Class III beta-tubulin expression and in vitro resistance to microtubule targeting agents

Br J Cancer. 2010 Jan 19;102(2):316-24. doi: 10.1038/sj.bjc.6605489. Epub 2009 Dec 22.


Background: Class III beta-tubulin overexpression is a marker of resistance to microtubule disruptors in vitro, in vivo and in the clinic for many cancers, including breast cancer. The aims of this study were to develop a new model of class III beta-tubulin expression, avoiding the toxicity associated with chronic overexpression of class III beta-tubulin, and study the efficacy of a panel of clinical and pre-clinical drugs in this model.

Methods: MCF-7 (ER+ve) and MDA-MB-231 (ER-ve) were either transfected with pALTER-TUBB3 or siRNA-tubb3 and 24 h later exposed to test compounds for a further 96 h for proliferation studies. RT-PCR and immunoblotting were used to monitor the changes in class III beta-tubulin mRNA and protein expression.

Results: The model allowed for subtle changes in class III beta-tubulin expression to be achieved, which had no direct effect on the viability of the cells. Class III beta-tubulin overexpression conferred resistance to paclitaxel and vinorelbine, whereas downregulation of class III beta-tubulin rendered cells more sensitive to these two drugs. The efficacy of the colchicine-site binding agents, 2-MeOE2, colchicine, STX140, ENMD1198 and STX243 was unaffected by the changes in class III beta-tubulin expression.

Conclusion: These data indicate that the effect of class III beta-tubulin overexpression may depend on where the drug's binding site is located on the tubulin. Therefore, this study highlights for the first time the potential key role of targeting the colchicine-binding site, to develop new treatment modalities for taxane-refractory breast cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / metabolism*
  • Antineoplastic Agents / pharmacology
  • Binding Sites
  • Breast Neoplasms
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Drug Resistance, Neoplasm / physiology*
  • Female
  • Humans
  • Microtubules / chemistry
  • Microtubules / drug effects
  • Transfection
  • Tubulin / biosynthesis*
  • Tubulin Modulators / chemistry
  • Tubulin Modulators / metabolism*
  • Tubulin Modulators / pharmacology


  • Antineoplastic Agents
  • Tubulin
  • Tubulin Modulators