This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bianchi, N. O. Articles by de la Chapelle, A. Search for Related Content PubMed PubMed Citation Articles by Bianchi, N. O. Articles by de la Chapelle, A.

Damage and Repair Induced by Bleomycin in the Domain of Human Amplified MYC Oncogenes¹

IMBICE, 1900 La Plata, Argentina [N. O. B., M. S. B., D. L-L.], and Departments of Virology [K. A.] and Medical Genetics [A. d. l. C.], University of Helsinki, Helsinki, Finland

Growing monolayer COLO320 human cells having a 30- to 40-fold amplification of a MYC domain were pulse treated for 15 min with increasing doses of bleomycin (BLM). Cellular DNA was extracted at the end of the BLM treatment or after an interval of 30 min, during which the cells were allowed to repair the DNA damage at 37°C in culture medium without BLM. Damage and repair in total cellular DNA was assessed by alkaline unwinding and by neutral and alkaline gel electrophoresis. The response to BLM in the domain of MYC oncogene was evaluated by Southern blotting of EcoRI-digested DNAs separated by neutral or alkaline gel electrophoresis. We found that MYC domains from COLO320HSR showed a higher frequency of double-strand DNA breaks than MYC domains from COLO320DM cells. At the level of total cellular DNA, both cell lines showed the same frequency of double-strand nicks. No repair of double-strand breaks was observed. Total DNA from COLO320HSR cells was more sensitive to single-strand breakage than DNA from COLO320DM. At the gene level, the frequency of single-strand scissions was higher in COLO320DM than in COLO320HSR MYC domains. Both cell lines had good capability to close single-strand scissions. However, at high BLM doses the damage was more efficiently repaired by COLO320DM cells. We propose that chromatin organization in total cellular DNA and in the amplified MYC domain probably plays an important role in the DNA response to BLM.

¹ This work was supported by The Sigrid Juselius Foundation, The Academy of Finland, The Folkhälsan Institute of Genetics, The Finnish Cancer Society, The Academy of Sciences of the Third World, and the Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET) and Comisión de Investigaciones Cientificas (CIC) of Argentina. D. López-Larraza is a fellow of CIC.

² To whom requests for reprints should be addressed, at IMBICE, CC403, 1900 La Plata, Argentina.

Received 6/19/89. Revised 11/27/89.

This article has been cited by other articles:

				L. K. Fritz, C. Suquet, and M. J. Smerdon Strand Breaks Are Repaired Efficiently in Human Ribosomal Genes J. Biol. Chem., May 31, 1996; 271(22): 12972 - 12976. [Abstract] [Full Text] [PDF]