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A single d(GpG) cisplatin adduct on the estrogen response element decreases the binding of the estrogen receptor
L Massaad-Massade1, C Massaad, F Legendre
1Université René Descartes, Laboratoire de Toxicologie Moléculaire, U-490 INSERM, 45 rue des Saints-Pères, 75270, Paris, France. liliane.massade@biomedicale.univ-paris5.fr
Abstract:
Both cisplatin and the estrogen receptor (ER) are known to bend DNA. The influence of the bending of sequences by the d(GpG)cisPt adduct binding of ER to estrogen response element (ERE)-like sequences was examined. Three ERE-like oligonucleotides with different affinities for ER and which include a GG in the linker sequence were designed in order to form a single central d(GpG)cisPt adduct. Using electrophoretic mobility shift assay and Scatchard analysis, it was shown that the presence of a single d(GpG)cisPt adduct in the linker sequence decreases the ER affinity for DNA. These results do not support a critical role of a DNA bend in the initial recognition of ERE by ER. Then, the platination of DNA outside of the ERE half-sites decreases the interaction of ER with ERE.
Insights
Cisplatin's DNA adducts, specifically d(GpG)cisPt, reduce estrogen receptor (ER) binding to estrogen response elements (ERE). DNA bending by these adducts is not critical for initial ER-ERE recognition, impacting ER-DNA interactions.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Estrogen receptor (ER) binding to estrogen response elements (ERE) is crucial for gene regulation.
- Cisplatin is a chemotherapy drug that forms DNA adducts, including d(GpG)cisPt.
- Both ER and cisplatin are known to induce DNA bending.
Purpose of the Study:
- To investigate how the d(GpG)cisPt adduct influences ER binding to ERE-like sequences.
- To determine the role of DNA bending induced by cisplatin adducts in ER recognition of ERE.
Main Methods:
- Design of three ERE-like oligonucleotides with varying ER affinities and a central GG sequence.
- Formation of a single central d(GpG)cisPt adduct within the linker region of oligonucleotides.
- Electrophoretic mobility shift assay (EMSA) and Scatchard analysis to assess ER-DNA binding.
Main Results:
- A single d(GpG)cisPt adduct in the linker sequence significantly decreased ER affinity for DNA.
- Platination of DNA outside the ERE half-sites also reduced ER interaction with ERE.
- These findings suggest DNA bending by the adduct is not essential for initial ER-ERE recognition.
Conclusions:
- The presence of cisplatin-induced d(GpG)cisPt adducts impairs estrogen receptor binding to DNA.
- DNA bending induced by these adducts does not play a critical role in the initial recognition of ERE by ER.
- Cisplatin's interaction with DNA, even outside EREs, can disrupt ER-DNA complex formation.