Krebszellen verstecken sich vor dem Immunsystem, und Wissenschaftler haben herausgefunden, was sie davor schützt

Cancer cells evade the immune system, and scientists have discovered what protects them during this process. Researchers from the Sanford Burnham Prebys Medical Discovery Institute and partner institutions across North America have identified environmental conditions that help cancer cells build a protective layer. Their findings, published August 7, 2026, in the journal Science Advances, suggest that changes within the tumor microenvironment, the surrounding mix of immune cells, connective tissue, blood vessels, proteins, and carbohydrates, can influence how effectively cancer cells hide. The researchers also identified a potential way to reduce this sugar-rich layer, which could potentially make it easier for the immune system to detect and eliminate cancer cells. The study focused on how the tumor environment alters cancer cells. Lead researcher and principal author Kevin Tharp, Ph.D., previously studied how physical pressure on cells can cause unexpected changes in mitochondrial function. He realized that tumors provide an ideal setting for such research because cancer cells are often exposed to significant mechanical forces. "Primary tumors are usually harder than the surrounding tissue," Tharp said. "This led me to hypothesize that the biochemical properties of cells affect the altered metabolic programs observed in tumors." One metabolic change commonly associated with tumors is reduced oxidative metabolism of glucose. Previous studies showed that this change might depend on the availability of nutrients around the cells, meaning it is not necessarily an inherent feature of the cancer cells themselves. To further investigate, Tharp and his colleagues exposed cells to abundant amounts of glucose while growing them under several different conditions. Some cells were placed in rigid environments designed to mimic the physical conditions surrounding primary tumors, while others were grown in softer environments resembling normal tissue. Scientists also divided the cells based on the type of nutrient medium in which they were cultured. One was a standard laboratory medium, while another was formulated to more closely match the composition of nutrients found in the human body. Both types were tested under normal and elevated glucose conditions, allowing the researchers to simulate hyperglycemia. High levels of glucose can thicken the sugar coating of cancer cells. These differences in the environment produced significant changes in the proteins produced by the cells, concentrations of metabolites inside them, and the thickness of the sugar layer covering their surfaces. This protective coating, known as the glycocalyx, is crucial for cell survival and interaction. It is important to note that excess glucose increased the thickness of the glycocalyx only when the cells were grown in a physiological medium that more accurately reflected the conditions inside the human body. Tharp explained that changes in the composition of the physiological medium and available metabolites for these tumor cells revealed different biological features of the metabolism of normal and tumor cells. The team then examined exactly how these metabolic changes affected the glycocalyx. It is composed of carbohydrates bound to proteins or lipids. These structures are called glycoconjugates. Since glucose provides part of the raw materials needed for the production of glycoconjugates, the team hypothesized that changes in glucose metabolism or hyperglycemia could influence the way this protective layer is built. "We noticed a striking difference between the glycoconjugates of cells grown in conventional media and those grown in media that better reflect the composition of nutrients in the human body," Tharp said. The researchers also discovered that hyperglycemia changes the composition of glycoconjugates produced by the cells. A key factor is HSF1. To understand why excess glucose is linked to a thicker glycocalyx, the researchers studied which proteins become more prevalent when cells are exposed to hyperglycemia. They found that the heat shock factor 1 (HSF1) plays a critical role in this process. HSF1 is a transcription factor that regulates the expression of heat shock proteins, which are involved in cellular stress responses. The study suggests that HSF1 activation under hyperglycemic conditions enhances the synthesis of glycoconjugates, thereby thickening the glycocalyx and helping cancer cells avoid detection by the immune system. The implications of this discovery are significant. By understanding how the tumor microenvironment influences the formation of the glycocalyx, researchers may develop new strategies to disrupt this protective layer. Targeting HSF1 or other factors involved in glycoconjugate synthesis could potentially make cancer cells more visible to the immune system, improving the effectiveness of immunotherapy. Future research will focus on validating these findings in animal models and eventually in clinical settings. Scientists are also exploring ways to manipulate the tumor microenvironment to weaken the glycocalyx and enhance immune recognition of cancer cells.