Jun 16, 2019 | Updated: 11:54 AM EDT

DNA Nanorobots Target HER2-Positive Breast Cancer Cells

Jun 07, 2019 01:48 PM EDT

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About 20% of breast cancers make high levels of a protein called human epidermal growth factor receptor 2 of HER2, according to the Mayo Clinic. When displayed on the surface of the cancer cells, this protein helps them proliferate and is linked with poor prognosis. Now, researchers have developed a DNA nanorobot that recognizes HER2 on breast cancer cells, targeting them for destruction.

The current therapies for HER2-positive breast cancer include monoclonal antibodies like trastuzumab, that bind to HER2 on cells and direct it to the lysosome. Lowering the levels of HER2 slows cancer cell proliferation and it triggers the death of the cell. Although monoclonal antibodies can lead to the death of cancer cells, they have side effects that are severe and that are difficult and expensive to create.

In a previous study, Yunfeng Lin and his team of researchers identified a short sequence of DNA, called an aptamer, that recognizes and binds HER2, targeting it for lysosomal degradation. It is the same way as monoclonal antibodies. But the aptamer was not a stable serum. The researchers wanted to see if adding a DNA nanostructure called tetrahedral framework nucleic acid or tFNA could increase the aptamer's biostability and anti-cancer activity.

The team designed a DNA nanorobot that consists of the tFNA with an attached HER2 aptamer. When injected into the subject mice, the nanorobots persisted in the bloodstream more than twice as long as the free aptamer. The researchers then added nanorobots to three breast cancer cell lines in Petri dishes, showing that they killed the HER2-positive cell line only. The addition of the tFNA allowed more of the aptamer to bind to HER2 than without tFNA, leading to reduced HER2 levels on cell surfaces.

The nanorobot is easier and is less expensive to make than the monoclonal antibodies, it needs further improvement before it could be used to treat breast cancer in the clinic, the researchers say.

There is a race in finding a fast cure for breast cancer. As of the latest study, it is proven that one out of eight women will be diagnosed with breast cancer in their lifetime. It is also the most commonly diagnosed cancer in women worldwide. Each year, it is estimated that around 250,000 women will be diagnosed with breast cancer in the United States alone and around 40,000 will die because of it.

There are around 3.3 million breast cancer survivors in the United States today. The great news is that each year, there is a decrease in the number of women who are diagnosed with breast cancer and the death toll has been declining since 1990, due to early detection, increased awareness and improving treatments.

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