Peroxidase-mediated dealkylation of tamoxifen, detected by electrospray ionization-mass spectrometry, and activation to form DNA adducts.

Tamoxifen (TAM) is extensively used for the treatment and prevention of breast cancer. Associated with TAM treatment is a two- to eightfold increase in risk of endometrial cancer. To understand the mechanisms associated with this increased risk several pathways for TAM metabolism and DNA adduct formation have been studied.

DNA alkylation products formed by 1-(2-chloroethyl)-1-nitrosourea as molecular dosimeters of therapeutic response.

This study has investigated if individual DNA adducts formed in human glioma cells treated with (3)H-1-(2-chloroethyl)-1-nitrosourea ((3)H-CNU) could be used as molecular dosimeters of response after CENU treatment. The levels of individual DNA alkylation products were compared with the induction of cytotoxicity in six human glioma cell lines after treatment with (3)H-CNU. The levels of seven DNA adducts N7-(2-hydroxyethyl)guanine, (N7-HOEtG); N7-(2-chloroethyl)guanine, (N7-ClEtG); 1,2-[diguan-7-yl]-ethane, (N7-bis-G); N1-(2-hydroxyethyl)-2-deoxyguanosine, N1-HOEtdG; 1-[N1-2-deoxyguanosinyl], 2-[N3-2-deoxycytidyl]-ethane, dG-dC; O(6)-(2-hydroxyethyl)-2-deoxyguanosine, O(6)-HOEtdG and phosphotriesters (PTE), were quantified in each of the cell lines following treatment with (3)H-CNU.

Levels and distribution of BCNU in GBM tumors following intratumoral injection of DTI-015 (BCNU-ethanol).

The alkylation products formed by in vitro treatment of DNA with tritium-labeled 1,3-bis(2-chloroethyl)-1-nitrosourea ((3)H-BCNU) were identified and quantified. Twelve adducts were resolved by high-performance liquid chromatography (HPLC). The principal DNA adducts formed by BCNU treatment corresponded to N-7-(2-hydroxyethyl)guanine (N7-HOEtG) (26%), N-7-(2-chloroethyl)guanine (15%), and phosphotriesters (19%).

Development of a holistic admission assessment: an integrated care pathway for the hospice setting.

This article describes the development of a holistic admission assessment for all inpatients admitted to a 66-bedded hospice, structured in the form of an integrated care pathway (ICP). The need for an improved assessment process was identified by clinical staff, who recognized that the existing assessment was not truly holistic and was dependent on the skills of the assessors. The assessment also lacked appropriate goals and actions.

Polyphenol associated-DNA adducts in lung and blood mononuclear cells from lung cancer patients.

The formation of smoking induced-DNA adducts is a critical factor in the induction of human lung cancer. As derivates of benzene and polyaromatic hydrocarbons (PAHs) are important compounds of tobacco smoke, in DNA isolated from human lung and blood mononuclear cells (MNCs) from 38 lung cancer patients, we used the (32)P-postlabeling assay to detect polyphenol associated DNA adducts. Two DNA adducts were detected in blood MNCs and lung tissue that co-chromatographed with DNA modifications from HL60 cells treated with combinations of benzene metabolites (e.

Formation of DNA adducts and induction of lacI mutations in Big Blue Rat-2 cells treated with temozolomide: implications for the treatment of low-grade adult and pediatric brain tumors.

Temozolomide (TMZ) is a chemotherapeutic agent used in the treatment of high-grade brain tumors. Treatment of patients with alkylating chemotherapeutic agents has been established to increase their risk for acute myelogenous leukemia. The formation of DNA adducts and induction of mutations are likely to play a role in the etiology of therapy-related acute myeloid leukemia.

Formation of DNA adducts and tumor growth delay following intratumoral administration of DTI-015.

Intratumoral (IT) administration of DTI-015 (BCNU in 100% ethanol) utilizes solvent facilitated perfusion for the treatment of tumors. RIF-1 tumors were treated by IT injection of either ethanol alone or 0.05-1.

Formation of DNA adducts in HL-60 cells treated with the toluene metabolite p-cresol: a potential biomarker for toluene exposure.

We have examined DNA adduct formation in myeloperoxidase containing HL-60 cells treated with the toluene metabolite p-cresol. Treatment of HL-60 cells with the combination of p-cresol and H(2)O(2) produced four DNA adducts 1: (75.0%), 2: (9.

Repair of DNA alkylation products formed in 9L cell lines treated with 1-(2-chloroethyl)-1-nitrosourea.

The purpose of this study has been to measure the formation and repair of individual DNA alkylation products in 9L, 9L-2 and BTRC-19 cell lines after treatment with 1-(2-chloroethyl)-1-nitrosourea (CNU). The levels of seven DNA adducts N7-(2-hydroxyethyl)-guanine, N7-(2-chloroethyl)-guanine; 1,2-(diguan-7-yl)-ethane, N1-(2-hydroxyethyl)-2-deoxyguanosine, 1-(N1-2-deoxyguanosinyl), 2-(N3-2-deoxycytidyl)-ethane, O(6)-(2-hydroxyethyl)-2-deoxyguanosine and phosphotriesters were separated by HPLC and quantified by liquid scintillation counting. The levels of N7-(2-hydroxyethyl)-guanine, N7-(2-chloroethyl)-guanine; O(6)-(2-hydroxyethyl)-2-deoxyguanosine and phosphotriesters were not significantly different in the three glioma lines.

Induction of lacI mutations in Big Blue Rat-2 cells treated with 1-(2-hydroxyethyl)-1-nitrosourea: a model system for the analysis of mutagenic potential of the hydroxyethyl adducts produced by 1,3-bis (2-chloroethyl)-1-nitrosourea.

We have investigated the genotoxic effects of 1-(2-hydroxyethyl)-1-nitrosourea (HENU). We have chosen this agent because of its demonstrated ability to produce N7-(2-hydroxyethyl) guanine (N7-HOEtG) and O(6)-(2-hydroxyethyl) 2'-deoxyguanosine (O(6)-HOEtdG); two of the DNA alkylation products produced by 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU). For these studies, we have used the Big Blue Rat-2 cell line that contains a lambda/lacI shuttle vector.

Formation of DNA adducts by microsomal and peroxidase activation of p-cresol: role of quinone methide in DNA adduct formation.

We have investigated the activation of p-cresol to form DNA adducts using horseradish peroxidase, rat liver microsomes and MnO(2). In vitro activation of p-cresol with horseradish peroxidase produced six DNA adducts with a relative adduct level of 8.03+/-0.

Levels of N7-(2-hydroxyethyl)guanine as a molecular dosimeter of drug delivery to human brain tumors.

The level of N7-(2-hydroxyethyl)guanine (N7-HOEtG), one of the DNA alkylation products formed by 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) treatment, was measured in human brain tumor samples by high performance liquid chromatography with electrochemical detection. The tumors from 6 recurrent chemotherapy-naive patients with recurrent glioblastoma multiforme were analyzed as controls. The mean level of N7-HOEtG in DNA of these specimens was 0.

Measurement of sister chromatid exchange induction in intracerebral brain tumors as a method for evaluation of therapeutic drug combinations.

Rats with 9L or 9L-2 intracerebral brain tumors were treated with streptozotocin (STZ) and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) at various doses either as single agents or in combination. Treatment of rats bearing 9L or 9L-2 tumors with either STZ or BCNU produced a significant increase the level of sister chromatid exchanges (SCEs) (p < .001).

Effect of cations on the formation of DNA alkylation products in DNA reacted with 1-(2-Chloroethyl)-1-nitrosourea.

The purpose of this study was to examine the influence of cations on the formation of the individual DNA alkylation products derived from 1-(2-chloroethyl)-1-nitrosourea (CNU). Reaction of calf-thymus DNA with [(3)H]CNU in 10 mM triethanolamine buffer produced 13 DNA adducts. Seven of these adducts were identified as N7-(2-hydroxyethyl)guanine, N7-(2-chloroethyl)guanine, 1, 2-(diguan-7-yl)ethane, N1-(2-hydroxyethyl)-2-deoxyguanosine, 1-(N1-2-deoxyguanosinyl)-2-(N3-2-deoxycytidyl)ethane, O(6)-(2-hydroxyethyl)-2-deoxyguanosine, and phosphotriesters.

Oxidation of eugenol to form DNA adducts and 8-hydroxy-2'-deoxyguanosine: role of quinone methide derivative in DNA adduct formation.

We have investigated the activation of eugenol to form DNA adducts and oxidative base damage. Treatment of myeloperoxidase containing HL-60 cells with eugenol, produced a dose-dependent formation of three DNA adducts as detected with P1-enhanced 32P-post-labeling. Incubation of HL-60 cells with the combination of 100 microM eugenol and 100 microM H2O2 potentiated the levels of DNA adduct in HL-60 cells by 14-fold, which suggests peroxidase activation in adduct formation.

Formation of DNA adducts and oxidative base damage by copper mediated oxidation of dopamine and 6-hydroxydopamine.

We have investigated the formation of DNA adducts and oxidative base damage produced by copper sulfate activation of dopamine and 6-hydroxydopamine. In the presence of 10 microM copper sulfate both 100 microM dopamine and 100 microM 6-hydroxydopamine formed three similar DNA adducts with relative adduct levels of 8.36 +/- 2.

Detection of N7-(2-hydroxyethyl)guanine adducts in DNA and 9L cells treated with 1-(2-chloroethyl)-1-nitrosourea.

A sensitive analytical method, HPLC-ED, was developed for the measurement of N7-(2-hydroxyethyl)guanine (N7-HOEtG). A detection limit of 3.2 N7-HOEtG/10(8) nucleotides was obtained with this method.

Investigation of the DNA adducts formed in B6C3F1 mice treated with benzene: implications for molecular dosimetry.

We have investigated the formation of DNA adducts in the bone marrow and white blood cells of male B6C3F1 mice treated with benzene using P1-enhanced 32P-postlabeling. No adducts were detected in the bone marrow of controls or mice treated with various doses of benzene once a day. After twice-daily treatment for 1 to 7 days with benzene, 440 mg/kg, one major (no.

An investigation of multiple biomarkers among workers exposed to styrene and styrene-7,8-oxide.

Investigations of cancer and cytogenetic damage among reinforced-plastics workers have produced contradictory results. In all studies, the focus has been on styrene rather than the carcinogen, styrene-7,8-oxide (SO), traces of which are generated during the manufacturing process. Because styrene is present at very high levels and is metabolized almost exclusively through SO, coexposures to SO have been discounted.

Activation of 4-hydroxytamoxifen and the tamoxifen derivative metabolite E by uterine peroxidase to form DNA adducts: comparison with DNA adducts formed in the uterus of Sprague-Dawley rats treated with tamoxifen.

Daily intraperitoneal treatment of female Sprague-Dawley rats with either 5, 10 or 20 mg/kg tamoxifen (TAM) for 1 week increased the level of peroxidase activity in the uterus 2- to 10-fold compared to the control level. Using uterine extracts prepared from control and TAM treated animals, we investigated the activation of 4-hydroxytamoxifen (4-HO-TAM) and (E,Z)-1,2-diphenyl-1-(4-hydroxyphenyl)-but-1-ene (cis/trans-metabolite E) to form DNA adducts. Activation of 4-HO-TAM by uterine extracts prepared from either control or TAM-treated rats produced one major (a) and two minor DNA (b and c) adducts.

Production of 8-hydroxy-2'-deoxguanosine in DNA by microsomal activation of tamoxifen and 4-hydroxytamoxifen.

Using rat liver microsomal preparations, we have investigated the activation of the anti-estrogen compound tamoxifen (TAM) and its metabolite 4-hydroxytamoxifen (4-OH-TAM) to form 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in DNA. When reduced nicotinamide adenine dinucleotide phosphate (NADPH) was used as a cofactor in microsomal activation of either TAM or 4-OH-TAM, the levels of 8-OH-dG were 3-fold higher than in microsomes plus cofactor only. In contrast, no significant increase in the level of 8-OH-dG was detected in DNA samples from microsomal activation of either TAM or 4-OH-TAM with cumene hydroperoxide as the cofactor.

Role of hydrogen peroxide in the formation of DNA adducts in HL-60 cells treated with benzene metabolites.

We have investigated the influence of peroxides on DNA adduct formation in HL-60 cells treated with polyphenolic metabolites of benzene. Treatment of HL-60 cells with 50 microM hydroquinone (HQ), 500 microM catechol (CAT) or 200 microM 1,2,4-benzenetriol (BT) resulted in adduct levels of 0.27, 0.

Synthesis of N2-(4-hydroxyphenyl)-2'-deoxyguanosine 3'-phosphate: comparison by 32P-postlabeling with the DNA adduct formed in HL-60 cells treated with hydroquinone.

A new adduct has been isolated from the reaction of guanosine 3'-phosphate and p-benzoquinone. The structure of this adduct has been determined as N2-(4-hydroxyphenyl)-guanosine 3'-phosphate. 32P-Postlabeling showed that this adduct is similar to the DNA adduct formed in HL-60 cells treated with hydroquinone.

Reaction of N-(2-chloroethyl)-N-nitrosoureas with DNA: effect of buffers on DNA adduction, cross-linking, and cytotoxicity.

N-(2-Chloroethyl)nitrosoureas (CNU) are clinically used anticancer drugs whose cytotoxicity is associated with the generation of DNA interstrand cross-links. While studying the sequence selectivity for a series of CNU, a dramatic increase in the formation of N7-alkyldeoxyguanosine was observed when Tris buffer was used rather than phosphate or cacodylate buffers. Moreover, the formation of N7-alkyldeoxyguanosine lesions continues in Tris long after all of the CNU has hydrolyzed.

Detection of DNA adducts in the white blood cells of B6C3F1 mice treated with benzene.

We have employed the P1-enhanced 32P-postlabeling procedure to detect the formation DNA of adducts in the white blood cells (WBC) of B6C3F1 mice treated by i.p. injection with benzene.