KAI1-induced autophagy inhibiting apoptosis through the downregulation of Caspase-3 activation

Abstract

Objective To explore the pathway of KAI1 induced autophagy regulating apoptosis in human pancreatic cancer cell line MiaPaCa-2.Methods There were three groups in the experiment,which were extracellular regulated protein kinases (ERK) phosphorylation inhibitor PD98059 pretreated group,Caspase-3 activation inhibitor VAD-FMK pretreated group and no PD98059 or VAD-FMK pretreated groups.And each group was divided into three sub groups with different treatment,which were adenovirus AD5-null vector infected control group,the human KAI1 gene recombinant adenovirus vector AD5 KAI1 infected group and autophagy inhibitor 3-MA pretreated and AD5-KAI1 infected group.The cell apoptosis was observed by AnnexinV-FITC/PI double staining.Caspase-3 activation level was evaluated by flow cytometry.ERK phosphorylation and poly(ADPribose) polymerase (PARP) cleavage were determined by Western blot.Results After the cancer cells infected with AD5 KAI1,KAI1 protein was expressed and GFP-LC3 green particles increased.Caspase-3 activation,PARP cleavage,ERK phosphorylation and apoptosis increased obviously.After autophagy inhibitor 3-MA pretreated,the percentage of apoptosis increased from (63.0 ± 7.9)％ to (88.0±4.5) ％ and Caspase-3 activation increased from (34.0±2.8) ％ to (44.2±4.0) ％ and PARP cleavage more.The apoptosis induced by 3-MA could be totally inhibited by Caspase-3 activation inhibitor VAD-FMK pretreated but could not be inhibited by ERK phosphorylation inhibitor PD98059.Conclusion KAI1- induced autophagy inhibits apoptosis through the downregulation of Caspase-3activation and PARP cleavage instead of ERK phosphorylation. Key words: Genes, Tumor Suppressor; Autophagy; Apoptosis; Caspase 3; Phosphorylation