Paclitaxel conjugation with the analog of the gonadotropin-releasing hormone as a targeting moiety

A new targeted conjugates in which paclitaxel was used as a cytostatic compound and an analog of the gonadotropin-releasing hormone (GnRH) as a targeting moiety were synthesized. The molecule of the peptide hormone GnRH was modified to allow its connection to paclitaxel via spacer. The conjugates were prepared as prodrugs using 2'-hydroxyl group of paclitaxel. 4-Maleimidobutyric acid and chloroacetic acid served as spacers. The structures of the prepared derivatives were analysed by NMR and HR-MS. The conjugates MP264 and MP265 were chosen and their antiproliferative effect was tested in the breast cancer cell line MCF-7 using the MTT test of cell viability and neutral red uptake test. In MCF-7 cells, conjugate MP265 showed higher antiproliferative effect than paclitaxel alone. Receptor saturation tests showed that the unconjugated peptide analog of GnRH decreased efficacy of conjugate MP265 in concentration- and time-dependent manner. In conclusion, the paclitaxel conjugate with the analog of GnRH exhibited targeted antiproliferative effect for which its further testing will be implemented. (C) 2011 Elsevier B.V. All rights reserved.