Doxorubicin effects on contractile structures and molecules

The effects of doxorubicin on embryonic spinal motoneurons cultured in vitro: cytoskeletal response

The interaction of doxorubicin with tubulin in spinal motoneuronal cells cultured in vitro has been examined by laser scan microscopy with an immunocytological double staining technique, and by biochemical analysis. Results obtained by laser scan microscopy indicate that doxorubicin (2 x 10(-8) M) was able to induce fragmentation or disappearance of microtubules in motoneuronal cells. Motoneurons were identified by their positivity to anti-CAT antibody. This observation was then studied by biochemical analysis on purified calf brain tubulin. Even treatment with a high dose of doxorubicin (1.2 x 10(-5) M) does not impair tubulin polymerization. The finding supports the possibility that doxorubicin interacts with MAPs or other polypeptides present in the cytomatrix that coassemble with tubulin and are necessary for microtubule formation.

Interaction of cardiac alpha-actinin and actin in the presence of doxorubicin

The therapeutic use of doxorubicin (an antitumoral antibiotic belonging to the anthracycline group) is limited by its cardiotoxicity. Adriamycin (DXR) causes myocardial subcellular damage, such as myocytolysis, disarray of actin filaments, and alterations in the Z-band with loss of sarcomeric organization. We studied the effect of stoichiometrical concentrations of DXR on the interaction between cardiac actin and alpha-actinin in solution. Doxorubicin inhibits the formation of alpha-actinin/actin tridimensional networks and bundles. The main effect of the drug seems to be on the size of the actin polymers.