Salubrinal protects against cigarette smoke extract-induced HBEpC apoptosis likely via regulating the activity of PERK-eIF2α signaling pathway.

Background And Aims: Endoplasmic reticulum (ER) stress plays an important role in cigarette smoke extract (CSE)-induced apoptotic cell death, which is an important pathogenic factor of chronic obstructive pulmonary disease (COPD). The aim of this study was to explore the role of the PERK-eIF2 pathway in CSE-induced human bronchial epithelial (HBE) cell apoptosis and to evaluate the protective effects and possible mechanism of salubrinal (Sal) on CSE-induced HBE cell apoptosis.

Methods: Normal human bronchial epithelial cells (HBEpC) were cultured and then treated with CSE alone or together with Sal or preincubated with or without PERK siRNA. Expressions of p-PERK/PERK, p-eIF2α/eIF2α, and caspase 3 and 4 were detected with PCR, Western blot, and immunofluorescence. Apoptosis was detected using AnnexinV-PI flow cytometry.

Results: CSE induced apoptotic cell death and caused a dynamic change in PERK-eIF2α pathway activity following the course of CSE exposure. The knockdown of PERK suppressed the expression of both PERK and p-eIF2a and caused a great increase in cell apoptosis. Sal could eliminate the effects of PERK knockdown, protecting the cells against the CSE insult, and this protection was accomplished through maintaining the homeostasis of PERK- eIF2α pathway.

Conclusions: PERK-eIF2α pathway mediates the CSE-induced HBE cell apoptosis. The intactness of PERK-eIF2α pathway is crucial for HBE cell survival under CSE insult. Sal can protect against CSE-induced HBE cell apoptosis, and this effect is likely achieved through maintaining the homeostasis of PERK- eIF2α pathway.