Toxicity of platinum(II) amino acid (N,O) complexes parallels their binding to DNA as measured in a new solid phase assay involving a fluorescent HMG1 protein construct readout.
The compound [Pt(lysine)Cl2] (Kplatin) was previously identified in a study of platinum amino acid complexes as a potential antitumor drug candidate. The DNA binding properties, high mobility group (HMG)-domain protein affinity for the platinated DNA, and cytotoxicity against HeLa cells of Kplatin and three related (N,O) chelated platinum(II) amino acid complexes, [Pt(arginine)Cl2] (Rplatin), K[Pt(Nepsilon-acetyllysine)Cl2] (NacKplatin), and K[Pt(norleucine)Cl2] (Norplatin), are reported. The four complexes have identical PtCl2(N,O) coordination environments. A new solid phase screening methodology was devised in which platinated DNA probes are covalently attached to a nylon support and tested for their ability to bind a fluorescently labeled HMG-domain protein. The fluorescent HMG-domain protein was generated by expressing a fusion of the green fluorescent protein (GFP) with recombinant rat HMG1. Binding revealed by the solid phase method correlated well with the results of gel mobility shift and HeLa cytotoxicity assays. These results suggest that the net charge on the complex, rather than the nature of the side chain, is the most important factor underlying the DNA binding properties and toxicity of amino acid (N,O) chelated platinum complexes. This property explains why Kplatin was previously selected from the pool of platinum amino acid complexes based on the ability of its DNA adducts to bind HMG1.
Ziegler
C J
CJ
Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139, USA.
Sandman
K E
KE
Liang
C H
CH
Lippard
S J
SJ
D000818:Animals; D002945:Cisplatin / Q000031:analogs & derivatives / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D018736:DNA Adducts / Q000032:analysis; D004354:Drug Screening Assays, Antitumor / Q000379:methods*; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006367:HeLa Cells / Q000187:drug effects; D006609:High Mobility Group Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008164:Luminescent Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D008239:Lysine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000633:toxicity; D009944:Organoplatinum Compounds / Q000378:metabolism* / Q000633:toxicity*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018675:Toxicity Tests / Q000379:methods
D018736:DNA Adducts; D006609:High Mobility Group Proteins; D008164:Luminescent Proteins; D009944:Organoplatinum Compounds; D011993:Recombinant Fusion Proteins; C401402:dichloro(lysine)platinum(II); D049452:Green Fluorescent Proteins; D004247:DNA; D008239:Lysine; D002945:Cisplatin