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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1994-10-25
pubmed:abstractText
Okadaic acid (OA), a specific protein phosphatase inhibitor, has various biological functions. To elucidate the mechanism of OA resistance, we have established a small-cell lung-cancer subline (H69/OA100) resistant to the growth-inhibitory effect of OA; this was done by using the parental cell line (H69) and increasing the concentration of OA. H69/OA100 was about 8 times more resistant to OA than H69. Intracellular retention of the fluorescent OA derivative in H69/OA100 was the same as that in H69. The catalytic activity of protein phosphatase from H69/OA100 was significantly reduced compared with that from H69. The protein phosphatase from H69/OA100 was 3.6 times more resistant to OA than that from H69. We examined the effect of OA on the activity of the immunoprecipitated protein phosphatase type I (PPI) and type 2A (PP2A) from the 2 cell lines. The PPI and PP2A from H69/OA100 showed more resistance to OA than those from H69. We next examined the effect of OA on the cell cycle of H69 and H69/OA100. In H69, G2/M block was observed at an OA concentration of 30 ng/ml whereas in H69/OA100, no G2/M block was observed at concentrations up to 100 ng/ml OA. We finally evaluated the amount of p34cdc2 kinase expression and the phosphorylation status of p34cdc2. There was no difference in p34cdc2 expression between H69 and H69/OA100 at several concentrations of OA. However, dephosphorylation of p34cdc2 was observed at 30 ng/ml OA in H69, but not in H69/OA100 up to 100 ng/ml OA. These data suggest that the resistance to OA and the resistance of the cell-cycle block to OA in H69/OA100 might be due to alteration of protein phosphatase activity.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0020-7136
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
58
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
882-90
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Establishment of a human small-cell lung-cancer subline resistant to okadaic acid.
pubmed:affiliation
Pharmacology Division, National Cancer Center Research Institute, Tokyo, Japan.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't