title: Recognition of DNA modified by trans-[PtClNH(4-hydroxymethylpyridine)] by tumor suppressor protein p53 and character of DNA adducts of this cytotoxic complex.
abstract: trans-[PtCl(2)NH(3)(4-Hydroxymethylpyridine)] (trans-PtHMP) is an analogue of clinically ineffective transplatin, which is cytotoxic in the human leukemia cancer cell line. As DNA is a major pharmacological target of antitumor platinum compounds, modifications of DNA by trans-PtHMP and recognition of these modifications by active tumor suppressor protein p53 were studied in cell-free media using the methods of molecular biology and biophysics. Our results demonstrate that the replacement of the NH(3) group in transplatin by the 4-hydroxymethylpyridine ligand affects the character of DNA adducts of parent transplatin. The binding of trans-PtHMP is slower, although equally sequence-specific. This platinum complex also forms on double-stranded DNA stable intrastrand and interstrand cross-links, which distort DNA conformation in a unique way. The most pronounced conformational alterations are associated with a local DNA unwinding, which was considerably higher than those produced by other bifunctional platinum compounds. DNA adducts of trans-PtHMP also reduce the affinity of the p53 protein to its consensus DNA sequence. Thus, downstream effects modulated by recognition and binding of p53 protein to DNA distorted by trans-PtHMP and transplatin are not likely to be the same. It has been suggested that these different effects may contribute to different antitumor effects of these two transplatinum compounds.
authors.affiliation: Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
authors.forename: Kristýna
authors.initials: K
authors.lastname: Stehlíková
authors.forename: Jana
authors.initials: J
authors.lastname: Kaspárková
authors.forename: Olga
authors.initials: O
authors.lastname: Nováková
authors.forename: Alberto
authors.initials: A
authors.lastname: Martínez
authors.forename: Virtudes
authors.initials: V
authors.lastname: Moreno
authors.forename: Viktor
authors.initials: V
authors.lastname: Brabec
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002942:Circular Dichroism; D004247:DNA / Q000187:drug effects / Q000378:metabolism*; D018736:DNA Adducts / Q000737:chemistry / Q000378:metabolism*; D009841:Oligonucleotides; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D011485:Protein Binding; D011725:Pyridines / Q000494:pharmacology*; D013054:Spectrophotometry, Atomic; D013056:Spectrophotometry, Ultraviolet; D013890:Thiourea / Q000737:chemistry; D014158:Transcription, Genetic; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D018736:DNA Adducts; D009841:Oligonucleotides; D009944:Organoplatinum Compounds; D011725:Pyridines; D016159:Tumor Suppressor Protein p53; C507746:trans-PtCl(2)NH(3)(4-hydroxymethylpyridine); D004247:DNA; D013890:Thiourea