Odorant Receptors and Cancer

Odorant receptors (ORs) constitute the largest family of G protein-coupled receptors (GPCRs), with nearly 400 receptors identified in humans. The "omics" era has revealed an unexpected expression of ORs beyond olfactory tissues. For many decades these receptors were neglected from cancer research, largely due to the assumption that their expression in cancerous tissues was a background leakage, unrelated to conventional cancer pathways such as cell replication, differentiation, or DNA damage response. The Cancer Genome Atlas (TCGA) data shows, however, that OR expression profiles are specific to each tumor type. This evidence supports that ORs may be related to tumor malignancy. In this review, we explore the extranasal expression of ORs in cancer and discuss the potential implications of their presence in cancerous tissues.