Identification of a novel biomarker in tangeretin-induced cell death in AGS human gastric cancer cells

Proteomic analysis serves as an important biological tool for identifying biological events. Novel biomarkers of a specific disease such as cancer may be identified using these promising techniques. The aim of the present study was to investigate the effect of tangeretin and to identify potential biomarkers in AGS gastric cancer cells using a proteomics approach. The results of the present study revealed that tangeretin inhibited AGS cell viability dose-dependently with a half-maximal inhibitory concentration of 100 µM. Two-dimensional gel electrophoresis was performed to determine the potential biomarker between control and tangeretin (100 µM)-treated AGS cells. A total of 16 proteins was identified from 36 significant protein spots using matrix-assisted laser-desorption/ionization time-of-flight-mass spectrometry using peptide fingerprinting. The bioinformatics tools Protein ANalysis THrough Evolutionary Relationships (PANTHER) and Database for Annotation, Visualization and Integrated Discovery (DAVID) were used to identify the functional properties and association of the proteins obtained. Using western blot analysis, the regulatory pattern of four selected proteins, protein kinase Cε, mitogen-activated protein kinase 4, phosphoinositide 4-kinase and poly(ADP-ribose) polymerase 14, were successfully verified in replicate sample sets. These selected proteins are primarily involved in apoptosis signaling, angiogenesis, cell cycle regulation, receptor kinase binding, intracellular cytoplasmic and nuclear alterations. Therefore, aim of the present study was to identify potential diagnostic biomarkers from the functional categories of altered protein expression in tangeretin-inhibited AGS gastric cancer cell viability.