ABSTRACT
Treatment of HeLa cells with low intensity ultrasound and two cytostatic drugs, cycloplatin and methotrexate, resulted in a partial disassembly of microtubules and microfilaments. This disassembly was due to depolymerization and subsequent erroneous repolymeration of essential cytoskeletal proteins, resulting in formation of unusual arrangements, mainly small, granule-like structures. The combined action of ultrasound and cytostatics had a synergistic effect dependent on both the concentration of the drug and the time of sonication. The demonstrated changes in the cytoskeleton are considered to be non-specific to ultrasound treatment, reflecting only an altered vital state of the treated cells.
Subject(s)
Actin Cytoskeleton/drug effects , Antineoplastic Agents/pharmacology , HeLa Cells/ultrastructure , Methotrexate/pharmacology , Microtubules/drug effects , Organoplatinum Compounds/pharmacology , Ultrasonics , Actin Cytoskeleton/ultrastructure , Biopolymers , HeLa Cells/drug effects , Humans , Methotrexate/toxicity , Microtubules/ultrastructure , Organoplatinum Compounds/toxicity , Ultrasonics/adverse effectsABSTRACT
OBJECTIVE: The aim of this study was to establish: (i) which phase of the cell cycle is most sensitive to ultrasonic action; and (ii) whether and in which way ultrasound can influence components of the cytoskeleton. METHODS: HeLa cell monolayers grown on glass cover-slips in DEM medium were used in all experiments. For proliferation studies, the cell monolayers were trypsinized and the cells were resuspended in fresh medium. The structure of the cytoskeleton was studied by means of the indirect immunofluorescence method. The cells were sonicated by a cw ultrasound of 0.8 MHz at low SA intensities (50, 100 and 500 mW/cm2) for 5 and 10 min. RESULTS: The analysis of proliferation demonstrated that cells were most sensitive when undergoing M- and S-phases of the cell cycle. The ultrasonically induced disassembly of cytoskeleton components was most marked in microtubules and microfilaments due to depolymerization of basic proteins (tubulin and actin). The reaction of intermediate filaments was distinctly weaker. CONCLUSIONS: In-vitro treatment of tumour cells with low intensity ultrasound results in partial inhibition of proliferation as well as in partial disassembly of all components of the cytoskeleton. Ultrasonically induced changes of the cytoskeleton seem to be non-specific and temporary.
