Abstract P3-01-27: Ectonucleotidase ATP hydrolysis facilitates breast cancer bone metastasis

Abstract

Abstract Bone is the most common site for breast cancer metastasis. Osteocytes are the most abundant bone cell and can signal nearby cells by releasing ATP through connexin 43 hemichannels. We previously found that this signaling pathway hindered breast cancer growth in bone. In this study, we investigated the role of purinergic signaling on breast cancer bone metastasis in patient samples. Surprisingly, no ATP receptors were differentially expressed in bone metastases compared to other sites. However, enzymes that degrade ATP into adenosine (CD39/ENTPD1 and CD73/NT5E) were upregulated, as was the ADORA3 adenosine receptor (Limma, p=0.037, 0.016, 0.0019, respectively). We next investigated whether this expression signature in primary tumors predicts bone metastasis. In primary ER+ breast cancer, which predominately metastasizes to bone, high expression of these genes is correlated with lower distant metastasis-free survival (HR = 1.97, 1.49, 2.03, logrank p=0.0017, 0.0004, 0.0012). Moreover, this expression pattern is correlated with a bone metastasis signature (Spearman R=0.28, p=1.2 × 10−20). In a pharmacologic screen of 750 cancer cell lines, breast cancer lines and especially ER+ ones, are uniquely sensitive to a pan-adenosine receptor inhibitor (Limma, p=2.9 × 10−5) and ADORA3/2B inhibitor (p=5.4 × 10−5). Our findings suggest that an expression program to convert ATP to adenosine facilitates bone metastasis and begins in the primary tumor. ADORA3 inhibition is proposed as a pharmacologic strategy for preventing or treating bone metastasis. Furthermore, bone metastases should be analyzed in anti-CD39 and CD73 clinical trials. Citation Format: Daniel B Shropshire, Jaime Benavides, Jean X Jiang. Ectonucleotidase ATP hydrolysis facilitates breast cancer bone metastasis [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-01-27.