Oxidative stress and TGF-beta1: triggers of premature senescence in adult human prostate fibroblasts?
R. Gander, G. Untergasser, H. Rumpold, E. Plas, L. Tadic, P. Berger
Institute for Biomedical Aging Research, Department of Endocrinology, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria
Previous reports emphasize that oxidative stress-induced premature
senescence (SIPS) of human diploid fibroblasts (HDFs) is mainly
triggered by transforming growth factor beta 1 (TGF-b1). In the human
prostate TGF-b1 mediates the differentiation of fibroblasts to
myofibroblasts within a gradual process leading to a reactive stroma
that favours epithelial cell tumorigenesis. In this study, we wanted to
elucidate the role of oxidative stress via in vitro application of
tert-butylhydroperoxide (t-BHP) and recombiant TGF-b1 on proliferation,
differentiation and senescence of primary isolated human prostatic
stromal fibroblasts (PrSC). SIPS was evaluated by SA-beta-galactosidase
(SA-b-gal) staining after 3 days of TGF-b1 and t-BHP treatment.
Moreover, stromal differentiation markers (SMC-a-actin, calponin,
vimentin, JM-27), cell cycle regulators (p53, p27KIP1, p21Cip1,
p16ink4A, p15ink4B, Id-1) and senescence associated genes (IGFBP-3,
dkk3, PTHrP) were evaluated by quantitative PCR, western blot analysis
and immunofluorescence. Neither TGF-b1 nor t-BHP treatment
significantly induced SA-b-gal, p16inK4A or a terminal irreversible
growth arrest in PrSC. t-BHP led to a loss of proliferative activity,
induction of p21Cip1, but no signs of differentiation into
myofibroblast. In contrast, TGF-b1 stimulation was responsible for
growth arrest by induction of p15ink4B and IGFBP-3 as well as
down-regulation of Id-1, and induced differentiation into
myofibroblasts by increased expression levels of calponin, SMC-a-actin
tenascin and JM-27.
Conclusive, oxidative stress did not support transdifferentiation of
PrSC and thus tissue-remodelling in favour to reactive stroma.
Moreover, TGF-b1, a presumable executor molecule of oxidative stress,
acted completly distinct by supporting myofibroblast differentiation,
reactive stroma and expression of the benign prostatic hyperplasia
marker JM-27 in PrSC.
Key words:
cellular senescence, oxidative stress, TGF-beta, prostate fibroblasts
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