Proteomic signatures of infiltrative gastric cancer by proteomic and bioinformatic analysis

BACKGROUND Proteomic signatures of Ming's infiltrative gastric cancer(IGC)remain unknown.AIM To elucidate the molecular characteristics of IGC at the proteomics level.METHODS Twelve pairs of IGC and adjacent normal tissues were collected and their proteomes were analyzed by high performance liquid chromatography tandem mass spectrometry.The identified peptides were sequenced de novo and matched against the SwissProt database using Maxquant software.The differentially expressed proteins(DEPs)were screened using|log2(Fold change)|>1 and P-adj<0.01 as the thresholds.The expression levels of selected proteins were verified by Western blotting.The interaction network of the DEPs was constructed with the STRING database and visualized using Cytoscape with cytoHubba software.The DEPs were functionally annotated using clusterProfiler,STRING and DAVID for Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathways.P<0.05 was considered statistically significant.RESULTS A total of 7361 DEPs were identified,of which 94 were significantly up-regulated and 223 were significantly down-regulated in IGC relative to normal gastric tissues.The top 10 up-regulated proteins were MRTO4,BOP1,PES1,WDR12,BRIX1,NOP2,POLR1C,NOC2L,MYBBP1A and TSR1,and the top 10 down-regulated proteins were NDUFS8,NDUFS6,NDUFA8,NDUFA5,NDUFC2,NDUFB8,NDUFB5,NDUFB9,UQCRC2 and UQCRC1.The up-regulated proteins were enriched for 9 biological processes including DNA replication,ribosome biogenesis and initiation of DNA replication,and the cellular component MCM complex.Among the down-regulated proteins,17 biological processes were enriched,including glucose metabolism,pyruvic acid metabolism and fatty acidβ-oxidation.In addition,the mitochondrial inner membrane,mitochondrial matrix and mitochondrial proton transport ATP synthase complex were among the 6 enriched cellular components,and 11 molecular functions including reduced nicotinamide adenine dinucleotide dehydrogenase activity,acyl-CoA dehydrogenase activity and nicotinamide adenine dinucleotide binding were also enriched.The significant KEGG pathways for the up-regulated proteins were DNA replication,cell cycle and mismatch repair,whereas 18 pathways including oxidative phosphorylation,fatty acid degradation and phenylalanine metabolism were significantly enriched among the down-regulated proteins.CONCLUSION The proteins involved in cell cycle regulation,DNA replication and mismatch repair,and metabolism were significantly altered in IGC,and the proteomic profile may enable the discovery of novel biomarkers.

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.