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

Abstract

2-Methoxyestradiol (2-ME), an endogenous metabolite of 17beta-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 G(2)/M population, with a concomitant decrease in the G(1) 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 G(2) phase. Immunoblot analysis of the key cell-cycle regulatory proteins in the G(2)/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.

2-Methoxyestradiol: New perspectives in colon carcinoma treatment

“…The comparison between other cancer cell lines characterized by a different p53 behaviour will allow a better definition of the p53-independent role of p21. The effects of 2-ME on cell cycle we observed are in M a n u s c r i p t 13 agreement with previous reports on other cancer cell lines (Kumar et al 2001;Lin et al 2001;Dobos et al 2004;Li et al 2004;Kar et al 2008;Maran et al 2008). The above observations prompted us to investigate the possible pro-apoptotic effect of 2-ME.…”

Inhibition of MDA-MB-231 cell cycle progression and cell proliferation by C-2-substituted oestradiolmono- andbis-3-O-sulphamates

“…2-MeOE2 induces apoptosis and inhibits angiogenesis in many tumour models, indicating that this compound has considerable potential as an antitumour agent. [1][2][3][4][5][6][7][8][9][10][11] Previous studies from our group have shown that these sulphamoylated derivatives induce an irreversible G2-M arrest and inhibit proliferation of not only androgen receptor 1ve/2ve prostrate, ovarian, and breast cancer cells, but also cells resistant to conventional chemotherapeutic agents, such as adriamycin and cisplatin. 26,27 In all these studies, sulphamoylated derivatives of 2-MeOE2, 2-MeOE2-MATE, and 2-MeOE2bisMATE are significantly more potent at inducing cell cycle arrest and apoptosis than 2-MeOE2.…”

“…[12][13][14] Although the exact mechanism by which 2-MeOE2 induces its antiangiogenic and antitumour effects is not known, several cellular responses, such as G2-M cell cycle arrest, caspase-3 activation, BCL-2 phosphorylation, increased expression of FAS and p53, downregulation of HIF-1, mitochondrial release of cytochrome c, and inhibition of tubulin polymerisation, have been reported. 4,5,9,10,[15][16][17][18][19][20][21] However, it has been shown that its antimitotic effects are mediated via inhibition of tubulin polymerisation by binding to the colchicine binding site on tubulin. 19,20 Because of the antiproliferative properties associated with 2-MeOE2, several analogues of 2-MeOE2 have been synthesised and tested for various biological activities.…”

Potential Role of Estrogen Metabolite 2-Methoxyestradiol in Health and Disease

“…4 In contrast to its effects on malignant and transformed cells, 2-ME2 has minimal to no significant effects on the growth of normal cells including lymphocytes. [5][6][7][8][9] There are also indications that 2-ME2 affects actively proli ferating cells (with no effect on quiescent cells) possibly due to disrup tion of cellular events associated with proli feration.…”

“…5,9,12,20,30,31 At the biochemical and molecular levels, 2-ME2-induced G2-M cell cycle arrest has been characterized by the induction of cyclin B and Cdc2 kinase activity. 5,20,32 2-ME2 has also been reported to induce G2-M arrest in breast cancer cell lines regardless of hormone receptor status.…”