gms | German Medical Science

Cytostatic drugs are commonly used to prevent scarring after filtration surgery in patients with glaucoma. Complications associated with their use (such as, hypotony or endophthalmitis) drive the search for alternative treatment. The ideal drug should effectively inhibit proliferation without toxic side effects. Single application of b-radiation leads to long term growth arrest and expression of p53 in Tenon's fibroblasts, and it is assumed that the activation of p53 is one of the cellular triggers. Our aim was to examine the effect of overexpression of p53 on human Tenon's fibroblasts and to determine which pathway is involved downstream.

Two 1^st generation adenoviral vectors were used: One (rAd.p53/GFP) containing transgenes encoding for human p53 and green fluorescent protein (GFP) and one control, containing only the reporter gene (rAd.GFP). Successfully infected cells were detected using fluorescent microscopy. P53 expression was demonstrated using immunofluorescence staining and Western Blot. P21WAF1 was detected with Western Blot. Cell proliferation was investigated by determining cell densities, and the incorporation of 5'-bromodeoxyuridine (BrdU assay) during DNA-synthesis.

Overexpression of P53 could be detected in human Tenon's fibroblasts up to seven days following infection. Treatment of Tenon's fibroblasts with rAd.p53 resulted in significant inhibition of cell growth (down to 50.2 -74% of controls, p=0.0003-0.0048) and DNA-synthesis in vitro. Western Blot showed raised levels (up to 250%) of p21WAF1 in p53 positive cells.

p53 gene transfer leads to significant growth arrest of human Tenon's fibroblasts. P53 induces p21WAF1 expression. P21WAF1-dependent inhibition of cyclin dependent kinases is probably responsible for the growth arrest. p53 shows the potential to replace antiproliferative drugs in glaucoma surgery, even though its effects are transient with this vector system.