Tamoxifen and Fulvestrant Hybrids Showed Potency as Selective Estrogen Receptor Down-Regulators

Title:Tamoxifen and Fulvestrant Hybrids Showed Potency as Selective Estrogen Receptor Down-Regulators

Volume: 13 Issue: 3

Author(s): Takuji Shoda*, Masashi Kato, Takuma Fujisato, Yosuke Demizu, Hideshi Inoue, Mikihiko Naito and Masaaki Kurihara

Affiliation:

• National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501,Japan

Keywords: Tamoxifen, fulvestrant, estrogen receptor, selective estrogen receptor down-regulator, ER-positive breast cancer.

Abstract: Background: Estrogen receptors (ERs) are an important target for the management of breast cancers. Selective estrogen receptor down-regulators (SERDs) block ER activity, as well as reduce ERα protein levels in cells, and therefore are promising therapeutic agents for the treatment of breast cancers.

Objective: In order to develop potent SERDs, we prepared tamoxifen and fulvestrant hybrids and evaluated their binding activity and down-regulation of ERα.

Methods: We designed and synthesized tamoxifen derivatives, which had a 4,4,5,5,5- pentafluoropentyl group on the terminal alkyl chain. The oxidation state of the sulfur atom and alkyl length between the sulfur and nitrogen atoms were varied. Western blotting was performed to determine the ability to down-regulate ERα. Binding affinities of synthesized compounds were evaluated by a fluorescence polarization-based competitive binding assay.

Results: We successfully prepared nine compounds. Treatment with 11, 14, and 17 effectively reduced ERα protein levels in MCF-7 cells in a concentration-dependent manner. This reduction was inhibited by a proteasome inhibitor. The ability of 14 to down-regulate the ERα protein level was equal to fulvestrant. All compounds showed a largely equal affinity for ERα.

Conclusion: As indicated by Western blots, the ERα degradation activity was observed only in the series of butyl linker derivatives, namely, 11, 14, and 17. These findings suggest that the specific length of the alkyl chain is an important factor in controlling the down-regulation of ER. These results provide useful information for designing promising SERD candidates.

Cite this article as:

Shoda Takuji*, Kato Masashi, Fujisato Takuma, Demizu Yosuke, Inoue Hideshi, Naito Mikihiko and Kurihara Masaaki, Tamoxifen and Fulvestrant Hybrids Showed Potency as Selective Estrogen Receptor Down-Regulators, Medicinal Chemistry 2017; 13 (3) . https://dx.doi.org/10.2174/1573406412666160805101408

DOI https://dx.doi.org/10.2174/1573406412666160805101408	Print ISSN 1573-4064
Publisher Name Bentham Science Publisher	Online ISSN 1875-6638