An ambitious scientific initiative provides crucial information on the formation, evolution and resistance of cancerous tumors. In addition to new tools and new techniques to study them, we now have the most comprehensive maps ever created for a number of tumors. This cancer mapping project, led by the network Human Tumor Atlas Networkprovides insight into how malignant tumors develop.
A revolutionary approach to the study of tumors
Cancer, the result of genetic mutations that cause cells to proliferate in an uncontrolled manner, has long been studied through the genetic analysis of tumors. Until recently, these analyzes only allowed an overview, blended together, of all the cells in a sample, making it impossible to precisely identify each cell type.
Now, thanks to advanced mapping tools and innovative sequencing techniques, it is possible to detail the cellular composition of tumors, highlighting their complex and varied structure. Daniel Abravanel, from the Dana-Farber Cancer Institute, explains that tumors are ecosystems that are not only composed of cancer cells but also include immune cells and support cells, creating an intricate network of interactions.
A team of researchers analyzed the tumors of nearly 2,000 people with 20 types of cancer, using advanced techniques to isolate individual cells and identify their specific functions within tumors. This meticulous work made it possible to precisely map tumor cells and observe their organization and evolution over time.
Mapping and analysis of tumor microregions
Among the contributors to this research, Li Ding and his team from Washington University in St. Louis explored in depth 131 tumor areas of 78 patients affected by various types of cancer, including breast, colon and pancreas. Using a unique cellular sequencing technique, they were able to identify the active genes in each cell. The researchers also studied the spatial organization of cells in tumors using powerful microscopes, making it possible to reconstruct 3D models and understand how these cells interact with each other.
They found that cancer cells cluster into small, distinct regions called microregions, often influenced by similar genetic alterations. In these areas, immune cells also play a role, with activity that varies from one microregion to another, which appears to be a key factor in the development of tumor resistance to treatments.
Multicellular origin of certain tumors
Another notable aspect of the Human Tumor Atlas Network’s research concerns the origin of tumors. Contrary to the widely accepted hypothesis that a tumor usually arises from a single cell, Doug Winton of the University of Cambridge and his team have discovered that some tumors, notably those of the colon, can arise from multiple cells cooperating to form cancerous clusters. This discovery was made possible by the use of genetically modified mice, in which the cells become colored when they transform into cancer cells. Approximately 40% of the colon tumors observed had this multicellular origin.
Ken Lau of Vanderbilt University also contributed to this discovery by identifying biomarkers to track the evolution of tumors and create a molecular timeline of their development. These biomarkers thus make it possible to trace the stages of growth of a tumor.
Using this method, scientists examined the early stages of colon cancer in humans and animals and found that up to 30% of them had a multicellular origin. According to Lau, the size of a precancerous colon lesion is now the best way to predict whether it will develop into cancer. He continues: “ Knowing how colon cancer develops can help us screen for precancerous lesions and detect cancer earlier. »
Better understanding of tumor resistance and spread
Abravanel’s team focused on studying metastatic tumors in breast cancer patients, that is, tumors that have spread to other organs. Against all expectations, biopsies taken at different times from the same patient turned out to be genetically very similar, calling into question the idea that mutations evolve significantly over time in the same tumor.
Additionally, Ben Raphael of Princeton University developed an algorithm to measure the proportion of cancerous and non-cancerous cells in a tumor, as well as their interactions. This tool could offer valuable help in understanding how cells distribute and interact in a tumor, and therefore how the tumor grows and responds to treatments.
Detailed analysis of tumors and their evolution could make it possible to better adapt therapies to the specific characteristics of each patient, an approach which remains complex today. As Abravanel points out, the current challenge is to match the right treatment to the right patient, taking into account the specific dynamics of each cancer. These new maps and tools thus open the way to more targeted treatments and a better understanding of resistance mechanisms. In addition, here are 10 harmful things in your daily life that science strongly links to cancer.
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