Research News
Liver tissue section with a senescent liver cell directly in the center of the image. The senescent cell is stained homogenously in brown colour. Small immune cells are located in close proximity to the senescent cell and will eliminate the senescent cell. Photo: HZI
More information:
How the Immune System Fights Tumours
Hepatocellular carcinoma are one of the most frequent malignant cancer forms world-wide. It usually is caused by liver cirrhosis, in turn caused by chronic viral hepatitide infection (hepatitis B or C). Researchers at the Braunschweig Helmholtz Centre for Infection Research (HZI) around Professor Dr Lars Zender and at the Medical University Hanover now could demonstrate how a healthy immune system detects and kills potential cancer precursor cells in the liver in their early stages.
Cells with a particular propensity of degenerating into tumour cells – for instance, because of chemical stress or radioactive radiation – often stop their normal life cycle and enter into a state of dormancy called "senescence". In cooperation with colleagues from other research institutions, the HZI scientists found, that the senescence renders these cells identifiable for the immune system, thus subjecting them to intensified control by the body's defence system. The researchers assume that a mechanism similar to the one observed in the liver could play a key role also in other organs.
This newly identified mechanism could also serve to explain why HIV positive patients have an increased risk of liver cancer. In order to investigate this phenomenon, the researchers measured the number of senescent cells in the liver of hepatitis C patients, who were also HIV positive, and compared these with values taken from a control group of hepatitis C patients without additional HIV infection. "As expected, the first group displayed a significantly increased number of senescent cells", says Zender. "In HIV patients, the immune defence by T helper cells is impaired, so that senescent liver cells in the livers of HIV patients probably cannot be removed efficiently."
The authors of the study now hope, that the newly discovered mechanism will in future allow for new approaches in the prevention and treatment of cancer diseases.
