No matter how useful a particular drug may be, if it has adverse effects on healthy cells, that’s not a good thing, yes, that’s what we call side effects. Now, researchers have demonstrated a new way to passively and accurately target a drug by wrapping it in a transport that can only be unlocked by a certain RNA sequence specific to cancer.
The best treatments for cancer at the moment are radiotherapy and chemotherapy, but both have an unfortunate drawback: there is no particular selectivity for tumours. Radiation and chemicals can destroy and kill healthy cells throughout the body, leading to a range of unnecessary health side effects such as fatigue, nausea and hair loss.
In response, many scientists are working on how to make cancer treatment more like a passive trigger for landmines than an active attack. In the new study, researchers at the Technical University of Munich (TUM) and the Royal Institute of Technology in KTH developed a way to package drugs so that they can only be released where they are needed.
The main ingredient in this approach is mucous protein, a protein that exists in mucus form in the human body. It is secured together with synthetic DNA strands and added with glycerin to prevent mucous protein particles from dissolving and making them fold around the active ingredient – the drug itself. Once they stick together, the DNA strands do not let the bundles unwrive until they encounter the correct “key” – a specific microRNA molecule.
In this case, the team chose microRNAs found only in cancer. These microRNA strands bind to DNA to break the bonds that bind the packages together, releasing the drug. While many cells accept the packages, the team says only diseased cells can trigger the release of the drug.
“Cancer cells contain microRNA chains, and we know their structure very well,” said Ceren Kimna, lead author of the study. “To use them as keys, we modify the locks by carefully designing synthetic DNA strands to stabilize our drug carrier particles.”
The team says that because mucous proteins are already in the body, cell handling of open drug “packaging” should be no problem. Cancer is just one application of the technology. DNA can also be designed to respond to microRNA structures found in other diseases such as diabetes or hepatitis, the researchers said.
At present, the method is still at a very early stage and needs to be tested in more complex tumor models before being transferred to animals and hopefully humans.
The study was published in the journal ACS Nano.