The distinctive characteristic of malignant cells is that they multiply quickly and infinitely, and cannot die. For this reason, treatment has for a long time been based on growth-inhibiting substances. “The side effects on similarly fast-growing cells in the bone marrow, mucous membranes and blood must therefore also be factored in,” explains Dagmar Zweytick, from the Institute of Molecular Biosciences. Newer, less aggressive approaches take advantage of very specific differences between the surface of tumorous cells and healthy cells – and this is also the approach used by the research group at the University of Graz. Cancer cells have a specific negatively charged fat molecule on their outer surface. Our innate immune system produces peptides – short protein molecules – that can identify foreign cells by these negative charges and destroy them. In their naturally occurring form they are too weak to cure serious diseases. However, through targeted adaptation, derivatives of these molecules can be produced that could be used as a cancer treatment. In laboratory tests, and in vivo tests in mice, these substances, derived from the breast milk protein lactoferrin have already been successfully used to destroy tumours.
Sneaking in the therapy
What makes cancer life-threatening is firstly resilient cells that simply eject medications, or even prevent them from penetrating at all. Secondly, it is thought that chemo-resistant tumour stem-cells survive, remain for a long time in the body, and then suddenly begin to grow again or to form metastases. This is particularly problematic if they are located in the head, as the blood-brain barrier presents an insurmountable obstacle for most drug therapies.
However, lactoferrin derivatives are able to penetrate this barrier and to kill metastases. They are even effective against resistant types of cancer. The researchers are now working to improve the practical application of these substances. “Logically, the peptide should be delivered through the blood circulation system, so that it destroys all the cancer cells in the body. But to do that it needs to overcome certain obstacles and avoid being broken down itself,” explains Zweytick. So the next step is to “disguise” the substance so that it can reach the malignant cells intact. Once they find a way to do this the researchers hope to be able to develop a new medication. Despite this exciting prospect, Dagmar Zweytick is keen to emphasise: “The most important factors in fighting the disease remain early recognition and a healthy lifestyle.”
Read more about her research in the latest issue of UNIZEIT.