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

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.