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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1-2
pubmed:dateCreated
1997-2-21
pubmed:abstractText
GL331 is a semisynthetic topoisomerase II inhibitor derived from a plant toxin podophyllotoxin. In 72-h exposure assays, LD50 values of GL331 range from 0.5 to 2 microM, which are three- to ten-fold lower than those of its homologous compound etoposide (VP-16), depending on different cancer cell lines including nasopharyngeal, hepatocellular, gastric, cervical and colon cancer types. Apoptotic DNA ladders could be detected when cancer cells were treated with GL331 for 24 h even if the Bcl-2 and Bax protein levels were not altered during the period. Besides acting as topoisomerase II inhibitors, both GL331 and VP-16 decrease the cellular protein tyrosine kinase (PTK) activities in cancer cells. The activities of protein tyrosine phosphatase (PTP) are significantly increased after GL331 treatment but are not affected by VP-16. GL331-induced internucleosomal cleavage can be efficiently prevented by two inhibitors of PTP, sodium orthovanadate and zinc chloride, but not by okadaic acid, which inhibits serine/threonine phosphatase activity. These results indicate that GL331 may induce apoptotic cell death, and that activation of protein tyrosine phosphatases may be involved in this process.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0304-3835
pubmed:author
pubmed:issnType
Print
pubmed:day
20
pubmed:volume
110
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
77-85
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Protein tyrosine phosphatase activities are involved in apoptotic cancer cell death induced by GL331, a new homolog of etoposide.
pubmed:affiliation
National Health Research Institutes and Cooperative Clinical Research Laboratory at VGH-Taipei, Taiwan, ROC. tshuang@gate.sinica.edu.tw
pubmed:publicationType
Journal Article