title: Comparative efficacy of novel platinum(IV) compounds with established chemotherapeutic drugs in solid tumour models.
abstract: Platinum(II)-based anticancer drugs are associated with high reactivity and thus a poor biological stability. The platinum(IV)-complexes display potential advantages due to their greater stability and bioreductive activation, thereby allowing a greater proportion of the drug to arrive at the target intact. All compounds tested were able to produce cytotoxicity in monolayer cell cultures, however, the potencies of platinum(IV) drugs were lower than that observed for the platinum(II) compounds or established organic chemotherapeutic agents. There was no significant alteration in the potency of platinum(II) or (IV) compounds to produce cytotoxicity in multicellular tumour spheroids (MCTS) compared to monolayer cultures. All the organic and platinum-based cytotoxic agents produced, to varying degrees, either a retardation or reduction in MCTS growth. Proliferating cells were restricted to the outer two to three cellular layers in intermediate (d=350 microm) and large (d=600 microm) MCTS. Regardless of MCTS size, drug treatment produced a larger and more widely distributed proliferating cell population, consistent with the recruitment of quiescent cells to the proliferating pool following cytotoxic damage. Histology indicated that the predominant morphological change was that of apoptosis, although there was some drug-dependent effects such as the metaphase arrest produced by vinblastine and chromatin dispersal to the periphery of nuclei produced by doxorubicin. In summary, whilst the platinum(IV) derivatives were able to produce cytotoxicity via apoptosis, the introduction of a stable axial group significantly retarded the rate at which this occurred.
authors.affiliation: Centre for Heavy Metals Research, School of Chemistry, The University of Sydney, NSW 2006, Sydney, Australia.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Hall
authors.forename: Catherine
authors.initials: C
authors.lastname: Martin
authors.forename: David J P
authors.initials: DJ
authors.lastname: Ferguson
authors.forename: Roger M
authors.initials: RM
authors.lastname: Phillips
authors.forename: Trevor W
authors.initials: TW
authors.lastname: Hambley
authors.forename: Richard
authors.initials: R
authors.lastname: Callaghan
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D017209:Apoptosis; D001973:Bromodeoxyuridine / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D009336:Necrosis; D009944:Organoplatinum Compounds / Q000138:chemical synthesis / Q000494:pharmacology*; D018874:Spheroids, Cellular / Q000187:drug effects* / Q000473:pathology; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D009944:Organoplatinum Compounds; D001973:Bromodeoxyuridine; D002945:Cisplatin