Molecular Profiles of Breast Cancer in Hispanic/Latina

Breast cancer (BC) is the most common malignancy in women worldwide. Different risk factors are associated with the disease which is classified into several intrinsic subtypes according to expression of hormone receptors (estrogen and progesterone) and human epidermal growth factor receptor 2 (HER2). The advent of high throughput techniques has allowed the molecular classification of BC and development of diagnostic/prognostic tools to predict disease outcome and progression. However, most molecular classifications and diagnostic/prognostic tools were developed using samples from European/Caucasian women. Hispanic/Latino describes an admixed group of individuals with different fractions of European, African, and Indigenous American ancestries. We determined the frequency of the different intrinsic subtypes of BC in Colombia and their association with genetic ancestry and found that luminal B subtype was the most prevalent in Colombian women with BC. We found that African ancestry was associated with more aggressive forms of BC. We then used next-generation sequencing techniques to determine the underlying markers of luminal B subtype of BC in Colombia. We found 67 genes differentially expressed between luminal A and luminal B subtypes, and of those, six were common between patients with high European/low Indigenous American ancestries. Interestingly, three genes (ERBB2, MIEN1, and GRB7) form a genomic “block” in chromosome 17 from which ERBB2 and GRB7 are co-expressed. The expression of ERBB2 was independent of HER-2 labeling. Our results suggest a major role of ethnicity in the modulation of these genes in BC in Hispanic/Latina women and may be the basis for future larger studies to investigate the role of ethnicity in BC susceptibility in minority groups.