TY - JOUR
T1 - Chromosomal instability in an oxygen-tolerant variant of Chinese hamster ovary cells
AU - Gille, J. J.P.
AU - Mullaart, E.
AU - Vijg, J.
AU - Leyva, A. L.
AU - Arwert, F.
AU - Joenje, H.
N1 - Funding Information:
experimentalw ork and J.F. Koster, M.V.M. Lafleur, and K. Madan for commentso n the manuscript. This study was supported by the NetherlandsC ancer Foundation (Koningin Wil-helmina Fonds) and by the Foundation for FundamentalB iologicalR esearch( BION) which is subsidizedb y the NetherlandsO rganizationf or the Advancemenotf Pure Research( ZWO).
PY - 1989/1
Y1 - 1989/1
N2 - Background levels of chromosomal aberrations and sister-chromatid exchanges (SCEs) were determined in CHO-99 cells, an oxygen-tolerant variant substrain of Chinese hamster ovary (CHO-20) cells capable of stable proliferation under an atmosphere of 99% O2/1% CO2, a level of hyperoxia at which cultured mammalian cells normally cannot survive. The mean chromosomal aberration frequency in CHO-99 cells was as high as 1 aberration per cell (mainly chromatid and chromosome gaps and breaks) versus 0.05 aberration/cell in CHO-20 cells, while the SCE frequency was 1.7- to 2.1-fold increased. While most aberrations were apparently distributed at random over the chromosomes, up to 31% of the aberrations appeared to be involved in site-specific fragility at a homologous site in chromosomes Z3 and Z4. Immediately upon shifting CHO-99 cells to air-equilibrated conditions their SCE frequency decreased to the control level, whereas the aberration rate persisted at a still elevated level of 0.16-0.31 aberration per cell, even after a culture period of 14 weeks under normoxia. This indicates that at least part of the chromosomal instability is a constitutional property of the variant cells, i.e., not directly dependent upon hyperoxic stress. In CHO-99 × CHO-20 hybrids the occurrence of chromatid-type aberrations and fragile site but not that of chromosome-type aberrations was suppressed under normoxic conditions, suggesting that chromatid-type aberrations and fragile site expression on the one hand and chromosome-type aberrations on the other hand are mediated by different constitutional defects in CHO-99 cells. No gross alterations in (deoxy)ribonucleoside triphosphate pools were detected in CHO-99 cells that could be held responsible for their chromosomal instability. In addition, no increased level of DNA damage was detected by the technique of alkaline elution. The excessive chromosomal instability in CHO-99 cells, as observed under hyperoxic conditions, may originate from reactive intermediates giving rise to DNA double-strand breaks and/or a type of DNA lesion that is resistant to the conditions of the alkaline elution technique. However, alternative mechanisms based upon reactive species interfering with DNA replication/repair processes cannot be excluded.
AB - Background levels of chromosomal aberrations and sister-chromatid exchanges (SCEs) were determined in CHO-99 cells, an oxygen-tolerant variant substrain of Chinese hamster ovary (CHO-20) cells capable of stable proliferation under an atmosphere of 99% O2/1% CO2, a level of hyperoxia at which cultured mammalian cells normally cannot survive. The mean chromosomal aberration frequency in CHO-99 cells was as high as 1 aberration per cell (mainly chromatid and chromosome gaps and breaks) versus 0.05 aberration/cell in CHO-20 cells, while the SCE frequency was 1.7- to 2.1-fold increased. While most aberrations were apparently distributed at random over the chromosomes, up to 31% of the aberrations appeared to be involved in site-specific fragility at a homologous site in chromosomes Z3 and Z4. Immediately upon shifting CHO-99 cells to air-equilibrated conditions their SCE frequency decreased to the control level, whereas the aberration rate persisted at a still elevated level of 0.16-0.31 aberration per cell, even after a culture period of 14 weeks under normoxia. This indicates that at least part of the chromosomal instability is a constitutional property of the variant cells, i.e., not directly dependent upon hyperoxic stress. In CHO-99 × CHO-20 hybrids the occurrence of chromatid-type aberrations and fragile site but not that of chromosome-type aberrations was suppressed under normoxic conditions, suggesting that chromatid-type aberrations and fragile site expression on the one hand and chromosome-type aberrations on the other hand are mediated by different constitutional defects in CHO-99 cells. No gross alterations in (deoxy)ribonucleoside triphosphate pools were detected in CHO-99 cells that could be held responsible for their chromosomal instability. In addition, no increased level of DNA damage was detected by the technique of alkaline elution. The excessive chromosomal instability in CHO-99 cells, as observed under hyperoxic conditions, may originate from reactive intermediates giving rise to DNA double-strand breaks and/or a type of DNA lesion that is resistant to the conditions of the alkaline elution technique. However, alternative mechanisms based upon reactive species interfering with DNA replication/repair processes cannot be excluded.
KW - Chinese hamster ovary cells
KW - Chromosome aberrations
KW - Genetic instability
KW - Oxygen tolerance
KW - Sister-chromatid exchange
UR - http://www.scopus.com/inward/record.url?scp=0024536891&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0024536891&partnerID=8YFLogxK
U2 - 10.1016/0921-8734(89)90037-4
DO - 10.1016/0921-8734(89)90037-4
M3 - Article
C2 - 2911268
AN - SCOPUS:0024536891
SN - 0921-8734
VL - 219
SP - 17
EP - 28
JO - Mutation Research DNAging
JF - Mutation Research DNAging
IS - 1
ER -