Psoralen plus UVA (PUVA) induced premature senescence as a model for stress-induced premature senescence.

Following psoralen photoactivation (PUVA treatment) human dermal fibroblasts undergo long-term growth arrest as well as morphological and functional changes reminiscent of replicative senescence. Although the molecular description of cellular senescence is still incomplete, replicative senescence of cultured human cells has been suggested to reflect cellular aging in vitro. Recently, the term stress-induced premature senescence (SIPS) was introduced to define in vitro models with longterm growth arrest upon exposure to sublethal stressors (i.

Induction of manganese superoxide dismutase in human dermal fibroblasts: a UV-B-mediated paracrine mechanism with the release of epidermal interleukin 1 alpha, interleukin 1 beta, and tumor necrosis factor alpha.

Background: Reactive oxygen species generated in the skin by UV irradiation promote photoaging and photocarcinogenesis. The manganese (Mn) superoxide dismutase (SOD) is a primary antioxidant enzyme that crucially contributes to the homeostasis of oxygen radicals within the mitochondria, and thus critically participates in the control of senescence and tumor generation.

Objective: To determine whether repetitive UV-B exposure, as practiced for light hardening during phototherapy for various photodermatoses, can enhance the adaptive antioxidant response by up-regulating MnSOD activity in either the epidermal or the dermal skin compartment.

Human dermal fibroblasts escape from the long-term phenocopy of senescence induced by psoralen photoactivation.

We have previously shown that following psoralen photoactivation (PUVA treatment) human dermal fibroblasts undergo long-term growth arrest as well as morphological and functional changes reminiscent of cellular senescence [ 1 ]. In the absence of molecular data on what constitutes normal senescence, it has been difficult to decide whether these PUVA-induced changes reflect cellular senescence or rather a mimic thereof. We herein report that PUVA-induced growth arrest, the senescent phenotype with long-term induction of senescence-associated beta-galactosidase, as well as increased expression of matrix metalloprotease-1 are fully reversible at days 100 to 130 post PUVA treatment in four independently tested fibroblast strains.