Researchers from the Moscow Institute of Physics and Technology (MIPT), the Engelhardt Institute of Molecular Biology (EIMB RAS), the Institute of Bioorganic Chemistry (IBCh) and a number of other Russian research centers have developed a new method of diagnosing colorectal cancer. The results of the study have been published in Cancer Medicine.
The scientists have created a hydrogel-based biochip to help detect bowel cancer i.e. colorectal cancer (CRC). CRC is the third most common type of cancer and it develops with minimal clinical symptoms in the early stages. Despite doctors’ efforts, the 5-year survival rate does not exceed 36%. Treatment is only effective, and patients only have a good chance of recovery, if the cancer is detected early.
Diagnostic methods that are currently in use are not sufficient. Analyses carried out in vitro have low specificity and invasive studies such as colonoscopy are not only traumatic, but they are also not always suitable for an early diagnosis, as they do not give a complete picture of the development and distribution of colorectal cancer.
The method proposed by scientists from EIMB RAS, MIPT, the Russian Scientific Center of Surgery, Sechenov First Moscow State Medical University, the Institute of Bioorganic Chemistry, and Buyanov City Clinical Hospital is based on the simultaneous detection of various substances in patients’ blood. These substances are autoantibodies against tumor-associated glycans, which can be found in serum at the early stages of cancer, immunoglobulins of different classes, and oncomarkers (molecules produced by tumor cells).
Oncomarkers are already widely used to detect cancer. However, the combination which is used to detect CRC (carcinoembryonic antigen (CEA) with carbohydrate antigen (CA) 19-9) is not sensitive enough and is only able to detect 1 in 2 cases of the disease. To increase diagnostic sensitivity, researchers turned to glycobiology, a rapidly developing science that is focused on the most important biological molecules – glycans.
The best known glycans are amylum, chitin and cellulose. In terms of chemistry, glycans are biopolymers consisting of a large number of monosaccharides (glucose and fructose are commonly known examples) linked glycosidically (by oxygen atoms). Besides acting as nutrients and building materials for cells, glycans are important for the contact between cells, appropriate organ growth and much more. Tumor cells have special glycans enabling scientists to differentiate them from healthy cells, and this is the key aspect of the new study.
To detect tumor-associated glycans, scientists use autoantibodies. Antibodies are molecules produced by the immune system to attack enemy cells with high precision. They are “fine-tuned” to interact with a particular target. Antibodies against the influenza virus, for example, interact only with the protein contained in the viral particles of a certain strain, and autoantibodies against tumor-associated glycans react exclusively with glycans that are only found in CRC cells.
Antibodies are able to define target cells and initiate the process of destroying them. Any cells may become a target if they have transformed to cancer cells or become infected with a virus. Many laboratory diagnostic methods and scientific experiments are based on the unique capacity of antibodies to selectively detect other molecules.