Glutathione Response after UVA Irradiation in Mitotic and Postmitotic Human Skin Fibroblasts and Keratinocytes

• Published in: Photochemistry and photobiology 1997-04, Vol.65 (4), p.680-684
• Main Authors: Niggli, Hugo J., Applegate, Lee A.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Child; Child, Preschool; Fibroblasts - cytology; Fibroblasts - metabolism; Fibroblasts - radiation effects; Glutathione - metabolism; Humans; Infant; Keratinocytes - cytology; Keratinocytes - metabolism; Keratinocytes - radiation effects; Mitosis; Skin - cytology; Skin - metabolism; Skin - radiation effects; Ultraviolet Rays
• ISSN: 0031-8655; 1751-1097
• DOI: 10.1111/j.1751-1097.1997.tb01911.x

— Since Hayflick's pioneering work in the early sixties, human diploid fibroblasts have become a widely accepted in vitro model system. Recently, Bayreuther and co‐workers extended this experimental approach showing that fibroblasts in culture resemble, in their design, the hemopoietic stem‐cell differentiation system. They found that the chemical agent mitomycin C accelerates the differentiation pathway from mitotic to postmitotic fibroblasts. We measured the response of endogenous glutathione levels after UVA irradiation (320‐400 nm) in mitotic and mitomycin C‐induced postmitotic human skin fibroblasts and foreskin‐derived keratinocytes. The initial levels in mitotic foreskin derived human fibroblasts were 14.4 nmol glutathione per mg protein, whereas a 30% higher value was obtained in matching foreskin‐derived keratinocytes. Similiar elevated levels of this important intracellular free radical scavenging system were found in fibroblasts of a donor suffering from xeroderma pigmentosum. Furthermore, three to four times higher levels of glutathione in mitomycin C‐treated mitotic fibroblasts have been determined. In mitotic skin fibroblasts, UVA irradiation resulted in a depletion of glutathione up to 90% following a fluence of 1.0 MJ/m2UVA radiation. Higher initial glutathione levels were found in keratinocytes and mitomycin C‐treated skin fibroblasts. In these fibroblasts a 70% depletion was detected and a much lower depletion (10‐20%) was seen in some keratinocyte cell lines following fluences up to 1.0 MJ/m2. The depletion in skin fibroblasts was retained after 24 h following a fluence of 0.75 MJ/m2UVA light. In view of the fact that glutathione has been shown to be involved in a variety of metabolic processes and plays a role in cellular protection against UVA radiation, our results imply that the fibroblast differentiation system is a very useful tool to unravel the complex mechanism of UVA‐induced oxidative stress.