Back when food was scarce, carrying a few extra pounds around increased your odds of surviving a famine. But even then, being extremely overweight wasn’t particularly advantageous since you still had to do physical labor such as farming or hunting.
Today, 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 identified 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.
The battle for fuel
In a new study, Harvard Medical School researchers have uncovered 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.
Published in cell, the research team shows that a high-fat diet reduces the numbers and antitumor 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 significantly 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.
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