Linked Life Data

10544021

Source:http://linkedlifedata.com/resource/pubmed/id/10544021

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1999-12-22
pubmed:abstractText
Overexpressed MDM2 inactivates wild-type (wt) p53 in various human tumors. However, whether and how the wild-type p53 can be activated by anticancer drug treatment in the presence of excess MDM2 is still unclear. In the present study, we showed that the topoisomerase II inhibitor of widely used anticancer drugs etoposide and doxorubicin activated wt p53 in BL2, a Burkitt's lymphoma cell line which overexpressed MDM2. Activation of p53 was followed by apoptosis in BL2 cells, while the same drug treatment did not induce apoptosis in Raji cells, another Burkitt's lymphoma cell line which carried mutant p53. Activation of p53 was accompanied by phosphorylation of p53 at Ser-15 and elevated p21 and MDM2, both of which were at least partly blocked by wortmannin, a kinase inhibitor against proteins with a PI3 kinase domain. Although MDM2 protein was rapidly cleaved and degraded after anticancer drug treatment, cotreatment with caspase inhibitor Z-VAD blocked degradation, while wt p53 remained activated, suggesting MDM2 degradation not to be essential for the activation of p53. Treatment with proteasome inhibitor stabilized p53 without being further phosphorylated. This p53 was co-immunoprecipitated with MDM2, but p53 activated by etoposide or doxorubicin barely complexed with MDM2. These results suggest that the wild-type p53 in MDM2-overexpressing cells can be activated by anticancer drugs through phosphorylation of p53, alleviating inhibitory action by MDM2, and activating caspases which in turn downregulates MDM2. The activation of p53 in MDM2-overexpressing tumor cells, which does not require the downregulation of MDM2, may have important implications in cancer therapy.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0006-291X
pubmed:author
pubmed:copyrightInfo
Copyright 1999 Academic Press.
pubmed:issnType
Print
pubmed:day
2
pubmed:volume
264
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
860-4
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Activation of p53 in MDM2-overexpressing cells through phosphorylation.
pubmed:affiliation
Department of Molecular Cellular Oncology, Tokyo Medical and Dental University, 1-5-45, Yushima, Tokyo, Bunkyo-ku, 113-8549, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't