Research suggests dietary change starves cancer cell

A new study from the University of Michigan Rogel Cancer Center has found that a dietary change could be a key to enhancing colon cancer treatment. Cancer cells need nutrients to survive and grow. One of the most important nutrient-sensing molecules in a cell is called mTORC1. Often called a master regulator of cell growth, it allows cells to sense different nutrients and thereby grow and proliferate. When nutrients are limited, cells dial down the nutrient-sensing cascade and turn off mTORC1. Researchers found in cells and in mice that a low-protein diet blocked the nutrient signalling pathway that fires up a master regulator of cancer growth. Results are published in Gastroenterology. The regulator, mTORC1, controls how cells use nutritional signals to grow and multiply. It's highly active in cancers with certain mutations and is known to cause cancer to become resistant to standard treatments. A low-protein diet, and specifically a reduction in two key amino acids, changed the nutritional signals through a complex called GATOR. GATOR1 and GATOR2 work together to keep mTORC1 in business. When a cell has plenty of nutrients, GATOR2 activates mTORC1. When nutrients are low, GATOR1 deactivates mTORC1. Limiting certain amino acids blocks this nutrient signalling. Previous efforts to block mTORC have focused on inhibiting its cancer-causing signals. But these inhibitors cause significant side effects - and when patients stop taking it, cancer comes back. The study suggests that blocking the nutrient pathway by limiting amino acids through a low-protein diet offers an alternative way to shut down mTORC. Researchers confirmed their findings in cells and mice, where they saw that limiting amino acids stopped cancer from growing and led to increased cell death. They also looked at tissue biopsies from patients with colon cancer, which confirmed high markers of mTORC correlated with more resistance to chemotherapy and worse outcomes. The risk with a low-protein diet is that people with cancer often experience muscle weakness and weight loss, which limiting protein could exasperate.