Telomerase activity and p53 expression in pterygia

PURRPOSE. To investigate telomerase activity and p53 expression in pterygia l tissue. METHODS. Pterygia tissue was obtained during excisional surgery from 35 eye s of 35 patients, and superior bulbar conjunctival tissue from the same eve was also sampled as control when possible. Fluorescence telomeric repeat a mplification protocol was used to measure telomerase activity in whole pter ygium samples from 9 cases and in the epithelium and stroma of pterygium fr om another 10 cases. p53 protein content was measured by enzyme-linked immu nosorbent assay (ELISA) in tissues obtained from 7 eyes, as well as in epit helial cell suspensions collected by brush cytology in 8 eyes. Six samples were also analyzed for UV-specific mutations in the p53 gene by the single- strand conformation polymorphism technique and DNA sequencing. A conjunctiv al epithelial cell line was irradiated with sublethal levels of UV-B to Inv estigate whether telomerase activity can be induced in vitro. RESULTS. In all, 63% of pterygia samples demonstrated telomerase activity, whereas all 10 paired conjunctival control samples were negative (P = 0.05, chi-square test). Of the 10 samples in which telomerase activity was measu red separately in the epithelium and stroma of pterygia, 5 samples were pos itive in the epithelium, only 1 of which had activity in the stroma. Averag e telomerase activity in positive samples was 18.44 +/- 8.77 U/mu g protein , compared with telomerase activity measured in a carcinoma in situ patient (33.73 U/mu g), and in an immortalized conjunctival epithelial cell Line ( 50.72 +/- 15.55 U/mu g). Telomerase activity was not upregulated in this ce ll line by UV-B exposure. All 6 pterygia samples tested for p53 mutations d id not reveal the UV-specific mutations in exons 5, 6, 7, or 8. No statisti cal significance was observed in the pterygium or conjunctiva p53 protein l evels in epithelial cells collected by brush cytology, while p53 protein le vel was lower in pterygia when measured in whole tissue samples. CONCLUSIONS. Telomerase activity was detected in some pterygia, mostly in t he epithelium. Pterygia was not associated with an increase in epithelial p 53 protein content measured by ELISA.