Inactivation of wild-type p53 by a dominant negative mutant renders MCF-7 cells resistant to tubulin-binding agent cytotoxicity

Br J Cancer. 2001 Sep 14;85(6):902-8. doi: 10.1054/bjoc.2001.2017.


The present study was performed to gain insight into the role of p53 on the cytotoxicity of tubulin-binding agents (TBA) on cancer cells. Drug sensitivity, cell cycle distribution and drug-induced apoptosis were compared in 2 lines derived from the mammary adenocarcinoma MCF-7: the MN-1 cell line containing wild-type p53 (wt-p53) and the MDD2 line, containing a dominant negative variant of the p53 protein (mut-p53). The MDD2 cell line was significantly more resistant to the cytotoxic effects of vinblastine and paclitaxel than the MN1 cell line. MN1 cells, but not MDD2 cells, displayed wt-p53 protein accumulation as well as p21/WAF1 and cyclin G1 induction after exposure to TBA. Both cell lines arrested at G(2)/M after drug treatment. However exposure of MN1 cells to TBA resulted in a stronger variation in mitochondrial membrane potential, associated with cleavage of PARP, and more apoptosis, as measured by annexin V expression. After exposure to vinblastine, Raf 1 kinase activity was reduced in MDD2 cells but not in MN1 cells. Addition of flavopiridol to vinblastine- and paclitaxel-treated cells reversed the MDD2-resistant phenotype by inducing G(1)cell cycle arrest and inhibiting endoreduplication. We conclude that the p53 status of cancer cells influences their sensitivity to TBA cytotoxicity. This effect is likely to involve differences in the apoptotic cascade.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents, Phytogenic / metabolism*
  • Antineoplastic Agents, Phytogenic / toxicity
  • Blotting, Northern
  • Blotting, Western
  • Caspase 3
  • Caspase 9
  • Caspases / metabolism
  • Cell Cycle / drug effects
  • Cyclin G
  • Cyclin G1
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins / metabolism
  • Drug Resistance, Neoplasm
  • Flow Cytometry
  • Humans
  • Paclitaxel / metabolism
  • Paclitaxel / toxicity
  • Proto-Oncogene Proteins c-raf / metabolism
  • Tubulin / metabolism*
  • Tumor Cells, Cultured / drug effects*
  • Tumor Cells, Cultured / metabolism
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • Vinblastine / metabolism
  • Vinblastine / toxicity


  • Antineoplastic Agents, Phytogenic
  • CCNG1 protein, human
  • CDKN1A protein, human
  • Cyclin G
  • Cyclin G1
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • Tubulin
  • Tumor Suppressor Protein p53
  • Vinblastine
  • Proto-Oncogene Proteins c-raf
  • CASP3 protein, human
  • CASP9 protein, human
  • Caspase 3
  • Caspase 9
  • Caspases
  • Paclitaxel