesis of thromboxane A2 (TxA2), prostacyclin (PGI2) and PGs (PGD2, PGE2, PGF2alpha. COX-1 enzyme is expressed constitutively in most cells and tissues. Its expression remains constant under either physiological or pathological conditions controlling synthesis of those PGs primarily involved in the regulation of homeostatic functions. In contrast, COX-2 is an intermediate response gene that encodes a 71-kDa protein. COX-2 is normally absent from most cells but highly inducible in certain cells in response to inflammatory stimuli resulting in enhanced PG release. PGs formed by COX-2 primarily mediate pain and inflammation but have multiple effects that can favour tumorigenesis. They are more abundant in cancers than in normal tissues from which the cancers arise. COX-2 is a participant in the pathway of colon carcinogenesis, especially when mutation of the APC (Adenomatous Polyposis Coli) tumour suppressor gene is the initiating event. In addition, COX-2 up-regulation and elevated PGE2 levels are involved in breast carcinogenesis. It seems that there is a correlation between COX-2 level of expression and the size of the tumours and their propensity to invade underlying tissue. Inhibition by non-steroidal anti-inflammatory drugs (NSAIDs) of COX enzymes which significantly suppress PGE2 levels, reduced breast cancer incidence and protected against colorectal cancer. Therefore it is suggested that consumption of a diet enriched in n-3 PUFA (specifically EPA and DHA) and inhibition of COX-2 by NSAIDs may confer cardioprotective effects and provide a significant mechanism for the prevention and treatment of human cancers.
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PMID:Polyunsaturated fatty acids (PUFA) and eicosanoids in human health and pathologies. 1219 20

Colorectal cancers (CRCs) are one of the most common forms of cancer in Poland and one of the leading causes of death. The tumors have been attributed to genetic, dietary, and other environmental factors, but recently growth factors such as gastrin have also been implicated in the carcinogenesis. The relationship between plasma amidated and nonamidated gastrin in CRCs is controversial. This study was designed (1) to determine the plasma levels of progastrin and amidated gastrin in 50 CRC patients before and 3-6 months after removal of the tumor, (2) to determine the tumor concentrations of these gastrin peptides and the level of expression for gastrin mRNA and gastrin/CCK(B) receptor mRNA, (3) to examine the expression of cyclooxygenase COX-1 and COX-2 mRNA in CRC tissue, and (4) to compare the prevalence of Hp and its cytotoxic protein, CagA, and cytokines (TNFalpha, IL-1beta, and IL-8) in CRCs, before and after removal of tumor. It was found that the CRC, its resection margin, and the plasma contained severalfold higher levels of progastrin than of amidated gastrins and that the removal of the CRC tumor resulted in a marked reduction in plasma progastrin level without a significant alteration in plasma levels of amidated gastrins. Both gastrin and CCK(B)-R mRNA were detected in the cancer tissue and resection margin by RT-PCR, and similarly, COX-1 and COX-2 mRNA were expressed in these tissues of most CRCs. The seroprevalence of Hp, especially that expressing CagA, and levels of IL-1beta, but not other cytokines, were significantly higher in CRC patients than in 100 age-, gender-, and profession-matched controls and did not change significantly about 3-6 months after tumor resection. We conclude that (1) the CRC and its margin contain large amounts of progastrin and show gene expression of gastrin, CCK(B)-R, and COX-2; (2) removal of the CRC markedly reduces the plasma concentrations of progastrin; (3) the Hp infection rate is higher in CRC, and this may contribute to colorectal cancerogenesis via enhancement of progastrin and gastrin release; and (4) plasma progastrin concentrations might serve as a biomarker of CRC.
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PMID:Progastrin and cyclooxygenase-2 in colorectal cancer. 1235 42

In human colorectal adenomas or polyps, cyclooxygenase-2 is expressed predominantly by stromal (or interstitial) macrophages. Therefore, we tested the hypothesis that macrophage cyclooxygenase-2 has paracrine pro-tumorigenic activity using in vitro models of macrophage-epithelial cell interactions. We report that macrophages can promote tumorigenic progression of intestinal epithelial cells (evidenced by decreased cell-cell contact inhibition, increased proliferation and apoptosis, gain of anchorage-independent growth capability, decreased membranous E-cadherin expression, up-regulation of cyclooxygenase-2 expression, down-regulation of transforming growth factor-beta type II receptor expression and resistance to the anti-proliferative activity of transforming growth factor-beta(1)) in a paracrine, cyclooxygenase-2-dependent manner. Pharmacologically relevant concentrations (1-2 microM) of a selective cyclooxygenase-2 inhibitor had no detectable, direct effect on intestinal epithelial cells but inhibited the macrophage-epithelial cell signal mediating tumorigenic progression. Cyclooxygenase-2-mediated stromal-epithelial cell signalling during the early stages of intestinal tumorigenesis provides a novel target for chemoprevention of colorectal cancer (and other gastro-intestinal epithelial malignancies, which arise on a background of chronic inflammation, such as gastric cancer) and may explain the discrepancy between the concentrations of cyclooxygenase inhibitors required to produce anti-neoplastic effects in vitro and in vivo.
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PMID:Paracrine cyclooxygenase-2-mediated signalling by macrophages promotes tumorigenic progression of intestinal epithelial cells. 1237 Aug 7

Colorectal cancer is the second most common cause of cancer-related mortality in Europe and North America. Studies conducted in the last two decades have established the role of adjuvant therapy in stage III colon cancer. However, there is currently no international consensus with the role of adjuvant treatment in stage II disease. The introduction of irinotecan, oxaliplatin, oral fluoropyrimidines and raltitrexed has broadened the treatment options available for patients with advanced colorectal cancer. The integration of these drugs with the new molecular targeted therapies such as epidermal growth factor receptor, cyclooxygenase, angiogenesis and matrix metalloproteinase inhibition will form the basis of clinical research in the next few years and may, in the future, impact on the survival of patients with colorectal cancer. This review will focus on the place of chemotherapy in colorectal cancer, but not its role in combination with radiotherapy in rectal cancer.
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PMID:Chemotherapy in colorectal cancer: new options and new challenges. 1242 32

Non-steroidal anti-inflammatory drugs are chemopreventive for colorectal cancer. This effect is due in part to their ability to inhibit the inducible isoform of cyclooxygenase (COX-2). However, the cellular expression and role of COX-2 in the premalignant stages of colorectal tumourigenesis is unclear. COX-2 expression was assessed in 35 human colorectal adenomas and 38 sporadic invasive colorectal adenocarcinomas. Adenomas were classified as small (<5 mm in diameter), medium (5-10 mm), and large (>10 mm). All tissues were paraffin-embedded and formalin-fixed. COX-2 protein expression was determined using immunohistochemistry. COX-2 was detected in the epithelial cells in 35 of 38 carcinomas (92%) and in 8 of 8 (100%) lymph node metastases. All of the epithelial cells expressed COX-2 in 30 of 35 (86%) carcinomas and in 100% of the lymph node metastases. Twenty-three of 35 (66%) adenomas expressed COX-2 in the tumour epithelium. With an increase in the size of adenoma (<5 mm, 5-10 mm, >10 mm), there was an increase in (i) the proportion of adenomas with immunoreactive COX-2 in the epithelium (p = 0.036)-this was 38% in small adenomas and 82% in large adenomas; (ii) the extent of epithelial COX-2 staining within a given tumour (p = 0.003)-100% of epithelial cells were COX-2-positive in 15% of small adenomas and in 73% of large adenomas; and (iii) the intensity of epithelial COX-2 staining (p = 0.009)-strong COX-2 staining occurred in 8% of small adenomas and in 36% of large adenomas. COX-2 immunoreactivity was not detected in adjacent normal epithelium but was apparent in fibroblasts and inflammatory mononuclear cells of adjacent normal, adenoma, and carcinoma tissue. These results suggest that epithelial COX-2 activity is important for the growth and/or survival of adenomatous epithelial cells from an adenoma diameter of less than 5 mm and that there is a selective advantage for adenoma epithelial cells expressing higher levels of COX-2.
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PMID:Human colorectal adenomas demonstrate a size-dependent increase in epithelial cyclooxygenase-2 expression. 1243 11


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