IMBICE   05372
INSTITUTO MULTIDISCIPLINARIO DE BIOLOGIA CELULAR
Unidad Ejecutora - UE
artículos
Título:
Effect of bleomycin on interstitial telomeric sequences of immortalized Chinese hamster ovary cells
Autor/es:
SÁNCHEZ, J.; BIANCHI, M. S.; BOLZÁN, A. D.
Revista:
MUTATION RESEARCH-FUNDAMENTAL AND MOLECULAR MECHANISMS OF MUTAGENESIS
Editorial:
Elsevier
Referencias:
Lugar: Netherlands; Año: 2009 vol. 669 p. 139 - 146
ISSN:
0027-5107
Resumen:
The effect of the radiomimetic compound bleomycin (BLM) on interstitial telomeric sequences (ITSs)was
investigated in Chinese hamster ovary (CHO) cells by usingPNA-FISH with a pantelomeric probe.CHOcells
were exposedto increasing concentrations ofBLMand chromosomalaberrationswere analyzedinthe first
mitosis after treatment. Cytogenetic analysis revealed that 18.1%and 9.5% of the total aberrations observed
in cells exposed to BLM and harvested 18 h and 3 h after treatment, respectively, exhibited one or more
FISH-detectable telomeric signals. Most of the chromosome breaks exhibiting telomeric signals observed
in BLM-treatedcells occurredinthe centromeric regions of chromosomes. This observation, along with the
finding of entirely labeled acentric fragments in BLM-exposed cells but not in untreated cells, shows that
this antibiotic induces breakage at chromosomal sites containing ITSs. In addition, our results show that
heterochromatic ITSs are involved more than expected in the formation of chromosome/chromatid breaks
and perhaps chromatid exchanges induced by BLM, taking into account the percentage of the genome
covered by telomeric sequences. On the contrary, our data strongly suggest that ITSs are not preferentially
involved in the formation of dicentrics, multicentrics, centric rings, acentric fragments or chromatid
deletions induced by BLM. Moreover, our results show that BLM is capable of inducing amplification and
translocation of telomeric repeats, and suggest that this antibiotic produces breakage within centromeric
ITSs, although chromosome regions containing these sequences are not the preferential target for BLM
clastogenic action. On the other hand, our results show that BLM treatment increases the size of ITSs and
that this effect is not related to the chromosomal sensitivity of the exposed cells to this compound