Efficient DNA interstrand crosslinking by 6-thioguanine and UVA radiation

Brem, Reto; Daehn, Ilse; Karran, Peter

doi:10.1016/j.dnarep.2011.05.010

Cited by 46 publications

(63 citation statements)

References 29 publications

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“…Importantly, this sensitivity is independent of MMR indicating that it represents a novel mechanism of 6-TG toxicity. Taken together with a previously noted hypersensitivity of HR-defective xrcc2 cells (14) and the recently reported 6-TG sensitivity of cells deficient in the BRCA2 (also known as FANCD1) or BRCA1 proteins (9), these findings firmly implicate the FA and HR pathways in preventing some of the potentially lethal effects of 6-TG.…”

Section: Discussionmentioning

confidence: 71%

“…FA-deficient cells are typically hypersensitive to killing, chromosome breakage and particularly to radial chromosome induction by agents that cause DNA ICLs. They exhibit a similar pattern of sensitivity to 6-TG (14), and we show that ICLs are among the DNA lesions that efficiently block DNA replication in cells treated with 6-TG.…”

Section: Introductionmentioning

confidence: 78%

“…In a previous publication (14) we reported that the ROS produced when DNA 6-TG is activated by UVA induce ICLs and the chromosome aberrations that are typically associated with these DNA lesions. To investigate whether 6-TG induced ICLs independently of UVA activation, cells were treated with 6-TG and the introduction of ICLs was analyzed by the Comet assay.…”

Section: The Lethal Dna 6-tg Lesionsmentioning

confidence: 99%

“…Cell killing reflects the formation of potentially lethal DNA lesions that inhibit replication. Its effects are particularly marked in cells with defects in the Fanconi anemia (FA) and homologous recombination (HR) pathways and cells with defects in either pathway are extremely sensitive to 6-TG (9,14,16). Together the FA and HR pathway protect cells against DNA damage that arrests replication (reviewed in ref.…”

Section: Introductionmentioning

confidence: 99%

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Oxidation-Mediated DNA Cross-Linking Contributes to the Toxicity of 6-Thioguanine in Human Cells

Brem

Karran

2012

Cancer Research

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The thiopurines azathioprine and 6-mercaptopurine have been extensively prescribed as immunosuppressant and anticancer agents for several decades. A third member of the thiopurine family, 6-thioguanine (6-TG), has been used less widely. Although known to be partly dependent on DNA mismatch repair (MMR), the cytotoxicity of 6-TG remains incompletely understood. Here, we describe a novel MMR-independent pathway of 6-TG toxicity. Cell killing depended on two properties of 6-TG: its incorporation into DNA and its ability to act as a source of reactive oxygen species (ROS). ROS targeted DNA 6-TG to generate potentially lethal replication-arresting DNA lesions including interstrand cross-links. These triggered processing by the Fanconi anemia and homologous recombination DNA repair pathways. Allopurinol protected against 6-TG toxicity by acting as a ROS scavenger and preventing DNA damage. Together, our findings provide mechanistic evidence to support the proposed use of thiopurines to treat HR-defective tumors and for the coadministration of 6-TG and allopurinol as an immunomodulation strategy in inflammatory disorders. Cancer Res; 72(18); 4787-95. Ó2012 AACR.

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Section: Discussionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 78%

Section: The Lethal Dna 6-tg Lesionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oxidation-Mediated DNA Cross-Linking Contributes to the Toxicity of 6-Thioguanine in Human Cells

Brem

Karran

2012

Cancer Research

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“…[6][7][8] In the meantime, we became interested in the photo-induced interstrand cross-link of 6-thio-dG in the duplex DNA. However, the literature 9) and our own experiments indicated that 6-thio-dG in the oligonucleotide generates little photo-cross-linking with normal bases in the opposite DNA strand. The absorbed energy of 6-thio-dG might be consumed for other reactions such as the activation of molecular oxygen.…”

mentioning

confidence: 99%

Efficient Thymidine-Selective DNA Interstrand Photo-activated Crosslinking by the 6-Thioguanine Connected <i>via</i> an Ethylene-Linker to the 2′-Deoxyribose Unit

Nishioka

Oshiro

Onizuka

et al. 2016

CHEMICAL & PHARMACEUTICAL BULLETIN

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Cross-linking is a widely-used technology in the studies of DNA, RNA and their complexes with proteins. Intrinsically active alkylating moieties and photo-activated agents are chemically or enzymatically incorporated into nucleic acids. Thionucleobases resemble the corresponding natural bases, and form crosslinks by UVA irradiation. They form cross-links only with a site in close contact, thereby allowing identification of the contacts within the nucleic acids and/or between the nucleic acids and proteins in complex nucleoprotein assemblies. On the other hand, the thionucleobase forms a cross-link less efficiently for the reaction with the opposite natural base in the DNA duplex. In this study, 6-thioguanine was connected to 2′-deoxyribose through an ethylene linker at the 1′-position (Et-thioG). The linker was expected to bring the 6-thio group close to the nucleobase in the opposite strand. In a duplex in which the 2′-deoxy-6-thioguanosine (6-thio-dG) did not form a crosslink, Et-thioG efficiently formed crosslink with a high selectivity for T by UVA irradiation, but with a much lower efficiency for dA, dG, dC, 5-methyl-dC or dU. Interestingly, the yield of the photo-crosslinked product with dT was effectively improved in the presence of dithiothreitol or sodium hydrosulfide (NaSH) at a low UVA irradiation dose. The efficient and selective cross-link formation at a low UVA dose may be beneficial for the biological application of Et-thioG. Key words 6-thioguanosine; photo cross-link; UVAThe intra-and interstrand cross-linking of nucleic acids is a widely used technology for a variety of purposes; i.e., the induction of DNA damage, regulation and manipulation of genes, fixation of DNA nano-structure, etc. DNA cross-linking agents are chemically or enzymatically incorporated into nucleic acids, which include psoralen, 3-cyanovinylcarbazole, aziridine, quinone methide, aldehyde, abasic site, disulfide, benzophenone, bisamide, alkylating anticancer agents, etc. The 2-amino-6-vinylpurine derivative and 5-methyl-4-vinylpyrimidine-2-one have been developed by our group as unique cross-linking agents.1-4) 6-Thioguanosine, 4-thiothymine and 4-thiouridine are also cross-linking agents, and are characteristic in that they are activated by UVA irradiation to form a cross-link only with the close contact-site either at the nucleic acid or the protein in the complex.5) Because of this unique property, despite little knowledge about the photo-adducts, the thionucleobases have been extensively used to identify the close contact-sites of the nucleic acid. We have applied 6-thio-2′-deoxyguanosine (6-thio-dG) as a platform for the functionality-transfer reaction in the site-specific chemical modification of nucleic acids. [6][7][8] In the meantime, we became interested in the photo-induced interstrand cross-link of 6-thio-dG in the duplex DNA. However, the literature 9) and our own experiments indicated that 6-thio-dG in the oligonucleotide generates little photo-cross-linking with normal bases in the opposite DNA strand. The abs...

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Highly Efficient Fluorescent Interstrand Photo‐crosslinking of DNA Duplexes Labeled with 5‐Fluoro‐4‐thio‐2′‐O‐methyluridine

et al. 2014

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The formation of a fluorescent photoadduct between 5-fluoro-4-thiouridine ((FS) U), in the sequence context 5'-A(FS) UA-3' and incorporated into a synthetic oligonucleotide either at its 3'- or 5'-end, and one of the thymines of the TAT motif in a complementary target DNA strand led to photo-crosslinking of the two strands for several oligonucleotide constructs. Enzymatic digestion, MS, UV, and fluorescence spectral analyses of the interstrand crosslinked oligonucleotides revealed the identity of the thymidine that participates in the photo-crosslinking reaction as well as the diastereomeric structures of the crosslinks. The proposed pathways of interstrand photo-crosslinking are supported by experiments with isotopically labeled oligonucleotide constructs and visualized by means of molecular dynamics simulations.

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Efficient DNA interstrand crosslinking by 6-thioguanine and UVA radiation

Cited by 46 publications

References 29 publications

Oxidation-Mediated DNA Cross-Linking Contributes to the Toxicity of 6-Thioguanine in Human Cells

Oxidation-Mediated DNA Cross-Linking Contributes to the Toxicity of 6-Thioguanine in Human Cells

Efficient Thymidine-Selective DNA Interstrand Photo-activated Crosslinking by the 6-Thioguanine Connected <i>via</i> an Ethylene-Linker to the 2′-Deoxyribose Unit

Highly Efficient Fluorescent Interstrand Photo‐crosslinking of DNA Duplexes Labeled with 5‐Fluoro‐4‐thio‐2′‐O‐methyluridine

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