Label-free quantitative proteomic analysis of acquired herceptin resistance in gastric cancer cells / 药学学报

ABSTRACT

This study was designed to explore proteins differentially expressed in HER2 positive gastric cancer N87 cells and N87/R cells with an acquired resistance to herceptin based on label-free quantitative proteomics. The extracted proteins were reduced and alkylated, then digested using filter aided sample preparation (FASP); peptides were separated via small manual reversed phase column, analyzed by LC-MS/MS, and identified with protein database 2.1 search engine. Proteins were quantified by intensity based quantification (IBQ) to search for differential proteins by comparison with relatively quantified proteins. The enrichment and network construction in gene ontology (GO) terms, genes-disease and Wikipathway of differential proteins were established through Web Gestalt. A total of 8 509 proteins were detected, among them, 7 163 proteins were further analyzed by bioinformatics, of which 110 proteins were up-regulated and 70 were down-regulated in N87/R cells. The differential proteins showed a significant difference in cellular component, biological process and molecular function in GO terms, respectively. Genes-disease network analysis indicated the association of these differential proteins with neoplasm metastasis, neoplasm invasiveness and inflammation, etc. Wikipathway enrichment analysis revealed the relevance of several signaling pathways to herceptin resistance, which included IL-2, MAPK/ERK, mTOR, aurora A, Ret, NF-κB, immune-regulatory and metabolic pathway. Western blot showed a significant increase of ERK1/2 activities in N87/R cells compared with N87 cells. Correspondingly, SCH772984, a MAPK/ERK inhibitor, preferentially reduced the viability of N87/R cells. Taken together, our data suggested that the MAPK/ERK signaling pathway is one of the key pathways that mediate herceptin resistance. This study provides the basic information for exploring the mechanisms of acquired resistance to herceptin in gastric cancer cells.