Linked Life Data

10706128

Source:http://linkedlifedata.com/resource/pubmed/id/10706128

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2000-3-20
pubmed:abstractText
Cyclooxygenase-2 (COX-2) gene overexpression is suggested to play important roles in colorectal tumorigenesis. Epidemiological studies revealed that nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and sulindac, which inhibit COX activity, reduce colorectal cancer mortality. Current investigations have focused on delineating the molecular mechanisms that regulate COX-2 gene expression and the roles of NSAIDs in cancer chemoprevention. COX-2 catalyzes the production of prostaglandins (PGs) from arachidonic acid (AA), generated by phospholipases A2 (PLA2s), a family of acyl esterases that cause the release of AA from cellular phospholipids. Pancreatic secretory PLA2 (sPLA2), via its receptor (sPLA2R), transcriptionally activates COX-2 gene expression in several cell types, although a specific transcription factor mediating COX-2 expression has not yet been identified. Here, we report that a transcription factor, CCAAT/enhancer-binding protein beta(C/EBPbeta), plays a critical role in sPLA2IB-induced, receptor-mediated COX-2 gene expression in MC3T3E1 and NIH3T3 cells. Furthermore, treatment of these cells with NSAIDs in the presence of sPLA2IB appears to potentiate the stimulatory effects on COX-2 mRNA and COX-2 protein expression and a concomitant elevation in PG production. Most significantly, NSAID treatment appears to drastically suppress the production of cytosolic PLA2 (cPLA2) mRNA. The lack of sPLA2IB, sPLA2IIA, and sPLA2V mRNA expression in both NIH3T3 and MC3T3E1 cells suggests that cPLA2 is the most likely enzyme that catalyzes the release of AA, the rate-limiting substrate of COX for the production of PGs. Our results suggest that: (a) sPLA2IB receptor-mediated COX-2 expression is mediated via C/EBPbeta; (b) NSAIDs in the presence of sPLA2IB potentiate the stimulatory effects of sPLA2IB on COX-2 mRNA expression; and (c) despite the apparent stimulation of COX-2 expression by NSAIDs, they strikingly deprive COX-2 of its substrate, AA, by suppressing cPLA2 mRNA expression. Both AA and PGs regulate many vital biological functions (e.g., motility and invasiveness) that are dysregulated in most cancer cells, and they have profound effects on cellular differentiation. Our results raise the possibility that deprivation of COX-2 of its substrate by the suppression of cPLA2 mRNA expression is an additional mechanism used by NSAIDs to inhibit tumorigenesis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0008-5472
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
60
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1084-91
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Transcriptional regulation of cyclooxygenase-2 gene expression: novel effects of nonsteroidal anti-inflammatory drugs.
pubmed:affiliation
Section on Developmental Genetics, Heritable Disorders Branch, National Institute of Child Health and Human Development, NIH, Bethesda, Maryland 20892-1830, USA.
pubmed:publicationType
Journal Article