Lens epithelial cell death and reduction of anti-apoptotic protein Bcl-2 in human anterior polar cataracts

Purpose: In light of the growing body of data implicating apoptosis in cataractogenesis, and in particular, the reported detection of apoptosis in posterior capsular opacification, the purported etiology of which, like that of anterior polar cataracts, is an aberrant transdifferentiation of lens epithelial cells into myofibroblastic cells, we hypothesized that apoptosis could also occur in anterior polar cataracts. Here we sought to examine whether apoptotic cell death occurs in lens epithelial cells from patients with anterior polar cataracts. Methods: Cell death of lens epithelial cells from anterior polar cataracts, nuclear cataracts, and non-cataractous clear lenses was measured by TUNEL assay and DNA fragmentation assay. The expression of Bcl-2 and Bax was examined using reverse transcription-polymerase chain reaction and Western blot analysis. Results: Cell death was detected in specimen from patients with anterior polar cataracts by TUNEL assay. DNA fragmentation assay showed the characteristic laddering pattern from the genomic DNA from anterior polar cataracts. The expression of Bcl-2 mRNA and its protein was markedly decreased in lens epithelial cells from patients with anterior polar cataracts. Conclusions: This study suggests that apoptotic cell death might occur in lens epithelial cells from anterior polar cataracts and decreased expression of Bcl-2 might play a role in the pathologic cellular mechanism of anterior polar cataracts.