Recognition of DNA modified by trans-[PtClNH(4-hydroxymethylpyridine)] by tumor suppressor protein p53 and character of DNA adducts of this cytotoxic complex.
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.
Stehlíková
Kristýna
K
Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
Kaspárková
Jana
J
Nováková
Olga
O
Martínez
Alberto
A
Moreno
Virtudes
V
Brabec
Viktor
V
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*
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