The estrogens show negative activity in Ames test, but estrodiol and diethylstilbestrol in estrogens both are carcinogens based upon animal experiments and epidemiological investigation. It is concluded from the di-re...The estrogens show negative activity in Ames test, but estrodiol and diethylstilbestrol in estrogens both are carcinogens based upon animal experiments and epidemiological investigation. It is concluded from the di-region theory, a mechanism conception put forward by one of the present authors, that the carcinogenesis of estrogens is switched on by the covalent cross-link between complementary DNA bases induced by them. We verified for the first time by the DNA alkaline elution method that both estrodiol and diethylstilbestrol cause covalent cross-link between DNA-protein and DNA interstrands after metabolic activation with dosage correlation, but neither the non-carcinogens cholesterol nor pyrene can lead to these sorts of cross-link in the same condition. It has been known that there is a synergetic effect between estrogen and pollution of polycyclic aromatic hydrocarbons. Although non-carcinogenic pyrene alone cannot induce cross-link, its addition with equal molar quantity to estrodiol culture展开更多
Fanconi anemia(FA)is an autosomal or X-linked recessive disorder characterized by chromosomal instability,bone marrow failure,cancer susceptibility,and a profound sensitivity to agents that produce DNA interstrand cro...Fanconi anemia(FA)is an autosomal or X-linked recessive disorder characterized by chromosomal instability,bone marrow failure,cancer susceptibility,and a profound sensitivity to agents that produce DNA interstrand cross-link(ICL).To date,15 genes have been identified that,when mutated,result in FA or an FA-like syndrome.It is believed that cellular resistance to DNA interstrand cross-linking agents requires all 15 FA or FAlike proteins.Here,we review our current understanding of how these FA proteins participate in ICL repair and discuss the molecular mechanisms that regulate the FA pathway to maintain genome stability.展开更多
Exposure to toxic chemicals, especially chemotherapeutic drugs, may induce several DNA lesions, including DNA interstrand crosslinks. These crosslinks are considered toxic lesions to the dividing cells since they can ...Exposure to toxic chemicals, especially chemotherapeutic drugs, may induce several DNA lesions, including DNA interstrand crosslinks. These crosslinks are considered toxic lesions to the dividing cells since they can induce mutations, chromosomal rearrangements, and cell death. Many DNA interstrand crosslinks lesions can be generated by platinum-based chemotherapeutic agents. Satraplatin is a novel orally administered platinum-based chemotherapeutic agent. In the present study, we investigated DNA interstrand crosslinks lesions induced by oxaliplatin and satraplatin in lymphocytes obtained from colorectal cancer patients and healthy volunteers. Satraplatin demonstrated an increase in interstrand crosslinks in a dose-dependent manner in the Comet assay (p in vitro. Here, to the best of our knowledge we report for the first time evidence of DNA double strand breaks formation as a possible molecular mechanism of action for satraplatin.展开更多
Homologous recombination （HR） comprises a series of interrelated pathways that function in the repair of DNA double-stranded breaks （DSBs） and interstrand crosslinks （ICLs）. In addition, recombination provides c...Homologous recombination （HR） comprises a series of interrelated pathways that function in the repair of DNA double-stranded breaks （DSBs） and interstrand crosslinks （ICLs）. In addition, recombination provides critical support for DNA replication in the recovery of stalled or broken replication forks, contributing to tolerance of DNA damage. A central core of proteins, most critically the RecA homolog Rad51, catalyzes the key reactions that typify HR： homology search and DNA strand invasion. The diverse functions of recombination are reflected in the need for context-specific factors that perform supplemental functions in conjunction with the core proteins. The inability to properly repair complex DNA damage and resolve DNA replication stress leads to genomic instability and contributes to cancer etiology. Mutations in the BRCA2 recombination gene cause predisposition to breast and ovarian cancer as well as Fanconi anemia, a cancer predisposition syndrome characterized by a defect in the repair of DNA interstrand crosslinks. The cellular functions of recombination are also germane to DNA-based treatment modalities of cancer, which target replicating cells by the direct or indirect induction of DNA lesions that are substrates for recombination pathways. This review focuses on mechanistic aspects of HR relating to DSB and ICL repair as well as replication fork support.展开更多
The alkylating reactions of 1,2-epoxy-3,4-butene (EB) and 1,2,3,4-diepoxybutane (DEB)-the important metabolites of rodent carcinogenic 1,3-butadiene, with adenine and cytosine andinteraction with fragment of DNA on ma...The alkylating reactions of 1,2-epoxy-3,4-butene (EB) and 1,2,3,4-diepoxybutane (DEB)-the important metabolites of rodent carcinogenic 1,3-butadiene, with adenine and cytosine andinteraction with fragment of DNA on major groove-have been computed. Results show thatthere are little differences in activation energy between EB and DEB, so it is difficult to explain the fact that the mutagenicity of DEB is greater (about 100-fold) than that of EB by the ability of alkylation. it is also known that DEB can interstrand cross-link with DNA through two times alkylating reactions, whereas EB cannot. So this may contribute to the significant different genotoxicity of the two agents. Meanwhile, DEB can interstrand cross-link with many sequences of DNA in major groove vs. two in minor groove, which increases opportunity of interstrand cross-link with DNA in major groove. This difference may be the reason of base selection of DEB mutation. The deformation of some cross-linked DNA may also contribute to this展开更多
Since the beginning of the 1980s, Dai Qianhuan predicted based upon his di-region theory that the carcino-genesis switched on by the so-called physical carcinogenic factors including radiation, asbestos and foreign ma...Since the beginning of the 1980s, Dai Qianhuan predicted based upon his di-region theory that the carcino-genesis switched on by the so-called physical carcinogenic factors including radiation, asbestos and foreign matter implantation, is just initiated through the cross-linking between DNA complementary pair bases induced by them. In this note, it was evidenced with the DNA filter elution method that the oxygenase activated by asbestos induces the cross-linking between DNA inter-strands and DNA-protein with dosage correlation, in which over 80% of DNA inter-strand cross-link ratio account for the total cross-link ratio. Obviously, both of the cross-linkages are just induced by hydroxyl free radical, HO·, because the ferrous ion increased the cross-link ratios up to several times through Fenton reaction and vitamin C inhibited the cross-link ratios with factors of 8-9 by destroying the hydroxyl radical. Non-carcinogen but with lower free radical formation energy, pyrene, by culturing with asbestos展开更多
It is evidenced by the filter elution method that two carcinogenic aromatic hydrocarbons, benzo[a]pyrene and dibenzo[a,h]anthracene, two carcinogenic metal salts, beryllium chloride and cadmium chloride, four carcinog...It is evidenced by the filter elution method that two carcinogenic aromatic hydrocarbons, benzo[a]pyrene and dibenzo[a,h]anthracene, two carcinogenic metal salts, beryllium chloride and cadmium chloride, four carcinogenic aromatic amines, 2-aminofluorene, p-naphthylamine, 4-aminobiphenyl and benzidine, can all induce DNA interstrand and DNA-protein cross-link in L12io culture. However, under the same condition, the corresponding non-carcinogenic compounds, including benzo[k]fluorancene, anthracene, magnesium chloride, zinc chloride, a-naphthylamine, 2-aminobiphenyl and m-toluidine, cannot produce any cross-link adducts. All these results are consistent with the di-region theory that carcinogens are bio-bifunctional alkylation agents. This method can also be used to discriminate carcinogens and non-carcinogens.展开更多
E.coli AlkB is a direct DNA/RNA repair protein that oxidatively reverses N1 alkylated purines and N3 alkylated pyrimidines to regular bases.Previous crystal structures have revealed N1-methyl adenine(1-meA) recognitio...E.coli AlkB is a direct DNA/RNA repair protein that oxidatively reverses N1 alkylated purines and N3 alkylated pyrimidines to regular bases.Previous crystal structures have revealed N1-methyl adenine(1-meA) recognition by AlkB and a unique base flipping mechanism,but how the AlkB active site can accommodate bulky base adducts is largely unknown.Employing a previously developed chemical cross-linking technique,we crystallized AlkB with a duplex DNA containing a caged thymine base(cagedT).The structure revealed a flexible hairpin lid and a reorganized substrate recognition loop used by AlkB to accommodate cagedT.These observations demonstrate,at the molecular level,how bulky DNA adducts may be recognized and processed by AlkB.展开更多
To study the resistant mechanisms of cisplatin in human lung adenocarcinoma cell line A 549 DDP. A 549 DDP cells was established by stepwise increasing concentration of cisplatin (CDDP) in medium. Interstran...To study the resistant mechanisms of cisplatin in human lung adenocarcinoma cell line A 549 DDP. A 549 DDP cells was established by stepwise increasing concentration of cisplatin (CDDP) in medium. Interstrand cross linked DNA (ICL) was measured by ethidium bromide fluorescence assay. The intracellular and intranuclear accumulation of cisplatin was measured by atomic absorption spectrometry. The removal of GS X was determined by FCM and fluorescence microscopy. Results: The A 549 DDP cell line was 8.9 fold resistance relative to the parental A 549 cell line. The formation of ICL in A 549 was 6.28 times higher than that in A 549 DDP cells. The intracellular and intranuclear accumulation of cisplatin in A 549 cells was 5.9 times and 4.1 times higher than that in A 549 DDP cells, respectively. The ability of GS X pump pumped GS X complex (GS Pt) in A 549 DDP cells was higher than that in A 549 . The repair rate in A 549 DDP cells was 2 times higher than that in A 549 . Conclusions: Decreased accumulation and increased export of cisplatin might be the main mechanism of cisplatin resistant A 549 DDP cells while the enhanced repair capacity of DNA may play a role in CDDP resistance.展开更多
文摘The estrogens show negative activity in Ames test, but estrodiol and diethylstilbestrol in estrogens both are carcinogens based upon animal experiments and epidemiological investigation. It is concluded from the di-region theory, a mechanism conception put forward by one of the present authors, that the carcinogenesis of estrogens is switched on by the covalent cross-link between complementary DNA bases induced by them. We verified for the first time by the DNA alkaline elution method that both estrodiol and diethylstilbestrol cause covalent cross-link between DNA-protein and DNA interstrands after metabolic activation with dosage correlation, but neither the non-carcinogens cholesterol nor pyrene can lead to these sorts of cross-link in the same condition. It has been known that there is a synergetic effect between estrogen and pollution of polycyclic aromatic hydrocarbons. Although non-carcinogenic pyrene alone cannot induce cross-link, its addition with equal molar quantity to estrodiol culture
基金supported in part by grants from the China’s Fundamental Research Funds for the Central Universitiesthe National Natural Science Foundation of China(Grant No.31071243)the Natural Science Foundation of Zhejiang Province(Grant R2110569)(to J.H.).
文摘Fanconi anemia(FA)is an autosomal or X-linked recessive disorder characterized by chromosomal instability,bone marrow failure,cancer susceptibility,and a profound sensitivity to agents that produce DNA interstrand cross-link(ICL).To date,15 genes have been identified that,when mutated,result in FA or an FA-like syndrome.It is believed that cellular resistance to DNA interstrand cross-linking agents requires all 15 FA or FAlike proteins.Here,we review our current understanding of how these FA proteins participate in ICL repair and discuss the molecular mechanisms that regulate the FA pathway to maintain genome stability.
文摘Exposure to toxic chemicals, especially chemotherapeutic drugs, may induce several DNA lesions, including DNA interstrand crosslinks. These crosslinks are considered toxic lesions to the dividing cells since they can induce mutations, chromosomal rearrangements, and cell death. Many DNA interstrand crosslinks lesions can be generated by platinum-based chemotherapeutic agents. Satraplatin is a novel orally administered platinum-based chemotherapeutic agent. In the present study, we investigated DNA interstrand crosslinks lesions induced by oxaliplatin and satraplatin in lymphocytes obtained from colorectal cancer patients and healthy volunteers. Satraplatin demonstrated an increase in interstrand crosslinks in a dose-dependent manner in the Comet assay (p in vitro. Here, to the best of our knowledge we report for the first time evidence of DNA double strand breaks formation as a possible molecular mechanism of action for satraplatin.
文摘Homologous recombination （HR） comprises a series of interrelated pathways that function in the repair of DNA double-stranded breaks （DSBs） and interstrand crosslinks （ICLs）. In addition, recombination provides critical support for DNA replication in the recovery of stalled or broken replication forks, contributing to tolerance of DNA damage. A central core of proteins, most critically the RecA homolog Rad51, catalyzes the key reactions that typify HR： homology search and DNA strand invasion. The diverse functions of recombination are reflected in the need for context-specific factors that perform supplemental functions in conjunction with the core proteins. The inability to properly repair complex DNA damage and resolve DNA replication stress leads to genomic instability and contributes to cancer etiology. Mutations in the BRCA2 recombination gene cause predisposition to breast and ovarian cancer as well as Fanconi anemia, a cancer predisposition syndrome characterized by a defect in the repair of DNA interstrand crosslinks. The cellular functions of recombination are also germane to DNA-based treatment modalities of cancer, which target replicating cells by the direct or indirect induction of DNA lesions that are substrates for recombination pathways. This review focuses on mechanistic aspects of HR relating to DSB and ICL repair as well as replication fork support.
文摘The alkylating reactions of 1,2-epoxy-3,4-butene (EB) and 1,2,3,4-diepoxybutane (DEB)-the important metabolites of rodent carcinogenic 1,3-butadiene, with adenine and cytosine andinteraction with fragment of DNA on major groove-have been computed. Results show thatthere are little differences in activation energy between EB and DEB, so it is difficult to explain the fact that the mutagenicity of DEB is greater (about 100-fold) than that of EB by the ability of alkylation. it is also known that DEB can interstrand cross-link with DNA through two times alkylating reactions, whereas EB cannot. So this may contribute to the significant different genotoxicity of the two agents. Meanwhile, DEB can interstrand cross-link with many sequences of DNA in major groove vs. two in minor groove, which increases opportunity of interstrand cross-link with DNA in major groove. This difference may be the reason of base selection of DEB mutation. The deformation of some cross-linked DNA may also contribute to this
基金This work was supported by the National Natural Science Foundation of China (Grant No. 20042001).
文摘Since the beginning of the 1980s, Dai Qianhuan predicted based upon his di-region theory that the carcino-genesis switched on by the so-called physical carcinogenic factors including radiation, asbestos and foreign matter implantation, is just initiated through the cross-linking between DNA complementary pair bases induced by them. In this note, it was evidenced with the DNA filter elution method that the oxygenase activated by asbestos induces the cross-linking between DNA inter-strands and DNA-protein with dosage correlation, in which over 80% of DNA inter-strand cross-link ratio account for the total cross-link ratio. Obviously, both of the cross-linkages are just induced by hydroxyl free radical, HO·, because the ferrous ion increased the cross-link ratios up to several times through Fenton reaction and vitamin C inhibited the cross-link ratios with factors of 8-9 by destroying the hydroxyl radical. Non-carcinogen but with lower free radical formation energy, pyrene, by culturing with asbestos
文摘It is evidenced by the filter elution method that two carcinogenic aromatic hydrocarbons, benzo[a]pyrene and dibenzo[a,h]anthracene, two carcinogenic metal salts, beryllium chloride and cadmium chloride, four carcinogenic aromatic amines, 2-aminofluorene, p-naphthylamine, 4-aminobiphenyl and benzidine, can all induce DNA interstrand and DNA-protein cross-link in L12io culture. However, under the same condition, the corresponding non-carcinogenic compounds, including benzo[k]fluorancene, anthracene, magnesium chloride, zinc chloride, a-naphthylamine, 2-aminobiphenyl and m-toluidine, cannot produce any cross-link adducts. All these results are consistent with the di-region theory that carcinogens are bio-bifunctional alkylation agents. This method can also be used to discriminate carcinogens and non-carcinogens.
基金supported by the National Institute of Health (GM071440 to C.H.)Data collection was performed at GM/CA-CAT Beamline 23-ID-B at the Advanced Photon Source at Argonne National Laboratorysupport for this beamline comes from the National Institute of Health and the United States Department of Energy
文摘E.coli AlkB is a direct DNA/RNA repair protein that oxidatively reverses N1 alkylated purines and N3 alkylated pyrimidines to regular bases.Previous crystal structures have revealed N1-methyl adenine(1-meA) recognition by AlkB and a unique base flipping mechanism,but how the AlkB active site can accommodate bulky base adducts is largely unknown.Employing a previously developed chemical cross-linking technique,we crystallized AlkB with a duplex DNA containing a caged thymine base(cagedT).The structure revealed a flexible hairpin lid and a reorganized substrate recognition loop used by AlkB to accommodate cagedT.These observations demonstrate,at the molecular level,how bulky DNA adducts may be recognized and processed by AlkB.
文摘To study the resistant mechanisms of cisplatin in human lung adenocarcinoma cell line A 549 DDP. A 549 DDP cells was established by stepwise increasing concentration of cisplatin (CDDP) in medium. Interstrand cross linked DNA (ICL) was measured by ethidium bromide fluorescence assay. The intracellular and intranuclear accumulation of cisplatin was measured by atomic absorption spectrometry. The removal of GS X was determined by FCM and fluorescence microscopy. Results: The A 549 DDP cell line was 8.9 fold resistance relative to the parental A 549 cell line. The formation of ICL in A 549 was 6.28 times higher than that in A 549 DDP cells. The intracellular and intranuclear accumulation of cisplatin in A 549 cells was 5.9 times and 4.1 times higher than that in A 549 DDP cells, respectively. The ability of GS X pump pumped GS X complex (GS Pt) in A 549 DDP cells was higher than that in A 549 . The repair rate in A 549 DDP cells was 2 times higher than that in A 549 . Conclusions: Decreased accumulation and increased export of cisplatin might be the main mechanism of cisplatin resistant A 549 DDP cells while the enhanced repair capacity of DNA may play a role in CDDP resistance.
