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 Google Scholar Google Scholar Articles by Kuo, W.-L. Articles by Haidle, C. W. Search for Related Content PubMed PubMed Citation Articles by Kuo, W.-L. Articles by Haidle, C. W.

Neocarzinostatin-mediated DNA Damage and Repair in Wild-Type and Repair-deficient Chinese Hamster Ovary Cells¹

Departments of Molecular Biology [W-L. K., C. W. H.] and Physics [R. E. M.], The University of Texas, M. D. Anderson Hospital and Tumor Institute, Houston, Texas 77030

The formation and repair of neocarzinostatin (NCS)-mediated DNA damage were examined in two strains of Chinese hamster ovary cells. The response in strain EM9, a mutant line selected for its sensitivity to ethyl methanesulfonate and shown to have a defect in the repair of X-ray-induced DNA breaks, was compared with that observed in the parental strain (AA8). The DNA strand breaks and their subsequent rejoining were measured using the method of elution of DNA from filters under either alkaline (for single-strand breaks), or nondenaturing conditions (for double-strand breaks). Colony survival assays showed that the mutant was more sensitive to the action of NCS than was the parental strain by a factor of approximately 1.5. Elution analyses showed that the DNA from both strains was damaged by NCS; the mutant displayed more damage than the parent under the same treatment conditions. Single-strand breaks were produced with a frequency of about 10 to 15 times the frequency of double-strand breaks. Both strains were able to rejoin both single-strand breaks and double-strand breaks induced by NCS treatment. The strand break data suggest that the difference in NCS-mediated cytotoxicity between EM9 and AA8 cells may be directly related to the enhanced production of DNA strand breaks in EM9. However, the fact that much higher doses of NCS were required in the DNA studies compared to the colony survival assays implies that either a small number of DNA breaks occur in a critical region of the genome, or that lesions other than DNA strand breaks are partly responsible for the observed cytotoxicity.

¹ This investigation was supported by Grant G-441 from The Robert A. Welch Foundation.

² Recipient of a predoctoral fellowship stipend from The Robert A. Welch Foundation.

³ To whom requests for reprints should be addressed.

Received 5/ 9/83. Accepted 1/26/84.