Induction of macrophage-like differentiation of HL-60 leukemia cells by tumor necrosis factor-alpha: potential role of fos expression.
Tumor necrosis factor-alpha (TNF-alpha) is a macrophage-derived cytokine elicited during cellular responses to various microbial infections. TNF-alpha exerts direct cytotoxicity toward some tumor cells in vitro and produces hemorrhagic tumor necrosis in vivo. In human promyelocytic HL-60 leukemia cells, human recombinant TNF-alpha (rTNF-alpha) exhibits a small early proliferative effect (within 48 h), followed by marked cytostatic activity at 96 h after the addition of rTNF-alpha. Cytostasis is contiguous with an induction of cell differentiation along the monocyte/macrophage lineage. The cell proliferation effects and the induction of the differentiated phenotype are preceded by an approximate 5-fold increase in c-fos mRNA levels within 90 min after rTNF-alpha treatment of log phase HL-60 cells. Nuclear in vitro transcription assays indicate that the effect of rTNF-alpha on c-fos mRNA abundance is controlled at the transcriptional level. We have also used a postembedding immunocolloidal gold electron microscopy technique to localize and semiquantitate pp55c-fos proto-oncoprotein levels in the nucleus of both control and rTNF-alpha-treated HL-60 leukemia cells. In response to rTNF-alpha, we have observed a rapid and transient accumulation of pp55c-fos in discrete nuclear substructures within 2 h after treatment. C-fos staining appears in clusters, which are preferentially localized over semi-condensed chromatin and interchromatin granules. These results suggest that pp55c-fos is involved in the signal transduction system initiated by rTNF-alpha during the induction of HL-60 differentiation.
Squinto
S P
SP
Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, New Orleans 70119.
Doucet
J P
JP
Block
A L
AL
Morrow
S L
SL
Davenport
W D
WD
D002460:Cell Line; D002467:Cell Nucleus / Q000032:analysis / Q000473:pathology / Q000648:ultrastructure; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D005786:Gene Expression Regulation; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000473:pathology*; D008264:Macrophages / Q000473:pathology* / Q000648:ultrastructure; D008854:Microscopy, Electron / Q000379:methods; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000235:genetics*; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000494:pharmacology*
D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha