IGF2BP2 knockdown inhibits LPS-induced pyroptosis in BEAS-2B cells by targeting caspase 4, a crucial molecule of the non-canonical pyroptosis pathway

Insulin-like growth factor 2 (IGF2) mRNA-binding protein 2 (IGF2BP2) is a secreted protein that can bind to IGF2 and has been reported to promote inflammation. The data from the ENCORI database have predicted that IGF2BP2 can bind caspase 4, which mediates pyroptosis and promotes airway inflammation and lipopolysaccharide (LPS)-induced lung injury. The present study investigated whether IGF2BP2 can regulate LPS-induced lung cell inflammation by targeting caspase 4. Therefore, the non-tumorigenic lung epithelial cell line Beas-2B was transfected with short hairpin RNA (shRNA)-IGF2BP2 and stimulated with LPS. A number of parameters, including cell viability, production of interleukin (IL)-1β and IL-18, activation of gasdermin D (GSDMD) and the expression levels of IGF2BP2, caspase 4 and cleaved-caspase 1, were subsequently assessed using CCK-8, ELISA kits, western blotting and immunofluorescence staining, respectively. RNA pull-down assay was used to probe the possible interaction between IGF2BP2 and caspase 4 RNA. LPS treatment was found to inhibit cell viability, trigger IL-1β and IL-18 production and increase IGF2BP2 expression in a concentration-dependent manner. Compared with cells transfected with shRNA-negative control, cells that were transfected with shRNA-IGF2BP2 exhibited enhanced cell viability, reduced IL-1β and IL-18 concentrations, decreased GSDMD activation in addition to reduced expression levels of caspase 4 and cleaved-caspase 1 following stimulation with 1 µg/ml LPS. Concomitantly, the effects of IGF2BP2 silencing on caspase 4 expression were higher compared with those noted on caspase 1. In addition, binding of IGF2BP2 to caspase 4 RNA was also observed. To conclude, data from the present study suggest that IGF2BP2 knockdown inhibited LPS-induced Beas-2B cell inflammation by targeting caspase 4, thereby inhibiting the non-canonical pyroptosis pathway.