Background: In this study we applied a serological proteomics-based approach (SERPA) to identify tumor antigens that commonly induce a humoral immune response in patients with infiltrating ductal breast carcinomas.
Methods: Sera obtained at the time of diagnosis from 40 patients with invasive breast cancer and 42 healthy controls were screened individually for the presence of IgG antibodies to MCF-7 cell line proteins. Immunoreactive proteins were isolated and subsequently identified by MALDI-TOF mass spectrometry.
Results: We identified 26 proteins that reacted with antibodies in the sera from breast cancer patients. Among these antigens, a significantly higher frequency occurs against the molecular chaperone HSP60, the tumor suppressor prohibitin, beta-tubulin, the haptoglobin-related protein and peroxiredoxin-2. Immunoreactivity to hnRNPK, Mn-SOD and F1-ATPase was also clearly detected in the patients group, whereas scarcely in control sera. By contrast, two other antigens identified as cytokeratins 8 and 18, as well as, F1-actin were found to elicit humoral immune responses in both control and breast cancer patients' sera.
Conclusions: The immunoproteomic approach implemented here offers a powerful tool for determining novel tumor antigens that elicit a humoral immune response in patients with invasive breast cancer. These antigens and/or their related circulating antibodies may display clinical usefulness as potential diagnostic markers and provide a means for a better understanding of the molecular mechanisms underlying breast cancer development.