ABSTRACT
The effect of dopamine (DA) on the viability and morphology of cultured tumor THP-1 cells (human acute monocytic leukemia) was studied. DA in concentration of 10(-5) M had virtually no effect on the culture, while in concentration of 10(-4) M to 10(-3) M it stopped the growth and caused a sharp increase in cell death after 24 and 48 hours. Incubation with DA reduced the cell diameter, progressively increased their vacuolization and intensity of fluorescence after treatment by Falck method. Electron microscopical study has shown that cells exposed for 1 day to DA in the concentrations starting with 10(-4) M, demonstrated smoothing of their surface with the disappearance of microvilli and clasmatosis vesicles, actin filaments perforating the plasma membrane, the emergence of an increasingly dense network of filaments in the cytosole and karyoplasm and, finally, apoptotic cell death. It is suggested that the oncotherapeutic cellular target for DA is a cytosolic G-actin, which at a certain DA concentration, turns into filaments that damage the cells, break the cell cycle and cause cell death.
Subject(s)
Actin Cytoskeleton/drug effects , Dopamine/pharmacology , Actin Cytoskeleton/ultrastructure , Actins/drug effects , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Cell Line, Tumor , Cell Membrane/drug effects , Cell Membrane/ultrastructure , Cytosol/drug effects , Humans , Organelles/drug effects , Organelles/ultrastructureABSTRACT
We studied the effects of dopamine added to culture medium on survival of floating or adherent BHK-21 cells differing by organization of actin cytoskeleton. The viability of floating cells more drastically decreased with increasing dopamine concentration and duration of exposure than that of adherent cells. The cells worse adhered to the substrate and formed a monolayer. The formed monolayer degrades, cell borders become blurred, cells, polygonal in the control, are rounded. Preliminary blockade of dopamine receptors with haloperidol, inessential for cell survival and morphology, does not prevent the destructive effect of dopamine on the cells. Ultrastructural study revealed increased density of filamentous actin threads in deep compartments of cell cytoplasm after dopamine treatment, this increase being more pronounced in cells grown in suspension. Bearing in mind the polymerizing effect of dopamine on globular actin in vitro and the fact that the content of this protein in floating cells is higher than in adherent cells, we can conclude that the decrease in viability of BHK-21 cells is caused by interaction of dopamine with cytoplasmic globular actin.
