Abstract 3142: Circulating microRNAs can identify cancer-free women at risk for breast cancer

Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA Introduction: MicroRNAs (miRNAs) are well documented to regulate cancer cell activity by modulating signaling pathways to promote disease onset and progression. Recent evidence correlates miRNAs measured in the serum of breast cancer (BCa) patients to expression in breast tumors. Thus, miRNAs are important biomarkers for stages of tumor development. However, no studies have evaluated the potential of circulating miRNAs (c-miRNAs) as risk biomarkers that predict BCa development years before tumor identification. Objective: Use global miRNA analysis of serum from at-risk but pre-cancerous women who have subsequently been diagnosed with BCa or remain cancer-free to 1) identify expression levels of miRNAs with known BCa association, 2) define cohorts of c-miRNAs differentiating women later developing cancer from cancer-free women with similar clinical risk, and 3) provide insight into c-miRNA mechanisms that promote BCa development. Methods: Subjects were identified from a cohort of 571 women enrolled in the High Risk Breast Program at the UVM Cancer Center; 35 diagnosed with BCa since enrollment. Enrollment criteria included no prior cancer and increased BCa risk due to family history, benign breast disease, prior irradiation for Hodgkin's disease, known pathogenic abnormality, and/or > 20% lifetime modeled BCa risk score. Clinical data and serum are collected at study enrollment and subsequent cancer-free 4-year interval visits. 28 BCa cases were matched to controls for risk factor and age (+/- 5 yrs) at serum sampling (DCIS, Stage IV BCa, BRCA1/2 excluded). RNA was isolated from 68 serum samples representing 52 individual women following a standardized protocol (Farina et al J Cell Biochem 2014) and over 2500 mature human miRNAs profiled on Affymetrix microRNA v4.0 microarrays. Principal component analyses (PCA), hierarchical clustering, differential expression testing, gene ontology, and biological pathway analyses were performed. Results: Our analyses show that women who developed BCa (largely hormone receptor positive, HER2 and lymph node negative) share similar patterns of miRNA expression that differ from women who remain cancer-free. PCA, based on a subset of dynamic miRNAs, segregates serum samples into 3 groups: cancer, cancer-free, and overlapped. Several miRNAs consistently cluster together when cases are contrasted against controls suggesting a functional relationship in providing an environment ideal for BCa development. Pathway analyses of miRNA gene targets reveal enriched PDGF, Wnt, Ras, and MAPK signaling pathways. Conclusion: These data suggest that a cohort of dynamic c-miRNAs discriminates at-risk women who will develop BCa from those who will remain cancer-free. While we consider these findings preliminary until a larger sample set is screened, we conclude that circulating miRNAs will become valuable biomarkers of BCa risk. Citation Format: Nicholas H. Farina, Jon E. Ramsey, Melissa E. Sands, Tiffany J. Rounds, Janet L. Stein, Gary S. Stein, Jane B. Lian, Marie E. Wood. Circulating microRNAs can identify cancer-free women at risk for breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3142.