Lithium effects on DNA damage and repair of actively transcribed genes

It has been established that un-repaired DNA damage in active genes is expressed in inhibition of transcriptional activity, namely RNA synthesis. Lithium effects on DNA damage and repair in actively transcribed genes in cultured human fibroblasts was the focus of this investigation. Three cultured human skin fibroblasts lines have been used. Two were labelled 'normal' in previous RNA recovery testings and one showed abnormal sensitivity to UV light. In the 'normal' lines recovery of RNA synthesis after exposure to various lithium carbonate concentrations, (0.5, 1.0 and 1.5 mmol/l), was normal within 4 h. The UV sensitive cell line showed a markedly depressed recovery of RNA synthesis, although not statistically significant. A further set of experiments showed that combining lithium exposure and UV irradiation produced a synergistic effect as expressed in a greater reduction in recovery of RNA synthesis. Our results show that lithium-carbonate inhibits recovery of RNA synthesis in fibroblast's cultures when combined with UV irradiation.