Effects of Apoptin-Induced Endoplasmic Reticulum Stress on Lipid Metabolism, Migration, and Invasion of HepG-2 Cells

Abstract

In this study, we investigated the effects of Apoptin-induced endoplasmic reticulum (ER) stress on lipid metabolism, migration and invasion of HepG-2 cells, and preliminarily explored the relationship between endoplasmic reticulum stress, lipid metabolism, migration, and invasion. The effects of Apoptin on ER function and structure in HepG-2 cells were determined by flow cytometry, fluorescence staining and western blotting by assessing the expression levels of ER stress related proteins. The effects of Apoptin on HepG-2 cells’ lipid metabolism were determined by western blot analysis of the expression levels of triglyceride, cholesterol, and lipid metabolism related enzymes. The effects of Apoptin on HepG-2 cells’ migration and invasion were studied using migration and invasion assays and by Western-blot analysis of the expression of proteins involved in migration and invasion. The in vivo effects of endoplasmic reticulum stress on lipid metabolism, migration and invasion of HepG-2 cells were also investigated by immunohistochemistry analysis of tumor tissues from HepG2 cells xenografted nude mice models. Both in vitro and in vivo experiments showed that Apoptin can cause a strong and lasting ER stress response, damage ER functional structure, significantly change the expression levels of lipid metabolism related enzymes and reduce the migration and invasion abilities of HepG-2 cells. Apoptin can also affect HepG-2 cells’ lipid metabolism through endoplasmic reticulum stress and the abnormal expression of enzymes closely related to tumor migration and invasion. These results also showed that lipid metabolism may be one of the main inducements that reduce HepG-2 cells’ migration and invasion abilities.

Apoptin Causes Apoptosis in HepG-2 Cells by Inducing Stress Injury in the Endoplasmic Reticulum

“…Therefore, it is of great signi cance to investigate the speci c effect of ERS injury on the ER and apoptosis-related pathways in the mitochondria with regards to the induction of apoptosis. Our previous studies have found that Apoptin can cause a strong and lasting ER stress response and damage ER functional structure [12]. In the present study, we demonstrated that Apoptin can induce ERS injury, cause Ca 2+ imbalance, affect the structure and function of the mitochondria, and can induce signi cant changes in the expression of key proteins related to the ER and the mitochondria.…”

“…Collectively, these proteins lighten the load on the ER by reducing misfolding and helping to avoid the accumulation of unfolded proteins. In our previous study [12], we found that the expression levels of several stress-related proteins in the ER, including PERK, Calnexin, Ero1-lα, and BIP, were signi cantly higher in the HepG-2 cells infected with Ad-Vp3 then cells infected with Ad-Mock when tested at 12 h and 24 h post-infection. These changes were caused by ER stress.…”

“…Tumor tissues were isolated from HepG-2 cells nude mice xenograft models xenografted [12]. We then used immunohistochemical staining to investigate the ER apoptotic pathway, and a range of proteins involved in the apoptotic pathway in mitochondria, including Caspase-12, CHOP, AIF, HtrA2, Smac/Diablo, and Cyto-C. All immunohistochemical detection was performed by Servicebio (Wuhan, China).…”

“…Our previous study demonstrated that Apoptin induced signi cant changes in the expression levels of ERS-related proteins and caused a strong and lasting ERS response [12]. The effect of Apoptin on the structure of the ER was evaluated by electron microscopy.…”

Apoptin Inhibits Glycolysis and Regulates Autophagy by Targeting Pyruvate Kinase M2 (PKM2) in Lung Cancer A549 Cells

“…Apoptin is a small molecular weight apoptosis-inducing protein extracted from chicken anemia virus and can selectively kill a variety of human tumors cells without toxicity to normal human cells [ 16 , 17 ]. Apoptin can induce tumor cell-specific apoptosis independently of p53, and therefore, can kill tumor cells even if the p53 gene is mutated or inactivated.…”