Abstract 3936: Identification and validation of the potential biomarker insulin-like growth factor binding protein acid-labile subunit for breast cancer in African American women

Breast cancer is the most frequently diagnosed cancer in women, with an estimated 40, 730 breast cancer deaths in the US in 2015. African American (AA) women have a lower breast cancer incidence rate, but a higher breast cancer death rate, than non-Hispanic White women. Research indicates that breast tumor biology in AA women is different from that in Caucasian women. AA women are more likely to be diagnosed with breast cancer at an earlier age and with more aggressive form of the disease, characterized by higher grade and negative estrogen and progesterone receptor status. Because of the aggressive nature of these tumors and current lack of targeted therapies, identification of novel relevant protein markers is of great importance. The purpose of this study was to validate serum proteins that were previously identified by serum proteomic profiling in 22 serum samples by 2D-DIGE/MS analysis and a subset of samples by shotgun LC/MS technology. Methods and new data: The current study included serum samples from 15 African American breast cancer patients and 12 healthy controls. Patients were grouped into triple negative (TN), HER2 and Luminal A and B subtypes. Proteins of biological significance were validated using western blot analysis. For ceruloplasmin, and insulin-like growth factor binding protein acid-labile subunit (IGFBP-ALS), one-way ANOVA was used to compare mean density among the three groups. For Vitamin D Binding protein (VDB), a two-sample t-test was used to compare the density between the groups. Due to the small sample size, we have also conducted nonparametric tests. IGFBP-ALS was significantly lower in triple negative breast cancer patients (p = 0.016) and in HER2 (p = 0.025) subtypes. There was no significant difference in VDB protein in the luminal A and B subtypes (p = 0.98). Future efforts will focus on validating the identified panel of biomarkers to gain insight into their role(s) in the etiology of aggressive breast tumors. Funded by Susan G Komen for the Cure and SEED grant SPH.