Expression levels of the DNA repair enzyme HAP1 do not correlate with the radiosensitivities of human or HAP1-transfected rat cell lines.

2.50
Hdl Handle:
http://hdl.handle.net/10541/90802
Title:
Expression levels of the DNA repair enzyme HAP1 do not correlate with the radiosensitivities of human or HAP1-transfected rat cell lines.
Authors:
Herring, C J; Deans, B; Elder, Rhoderick H; Rafferty, Joseph A; MacKinnon, J; Barzilay, G; Hickson, I D; Hendry, Jolyon H; Margison, Geoffrey P
Abstract:
Apurinic/apyrimidinic (AP) sites in DNA are potentially lethal and mutagenic. They can arise spontaneously or following DNA damage from reactive oxygen species or alkylating agents, and they constitute a significant product of DNA damage following cellular exposure to ionizing radiation. The major AP endonuclease responsible for initiating the repair of these and other DNA lesions in human cells is HAP1, which also possesses a redox function. We have determined the cellular levels of this enzyme in 11 human tumour and fibroblast cell lines in relation to clonogenic survival following ionizing radiation. Cellular HAP1 levels and surviving fraction at 2 Gy (SF2) varied five- and tenfold respectively. However, no correlation was found between these two parameters following exposure to gamma-irradiation at low (1.1 cGy per min) or high (108 cGy per min) dose rates. To examine this further, wild-type and mutant versions of HAP1 were overexpressed, using an inducible HAP1 cDNA expression vector system, in the rat C6 glioma cell line which has low endogenous AP endonuclease activity. Induction of wild-type HAP1 expression caused a > fivefold increase in the capacity of cellular extracts to cleave an oligonucleotide substrate containing a single abasic site, but increased expression did not confer increased resistance to gamma-irradiation at high- or low-dose rates, or to the methylating agent methyl methanesulphonate (MMS). Expression in C6 cell lines of mutant forms of HAP1 deleted for either the redox activator or DNA repair functions displayed no apparent titrational or dominant negative effects. These studies suggest that the levels of endogenous AP endonuclease activities in the various cell lines examined are not limiting for efficient repair in cells following exposure to ionizing radiation or MMS. This contrasts with the correlation we have found between HAP1 levels and radiosensitivity in cervix carcinomas (Herring et al (1998) Br J Cancer 78: 1128-1133), indicating that HAP1 levels in this case assume a critical survival role and hence that established cell lines might not be a suitable model for such studies.
Affiliation:
CRC Section of Genome Damage and Repair, Paterson Institute for Cancer Research, Christie Hospital (NHS) Trust, Manchester, UK.
Citation:
Expression levels of the DNA repair enzyme HAP1 do not correlate with the radiosensitivities of human or HAP1-transfected rat cell lines. 1999, 80 (7):940-5 Br. J. Cancer
Journal:
British Journal of Cancer
Issue Date:
Jun-1999
URI:
http://hdl.handle.net/10541/90802
DOI:
10.1038/sj.bjc.6690447
PubMed ID:
10362100
Type:
Article
Language:
en
ISSN:
0007-0920
Appears in Collections:
All Paterson Institute for Cancer Research

Full metadata record

DC FieldValue Language
dc.contributor.authorHerring, C Jen
dc.contributor.authorDeans, Ben
dc.contributor.authorElder, Rhoderick Hen
dc.contributor.authorRafferty, Joseph Aen
dc.contributor.authorMacKinnon, Jen
dc.contributor.authorBarzilay, Gen
dc.contributor.authorHickson, I Den
dc.contributor.authorHendry, Jolyon Hen
dc.contributor.authorMargison, Geoffrey Pen
dc.date.accessioned2010-01-28T12:15:23Z-
dc.date.available2010-01-28T12:15:23Z-
dc.date.issued1999-06-
dc.identifier.citationExpression levels of the DNA repair enzyme HAP1 do not correlate with the radiosensitivities of human or HAP1-transfected rat cell lines. 1999, 80 (7):940-5 Br. J. Canceren
dc.identifier.issn0007-0920-
dc.identifier.pmid10362100-
dc.identifier.doi10.1038/sj.bjc.6690447-
dc.identifier.urihttp://hdl.handle.net/10541/90802-
dc.description.abstractApurinic/apyrimidinic (AP) sites in DNA are potentially lethal and mutagenic. They can arise spontaneously or following DNA damage from reactive oxygen species or alkylating agents, and they constitute a significant product of DNA damage following cellular exposure to ionizing radiation. The major AP endonuclease responsible for initiating the repair of these and other DNA lesions in human cells is HAP1, which also possesses a redox function. We have determined the cellular levels of this enzyme in 11 human tumour and fibroblast cell lines in relation to clonogenic survival following ionizing radiation. Cellular HAP1 levels and surviving fraction at 2 Gy (SF2) varied five- and tenfold respectively. However, no correlation was found between these two parameters following exposure to gamma-irradiation at low (1.1 cGy per min) or high (108 cGy per min) dose rates. To examine this further, wild-type and mutant versions of HAP1 were overexpressed, using an inducible HAP1 cDNA expression vector system, in the rat C6 glioma cell line which has low endogenous AP endonuclease activity. Induction of wild-type HAP1 expression caused a > fivefold increase in the capacity of cellular extracts to cleave an oligonucleotide substrate containing a single abasic site, but increased expression did not confer increased resistance to gamma-irradiation at high- or low-dose rates, or to the methylating agent methyl methanesulphonate (MMS). Expression in C6 cell lines of mutant forms of HAP1 deleted for either the redox activator or DNA repair functions displayed no apparent titrational or dominant negative effects. These studies suggest that the levels of endogenous AP endonuclease activities in the various cell lines examined are not limiting for efficient repair in cells following exposure to ionizing radiation or MMS. This contrasts with the correlation we have found between HAP1 levels and radiosensitivity in cervix carcinomas (Herring et al (1998) Br J Cancer 78: 1128-1133), indicating that HAP1 levels in this case assume a critical survival role and hence that established cell lines might not be a suitable model for such studies.en
dc.language.isoenen
dc.subjectCanceren
dc.subjectCultured Tumour Cellsen
dc.subject.meshAnimals-
dc.subject.meshCarbon-Oxygen Lyases-
dc.subject.meshCell Survival-
dc.subject.meshDNA Repair-
dc.subject.meshDNA-(Apurinic or Apyrimidinic Site) Lyase-
dc.subject.meshDeoxyribonuclease IV (Phage T4-Induced)-
dc.subject.meshDose-Response Relationship, Radiation-
dc.subject.meshGamma Rays-
dc.subject.meshGene Expression-
dc.subject.meshGlioma-
dc.subject.meshHumans-
dc.subject.meshImmunoblotting-
dc.subject.meshNeoplasms-
dc.subject.meshRadiation Tolerance-
dc.subject.meshRats-
dc.subject.meshTransfection-
dc.subject.meshTumor Cells, Cultured-
dc.titleExpression levels of the DNA repair enzyme HAP1 do not correlate with the radiosensitivities of human or HAP1-transfected rat cell lines.en
dc.typeArticleen
dc.contributor.departmentCRC Section of Genome Damage and Repair, Paterson Institute for Cancer Research, Christie Hospital (NHS) Trust, Manchester, UK.en
dc.identifier.journalBritish Journal of Canceren

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