Apigenin inhibits growth and induces G2/M arrest by modulating cyclin-CDK regulators and ERK MAP kinase activation in breast carcinoma cells

Anticancer Res. Jan-Feb 2001;21(1A):413-20.

Abstract

We have previously reported that apigenin inhibits the growth of thyroid cancer cells by attenuating epidermal growth factor receptor (EGF-R) tyrosine phosphorylation and phosphorylation of ERK mitogen-activated protein (MAP) kinase. In this study, we assessed the growth inhibitory effect of apigenin on MCF-7 breast carcinoma cells that express two key cell cycle regulators, wild-type p53 and the retinoblastoma tumor suppressor protein (Rb), and MDA-MB-468 breast carcinoma cells that are mutant for p53 and Rb negative. We found that apigenin potently inhibited growth of both MCF-7 and MDA-MB-468 breast carcinoma cells. The approximate IC50 values determined after 3 days incubation, were 7.8 micrograms/ml for MCF-7 cells, and 8.9 micrograms/ml for MDA-MB-468 cells, respectively. Because the cell cycle studies using FACS showed that both MCF-7 and MDA-MB-468 cells were arrested in G2/M phase after apigenin treatment, we studied the effects of apigenin on cell cycle regulatory molecules. We observed that G2/M arrest by apigenin involved a significant decrease in cyclin B1 and CDK1 protein levels, resulting in a marked inhibition of CDK1 kinase activity. Apigenin reduced the protein levels of CDK4, cyclins D1 and A, but did not affect cyclin E, CDK2 and CDK6 protein expression. In MCF-7 cells, apigenin markedly reduced Rb phosphorylation after 12 h. We also found that apigenin treatment resulted in a dose- and time-dependent inhibition of ERK MAP kinase phosphorylation and activation in MDA-MB-468 cells. These results suggest that apigenin is a promising antibreast cancer agent and its growth inhibitory effects are mediated by targeting different signal transduction pathways in MCF-7 and MDA-MB-468 breast carcinoma cells.

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Apigenin
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology
  • CDC2 Protein Kinase / metabolism
  • Carcinoma / metabolism*
  • Carcinoma / pathology
  • Cell Division / drug effects
  • Cyclin-Dependent Kinases / metabolism*
  • Cyclins / metabolism*
  • Female
  • Flavonoids / pharmacology*
  • G2 Phase / drug effects
  • Humans
  • Kinetics
  • MAP Kinase Signaling System / drug effects*
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases / metabolism
  • Mitosis / drug effects
  • Phosphorylation
  • Retinoblastoma Protein / metabolism
  • Tumor Cells, Cultured

Substances

  • Antineoplastic Agents
  • Cyclins
  • Flavonoids
  • Retinoblastoma Protein
  • Apigenin
  • CDC2 Protein Kinase
  • Cyclin-Dependent Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases