In vivo inhibition of angiogenesis by sulphamoylated derivatives of 2-methoxyoestradiol

Abstract

Drugs that inhibit growth of tumours and their blood supply could have considerable therapeutic potential. 2-Methoxyoestradiol-3,17-O,O-bis-sulphamate (2-MeOE2bisMATE) has been shown to inhibit the proliferation of MCF-7 (ER+) breast cancer cells and angiogenesis in vitro. 2-MeOE2bisMATE and its analogue, 17-Cym-2-MeOE2MATE, were investigated for their ability to inhibit in vivo angiogenesis and tumour growth. The mouse Matrigel plug assay for angiogenesis was used to investigate the effect of compounds on neovascularisation and was quantified using a FITC-dextran injection technique. Nude mice bearing tumours derived from MCF-7 cells were used to assess efficacy on tumour growth. Tumour sections were stained for VEGFR-2 and Ki67 to assess tumour angiogenesis and cell proliferation respectively. Matrigel plugs supplemented with basic fibroblast growth factor resulted in increased neovascularisation over 7 days. Oral administration of 2-MeOE2bisMATE for 7 days at 10 or 50 mg kg À1 significantly reduced neovascularisation to or below control levels respectively. 17-Cym-2-MeOE2MATE at 20 mg kg À1 was equally effective. 2-MeOE2bisMATE, dosed daily for 21 days, caused a 52% reduction in tumour growth at 5 mg kg À1 and 38% regression at 20 mg kg À1 . 17-Cym-2-MeOE2MATE (20 mg kg À1 ) reduced tumour growth by 92%. Immunohistochemistry revealed a reduction in angiogenesis and proliferation. Matrigel plug and tumour imaging after FITC-dextran injection indicated that 2-MeOE2bisMATE caused a marked disruption of vasculature. These sulphamoylated oestrogen derivatives have been shown to be potent inhibitors of angiogenesis in vivo. This, together with their ability to inhibit tumour growth, indicates the potential of this new class of drugs for further development for cancer therapy.

BCRP expression does not result in resistance to STX140 in vivo, despite the increased expression of BCRP in A2780 cells in vitro after long-term STX140 exposure

“…A novel oestrogen response element (ERE) has been found in the human BCRP promoter (Ee et al, 2004a, b), although it has also been suggested that oestradiol post-transcriptionally downregulates BCRP (Imai et al, 2005). Despite these observations, in this study the increased expression of BCRP in A2780.140 cells after long-term exposure to STX140 cannot be mediated by the ER as the A2780 cell line is ER negative and STX140 is non-oestrogenic (Chander et al, 2007).…”

“…As the IC 50 of STX140 in BCRPexpressing cells in vitro is only 1.5 -2 mM, this dose may be regularly or continuously exceeded in the in vivo model at a 20 mg kg À1 per day dose, resulting in good efficacy of STX140 in BCRP-expressing tumours in vivo. In addition to its antiproliferative properties, the anti-angiogenic qualities of STX140 also contribute to its efficacy in vivo, as STX140 has been shown to cause significant inhibition of angiogenesis when dosed at 10 mg kg À1 in a Matrigel plug assay (Chander et al, 2007) and at 20 mg kg À1 in xenograft models (Chander et al, 2007;Foster et al, 2008). This property would be unaffected by BCRP expression in the cancer cells of the tumour, adding to the efficacy of STX140 in BCRP-expressing tumours.…”

“…STX140 and other 2-substituted oestrogen sulphamates are highly effective at inhibiting the growth of cancer cells and angiogenesis, both in vitro and in vivo (Chander et al, 2007;Newman et al, 2007;Foster et al, 2008). Previous work has indicated that these compounds are also active against cell lines and tumours resistant to other chemotherapeutic regimens, including those which express P-glycoprotein (Day et al, 2003;Suzuki et al, 2003;Newman et al, 2008).…”

“…One of the most efficacious of these compounds is 2-methoxyoestradiol-3,17-O,O-bis-sulphamate (STX140). It is highly anti-proliferative and anti-angiogenic in vitro (Raobaikady et al, 2003;Newman et al, 2004), and is orally bioavailable (Ireson et al, 2004;Newman et al, 2006), potently inhibiting tumour growth (Utsumi et al, 2005;Foster et al, 2008) and angiogenesis (Chander et al, 2007) in vivo. STX140 is currently in pre-clinical development as a novel anticancer therapy .…”

The in vivo properties of STX243: a potent angiogenesis inhibitor in breast cancer

“…MDA-MB-231 xenograft tumours were used to compare the in vivo efficacy of all three compounds, and a tumour resistance study was conducted to investigate the ability of STX243 to inhibit the growth of paclitaxel-resistant MCF-7dox40 xenograft tumours. The antiangiogenic potential of STX243 was also evaluated using an established Matrigel plug-based methodology (Passaniti et al, 1992;Prewett et al, 1999;Chander et al, 2007). To ascertain whether the biological properties of STX243 could overcome the oral bioavailability problems encountered with 2-MeOE2, the pharmacokinetics of STX243 were examined in adult female Wistar rats.…”