Cancer cells are the safe nests of bacteriaThis conclusion comes from a rigorous study of cancer samples from more than 1,000 different human cancersThe study, led by the Weizmann Institute for Science, found bacteria in all types of cancer, from the brain to bones to breast cancer, and even found a unique population of bacteria in every cancerStudies have shown that understanding the relationship between cancer cells and their 'micromicrobiomes' may help predict the potential effectiveness of certain treatments, or may point the way to manipulate these bacteria in the future to enhance the role of cancer treatmentsThe results of the study were published in the journal ScienceA few years ago, DrRavid Straussman of the Institute's Department of Molecular Cell Biology discovered bacteria lurking in human pancreatic tumor cells that have been shown to protect cancer cells from chemotherapy drugs by 'digesting' and inactivating themWhile other studies have also found bacteria in tumor cells, Straussman and his team question whether such a host might be a rule, not an exceptionTo find out, DrDeborah Nejman and Ilana Livyatan of the Straussman team and DrGarold Fuks of the Department of Complex Systems Physics worked with oncologists and researchers around the worldThe work is also led by DrNoam Shental of the Department of Mathematics and Computer Science at the Open University of Israel
Eventually, the team conducted a detailed study that described bacteria in these cancers at high resolution -- including the brain, bones, breasts, lungs, ovaries, pancreas, colorectal and melanomaThey found that every cancer from the brain to the bone has bacteria, and that different types of cancer have different bacterial typesHowever, the number and diversity of bacteria in breast cancer is highest The team showed that more bacteria can be found in breast tumors than in the tissues surrounding normal breast tumors, and that some bacteria are found in tumor tissue first, rather than in normal tissue around the tumor In order to get these results, the team must overcome several challenges First, the number of bacteria in tumor samples is relatively small, and researchers must find a way to focus on the tiny cells in these cells They must also eliminate any possible external pollution To do this, they used hundreds of negative controls and created a series of computational filters to clear any trace of any bacteria that might come from outside the tumor sample The team was able to grow bacteria directly from human breast tumors, and their results showed that the bacteria found in those tumors were alive The electron microscopes of these bacteria show that they prefer specific locations within cancer cells -- close to the nucleus Different cells have different bacteria The team also reported that bacteria are present not only in cancer cells, but also in immune cells in tumors Straussman said: 'Some of these bacteria may enhance the anti-cancer immune response, while others may inhibit this response -- a finding that may be particularly relevant to understanding the effectiveness of certain immunothetherapies In fact, when the team compared bacteria from the melanoma sample group, they found that there were different bacterial concentrations in melanomas that responded to immunotherapy and had a poor response
Straussman believes the study could also explain why some bacteria like cancer cells and why each cancer has its own typical microbiome: the differences are clearly due to the environment provided in each tumor cell environment In other words, bacteria may depend on certain metabolites that are produced or stored in specific tumors For example, when the team compared bacteria found in smokers' lung tumors with those found in patients who had never smoked, they found a difference When the researchers compared the genes of the two groups of bacteria, the differences were even more pronounced: smokers had more genes in lung cancer cells to metabolize nicotine, toluene, phenol and other chemicals found in cigarette smoke In addition to showing unique bacterial populations in some of the most common cancer cells, the researchers believe the methods they developed could be used to answer some of the key questions about the role of these bacteria: Do bacteria eat the nutrients of cancer cells, or do they serve the cells? At what stage did they settle in? How do they promote or hinder the growth of cancer? What are their effects on the response to various cancer treatments?
'Tumors are a complex ecosystem, all of which are part of what we call the tumor microenvironment, in addition to cancer cells, immune cells, matrix cells, blood vessels, nerves, and other components Our research, as well as other laboratory studies, clearly shows that bacteria are also an integral part of the tumor microenvironment Straussman said: 'We hope that by finding out exactly how they adapt to the general tumor ecology, we can find new ways to treat cancer ' Source: Translational Medicine Platform