EGCG Mitigates Apoptosis of Lens Epithelial Cells in Age-Related Cataract via the PAK1/Cleaved Caspase-3 Pathway.

Abstract

Background: Oxidative damage and apoptosis of lens epithelial cells (LECs) are the primary factors contributing to the development of age-related cataracts (ARC). The potential protective effects of epigallocatechin gallate (EGCG) on LECs remain unclear despite its remarkable antioxidant and anti-apoptotic properties. The aim of this study was to explore the role of serine/threonine-protein kinase (PAK1) in EGCG-mediated attenuation of H2O2-induced apoptosis of LECs in vivo and in vitro.

Methods: PAK1 expression was assessed in the anterior capsule of the lens from mice and patients with and without ARC using western blotting and immunohistochemistry. Human lens epithelial B3 (HLE-B3) cells were pre-treated with EGCG+H2O2 or H2O2 only, and PAK1 expression was determined using qRT-PCR and western blotting. Apoptosis (following PAK1 overexpression or silencing) and cell survival were assessed using Hoechst 33342 staining and a cell counting Kit-8 assay, respectively. Cleaved caspase-3 was measured in transected cells, aged/young mice, and mice treated with EGCG via western blotting.

Results: PAK1 expression was significantly lower in ARC LECs than in control LECs. In HLE-B3 cells, EGCG+H2O2 treatment upregulated PAK1 mRNA and protein expression when compared with H2O2 alone. PAK1 overexpression alleviated H2O2- induced apoptosis in LECs, while low expression weakened EGCG's protective effects. PAK1 overexpression reduced cleaved caspase-3 expression in H2O2-treated cells, whereas PAK1 silencing increased its expression in EGCG+H2O2-treated cells. EGCG decreased cleaved caspase-3 expression in H2O2-treated cells. These results suggest that PAK1 inhibits cleaved caspase-3 expression, thereby enhancing EGCG's attenuation of H2O2-induced LEC apoptosis.

Conclusion: The PAK1/cleaved caspase-3 pathway plays a key role in EGCG's protective effects on the development of ARC. This provides a new therapeutic target for the use of EGCG in preventing and treating ARC.