Alisol B 23-acetate-induced HepG2 hepatoma cell death through mTOR signaling-initiated G_1 cell cycle arrest and apoptosis: A quantitative proteomic study

Objective: The present study aimed to investigate the molecular events in alisol B 23-acetate(ABA) cytotoxic activity against a liver cancer cell line.Methods: First, we employed a quantitative proteomics approach based on stable isotope labeling by amino acids in cell culture(SILAC) to identify the different proteins expressed in HepG2 liver cancer cells upon exposure to ABA. Next, bioinformatics analyses through DAVID and STRING on-line tools were used to predict the pathways involved. Finally, we applied functional validation including cell cycle analysis and Western blotting for apoptosis and mTOR pathway-related proteins to confirm the bioinformatics predictions.Results: We identified 330 different proteins with the SILAC-based quantitative proteomics approach. The bioinformatics analysis and the functional validation revealed that the mTOR pathway, ribosome biogenesis, cell cycle, and apoptosis pathways were differentially regulated by ABA. G1 cell cycle arrest, apoptosis and mTOR inhibition were confirmed.Conclusions: ABA, a potential mTOR inhibitor, induces the disruption of ribosomal biogenesis. It also affects the mTOR-MRP axis to cause G1 cell cycle arrest and finally leads to cancer cell apoptosis.

Hypoxia-mimicking 3D bioglass-nanoclay scaffolds promote endogenous bone regeneration

Large bone defect repair requires biomaterials that promote angiogenesis and osteogenesis.In present work,a nanoclay(Laponite,XLS)-functionalized 3D bioglass(BG)scaffold with hypoxia mimicking property was prepared by foam replication coupled with UV photopolymerization methods.Our data revealed that the incorporation of XLS can significantly promote the mechanical property of the scaffold and the osteogenic differentiation of human adipose mesenchymal stem cells(ADSCs)compared to the properties of the neat BG scaffold.Desferoxamine,a hypoxia mimicking agent,encourages bone regeneration via activating hypoxia-inducible factor-1 alpha(HIF-1α)-mediated angiogenesis.GelMA-DFO immobilization onto BG-XLS scaffold achieved sustained DFO release and inhibited DFO degradation.Furthermore,in vitro data demonstrated increased HIF-1αand vascular endothelial growth factor(VEGF)expressions on human adipose mesenchymal stem cells(ADSCs).Moreover,BG-XLS/GelMA-DFO scaffolds also significantly promoted the osteogenic differentiation of ADSCs.Most importantly,our in vivo data indicated BG-XLS/GelMA-DFO scaffolds strongly increased bone healing in a critical-sized mouse cranial bone defect model.Therefore,we developed a novel BG-XLS/GelMA-DFO scaffold which can not only induce the expression of VEGF,but also promote osteogenic differentiation of ADSCs to promote endogenous bone regeneration.