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- Title
UVA radiation causes DNA strand breaks, chromosomal aberrations and tumorigenic transformation in HaCaT skin keratinocytes.
- Authors
Wischermann, K; Popp, S; Moshir, S; Scharfetter-Kochanek, K; Wlaschek, M; de Gruijl, F; Hartschuh, W; Greinert, R; Volkmer, B; Faust, A; Rapp, A; Schmezer, P; Boukamp, P
- Abstract
The role of UVA-radiation—the major fraction in sunlight—in human skin carcinogenesis is still elusive. We here report that different UVA exposure regime (4 × 5 J/cm2 per week or 1 × 20 J/cm2 per week) caused tumorigenic conversion (tumors in nude mice) of the HaCaT skin keratinocytes. While tumorigenicity was not associated with general telomere shortening, we found new chromosomal changes characteristic for each recultivated tumor. Since this suggested a nontelomere-dependent relationship between UVA irradiation and chromosomal aberrations, we investigated for alternate mechanisms of UVA-dependent genomic instability. Using the alkaline and neutral comet assay as well as γ-H2AX foci formation on irradiated HaCaT cells (20–60 J/cm2), we show a dose-dependent and long lasting induction of DNA single and double (ds) strand breaks. Extending this to normal human skin keratinocytes, we demonstrate a comparable damage response and, additionally, a significant induction and maintenance of micronuclei (MN) with more acentric fragments (indicative of ds breaks) than entire chromosomes particularly 5 days post irradiation. Thus, physiologically relevant UVA doses cause long-lasting DNA strand breaks, a prerequisite for chromosomal aberration that most likely contribute to tumorigenic conversion of the HaCaT cells. Since normal keratinocytes responded similarly, UVA may likewise contribute to the complex karyotype characteristic for human skin carcinomas.Oncogene (2008) 27, 4269–4280; doi:10.1038/onc.2008.70; published online 31 March 2008
- Subjects
ULTRAVIOLET radiation; TUMOR growth; NUCLEOTIDE sequence; CHROMOSOME abnormalities; TELOMERES
- Publication
Oncogene, 2008, Vol 27, Issue 31, p4269
- ISSN
0950-9232
- Publication type
Article
- DOI
10.1038/onc.2008.70