Microtubules and resistance to tubulin-binding agents.

Microtubules are dynamic structures composed of alpha-beta-tubulin heterodimers that are essential in cell division and are important targets for cancer drugs. Mutations in beta-tubulin that affect microtubule polymer mass and/or drug binding are associated with resistance to tubulin-binding agents such as paclitaxel. The aberrant expression of specific beta-tubulin isotypes, in particular betaIII-tubulin, or of microtubule-regulating proteins is important clinically in tumour aggressiveness and resistance to chemotherapy. In addition, changes in actin regulation can also mediate resistance to tubulin-binding agents. Understanding the molecular mechanisms that mediate resistance to tubulin-binding agents will be vital to improve the efficacy of these agents.