Increased erythroid potentiating activity/tissue inhibitor of metalloproteinases and jun/fos transcription factor complex characterize tumor promoter-induced megakaryoblastic differentiation of K562 leukemia cells.
Molecular cloning has revealed that erythroid potentiating activity (EPA) and tissue inhibitor of metalloproteinases (TIMP) represent two distinct activities of a single protein. We have studied the expression of the EPA/TIMP gene at the mRNA and protein levels during 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced megakaryoblastic differentiation of K562 human chronic myeloid leukemia cells. Northern hybridization analysis showed that the EPA/TIMP mRNA was increased within 3 hours of TPA-induction and reached maximal levels (about 50-fold induction) during the first day of treatment. The expression of mRNAs for two major metalloproteinases, collagenase-I and stromelysin, were activated in parallel in the differentiation-induced K562 cells. The increase of EPA/TIMP mRNA correlated with increased EPA/TIMP protein biosynthesis and secretion: the TPA-induced cells secreted substantially enhanced amounts of metabolically labeled proteins, of which EPA/TIMP represented up to 50% after the first day of treatment (over 100-fold induction). The induction of EPA/TIMP mRNA was associated with its increased transcription. EPA/TIMP induction required continuous protein synthesis, being completely inhibited by addition of the protein synthesis inhibitor cycloheximide simultaneously with TPA, but only partially inhibited in a time-dependent manner if cycloheximide was added after TPA. Unlike in other cells tested, the jun and c-fos transcription factor mRNAs showed a prolonged biphasic induction response in K562 cells during TPA treatment. This response was associated with enhanced activity of a transfected recombinant reporter plasmid containing binding sites for the jun/fos transcription factor complex (AP-1) similar to the TPA-responsive element (TRE) sequence we found in the EPA/TIMP gene promoter. We suggest that the induction of EPA/TIMP and several other genes specific for the differentiating K562 cells may be a consequence of the sustained activation of immediate early genes encoding transcription factors, such as jun and c-fos.
Alitalo
R
R
Transplantation Laboratory, University of Helsinki, Finland.
Partanen
J
J
Pertovaara
L
L
Hölttä
E
E
Sistonen
L
L
Andersson
L
L
Alitalo
K
K
D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism / Q000473:pathology*; D008222:Lymphokines / Q000235:genetics / Q000378:metabolism*; D003012:Microbial Collagenase / Q000037:antagonists & inhibitors*; D014176:Protein Biosynthesis; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger / Q000235:genetics; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D019714:Tissue Inhibitor of Metalloproteinases; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D006023:Glycoproteins; D008222:Lymphokines; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D019714:Tissue Inhibitor of Metalloproteinases; D014157:Transcription Factors; D003012:Microbial Collagenase; D013755:Tetradecanoylphorbol Acetate