Biochemical evidence for deficient DNA repair leading to enhanced G2 chromatid radiosensitivity and susceptibility to cancer

Journal Article · Sat Nov 01 00:00:00 EST 1986 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3576817· OSTI ID:6928395

Gantt, R; Parshad, R; Price, F M; Sanford, K K

Human tumor cells and cells from cancer-prone individuals, compared with those from normal individuals, show a significantly higher incidence of chromatid breaks and gaps seen in metaphase cells immediately after G2 X irradiation. Previous studies with DNA repair-deficient mutants and DNA repair inhibitors strongly indicate that the enhancement results from a G2 deficiency(ies) in DNA repair. We report here biochemical evidence for a DNA repair deficiency that correlates with the cytogenetic studies. In the alkaline elution technique, after a pulse label with radioactive thymidine in the presence of 3-acetylaminobenzamide (a G2-phase blocker) and X irradiation, DNA from tumor or cancer-prone cells elutes more rapidly during the postirradiation period than that from normal cells. These results indicate that the DNA of tumor and cancer-prone cells either repairs more slowly or acquires more breaks than that of normal cells; breaks can accumulate during incomplete or deficient repair processes. The kinetic difference between normal and tumor or cancer-prone cells in DNA strand-break repair reaches a maximum within 2 h, and this maximum corresponds to the kinetic difference in chromatid aberration incidence following X irradiation reported previously. These findings support the concept that cells showing enhanced G2 chromatid radiosensitivity are deficient in DNA repair. The findings could also lead to a biochemical assay for cancer susceptibility.

• Research Organization: National Cancer Institute, Bethesda, MD
• OSTI ID: 6928395
• Journal Information: Radiat. Res.; (United States), Vol. 2
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
TUMOR CELLS
DNA REPAIR
RADIOSENSITIVITY
CHROMATIDS
IN VITRO
NEOPLASMS
X RADIATION
ANIMAL CELLS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
DISEASES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
RADIATIONS
RECOVERY
REPAIR
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture