Interaction of some estrogenic drugs with tubulin. Formation of twisted ribbon structures.

We studied the action of E-diethylstilbestrol (E-DES), erythro-hexestrol (erythro-HES), and E,E-dienestrol (E,E-DIES) on microtubule formation. The three drugs inhibit this formation from microtubular protein; the percentages of inhibition were, respectively, 15% and 45% for 1.25 X 10-s M E-DES and E,E-DIES. With purified tubulin 6S, 7.5 X 10(-6) M E,E-DIES and erythro-HES induced a 20% inhibition. In the case of E-DES, our results are in good agreement with previous ones. These drugs partially disrupt preformed microtubules. Moreover, when E,E-DIES (5 X 10(-5) M) is added to tubulin, loosely organized aggregates composed of twisted ribbon structure are formed. In the case of erythro-HES, similar structures were observed but at higher concentrations. With E-DES, no organized structures are present.