High‐throughput proteomic profiling of nipple aspirate fluid from breast cancer patients compared with non‐cancer controls: A step closer to clinical feasibility

Abstract

Background: Early detection of breast cancer (BC) is critical for increasing survival rates. However, current imaging approaches can provide ambiguous results, requiring invasive tissue biopsy for a definitive diagnosis. Multi‐dimensional mass spectrometric analysis has highlighted the invaluable potential of nipple aspirate fluid (NAF) as a non‐invasive source of early detection bi-omarkers, by identifying a multitude of proteins representative of the changing breast microenvi-ronment. However, technical challenges with biomarker validation in large cohorts remain due to low sample throughput, impeding progress towards clinical utility. Rather, by employing a high-throughput method, that is more practicable for clinical utility, perturbations of the most abundant NAF proteins in BC patients compared with non‐cancer (NC) controls could be monitored and val-idated in larger groups. Method: We characterized matched NAF pairs from BC (n = 9) and NC (n = 4) volunteers, using a rapid one dimensional liquid chromatography‐mass spectrometry (1D LC‐ MS/MS) approach. Results: Overall, 198 proteins were relatively quantified, of which 40 were sig-nificantly differentiated in BC samples, compared with NC (p ≤ 0.05), with 26 upregulated and 14 downregulated. An imbalance in immune response and proteins regulating cell growth, maintenance and communication were identified. Conclusions: Our findings show 1D LC‐MS/MS can quantify changes reflected in the NAF proteome associated with breast cancer development.