Characterization of spontaneous and induced mutations in SV40-transformed normal and ataxia telangiectasia cell lines

Abstract

Spontaneous and induced mutations at the HPRT locus were analyzed in one normal (MRC5CV1) and one ataxia telangiectasia (AT5BIVA) SV40-transformed cell line derived from male donors. Multiplex PCR and Southern analyses revealed a high frequency of spontaneous deletion mutations that may be a consequence of the SV40 transformation. Four mutagens (ethyl methanesulfonate, bromodeoxyuridine, bleomycin, adriamycin), which differ in their types of primary DNA lesions, caused specific patterns of mutations. By using fluorescence in situ hybridization (FISH) techniques, we were able to show that more than 90% of the AT5BIVA cells contained two X chromosomes with HPRT alleles, while in more than 90% of the MRC5CV1 cells genomic hemizygosity for the HPRT gene was found. Taking into account these findings we found that the AT5BIVA cell line possesses spontaneous hypermutability as well as hypersensitivity and hypermutability to bleomycin (BLM) and adriamycin (AM). Both mutagens induced deletion mutations in both cell lines, but more complex mutations and larger deletions were found in AT5BIVA cells.

Genomic DNA is captured and amplified during double-strand break (DSB) repair in human cells

“…In agreement with the majority of reports that used cells or cell extracts, we found that AT cells exhibited similar relative DSB repair proficiency, but a signifi-cantly reduced repair fidelity (Po0.001), compared to a normal cell line (Table 1) (Cox et al, 1986;Runger et al, 1992;Powell et al, 1993;Tatsumi-Miyajima et al, 1993;Roscheisen et al, 1994;Dar et al, 1997;Lobrich et al, 2000;Li et al, 2001;Tachibana and Sasaki, 2002). We observed 4% of the DSBs repaired in normal cells suffered a loss of lacZ, whereas 20% of colonies showed misrepair events in AT cells.…”

Spontaneously immortalized cell lines obtained from adult Atm null mice retain sensitivity to ionizing radiation and exhibit a mutational pattern suggestive of oxidative stress

“…Virally transformed human lymphocytes and ®bro-blasts from A-T patients are available (Meyn, 1993;Pandita and Hittelman, 1992;Cole et al, 1988;Roscheisen et al, 1994), but the presence of viral oncoproteins can complicate the interpretation of data obtained with these immortalized cell lines. Recently, telomerase expression has been used to extend the life span of human A-T ®broblasts without apparent loss of radiation sensitivity (Wood et al, 2001).…”

Plant Science and Human Nutrition: Challenges in Assessing Health-Promoting Properties of Phytochemicals

“…However, such transformed cells typically exhibit significant alterations in physiological and biological properties. Most notably, these cells are associated with aneuploidy, epigenetic changes, spontaneous hypermutability, loss of contact inhibition (the characteristic of healthy cells to arrest growth in response to contact with other cells), and alterations in biochemical functions related to cell cycle checkpoints, such as Rb, p53, and pp2A proteins (Huschtscha and Holliday, 1983;Rö scheisen et al, 1994;Velicescu et al, 2003;Ahuja et al, 2005).…”