BSCI-16. Olfactory receptor 5B21 drives breast cancer metastasis

Olfactory receptors (ORs), responsible for the sense of smell, play an essential role in physiological processes (even outside the nasal epithelium) and cancer. In breast cancer, however, the expression and role of ORs remain understudied. We examined the significance of ORs transcript abundance in breast cancer metastasis to different tissues including the brain, bone, and lung. While we found 20 OR genes to be differentially expressed in different metastasis versus primary tumor, OR5B21 displayed high relation with all metastases. Knockdown of OR5B21 significantly decreased the invasion and migration of breast cancer cells in culture as well as metastasis to different organs including the brain, in vivo. On the other hand, overexpression of OR5B21 in the primary cells had the opposite effect. Mechanistically, OR5B21 was associated with epithelial to mesenchymal transition through STAT3/NFkB/CEBPβ signaling pathway. We propose OR5B21 (and potentially other ORs) as a novel oncogene contributing to breast cancer metastasis, and as a potential target for therapy.