Comparison of DNA damage and repair following radiation challenge in buccal cells and lymphocytes using single-cell gel electrophoresis

Purpose: To develop a reproducible single-cell gel electrophoresis assay for DNA damage and repair in buccal mucosa and sublingual exfoliated cells. Materials and methods: Buccal mucosa and sublingual cells and lymphocytes from six individuals (three males, three females, aged 34-45 years) were challenged with increasing doses of gamma-rays. DNA strand breaks and DNA repair were measured using the single-cell gel electrophoresis assay. Results: Baseline DNA strand breaks were significantly greater in buccal mucosa and sublingual cells compared with lymphocytes. Buccal mucosa and sublingual cells did not differ from each other with respect to induction of DNA strand breaks by 2 or 4 Gy gamma-rays. However, they showed a smaller increase in gamma-ray-induced DNA strand breaks compared with lymphocytes (32-53% less than lymphocytes; ANOVA p<0.0001). Unlike lymphocytes, which repaired 83% of DNA strand breaks, buccal mucosa and sublingual cells exhibited only a minimal capacity for DNA repair (approximately 0-14% of the level in lymphocytes). Conclusions: Buccal mucosa and sublingual cells exhibit an apparent resistance to the expression of radiation-induced DNA strand breaks in vitro and an apparent lack of DNA strand break repair in the single-cell gel electrophoresis assay.