Obesity has been linked to increased risk for over a dozen different types of cancer, as well as worse prognosis and survival.
Over the years, scientists have found obesity-related processes that drive tumor growth, such as metabolic changes and chronic inflammation, but a detailed understanding of the interplay between obesity and cancer has remained elusive.
In a new study, researchers found a new piece of this puzzle, with surprising implications for cancer immunotherapy: Obesity allows cancer cells to outcompete tumor-killing immune cells in a battle for fuel.
The research was conducted by a team at Harvard Medical School.
In the study, the team showed that a high-fat diet could reduce the numbers and anti-tumor activity of CD8+ T cells, a critical type of immune cell, inside tumors.
This occurs because cancer cells reprogram their metabolism in response to increased fat availability to better gobble up energy-rich fat molecules, depriving T cells of fuel and accelerating tumor growth.
The team found that blocking this fat-related metabolic reprogramming strongly reduced tumor volume in mice on high-fat diets.
Because CD8+ T cells are the main weapon used by immunotherapies that activate the immune system against cancer, the study results suggest new strategies for improving such therapies.
These results serve as a foundation for efforts to better understand how obesity affects cancer and the impact of patient metabolism on treatment outcomes.
The study provides a high-resolution metabolic atlas to mine for insights into obesity, tumor immunity and the crosstalk and competition between immune and tumor cells.
One author of the study is Marcia Haigis, a professor of cell biology.
The study is published in Cell.
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