Is there A link between stem cells, bacteria and cancer?
Scientists have long believed that an increase in stem cell turnover plays a part in the development of cancer, and now new research has uncovered findings that could strengthen the link.
A study was carried out by the Max Planck Institute in Berlin in conjunction with researchers in Stanford, California, and examined the presence of bacteria and it’s impact on stem cell regeneration. The survival rate for stomach cancer is low, mainly because patients don’t present any symptoms until the cancer has reached an advanced stage. Stomach cancer, or gastric cancer, is caused by the bacterium Helicobacter pylori, which is naturally present in all humans. However, this bacteria acts differently to tumour viruses, leaving scientists in the dark as to how they actually cause cancer. The new research has revealed that this bacterium “sends stem cell renewal in the stomach into overdrive”, a discovery that could open doors to further understanding the cause and therefore treatment of stomach cancer.
About the research
The study confirmed that in the majority of cases, patients with most stomach cancer experience chronic infections with H. pylori bacterium.
Prof. Dr. Thomas F. Meyer specialises in molecular biology, and worked alongside
fellow researchers at the Max Planck Institute for Infection Biology in Berlin. Having spent many years examining the impact H. pylori has on the stomach’s epithelium cells, the team were in search of answers as to why cancer was able to form in an environment in which cells are being replenished so rapidly. As stem cells are the longest living cells in the stomach, the researchers began their search for answers here. While it had previously been believed that H. pylori affected only the rapidly-replaced surface cells, but the research revealed that the bacteria managed to infiltrate the stem cells, causing them to rapidly multiply.
The team arrived at this conclusion following tracing the behaviour of two different types of stem cells in the stomach of mice. According to Science News Online:
Both respond to a signalling molecule called Wnt, which maintains stem cell turnover in many adult tissues. Crucially, they discovered that myofibroblast cells in the connective tissue layer directly underneath the glands produce a second stem cell driver signal, R-spondin, to which the two stem cell populations responded differently. It is this signal, which turned out to control the response to H. pylori: Following infection, the signal is ramped up, silencing the more slowly cycling stem cell population and putting the faster cycling stem cell population into overdrive.
According to one of the study authors and clinical scientist Michael Sigal, these results substantiate the theory that chronic bacterial infections are strongly linked with cases of stomach. “Our findings show that an infectious bacterium can increase stem cell turnover,” he says. “Since H. pylori causes lifelong infections, the constant increase in stem cell divisions may be enough to explain the increased risk of carcinogenesis observed.”