Korean J Nucl Med.  2000 Apr;34(2):144-153.

Relationship between Radiation Induced Activation of DNA Repair Genes and Radiation Induced Apoptosis in Human Cell Line A431

• Bom HS
• Min JJ
• Choi KH
• Kim KK

Abstract

PURPOSE: The purpose of this study was to evaluate the relationship between radiation-induced activation of DNA repair genes and radiation induced apoptosis in A431 cell line. MATERALS AND METHODS: Five and 25 Gys of gamma radiation were given to A431 cells by a Cs-137 cell irradiator. Apoptosis was evaluated by flow cytometry using annexin V-fluorescein isothiocyanate and propidium iodide staining. The expression of DNA repair genes was evaluated by both Northern and Western blot analyses.
RESULTS
The number of apoptotic cells increased with the increased radiation dose. It increased most significantly at 12 hours after irradiation. Expression of p53, p21, and hRAD50 reached the highest level at 12 hours after 5 Gy irradiation. In response to 25 Gy irradiation, hRAD50 and p21 were expressed maximally at 12 hours, but p53 and GADD45 genes showed the highest expression level after 12 hours.
CONCLUSION
Induction of apoptosis and DNA repair by ionizing radiation were closely correlated. The peak time of inducing apoptosis and DNA repair was 12 hours in this study model. hRAD50, a recently discovered DNA repair gene, was also associated with radiation-induced apoptosis.

Keyword

radiation; apoptosis; DNA repair genes

MeSH Terms

Apoptosis*
Blotting, Western
Cell Line*
DNA Repair*
DNA*
Flow Cytometry
Gamma Rays
Humans*
Propidium
Radiation, Ionizing
DNA
Propidium