Growth hormone is touted as an anti-aging remedy, but scientists studying a group of short-statured Ecuadoreans might beg to differ.
These individuals, who live in a remote region of the Ecuadorean Andes, suffer from a genetic defect known as Laron syndrome and are unable to process growth hormone. They are indeed shorter than average — adults rarely grow more than 3 to 4 ft. tall — but they are also free from typical age-related chronic diseases such as cancer and diabetes. If they weren’t dying from non-age related causes such as alcoholism, accidents and convulsive disorders, they would probably outlive the average adult, thanks to their genetic gift.
Dr. Jaime Guevara-Aguirre, a diabetes expert at the Institute of Endocrinology, Metabolism and Reproduction in Quito, began studying the group of nearly 100 Laron individuals in 1987. When he noticed that they were not developing cancer or diabetes, despite being overweight, he collaborated with Dr. Valter Longo, a biologist at University of Southern California, who was interested in studying genetic mutations related to aging. (More on TIME.com: Streamlining Breast Cancer Care: Some Women May Not Need Lymph Node Surgery)
In a paper published in Science Translational Medicine, the scientists report that among the Laron-affected villagers, there were no cases of diabetes and only one case of non-fatal cancer over about 22 years of study. But among a group of more than 1,600 unaffected relatives who lived in the same towns, the rates were considerably higher — 17% were diagnosed with cancer and 5% with diabetes, comparable to the general Ecuadorean population.
The Laron individuals, say the authors, produce less insulin growth factor 1 (IGF-1), which stunts their growth but also prevents DNA damage to cells and promotes the death of damaged cells. With less IGF-1, the insulin they have is more sensitive to sugars, so these people are less likely to become resistant to insulin’s effects, and therefore practically shielded from developing diabetes, which occurs when the body fails to regulate the proper amount of insulin to process sugars in food. When the scientists mixed serum from the Laron patients with human cells, the cells were protected from free-radical damage, which results from metabolic processes as well as exposure to things such as the sun, and often triggers tumor growth.
Does that mean that the serum of Laron patients can cure cancer? Not quite. Nor should doctors lower everybody’s levels of growth hormone. It is not only critical to normal early development (children born with Laron’s who are given human growth hormone grow to normal height), but even in adulthood, lowering growth hormone levels to negligible levels can affect certain metabolic processes. Further, the effects of lowering growth hormone in healthy individuals with normal amounts aren’t known. (More on TIME.com: Study: The Link Between Diabetes and Depression Goes Both Ways)
But the authors argue that reducing the hormone in people with excessive levels might be a good place to start, since the trials would indicate whether the treatment helped them to ward off cancer and diabetes. In fact, there is already a drug that blocks growth hormone-binding that is used to treat gigantism, or acromegaly. Such a treatment might also be considered for those at greater risk of developing cancerous mutations, such as those undergoing chemotherapy, as Longo speculated in the Wall Street Journal:
“We’ve shown that if you reduce IGF-1 it causes some protection for human cells. Can we use the same to protect against the toxic effects” of chemotherapy?
There’s strong evidence from animal models that manipulating the growth hormone receptor that is mutated in Laron syndrome may prove useful in controlling chronic disease in people. Studies have shown, for example, that mice deficient in growth factor hormone live up to 40% longer than those with normal amounts of the hormone. (More on TIME.com: Want to Live Longer? Switch to Whole Grains)
While it’s clear that much more work needs to be done to confirm how the lack of growth hormone in the Laron patients could be turned into a potential strategy for avoiding cancer and diabetes, the study provides hope that a growth hormone–based drug might someday be developed to prevent cancer or diabetes and ensure a long life. It just turns out that it won’t be one that boosts growth-hormone levels, as many have claimed.