α‐Hederin induce gastric cancer cell death by blocking autophagic flux and triggering ER stress

Abstract

BackgroundGastric cancer (GC) is a prevalent refractory disease worldwide, especially in developing countries. α‐Hederin (α‐Hed) is a major active component of triterpenoid saponin isolated from Fructus Akebia, we found it showed significant anti‐proliferative and pro‐apoptotic activity against GC cells in a dose‐dependent manner.PurposeThis study aims to uncover the potential mechanism of α‐Hedin relation to anti‐GC activity.Study designCytotoxicity of a‐Hed to BGC‐823 and MGC‐803 cells was monitored by CCK8 and Annexin V‐FITC/PI apoptosis assay. Autophagic flux was examined by western blot analysis and the number of green fluorescent protein (GFP)‐LC3B puncta. ER Stress was also probed by western blot analysis. Cellular Reactive Oxygen Species (ROS) Detection Assay Kit was used to detect ROS level.ResultsGC cells growth was significantly inhibited and cell death was induced by α‐Hed in BGC‐823 and MGC‐803 cells. We subsequently discovered that α‐Hed promoted autophagosome formation by upregulatingthe expression of LC3‐II, Beclin‐1 and increasing GFP‐LC3B puncta formation. However, p62 was also upregulated, which was indicative of autophagic flux blockage. Comparing to α‐Hed treatment alone, the combinatorial treatment of α‐Hed and Bafilomycin A1 (Baf A1) did not obviously alter the expression of LC3‐II, suggest that α‐Hed blocked autophagic flux in GC cells. Nevertheless it was later discovered that expression of ATF6, IRE1α, and PERK were elevated after a‐Hed treatment in GC cells, which represents activation of three signaling arms of the Unfolded Protein Response. Besides, α‐Hed obviously increased cellular ROS levels in GC cells, and the ER stress‐regulated apoptosis related proteins such as CHOP, caspase‐12, and JNK also increased.ConclusionOur results suggest that α‐Hed induce GC cell death by influencing crosstalk between autophagy and ER Stress pathways.Support or Funding InformationNational Natural Science Foundation of China General Program (81973523)graphical abstractFigure 1