Olfactory Receptor Gene Involved in the Sense of Smell Helps Breast Cancer Spread to the Brain, Bones and Lung Study Reveals

Researchers from Massachusetts General Hospital (MGH) have found that an olfactory receptor gene responsible for the sense of smell plays a significant role in breast cancer spreading to the brain, bones, and lungs. The olfactory receptor gene 5B21 (OR5B21) not only relays sensory data to the brain but also drives cancer cells to other parts of the body, affecting cancer progression.

The team reported in their study, titled "Olfactory Receptor 5B21 Drives Breast Cancer Metastasis," published in Science, that inhibiting the gene OR5B21 will also decrease the metastasis of breast cancer cells. The findings demonstrate an important target for improved treatment and in preventing cancer cells from spreading.

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Olfactory Receptor Gene Involved in the Sense of Smell Help Breast Cancer Spread to the Brain, Study Reveals

Olfactory Receptor Gene 5b21 (OR5B21)

The olfactory system or the sense of smell detects and identifies many diverse odorant molecules that contain information about the environment. A paper published in the journal of the American Physiology Society humans has the same number of odorant receptor genes as a mouse, which is ~1,000 genes.

Humans can distinguish about 10,000 different odors due to odorant receptor genes that help discriminate between many odorant molecules. Studies in mice models demonstrate how the olfactory system functions in which researchers believed would likely apply to humans too, given their similarity.

According to the human gene database Gene Card, olfactory receptors interact with odorant molecules in the nose, triggering the sensory cells to relay information regarding a smell. The G protein will be activated and stimulate adenylyl cyclase (AC) and produce cAMP from ATP.

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OR5B21 Triggers Breast Cancer Cells to Metastasize

Breast cancer is leading cancer in women, with over two million cases reported every year. It is also the second leading malignancy after lung cancer, EurekAlert! reported. Since its migration to the brain and other parts of the body is considered the leading cause of mortality from the disease, scientists have been working to find new therapeutic targets to delay its spread.

Study co-corresponding author Dr. Litia Carvalho, an instructor of neurology at MGH, said that the olfactory receptor gene is overexpressed in many types of cancer, including prostate, melanoma, lung, and liver cancer. However, its role in breast cancer has been understudied.

The team used animal models and found that OR5B21 enhances the metastasis of breast cancer cells through a process called epithelial to mesenchymal transition (EMT). On the other hand, inhibiting them also delays the spread of breast cancer cells.

These findings indicate that future research is needed to determine how to inhibit the olfactory receptor gene to decrease cancer cell metastasis. They hope it could be the answer to the unmet medical need in preventing cancer metastasis to the brain, bones, and lungs, and therefore prolonging the life of cancer patients.