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Cause of breast cancer resistance to chemotherapy found
Last reviewed: 30.06.2025
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Breast cancer cells need the hormone estrogen to grow. Blocking estrogen receptors is often used to treat this disease, but the tumor has learned to "ignore" this therapy. Scientists have discovered a protein that causes this resistance.
Breast cancer is one of the most common forms of cancer; in the UK alone, 46,000 women are diagnosed with it every year. More than 75% of cases can be treated with anti-estrogen therapy. This is because cancer cells often contain receptors for the hormone estrogen on their surface (it is believed that these cells need it for growth). Consequently, doctors are quite successful in suppressing the development of neoplasms with various estrogen receptor blockers (for example, tamoxifen) - but not when the tumor develops resistance to such drugs.
Resistance to chemotherapy is one of the most difficult problems in modern oncology. Its severity is largely due to the fact that different types of cancer "get used" to drugs in different ways, and the fight against this phenomenon literally turns into a fight with a many-headed monster. However, in the case of breast cancer, resistance to antiestrogen therapy has apparently been defeated. Scientists from Imperial College, University of London (UK) report that they have discovered the protein responsible for such resistance.
In a paper published in the journal Nature Medicine, the researchers describe a protein called LMTK3 isolated from human tumor cells resistant to the estrogen receptor blocker tamoxifen. In mice, tumors shrank rapidly when the scientists genetically suppressed the protein. Patients with a poor prognosis who were poorly responsive to chemotherapy had higher levels of the protein in their tumor cells than patients who responded to treatment. In addition, the incidence of mutations in the LMTK3 gene correlated with how long cancer patients lived.
Scientists note that the gene of this protein is also present in the closest relatives of humans - chimpanzees. But at the same time, monkeys do not suffer from estrogen-dependent breast cancer at all, although the LMTK3 gene itself is very similar in chimpanzees and humans. Perhaps the changes in LMTK3 gave us some evolutionary advantages, but at the same time made us more sensitive to this form of cancer. One way or another, chimpanzees are not suitable as a test subject for developing new anti-cancer therapy, which in some ways complicates the task. On the other hand, the researchers have already decided on the direction of the search: the LMTK3 protein is a kinase, an enzyme that can regulate the activity of other proteins by attaching phosphoric acid residues to their molecules. Knowing the mechanism of the protein that causes drug resistance should make it easier to overcome this resistance.