More pronounced salt dependence and higher reactivity for platination of the hairpin r(CGCGUUGUUCGCG) compared with d(CGCGTTGTTCGCG)

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More pronounced salt dependence and higher reactivity for platination of the hairpin r(CGCGUUGUUCGCG) compared with d(CGCGTTGTTCGCG). / Hägerlöf, Margareta; Papsai, Pal; Chow, Christine S.; Elmroth, Sofi.

In: Journal of Biological Inorganic Chemistry, Vol. 11, No. 8, 2006, p. 974-990.

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T1 - More pronounced salt dependence and higher reactivity for platination of the hairpin r(CGCGUUGUUCGCG) compared with d(CGCGTTGTTCGCG)

AU - Hägerlöf, Margareta

AU - Papsai, Pal

AU - Chow, Christine S.

AU - Elmroth, Sofi

PY - 2006

Y1 - 2006

N2 - The DNA interference pathways exhibited by cisplatin and related anticancer active metal complexes have been extensively studied. Much less is known to what extent RNA interaction pathways may operate in parallel, and perhaps contribute to both antineoplastic activity and toxicity. The present study was designed with the aim of comparing the reactivity of two model systems comprising RNA and DNA hairpins, r(CGCGUUGUUCGCG) and d(CGC GTTGTTCGCG), towards a series of platinum(II) complexes. Three platinum complexes were used as metallation reagents; cis-[ptCl(NH3)(2)(OH2)](+) (1), cis-[PtCl(NH3)(C-C6H11NH2)(OH2)](+) (2), and trans[PtCl(NH3)(quinoline)(OH2)](+) (3). The reaction kinetics were studied at pH 6.0, 25 degrees C, and 1.0 mM < 1: 500 mM. For both types of nucleic acid targets, compound 3 was found to react about 1 order of magnitude more rapidly than compounds 1 and 2. Further, all platinum compounds exhibited a more pronounced salt dependence for the interaction with r(CGCGUUGUUCGCG). Chemical and enzymatic cleavage studies revealed similar interaction patterns with r(CGCGUUGUUCGCG) after long exposure times to 1 and 2. A substantial decrease of cleavage intensity was found at residues G4 and G7, indicative of bifunctional adduct formation. Circular dichroism studies showed that platinum adduct formation leads to a structural change of the ribonucleic acid. Thermal denaturation studies revealed platination to cause a decrease of the RNA melting temperatures by 5-10 degrees C. Our observations therefore suggest that RNA is a kinetically competitive target to DNA. Furthermore, platination causes destabilization of RNA structural elements, which may lead to deleterious intracellular effects on biologically relevant RNA targets.

AB - The DNA interference pathways exhibited by cisplatin and related anticancer active metal complexes have been extensively studied. Much less is known to what extent RNA interaction pathways may operate in parallel, and perhaps contribute to both antineoplastic activity and toxicity. The present study was designed with the aim of comparing the reactivity of two model systems comprising RNA and DNA hairpins, r(CGCGUUGUUCGCG) and d(CGC GTTGTTCGCG), towards a series of platinum(II) complexes. Three platinum complexes were used as metallation reagents; cis-[ptCl(NH3)(2)(OH2)](+) (1), cis-[PtCl(NH3)(C-C6H11NH2)(OH2)](+) (2), and trans[PtCl(NH3)(quinoline)(OH2)](+) (3). The reaction kinetics were studied at pH 6.0, 25 degrees C, and 1.0 mM < 1: 500 mM. For both types of nucleic acid targets, compound 3 was found to react about 1 order of magnitude more rapidly than compounds 1 and 2. Further, all platinum compounds exhibited a more pronounced salt dependence for the interaction with r(CGCGUUGUUCGCG). Chemical and enzymatic cleavage studies revealed similar interaction patterns with r(CGCGUUGUUCGCG) after long exposure times to 1 and 2. A substantial decrease of cleavage intensity was found at residues G4 and G7, indicative of bifunctional adduct formation. Circular dichroism studies showed that platinum adduct formation leads to a structural change of the ribonucleic acid. Thermal denaturation studies revealed platination to cause a decrease of the RNA melting temperatures by 5-10 degrees C. Our observations therefore suggest that RNA is a kinetically competitive target to DNA. Furthermore, platination causes destabilization of RNA structural elements, which may lead to deleterious intracellular effects on biologically relevant RNA targets.

KW - DNA damage

KW - toxicity

KW - anticancer drug

KW - nucleic acid

U2 - 10.1007/s00775-006-0157-y

DO - 10.1007/s00775-006-0157-y

M3 - Article

VL - 11

SP - 974

EP - 990

JO - Journal of Biological Inorganic Chemistry

JF - Journal of Biological Inorganic Chemistry

SN - 1432-1327

IS - 8

ER -