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

Abstract

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. Similar 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/m2 UVA 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/m2 UVA 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.

Ultraviolet Radiation Increases the Toxicity of Pyrene, 1-Aminopyrene and 1-Hydroxypyrene to Human Keratinocytes

“…This agrees with what is already known about UV-A light causing damage to cellular DNA, resulting in cell death [7–8]. The toxic effects of UV-A irradiated PAHs to human cells, is established.…”

Role of Reduced Glutathione Efflux in Apoptosis of Immortalized Human Keratinocytes Induced by UVA

“…GSH to GSSG was found to be the predominant reaction for glutathione, causing the depletion of intracellular GSH (24,50). No significant GSH efflux was observed, as was the case in our studies.…”

Laser-ultraviolet-A-induced ultraweak photon emission in mammalian cells

“…31,32 As aging parameter DL measurements show no significance in contrast to the previously cited method, while comparing melanoma with normal cells as shown in Table 2 indicates that UV-A-induced DL can serve as a marker of carcinogenesis. Note that for this testing, well-defined fibroblastic cells 10,24,[31][32][33] as well as melanomic cells were used. 20,34,35 Nevertheless, further investigations are necessary to confirm this observation.…”