Identification of mitogen-activated protein kinase kinase as a chemoresistant pathway in MCF-7 cells by using gene expression microarray

Surgery. 2002 Aug;132(2):293-301. doi: 10.1067/msy.2002.125389.


Background: Components of the mitogen-activated protein kinase (MAPK) cascade have been implicated in apoptotic regulation. This study used gene expression profiling analysis to identify and implicate mitogen-activated protein kinase kinase (MEK5)-BMK1 (big mitogen-activated kinase-1)/extracellular signal related protein kinase (ERK5) pathway as a novel target involved in chemoresistance.

Methods: Differential gene expression between apoptotically sensitive (APO+) and apoptotically resistant (APO-) MCF-7 cell variants was determined by using microarray and confirmed by reverse transcriptase- polymerase chain reaction (RT-PCR). An apoptotic/viability reporter gene assay was used to deter-mine the effects of the transfection of a dominant-negative mutant of BMK1 (BMK1/DN) in conjunction with apoptotic-inducing agents (etoposide, tumor necrosis factor-alpha [TNF], or TNF-related apoptosis-inducing ligand [TRAIL]), with or without phorbol ester (PMA).

Results: Of the 1186 genes detected through microarray analysis, MEK5 was increased 22-fold in APO- cells. Overexpression of MEK5 was confirmed by using RT-PCR analysis. Expression of BMK1/DN alone resulted in a dose-dependent increase in cell death versus control (P <.05). In addition, BMK1/DN enhanced the sensitivity of MCF-7 cells to treatment-induced cell death (P <.05). The ability of PMA to partially suppress TRAIL- and TNF-induced cell death was inhibited by BMK1/DN. However, only TRAIL-induced activity suppression reached statistical significance (P <.05).

Conclusions: The overexpression of MEK5 in APO- MCF-7 breast carcinoma cells shows that this MAPK signaling protein represents a potent survival molecule. Molecular inhibition of MEK5 signaling may represent a mechanism for sensitizing cancer cells to chemotherapeutic regimens.

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents, Phytogenic / pharmacology
  • Apoptosis / drug effects
  • Apoptosis / genetics
  • Apoptosis Regulatory Proteins
  • Breast Neoplasms*
  • Carcinogens / pharmacology
  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Drug Resistance, Neoplasm / genetics*
  • Etoposide / pharmacology
  • Female
  • Humans
  • MAP Kinase Kinase 5
  • Membrane Glycoproteins / pharmacology
  • Mitogen-Activated Protein Kinase 7
  • Mitogen-Activated Protein Kinase Kinases / genetics*
  • Mitogen-Activated Protein Kinases / genetics
  • Oligonucleotide Array Sequence Analysis
  • Phorbol Esters / pharmacology
  • TNF-Related Apoptosis-Inducing Ligand
  • Tumor Cells, Cultured / cytology
  • Tumor Cells, Cultured / drug effects
  • Tumor Cells, Cultured / enzymology
  • Tumor Necrosis Factor-alpha / pharmacology


  • Antineoplastic Agents
  • Antineoplastic Agents, Phytogenic
  • Apoptosis Regulatory Proteins
  • Carcinogens
  • Membrane Glycoproteins
  • Phorbol Esters
  • TNF-Related Apoptosis-Inducing Ligand
  • TNFSF10 protein, human
  • Tumor Necrosis Factor-alpha
  • Etoposide
  • Mitogen-Activated Protein Kinase 7
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 5
  • MAP2K5 protein, human
  • Mitogen-Activated Protein Kinase Kinases