[Morphological bases of dopamine effect on HEP-2 tumor cells viability]

The purpose of the present investigation was to study the morpho-functional organization of a classical object of cytological research - cultured HEp-2 tumor cells, using dopamine as a penetrating agent, inducing the polymerization of cytosolic actin. It was demonstrated that dopamine introduced into the incubation medium reduced viability and caused morphological disturbances of cultured HEp-2 cells; these effects were proportional to dopamine concentrations (1.0 x 10(-4) M to 1.0 x 10(-3) M) and exposure duration (2 to 3 days). These cells, according to ultrastructural data, underwent fusion and lysis because of the appearance of actin filaments network in the loci of globular actin prevalence in control cells. Dopamine receptors had no effect on cytotoxic effect of dopamine. This was indicated by fluorescent microscopical evidence of dopamine penetration into experimental cells in the presence of haloperidol, as well as destruction of HEp-2 cells under the action of pyrimidinethione, similar to dopamine by characteristics, but lacking its own receptors. It is suggested that cytoplasmic target for dopamine is globular actin and that induced polymerization of this cytoskeletal protein caused injury to tumour cells.