The role of mitochondria in cancer is becoming clearer

A new concept is emerging in the field of oncology: the internal architecture of tumor cells, at its finest, appears to be related to the aggressiveness of tumors. Researchers’ attention is, in fact, focused on the main building block: the mitochondria, or more precisely, the supply of mitochondria that power each cell. These microscopic “power plants” actually take on a variety of morphologies and spatial distributions within cancer cells depending on the nutrient sources they use. This is stated in a study published in the journal on March 15 ability.

Mitochondria play a critical role in the processes that cause tumors to grow. It must be said that the energy needs of these tumors are very high: we are talking about feeding their unbridled growth. In 2016, a Belgian team showed that cancer cells can alternately feed on carbohydrates, lipids or proteins, depending on the oxygen level and acidity of the environment around them. “Several studies have shown that flexible mitochondria, that is, able to use different substrates for energy production, can promote tumor growth.”– says Alan Pagano, a lecturer at the Faculty of Sport Sciences in Strasbourg. When the environment becomes too acidic, cancer cells tend to abandon glucose—the main fuel of normal cells—in favor of glutamine, an amino acid that builds proteins. They can also use fatty acids for their growth.

Two imaging techniques

In a new study, a team at the University of California created genetically modified mice that carried specific mutations in lung tissue. These rodents sometimes developed adenocarcinoma of the lung, sometimes squamous cell carcinoma of the lung. Mingqi Han, the study’s first author, and his colleagues then used two imaging techniques, positron emission tomography and volumetric electron microscopy, to draw high-resolution three-dimensional maps of the mitochondrial networks colonizing these tumor cells. Thanks to artificial intelligence, they were able to quantify the shapes and distributions of thousands of mitochondria in hundreds of cells corresponding to all these tumors.

Researchers have identified three types of mitochondrial frameworks. Type 1 mitochondria have an elongated shape, their inner membranes are relatively parallel to each other; And they are distributed in the internal environment of the cell (“cytoplasm”). In addition, they are often associated with lipid droplets. ” These mitochondria are more abundant in cells that use different nutrient sources: fatty acids, glucose, and glutamine.Christophe Grosset, director of research at the Inserm Institute of Oncology in Bordeaux, explains. “These are more aggressive tumor cells”Adds Rafael Rodríguez, CNRS Research Director at the Institut Curie (Paris).