Different regulation of plasminogen activator inhibitor 2 gene expression by phorbol ester and cAMP in human myeloid leukemia cell line PL-21.
Previous studies have shown that protein kinase C (PKC) activators and dibutyryl cyclic AMP (Bt2cAMP) synergistically increase the antigen level of plasminogen activator inhibitor type-2 (PAI-2) in a human myeloid leukemia cell line PL-21. To clarify the mechanism, PAI-2 gene expression induced by phorbol myristate acetate (PMA), a PKC activator, and Bt2cAMP was investigated by Northern blot hybridization using a PAI-2 cDNA probe cloned from a human placental library. The level of PAI-2 mRNA was markedly increased in response to PMA and reached a maximum 5-9 h after stimulation. Nuclear run-on assay revealed an increase in PAI-2 gene transcription in PMA-treated cells. The induction was inhibited by inhibiting de novo protein synthesis with cycloheximide (CHX). cAMP also increased PAI-2 mRNA level in a dose-dependent manner. The increase began within 2 hours and, contrary to the case of PMA, the mRNA levels were maintained. Moreover, cAMP-induced increase in PAI-2 mRNA was not inhibited by CHX, rather enhanced. PMA and cAMP synergistically induced PAI-2 gene expression, which was completely inhibited by CHX. The cells pretreated with PMA for 24 h did not any more respond to stimulation with PMA but responded to cAMP and PAI-2 mRNA level was increased. The apparent half-life of constitutive level PAI-2 mRNA in PL-21 cells, determined by actinomycin-D-decay experiments, was approximately 2 h. Those induced by PMA and cAMP were approximately 5 h and 2 h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Clinical Laboratory Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
K
K
Niiya
T
T
Taniguchi
M
M
Shinbo
T
T
Ishikawa
S
S
Tazawa
Y
Y
Hayakawa
N
N
Sakuragawa
D003994:Bucladesine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics*; D017396:Plasminogen Activator Inhibitor 2 / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis; D013755:Tetradecanoylphorbol Acetate / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D017396:Plasminogen Activator Inhibitor 2; D012333:RNA, Messenger; D003994:Bucladesine; D003513:Cycloheximide; D013755:Tetradecanoylphorbol Acetate