Improved diagnostic screening has led to earlier detection of many
tumors, but screening may still miss many aggressive
tumor types. Proteomic and genomic profiling studies of
breast cancer samples have identified
tumor markers that may help improve screening for more aggressive, rapidly growing breast
cancers. To identify potential blood-based
biomarkers for the early detection of
breast cancer, we assayed serum samples via matrix-assisted
laser desorption ionization-time of flight mass spectrometry from a rat model of mammary
carcinogenesis. We found elevated levels of a fragment of the
protein dermcidin (
DCD) to be associated with early progression of N-
methylnitrosourea-induced
breast cancer, demonstrating significance at weeks 4 (p = 0.045) and 5 (p = 0.004), a time period during which mammary pathologies rapidly progress from ductal
hyperplasia to
adenocarcinoma. The highest serum concentrations were observed in rats bearing palpable mammary
carcinomas. Increased
DCD was also detected with immunoblotting methods in 102 serum samples taken from women just prior to
breast cancer diagnosis. To validate these findings in a larger population, we applied a 32-gene in vitro
DCD response signature to a dataset of 295
breast tumors and assessed correlation with intrinsic
breast cancer subtypes and overall survival. The
DCD-derived gene signature was significantly associated with subtype (p < 0.001) and poorer overall survival [HR (95 % CI) = 1.60 (1.01-2.51), p = 0.044]. In conclusion, these results present novel evidence that
DCD levels may increase in early
carcinogenesis, particularly among more aggressive forms of
breast cancer.