BACKGROUND: Breast cancer (BC) is one of the most common cancers and is among the main causes of death in females around the world. Although several serum biomarkers have been identified for breast cancer, due to lack of adequate sensitivity and specificity they do not adequately distinguish BC from confounding conditions. New approaches are urgently needed to improve BC detection and treatment.

MATERIAL AND METHODS: Eighty serum samples from 20 healthy individuals and 60 patients with BC (22 triple-negative breast cancer, TNBC; 38 non-triple-negative breast cancer, NTNBC) were included. Protein profiling of serum samples was analyzed using surface-enhanced laser desorption/ionization time-of-flight mass spectroscopy (SELDI-TOF-MS). Candidate biomarkers were purified by SDS-PAGE electrophoresis and identified by MALDI-TOF/TOF.

RESULTS: The candidate biomarker positioned at 6447.9 m/z was significantly decreased in BC patients. Moreover, the expression intensity of the candidate biomarker was weaker in the TNBC and pre-surgery group compared with the NTNBC and post-surgery group. We ultimately identified the biomarker as apolipoprotein C-I (ApoC-I). Furthermore, we found that ApoC-I peptides inhibited proliferation of human breast cancer cells in vitro and suppressed tumor growth in vivo.

CONCLUSIONS: These results suggest that ApoC-I peptides may be a potential diagnostic biomarker and therapeutic approach for BC.

Keywords: Amino Acid Sequence, Apolipoprotein C-I - metabolism, Biomarkers, Tumor - metabolism, Blood Proteins - metabolism, Breast Neoplasms - surgery, Case-Control Studies, Cell Proliferation - drug effects, MCF-7 cells, Peptides - metabolism, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, young adult