Elena Gadoni

Cytoskeletal modifications induced by 4-hydroxynonenal

The antiproliferative action of 4-hydroxynonenal (HNE) could be related to an interaction with cytoskeletal structures. In this paper the effects exerted by HNE on microtubules and on microfilaments are examined by immunofluorescence. HNE alters cell morphology causing both the depolymerization of the microtubular structures and the dissolution of the stress-fibres. Taxol protects microtubules, preventing the depolymerizing effect of the aldehyde. The action of HNE could be attributed to its affinity for sulphydryl groups, which are essential in maintaining tubulin and actin both in the polymerized form.

Effects of some aldehydes on brain microtubular protein

4-Hydroxynonenal is one of the main breakdown products of lipid peroxidation. It has an antiproliferative effect, which may partly be the consequence of an interaction with cytoskeletal structures. Its effects on microtubular protein are compared with those of homologous aldehydes with the same number of carbon atoms, and with that of benzaldehyde. Unlike the other aliphatic aldehydes, this latter aldehyde does not impair microtubular functions at every concentration in the range. Nonanal has the greatest effect on tubulin polymerization, whereas it only slightly impairs colchicine binding activity. 2-Nonenal and 4-hydroxynonenal have less inhibiting effect on tubulin polymerization; their effect on colchicine binding activity is dose-dependent. The targets of 4-hydroxynonenal on tubulin are -SH groups; the action mechanism of other aldehydes has not yet been identified.

Phenylazoxycyanide damages microtubular protein more than its reference antibiotic, calvatic acid

The effect of phenylazoxycyanide and calvatic acid, its reference antibiotic, on some functions of tubulin obtained from different sources has been studied. Our purpose was to establish a possible correlation between the antitumour activity of these drugs and their antimicrotubular action. Microtubules are subcellular structures involved in proliferation and maintenance of the cell shape and probably in malignant transformation; indeed most antimitotic drugs influence the stability of microtubules through the interaction with tubulin, their main protein. In this work we found phenylazoxycyanide impairs, more than calvatic acid, polymerization of purified tubulin from calf brain. It also damages, in a dose-dependent manner, colchicine-binding ability of tubulin derived from rat liver and AH-130 Yoshida ascite hepatoma cells. Compounds displaying an azoxycyano group may represent new antimicrotubular agents and their effect could be modulated by the different polarity and structural characteristic of the molecule.