2-Methoxyestradiol blocks cell-cycle progression at G2/M phase and inhibits growth of human prostate cancer cells

Addanki P. Kumar, Gretchen E. Garcia, Thomas J. Slaga

Research output: Contribution to journalArticle

81 Scopus citations

Abstract

2-Methoxyestradiol (2-ME), an endogenous metabolite of 17β-estradiol, is present in human blood and urine. Here we show for the first time that 2-ME significantly inhibited the growth of normal prostate epithelial cells and androgen-dependent LNCaP and androgen-independent DU145 prostate cancer cells. This growth inhibition was accompanied by a twofold increase in the G2/M population, with a concomitant decrease in the G1 population, as shown by cell-cycle analysis. 2-ME treatment affected the cell-cycle progression of prostate cancer cells specifically by blocking cells in the G2 phase. Immunoblot analysis of the key cell-cycle regulatory proteins in the G2/M phase showed a 14-fold increase in the expression of p21 and an eightfold increase in the expression of p34 cell division cycle 2 (cdc2). We also found an accumulation of phosphorylated cdc2 after 2-ME treatment. Furthermore, Wee 1 kinase was detectable after 2-ME treatment. 2-ME treatment also led to an increase in the activity of caspase-3, followed by apoptosis, as shown by terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate-biotin nick end-labeling and fluorescein isothiocyanate-poly(ADP-ribose) polymerase assay. Estrogen receptor levels did not change after treatment with 2-ME. Examination of the signaling pathways that mediate 2-ME-induced apoptosis showed reduction in the level of p53 expression and its DNA-binding activity. Given the fact that p53 mutations are common in patients with metastatic prostate cancer, our finding that 2-ME-mediated growth inhibition of human prostate cancer cells occurred in a p53-independent manner has considerable clinical significance. These findings, combined with the limited toxicity of 2-ME, may have significant implications for alternative treatment of advanced prostate cancer.

Original languageEnglish (US)
Pages (from-to)111-124
Number of pages14
JournalMolecular Carcinogenesis
Volume31
Issue number3
DOIs
StatePublished - Aug 23 2001
Externally publishedYes

Keywords

  • Apoptosis
  • Estrogenic metabolite
  • Wee1 kinase

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research

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