Abstract
Purpose :
The present study aims to understand the mechanism of lens epithelial cells’ strong anti-apoptosis capacity and survival rate in the mature human lens that, on the one hand, maintains lens transparency over several decades, while on the other hand increases the risk of posterior capsule opacification (PCO).
Methods :
Cell viability and apoptosis were analyzed in FHL124 cells under TNFα stimulation and were compared with HeLa cells. The TNFα mediated inflammatory signaling, cell survival genes were screened by real-time PCR, and key genes were confirmed by shRNA knocking down and immunoblot analysis.
Results :
FHL124 cells demonstrate strong resistance to TNFα mediated cell death compared to HeLa cells. Harsh stimulation with TNFα and cycloheximide (CHX) triggers almost entire HeLa cell death within 7hr but not FHL124 cells even after 24hr stimulation. Further studies suggest that FHL124 cells are able to block caspase 8 activation and subsequently preventing caspase 3 activation, PARP-1 cleavage, and cell death. Interestingly, despite spontaneous activation of transcription factors, NFκB and AP-1, and upregulation of multiple cell survival and anti-apoptotic genes in both cell types, only FHL124 cells managed to survive under TNFα challenge. By screening and comparing the cell survival genes, the cellular FLICE-like inhibitory protein (cFLIP) is found highly expressed in FHL124 cells and substantially upregulated by TNFα stimulation. FHL124 cells with a mild cFLIP 37 knockdown manifest a profound apoptotic response to TNFα and CHX treatment similar to Hela cells.
Conclusions :
Lens cells demonstrate a high level of resistance to stress-induced apoptosis relative to HeLa cells. cFLIP is abundant in lens epithelial cells and is further upregulated in the presence of stressors. A reduction in cFLIP renders lens epithelial cells more susceptible to apoptosis and therefore suggest that cFLIP plays a critical role in lens cell survival.
This is a 2021 ARVO Annual Meeting abstract.