Expression of intermediate filament proteins in TPA-induced MPC-11 and HL-60 cells.
Under normal culture conditions, the tumor cell lines MPC-11 and HL-60 exhibit high rates of proliferation and show a peculiar expression of intermediate filament proteins as they appear to synthesize only lamin B. A 48-h exposure of murine plasmacytomas MPC-11 to the phorbol ester TPA reduces their growth and induces vimentin synthesis without affecting the composition of their nuclear lamina. When applied to human leukemic promyelocytes HL-60, such treatment promotes their maturation into macrophage-like cells: their proliferative ability is suppressed, a differentiated phenotype is developed, and their content in intermediate filament proteins now includes vimentin and a full complement of lamins A, B, and C. In the present study, a kinetic analysis of vimentin and lamin A/C expression in relation to proliferation and differentiation has been performed in these two cellular systems. Proliferation rates of MPC-11 and HL-60 populations were evaluated by monitoring cell growth and measuring thymidine incorporation. Maturation of HL-60 cells was assessed by Giemsa staining and percentage of adherent cells. Expression of vimentin and lamins A/C was analyzed using immunofluorescence and immunoblotting techniques. Our data show that there is a relationship between the level of vimentin expression and the extent of growth inhibition in both systems. They also suggest that the expression of lamins A/C during the TPA-induced maturation of HL-60 promyelocytes might be part of the processes which lock these cells into the macrophage pathway.
Paulin-Levasseur
M
M
Department of Biology, University of Ottawa, Ontario, Canada.
Julien
M
M
D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation; D002455:Cell Division; D005455:Fluorescent Antibody Technique; D006801:Humans; D007381:Intermediate Filament Proteins / Q000378:metabolism*; D007700:Kinetics; D034904:Lamin Type A; D034921:Lamin Type B; D034882:Lamins; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism*; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism; D010641:Phenotype; D010954:Plasmacytoma / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000633:toxicity*; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects*; D014746:Vimentin / Q000096:biosynthesis
D007381:Intermediate Filament Proteins; D034904:Lamin Type A; D034921:Lamin Type B; D034882:Lamins; D009687:Nuclear Proteins; D014746:Vimentin; D013755:Tetradecanoylphorbol Acetate; D013936:Thymidine