Chemistry, antiproliferative properties, tumor selectivity and molecular mechanisms of novel gold(III) compounds for cancer treatment: a systematic study

The antiproliferative properties of a group of 13 structurally diverse gold(III) compounds, including six mononuclear gold(III) complexes, five dinuclear oxobridged gold(III) complexes, and two organogold(III) compounds, toward several human tumor cell lines were evaluated in vitro using a systematic screening strategy. Initially all compounds were tested against a panel of 12human tumor cell lines, and the best performers were tested against a larger 36-cell-line panel. Very pronounced antiproliferative properties were highlighted in most cases, with cytotoxic potencies commonly falling in the low micromolar—and even nanomolar—range. Overall, goodto- excellent tumor selectivity was established for at least seven compounds, making them particularly attractive for further pharmacological evaluation. Compare analysis suggested that the observed antiproliferative effects are caused by a variety of molecular mechanisms, in most cases ‘‘DNA-independent,’’ and completely different from those of platinum drugs. Remarkably, some new biomolecular systems such as histone deacetylase, protein kinase C/staurosporine, mammalian target of rapamycin/rapamycin, and cyclin-dependent kinases were proposed for the first time as likely biochemical targets for the gold(III) species investigated. The results conclusively qualify gold(III) compounds as a promising class of cytotoxic agents, of outstanding interest for cancer treatment, while providing initial insight into their modes of action.