Preliminary study on quantitative proteomic analysis of differentially expressed proteins in HER-2 positive and negative breast cancer

Abstract

Objective To seek differentially expressed proteins for human epithelial growth factor receptor-2 (HER-2) negative and positive breast carcinoma through establishing proteins profiles, and to provide new prognostic markers and therapeutic targets for patients with breast cancer. Methods HER-2 positive and negative breast cancer protein expression profiles were established using proteomic isobaric tags for relative and absolute quantitation (iTRAQ) technology. Differences of protein expression were identified and parts of differential expression proteins were analyzed by bio-informatics, including protein function annotation and GO classification analysis and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway analysis. Results Proteomic analysis of breast cancer tissue with identified HER-2 positive and negative groups showed 4 999 diffe-rentially expressed proteins by iTRAQ. Based on the criteria of the ratio of HER-2(+ )/HER-2(-)≥3, 119 up-regulated proteins were identified in HER-2 positive group. Based on the criteria of the ratio of HER-2(+ )/HER-2(-)≤0.5, 47 down-regulated proteins were identified in HER-2 positive group. The results of GO analysis showed that the molecular function, biological process and cellular composition of differentially expressed proteins were complex between HER-2 positive and negative breast cancer. There were differences in the distribution of up-regulated proteins and down-regulation of proteins. KEGG pathway analysis showed that differentially expressed proteins involved in 168 signal pathways. Conclusion There are differentially expressed proteins between HER-2 positive and negative breast cancer, which involve complex molecular function, biological process and signaling pathway. Key words: Breast neoplasms; Receptor, epidermal growth factor; Proteomics; Computational biology