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dc.contributor.authorChinnasamy, Nachimuthu
dc.contributor.authorFairbairn, Leslie J
dc.contributor.authorLaher, J
dc.contributor.authorWillington, Mark
dc.contributor.authorRafferty, Joseph A
dc.date.accessioned2010-02-23T09:33:43Z
dc.date.available2010-02-23T09:33:43Z
dc.date.issued1998-08-07
dc.identifier.citationModulation of O6-alkylating agent induced clastogenicity by enhanced DNA repair capacity of bone marrow cells. 1998, 416 (1-2):1-10 Mutat. Res.en
dc.identifier.issn0027-5107
dc.identifier.pmid9725988
dc.identifier.urihttp://hdl.handle.net/10541/92695
dc.description.abstractThe murine bone marrow micronucleus assay has been used to examine (1) the potentiation of fotemustine and streptozotocin induced-clastogenicity by the O6-alkylguanine-DNA alkyltransferase (ATase) inactivator O6-benzylguanine (O6-beG) and (2) the level of protection afforded against this potentiation by retrovirus-mediated expression of an O6-beG-resistant mutant of human ATase (haTPA/GA) in mouse bone marrow. Both fotemustine and streptozotocin induced significantly higher levels of micronucleated polychromatic erythrocytes (p < 0.001 for the highest doses studied) compared to those seen in vehicle-treated animals. The number of micronuclei produced by either agent was dramatically elevated by pretreatment with O6-beG (p < 0.001). Furthermore, in myeloablated mice reconstituted with bone marrow expressing the O6-beG-resistant hATPA/GA as a result of retroviral gene transfer, the frequency of micronucleus formation following exposure of mice to otherwise clastogenic doses of fotemustine or streptozotocin, in the presence of O6-beG, wash highly significantly reduced (p < 0.001 for both agents) relative to that in mock transduced controls. These data clearly implicate O6-chloroethyl- and O6-methylguanine as clastogenic lesions in vivo and establish ATase as a major protective mechanism operating to reduce the frequency of such damage. The potentiation of drug induced clastogenicity by O6-beG suggests that the clinical use of this inactivator in combination with O6-alkylating agents, could substantially increase the risk of therapy related malignancy. Nevertheless the use of hATPA/GA as a protective mechanism via gene therapy may overcome this risk.
dc.language.isoenen
dc.subject.meshAlkyl and Aryl Transferases
dc.subject.meshAlkylating Agents
dc.subject.meshAnimals
dc.subject.meshBone Marrow Cells
dc.subject.meshBone Marrow Transplantation
dc.subject.meshDNA Repair
dc.subject.meshDrug Synergism
dc.subject.meshEnzyme Inhibitors
dc.subject.meshFemale
dc.subject.meshGene Expression
dc.subject.meshGuanine
dc.subject.meshHumans
dc.subject.meshMale
dc.subject.meshMice
dc.subject.meshMicronucleus Tests
dc.subject.meshMutagens
dc.subject.meshMutation
dc.subject.meshNitrosourea Compounds
dc.subject.meshOrganophosphorus Compounds
dc.subject.meshStreptozocin
dc.titleModulation of O6-alkylating agent induced clastogenicity by enhanced DNA repair capacity of bone marrow cells.en
dc.typeArticleen
dc.contributor.departmentCRC Section of Haemopoietic Cell, Paterson Institute for Cancer Research, Christine Hospital NHS Trust, Mancester M20 4BX, UK.en
dc.identifier.journalMutation Researchen
html.description.abstractThe murine bone marrow micronucleus assay has been used to examine (1) the potentiation of fotemustine and streptozotocin induced-clastogenicity by the O6-alkylguanine-DNA alkyltransferase (ATase) inactivator O6-benzylguanine (O6-beG) and (2) the level of protection afforded against this potentiation by retrovirus-mediated expression of an O6-beG-resistant mutant of human ATase (haTPA/GA) in mouse bone marrow. Both fotemustine and streptozotocin induced significantly higher levels of micronucleated polychromatic erythrocytes (p < 0.001 for the highest doses studied) compared to those seen in vehicle-treated animals. The number of micronuclei produced by either agent was dramatically elevated by pretreatment with O6-beG (p < 0.001). Furthermore, in myeloablated mice reconstituted with bone marrow expressing the O6-beG-resistant hATPA/GA as a result of retroviral gene transfer, the frequency of micronucleus formation following exposure of mice to otherwise clastogenic doses of fotemustine or streptozotocin, in the presence of O6-beG, wash highly significantly reduced (p < 0.001 for both agents) relative to that in mock transduced controls. These data clearly implicate O6-chloroethyl- and O6-methylguanine as clastogenic lesions in vivo and establish ATase as a major protective mechanism operating to reduce the frequency of such damage. The potentiation of drug induced clastogenicity by O6-beG suggests that the clinical use of this inactivator in combination with O6-alkylating agents, could substantially increase the risk of therapy related malignancy. Nevertheless the use of hATPA/GA as a protective mechanism via gene therapy may overcome this risk.


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