Radiosensitivity and double-strand break rejoining in tumorigenic and non-tumorigenic human epithelial cell lines

• Published in: International journal of radiation biology 1997-07, Vol.72 (1), p.91-100
• Main Author: DAZA , H. SCHUssLER, T. J. McMILLAN, S. C. GIROD and P. PFEIFFER, P.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Biological and medical sciences; Carcinoma, Squamous Cell - metabolism; Carcinoma, Squamous Cell - radiotherapy; Cell Line; Cell Survival - radiation effects; Cell-Free System; DNA - drug effects; DNA - metabolism; DNA - radiation effects; DNA Damage; DNA Repair - physiology; DNA Restriction Enzymes - metabolism; DNA Restriction Enzymes - pharmacology; DNA, Neoplasm - drug effects; DNA, Neoplasm - metabolism; DNA, Neoplasm - radiation effects; Epithelial Cells; Epithelium - physiology; Epithelium - radiation effects; Fundamental and applied biological sciences. Psychology; Humans; Keratinocytes - cytology; Keratinocytes - physiology; Keratinocytes - radiation effects; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Mutagenesis. Repair; Radiation Tolerance - physiology; Space life sciences; Tongue Neoplasms - metabolism; Tongue Neoplasms - radiotherapy; Tumor Cells, Cultured - radiation effects
• ISSN: 0955-3002; 1362-3095
• DOI: 10.1080/095530097143572

Radiosensitivity and repair of DNA damage induced by ionizing radiation and restriction enzymes were investigated in three human epithelial cell lines: two tumorigenic squamous carcinoma cell lines (SCC-4 and SCC-25), and a nontumorigenic epidermal keratinocyte cell line (RHEK-1). Sensitivity to ionizing radiation was determined using a clonogenic cell survival assay, which showed SCC-4 to be more radiosensitive than SCC-25 and RHEK-1, which in turn displayed about equal sensitivity. Using DNA precipitation under alkaline conditions for the analysis of induction and repair of DNA single-strand breaks (ssb), an increased level of ssb induction was found for SCC-4 while the efficiency of ssb repair was about equal in all three cell lines. Using pulsed-field gel electrophoresis (PFGE) for the measurement of induction and repair of DNA double-strand breaks (dsb), no consistent differences were detected between the three cell lines. A plasmid reconstitution assay was used to determine the capacity to rejoin restriction enzyme-induced dsb in whole-cell extracts prepared from the three cell lines. In these experiments, dsb rejoining was shown to be significantly reduced in the most radiosensitive SCC-4 cell line while it was about equal in RHEK-1 and SCC-25. The results indicate that plasmid reconstitution in cell-free extracts is a sufficiently sensitive assay to detect differences in repair capacity among tumour cell lines of different radiosensitivity which remain undetectable by DNA precipitation and PFGE.