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Nicole Wagner, Kay D. Wagner, Mark Sefton, Alfredo Rodríguez–Tébar, Rosemarie Grantyn; An Abnormal Response of Retinoblastoma Cells (Y-79) to Neurotrophins. Invest. Ophthalmol. Vis. Sci. 2000;41(7):1932-1939.
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purpose. To clarify the expression of neurotrophins and their receptors in
retinoblastoma (Rb) cells, to elucidate their potential role in the
proliferation of neuroectodermal tumor cells, and to establish
conditions for Rb cell differentiation.
methods. The Rb-derived cell line Y-79 was grown in serum-free suspension or
monolayer culture. Proliferating and differentiated cells were isolated
and submitted to semiquantitative reverse transcription–polymerase
chain reaction (RT-PCR) analysis, immunostaining, and flow cytometry.
The proliferation rate of the cells was estimated by
5-bromo-2′-deoxyuridine (BrdU) incorporation, and the effects of
neurotrophins and laminin on BrdU-incorporation, process outgrowth, or
immunostaining were determined.
results. In contrast to previously studied normal retinal precursor cells,
Y-79 cells not only express nerve growth factor (NGF), brain-derived
neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and p75, but
also the corresponding high affinity receptors TrkA, TrkB, and TrkC.
Proliferation was stimulated by exogenous and endogenous neurotrophin
receptor ligands. Inhibition of protein kinase phosphorylation with
K252a blocked proliferation and promoted differentiation. The effect of
K252a on differentiation was enhanced by the addition of soluble
laminin. After 9 days of combined treatment, the fraction of
differentiated cells amounted to 30%, differentiation being
characterized by improved attachment, neurite outgrowth, expression of
NF-68, and a loss of glial fibrillary acidic protein (GFAP) and
parvalbumin immunoreactivity. These changes were accompanied by a
downregulation of TrkB and TrkC, but not TrkA or p75. Differentiated
cells were isolated and further grown in the absence of K252a. However,
despite the high level of TrkA expression in differentiated cells, the
addition of NGF had no effect on their survival.
conclusions. A mitogenic action of neurotrophins could contribute to retinal tumor
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