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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
2007-9-24
pubmed:abstractText
Unconjugated bilirubin (UCB) is the major degradation product of the heme catabolism. A growing body of evidences suggests that UCB plays major biological effects by inhibiting cell proliferation in cancer cell lines and eliciting cell toxicity particularly in neurons and glial cells. Early molecular events responsible for bilirubin-induced cytotoxicity remain poorly understood. Using HeLa cells and mouse embryonic fibroblasts, we found that UCB at a concentration of free pigment (Bf) of 80 nM induced oxidative stress, promoting a significant increase in intracellular reactive oxygen species (ROS) and a decreased cell survival (by the MTT test). The ROS increase activated the antioxidant cell response through APE1/Ref-1, a master redox regulator in eukaryotic cells. Activation of APE1/Ref-1 was followed by a concomitant activation of Egr-1 transcription factor and by an upregulation of PTEN tumor suppressor, an Egr-1 target gene, leading to inhibition of cell growth. Blocking ROS generation with N-acetylcysteine pretreatment, restored cell survival, limited the upregulation of PTEN in response to UCB, and prevented the inhibition of cell proliferation. HeLa cells transfected with mutants of the PTEN promoter or silenced with APE1/Ref-1 small interference RNA confirmed that UCB modulates a signaling pathway involving APE1/Ref-1, Egr-1, and PTEN. These findings describe a new molecular pathway involved in the cytotoxic effects of UCB.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0946-2716
pubmed:author
pubmed:issnType
Print
pubmed:volume
85
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1099-112
pubmed:dateRevised
2011-7-8
pubmed:meshHeading
pubmed-meshheading:17479230-Acetylcysteine, pubmed-meshheading:17479230-Animals, pubmed-meshheading:17479230-Apoptosis, pubmed-meshheading:17479230-Bilirubin, pubmed-meshheading:17479230-Cell Communication, pubmed-meshheading:17479230-Cell Differentiation, pubmed-meshheading:17479230-Cell Proliferation, pubmed-meshheading:17479230-Cell Survival, pubmed-meshheading:17479230-DNA-(Apurinic or Apyrimidinic Site) Lyase, pubmed-meshheading:17479230-Electrophoretic Mobility Shift Assay, pubmed-meshheading:17479230-Enzyme Activation, pubmed-meshheading:17479230-Fibroblasts, pubmed-meshheading:17479230-Gene Expression Regulation, pubmed-meshheading:17479230-HeLa Cells, pubmed-meshheading:17479230-Humans, pubmed-meshheading:17479230-Mice, pubmed-meshheading:17479230-PTEN Phosphohydrolase, pubmed-meshheading:17479230-RNA, Small Interfering, pubmed-meshheading:17479230-Reactive Oxygen Species, pubmed-meshheading:17479230-Transcription Factors
pubmed:year
2007
pubmed:articleTitle
Bilirubin-induced cell toxicity involves PTEN activation through an APE1/Ref-1-dependent pathway.
pubmed:affiliation
Department of Biomedical Sciences and Technologies, University of Udine, 33100, Udine, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't