Hepatocyte growth factor induces proliferation of lens epithelial cells through activation of ERK1/2 and JNK/SAPK

PURPOSE. Posterior capsule opacification (PCO) is caused by proliferation and migration of lens epithelial cells (LECs) remaining after cataract surgery. In this study, the effect of HGF in LECs and the signaling pathways that contribute to HGF-induced proliferation were investigated. METHODS. Capsular bags prepared from porcine eyes were maintained in serum-free DMEM. The human lens epithelial B3 cells (HLE B3) and rat lens epithelial explants were cultured in MEM supplemented with 20% FCS and medium 199 with 0.1% BSA, respectively. Cell proliferation was determined by MTT assay, proliferating cell nuclear antigen ( PCNA) expression, or flow cytometry. An antisense oligonucleotide was used to inhibit cyclin D1 expression. Activation of the mitogen activated protein kinase ( MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways was detected by immunoblot analysis. RESULTS. The proliferation of LECs in a capsular bag culture was significantly inhibited by treatment with the neutralizing antibody for HGF receptor. Stimulation of HLE B3 with hepatocyte growth factor ( HGF) activated the MAPKs, ERK, and JNK/ SAPK, but not p38. Activation of both ERK and JNK/ SAPK was necessary for the HGF-stimulated induction of cyclin D1, which in turn was necessary for the HGF-induced proliferation of LECs. PI3K also participated in the regulation of cyclin D1 expression upstream of ERK and JNK/ SAPK. CONCLUSIONS. The data indicate that HGF is a potent growth factor for LECs and may contribute to the development of PCO and suggest that the signaling pathways involved in HGF-stimulated proliferation may constitute potential therapeutic targets in the treatment of PCO.