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Shigeto Shimmura, Misaki Ishioka, Kazuomi Hanada, Jun Shimazaki, Kazuo Tsubota; Telomerase Activity and p53 Expression in Pterygia. Invest. Ophthalmol. Vis. Sci. 2000;41(6):1364-1369.
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purpose. To investigate telomerase activity and p53 expression in pterygial
methods. Pterygia tissue was obtained during excisional surgery from 35 eyes of
35 patients, and superior bulbar conjunctival tissue from the same eye
was also sampled as control when possible. Fluorescence telomeric
repeat amplification protocol was used to measure telomerase activity
in whole pterygium samples from 9 cases and in the epithelium and
stroma of pterygium from another 10 cases. p53 protein content was
measured by enzyme-linked immunosorbent assay (ELISA) in tissues
obtained from 7 eyes, as well as in epithelial 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 conjunctival
epithelial cell line was irradiated with sublethal levels of UV-B to
investigate 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 measured separately in the epithelium and
stroma of pterygia, 5 samples were positive in the epithelium, only 1
of which had activity in the stroma. Average telomerase activity in
positive samples was 18.44 ± 8.77 U/μg protein, compared with
telomerase activity measured in a carcinoma in situ patient (33.73
U/μg), and in an immortalized conjunctival epithelial cell line
(50.72 ± 15.55 U/μg). Telomerase activity was not upregulated
in this cell line by UV-B exposure. All 6 pterygia samples tested for
p53 mutations did not reveal the UV-specific mutations in exons 5, 6,
7, or 8. No statistical significance was observed in the pterygium or
conjunctiva p53 protein levels in epithelial cells collected by brush
cytology, while p53 protein level was lower in pterygia when
measured in whole tissue samples.
conclusions. Telomerase activity was detected in some pterygia, mostly in the
epithelium. Pterygia was not associated with an increase in epithelial
p53 protein content measured by ELISA.
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