Enhancement of therapeutic effect in breast cancer with a steroid-conjugated ruthenium complex

Abstract

A new hybrid metallic prodrug Te–S–S–NHC–Ru (Te–S–S–NHC: 17-α-[1,3-bis(4-(tert-butyl)benzyl)-4-methyl-2,3-dihydro-1H-imidazole-bis(2-diethylcarbonate)disulfide-1H-1,2,3-triazol-1-yl]-19-testosterone) was designed and synthesized by a targeting group-drug conjugate strategy with 17α-ethynyl testosterone as the carrier vector to conjugate to our previously reported ruthenium N-heterocyclic carbene complex (NHC–Ru) with a disulfide linkage. It could be applied as a GSH-induced therapeutics system with high selectivity over potential interference by various biological compounds. The anticancer activity of the new ruthenium complex was investigated in vitro and in vivo. MTT assay against progesterone receptor positive MCF-7 (PR+) and progesterone receptor negative MBA-MD-231 (PR−) human breast cancer cell lines revealed that the cytotoxicity of the PR-targeted agent was significantly higher in PR(+) than in PR(−) cells caused by the selective cellular uptake. Moreover, in vivo antitumor activity studies indicated that Te–S–S–NHC–Ru induced a smaller tumor volume and a longer survival time of tumor-bearing mice after treatment. Thus Te–S–S–NHC–Ru may be a promising ruthenium-based anti-cancer agent for the effective treatment of tumors.