DNA damage and repair in Gorlin syndrome and normal fibroblasts after aminolevulinic acid photodynamic therapy: a comet assay study.

Using normal, untransformed, human fibroblasts, the effectiveness of aminolevulinic (ALA)-mediated photodynamic therapy (PDT) was investigated in terms of both clonogenic survival and DNA damage. The response of normal fibroblasts was then compared with Gorlin syndrome-derived fibroblasts (basal cell nevus syndrome [BCNS]). In terms of clonogenic survival, no significant differences were observed between the two groups of cells. Using the alkaline comet assay, initial DNA damage after PDT was measured. Some DNA damage was detected at higher doses, but this was fully repaired within 24 h of treatment. The BCNS-derived cells showed levels of initial damage that did not differ significantly from normal lines.