Annonacin induces cell cycle-dependent growth arrest and apoptosis in estrogen receptor-α-related pathways in MCF-7 cells

J Ethnopharmacol. 2011 Oct 11;137(3):1283-90. doi: 10.1016/j.jep.2011.07.056. Epub 2011 Aug 4.


Ethnopharmacological relevance: Tamoxifen resistance is common in estrogen receptor-α (ERα)-positive breast cancers. Pawpaw and soursop are anticancer annonaceous plants in complementary medicine. Thus, we studied the effects of annonacin, an annonaceous acetogenin, in breast cancer cells.

Materials and methods: Cell growth and ERα-related pathways were studied. The effects of annonacin were tested in MCF-7 xenografts in nude mice.

Results: In ERα-positive MCF-7 cells, annonacin (half-effective dose ED(50) = 0.31 μM) and 4-hydroxytamoxifen (ED(50) = 1.13 μM) decreased cell survival whereas annonacin (0.5-1 μM) increased cell death at 48 h. Annonacin and 4-hydroxytamoxifen were additive in inhibiting cell survival. Annonacin (0.1 μM) induced G(0)/G(1) growth arrest while increasing p21(WAF1) and p27(kip1) and decreasing cyclin D1 protein expression. Annonacin (0.1μM) decreased cyclin D1 protein expression more than 4-hydroxytamoxifen (1 μM). Annonacin (0.1 μM) increased apoptosis while decreasing Bcl-2 protein expression. The combination of annonacin (0.1 μM) and 4-hydroxytamoxifen (1 μM) decreased Bcl-2 protein expression and ERα transcriptional activity more than annonacin (0.1 μM) did alone. Annonacin, but not 4-hydroxytamoxifen, decreased ERα protein expression. Moreover, annonacin decreased phosphorylation of ERK1/2, JNK and STAT3. In nude mice, annonacin decreased MCF-7 xenograft tumor size at 7-22 days. Moreover, annonacin decreased ERα, cyclin D1 and Bcl-2 protein expression in the xenograft at 22 days.

Conclusions: Annonacin induced growth arrest and apoptosis in ERα-related pathways in MCF-7 cells. Annonacin and 4-hydroxytamoxifen were additive in inhibiting cell survival and ERα transcriptional activity. Moreover, annonacin attenuated MCF-7 xenograft tumor growth while inhibiting ERα, cyclin D1 and Bcl-2 protein expressions in nude mice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents, Phytogenic / pharmacology*
  • Apoptosis / drug effects*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Cell Cycle Checkpoints / drug effects*
  • Cell Line, Tumor
  • Cyclin D1 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p27 / metabolism
  • Dose-Response Relationship, Drug
  • Estrogen Antagonists / pharmacology*
  • Estrogen Receptor alpha / antagonists & inhibitors*
  • Estrogen Receptor alpha / genetics
  • Estrogen Receptor alpha / metabolism
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Female
  • Furans / pharmacology*
  • Humans
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Lactones / pharmacology*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • Phosphorylation
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • STAT3 Transcription Factor / metabolism
  • Signal Transduction / drug effects
  • Tamoxifen / analogs & derivatives
  • Tamoxifen / pharmacology
  • Time Factors
  • Transfection
  • Tumor Burden / drug effects
  • Xenograft Model Antitumor Assays


  • Antineoplastic Agents, Phytogenic
  • CCND1 protein, human
  • CDKN1A protein, human
  • CDKN1B protein, human
  • Cyclin-Dependent Kinase Inhibitor p21
  • Estrogen Antagonists
  • Estrogen Receptor alpha
  • Furans
  • Lactones
  • Proto-Oncogene Proteins c-bcl-2
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • estrogen receptor alpha, human
  • Tamoxifen
  • Cyclin D1
  • Cyclin-Dependent Kinase Inhibitor p27
  • afimoxifene
  • annonacin
  • Extracellular Signal-Regulated MAP Kinases
  • JNK Mitogen-Activated Protein Kinases