Linked Life Data

2500450

Source:http://linkedlifedata.com/resource/pubmed/id/2500450

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1989-8-10
pubmed:abstractText
The human chronic myeloid leukemia cell line K562 acquires several megakaryoblastoid features when cultured in the presence of the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). We observed strongly increased secretion of several proteins into the culture media of K562 cells within a few hours of TPA treatment. Two of the major secreted polypeptides were identified by immunoprecipitation from media of metabolically labeled cultures as the tissue inhibitor of metalloproteinases (TIMP) and the type 1 plasminogen activator inhibitor (PAI-1). Maximal amounts of PAI-1 mRNA and secretion of PAI-1 polypeptides were observed after 24 hr of TPA treatment and PAI-1 persisted at elevated levels for several days. The induction of PAI-1 mRNA was dependent on de novo protein synthesis. Uninduced and induced cells secreted urokinase plasminogen activator in its single-chain proenzyme form (pro-u-PA), which was cleaved extracellularly to the active two-chain form as shown by pulse-chase labeling experiments. Upon TPA induction, the secretion of u-PA polypeptides increased severalfold, and there was a transient accumulation of pro-u-PA in the culture medium. However, this did not lead to increased u-PA activity in the cultures, since active u-PA was removed by complex formation with the large excess of coinduced PAI-1. Induction of u-PA mRNA was biphasic: The first peak of about tenfold increase in steady-state u-PA mRNA at 3 hr was followed by a steep decline to the baseline level at 12 hr, and a second, slower accumulation of u-PA mRNA occurred over the next few days. The biphasic accumulation of u-PA mRNA was also reflected in u-PA protein synthesis. We conclude that concerted changes in favor of a nonproteolytic extracellular environment occur in TPA-induced K562 cultures undergoing megakaryoblastoid differentiation. These changes include excessive secretion of TIMP and inhibition of the induced u-PA by the simultaneous accumulation of PAI-1.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0021-9541
pubmed:author
pubmed:issnType
Print
pubmed:volume
140
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
119-30
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:2500450-Cell Line, pubmed-meshheading:2500450-Culture Media, pubmed-meshheading:2500450-Electrophoresis, Polyacrylamide Gel, pubmed-meshheading:2500450-Enzyme Inhibitors, pubmed-meshheading:2500450-Glycoproteins, pubmed-meshheading:2500450-Humans, pubmed-meshheading:2500450-Leukemia, Myelogenous, Chronic, BCR-ABL Positive, pubmed-meshheading:2500450-Peptide Hydrolases, pubmed-meshheading:2500450-Plasminogen Activators, pubmed-meshheading:2500450-Plasminogen Inactivators, pubmed-meshheading:2500450-Precipitin Tests, pubmed-meshheading:2500450-RNA, Messenger, pubmed-meshheading:2500450-Tetradecanoylphorbol Acetate, pubmed-meshheading:2500450-Tissue Inhibitor of Metalloproteinases, pubmed-meshheading:2500450-Tumor Cells, Cultured, pubmed-meshheading:2500450-Urokinase-Type Plasminogen Activator
pubmed:year
1989
pubmed:articleTitle
Down-regulation of proteolytic activity in 12-O-tetradecanoyl-phorbol-13-acetate-induced K562 leukemia cell cultures: depletion of active urokinase by excess type 1 plasminogen activator inhibitor.
pubmed:affiliation
Transplantation Laboratory, University of Helsinki, Finland.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't