Correlation of Pit-1 gene expression and Pit-1 content with proliferation and differentiation in human myeloid leukemic cells.
The transcription factor pituitary-1 (Pit-1) is a homeodomain-containing protein that is expressed mainly in the pituitary, where it drives the expression of growth hormone, prolactin, and thyroid-stimulating hormone beta chain genes. In addition, Pit-1 is required for adequate pituitary cell growth and may be involved in the pathogenesis of pituitary adenomas. Pit-1 expression has been also reported in nonpituitary tissues, where it might be involved in the control of cell proliferation. In order to elucidate such a possibility, we have investigated the changes in both Pit-1 mRNA and Pit-1 immunoreactivity in HL-60 cells following the addition of several differentiating agents. Our results show that while high Pit-1 levels are found in exponentially growing HL-60 cells, a significant decrease occurs after induction of cells to differentiate along the macrophage lineage with 12-O-tetradecanoylphorbol-13-acetate (TPA). In contrast no changes were observed when cells were treated with interferon-alpha, which also induces differentiation of HL-60 cells that, at odds with TPA, is not accompanied with growth arrest. In all, these findings suggest that Pit-1 expression is specifically associated with proliferation in HL-60 cells, thus supporting the idea that one of the functions of nonpituitary Pit-1 may be the control of cell proliferation.
Costoya
J A
JA
Faculty of Medicine, University of Santiago de Compostela, Santiago de Compostela, 15705, Spain.
García-Barros
M
M
Gallego
R
R
Señarís
R
R
Arce
V M
VM
Devesa
J
J
D002454:Cell Differentiation; D002455:Cell Division; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D015870:Gene Expression; D018922:HL-60 Cells; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007951:Leukemia, Myeloid; D008934:Mitogens / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D008934:Mitogens; C494187:POU1F1 protein, human; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D007371:Interferon-gamma; D013755:Tetradecanoylphorbol Acetate