Usnic acid, a lichen metabolite, is known to exert
antimitotic and antiproliferative activities against normal and malignant human cells. Many
chemotherapy agents exert their activities by blocking cell cycle progression, inducing cell death through apoptosis. Microtubules,
protein structure involved in the segregation of chromosomes during mitosis, serve as chemotherapeutical targets due to their key role in cellular division as well as apoptosis. The aim of this work was to investigate whether
usnic acid affects the formation and/or stabilisation of microtubules by visualising microtubules and determining mitotic indices
after treatment. The
breast cancer cell line MCF7 and the
lung cancer cell line H1299 were treated with
usnic acid 29 microM for 24 hours and two positive controls:
vincristine (which prevents the formation of microtubules) or
taxol (which stabilizes microtubules). Treatment of MCF7 and H1299 cells with
usnic acid did not result in any morphological changes in microtubules or increase in the mitotic index. These results suggest that the
antineoplastic activity of
usnic acid is not related to alterations in the formation and/or stabilisation of microtubules.