Abstract 1283: Mutations in the Duffy Antigen Receptor for Chemokines (DARC/ACKR1) gene result in population-private variants

Abstract

Abstract By studying the breast cancer microenvironment, we can specifically address novel aspects of cancer development and progression at the molecular level. Chemokines are small signaling molecules that are an important component of this microenvironment, as they shape cellular composition of this space through recruitment of immune cells, among other functions. DARC, the Duffy Antigen Receptor for Chemokines, is an atypical chemokine receptor (ACKR1) that can bind different classes of chemokines. It is a non-signaling receptor that mainly acts as a regulator of chemokine homeostasis by removing them from circulation to recruit appropriate immune cell types. The purpose of this study is to determine how population-private variants of the DARC/ACKR1 gene across global population render distinct function and define aspects of human diversity in immune responses. A well-studied example of this would be the Duffy-null allele. This allele carries a mutation that is population-specific to recent decedents of Sub-Saharan Africans, and removes expression of DARC on red blood cells. Loss of expression on red blood cells presumably causes these “Duffy-Null” individuals to lose the ability to sequester chemokines, therefore losing homeostatic balance of these molecules in circulation. To identify additional mutations, we completed in silico analysis of minor allele frequencies across the gene in the 1000 Genomes Project data, and identified several other putative functional mutations that likely result in additional gene variants, specific to geographic ancestry groups and likely under similar selection as the Duffy null allele. We have prioritized our initial functional study to include mutations in the regulatory regions of the gene, as these mutations can change how and where the gene is expressed. Future work is focused on investigating these functional variants in situ, using human tissue and human breast cell lines, by isolating and re-engineering ancestry-specific variants in these cell lines. By identifying and determining functional outcomes of these population-specific mutation, we can observe differences in immune responses across these global populations, further defining the role that DARC/ACKR1 plays in the breast tumor microenvironment. Citation Format: Rachel Martini, Brittany Jenkins, Melissa Davis. Mutations in the Duffy Antigen Receptor for Chemokines (DARC/ACKR1) gene result in population-private variants [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1283. doi:10.1158/1538-7445.AM2017-1283