Aging affects every part of the human body, but some changes happen so gradually that people barely notice them. One of the most common age-related changes is the loss of muscle mass and strength.
Many older adults find that they become weaker, tire more easily, and have more difficulty performing everyday tasks. Although these changes are often considered a normal part of getting older, scientists are learning that muscle aging may have effects far beyond movement and physical strength.
Researchers have now discovered evidence that aging muscles may influence cancer development through a hidden communication system that operates deep inside the body.
The study, published in Nature Communications, was led by scientists at Duke-NUS Medical School in Singapore together with researchers from Singapore General Hospital and Cardiff University.
The team focused on sarcopenia, an age-related condition characterized by a gradual loss of muscle mass and muscle strength. Sarcopenia is becoming an increasingly important public health issue because people around the world are living longer. In Singapore, almost one-third of people aged 60 years and older are affected by the condition.
Sarcopenia can reduce mobility, limit independence, and increase the risk of falls and frailty. However, researchers have recently started to wonder whether aging muscles might also affect diseases that seem completely unrelated to movement, including cancer.
To explore this question, the scientists studied tiny particles called extracellular vesicles. These particles are released by cells and act like miniature delivery packages. They carry information from one cell to another in the form of proteins and genetic material.
Although extracellular vesicles are extremely small, they are increasingly recognized as important messengers that help different organs communicate with each other.
The researchers found that healthy muscles release large numbers of extracellular vesicles. In contrast, muscles affected by sarcopenia release fewer of these particles.
The scientists also discovered that the contents of these vesicles change as muscles age. In particular, they contain lower levels of a molecule called miR-7a-5p.
This molecule belongs to a group of genetic regulators known as microRNAs. These molecules help determine how genes function and influence the kinds of proteins cells produce. Earlier studies have suggested that miR-7a-5p plays an important role in restricting tumor growth.
As muscles age and produce fewer extracellular vesicles containing this protective molecule, important anti-cancer signals appear to weaken. The researchers believe this creates a biological environment that may make tumor growth easier.
The study also identified an important mechanism controlling this process. The release of extracellular vesicles from muscle cells depends on a signaling pathway that becomes less active with age. Fortunately, the researchers found evidence that this pathway can be reactivated through exercise.
This finding is particularly exciting because it suggests that lifestyle choices may influence these biological processes. Exercise has long been known to reduce the risk of many diseases, including some forms of cancer. The new study provides a possible explanation for one of the ways exercise may protect health.
Assistant Professor Tang Hong-Wen from Duke-NUS Medical School explained that muscles communicate with other cells through extracellular vesicles and that aging changes these messages in ways that can support tumor growth.
Dr. Kenon Chua from Singapore General Hospital pointed out that doctors frequently observe low muscle mass in patients with advanced cancer. He emphasized that maintaining healthy muscle volume through regular aerobic and resistance exercise is important not only for movement and independence but also for overall health.
The findings have opened new possibilities for medical research. Scientists hope that extracellular vesicles and the molecules they carry could eventually become biomarkers that help identify older people at greater risk of cancer. They may also serve as targets for new therapies designed to restore protective communication between muscles and other tissues.
The researchers are now planning studies involving human samples to determine whether extracellular vesicles and miR-7a-5p can be used in clinical settings.
When analyzing the findings, it becomes clear that this research changes the way scientists think about muscles. Rather than serving only as engines for movement, muscles appear to participate actively in communication networks that influence the entire body.
The discovery of a muscle-to-tumor signaling pathway may eventually lead to new approaches for cancer prevention and healthy aging. However, these findings are still preliminary and require confirmation in larger human studies.
The study nevertheless provides important new evidence that preserving muscle health through regular exercise may have benefits that extend far beyond strength and mobility and could potentially influence cancer risk itself.
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Source: Duke-NUS Medical School.
