Most people think of muscles as the parts of the body that help us walk, climb stairs, lift objects, and stay physically active. However, scientists now know that muscles do much more than create movement.
Skeletal muscles are also important communication centers that send chemical signals to other organs throughout the body. These signals help regulate metabolism, immune function, inflammation, and overall health.
As people grow older, muscles naturally become smaller and weaker. This age-related loss of muscle mass and strength is known as sarcopenia. Sarcopenia is very common among older adults. In Singapore, nearly one in three people over the age of 60 are affected by the condition. Similar patterns are seen around the world as populations continue to age.
The consequences of sarcopenia go beyond weaker muscles. Older adults with significant muscle loss often have difficulty walking, climbing stairs, carrying groceries, and performing daily activities independently. They are also more likely to fall, become frail, and experience a lower quality of life.
Scientists have also noticed another troubling pattern. Patients with advanced cancer often have low muscle mass. However, it has remained unclear whether aging muscles simply reflect poor health or whether they actively influence cancer development.
A new study published in Nature Communications suggests that aging muscles may directly affect cancer growth through a hidden communication system inside the body.
The research was conducted by scientists from Duke-NUS Medical School in Singapore, working with collaborators from Singapore General Hospital and Cardiff University. The team focused on tiny particles called extracellular vesicles.
Extracellular vesicles are extremely small sacs released by cells. Although they are microscopic, they play a major role in communication between different parts of the body. They carry proteins, fats, and genetic material from one cell to another, allowing cells to exchange information and influence each other’s behavior.
The researchers discovered that healthy muscles release large numbers of these extracellular vesicles. However, as muscles age and become affected by sarcopenia, they produce fewer of these important particles.
The scientists also found that the composition of these vesicles changes with age. In particular, the vesicles released by older muscles contain lower amounts of a tiny genetic molecule called miR-7a-5p.
MicroRNAs are very small pieces of genetic material that help regulate how cells function. They can influence which proteins cells make and how genes behave. Previous research has suggested that miR-7a-5p plays a role in slowing or suppressing tumor growth.
The new findings suggest that aging muscles gradually lose some of their natural ability to send protective anti-cancer signals throughout the body. As these signals weaken, conditions may become more favorable for tumor growth.
The researchers uncovered another important finding. They discovered that the release of extracellular vesicles from muscles is controlled by a biological pathway that naturally declines with age. Encouragingly, this pathway can be reactivated through exercise.
Assistant Professor Tang Hong-Wen from Duke-NUS Medical School explained that muscle cells communicate with other cells through extracellular vesicles and that aging changes these signals in ways that may promote tumor growth.
Dr. Kenon Chua from Singapore General Hospital said doctors have long observed a link between advanced cancer and low muscle mass. He noted that healthy muscles release many substances that are important for overall health and emphasized that maintaining muscle mass through regular exercise becomes increasingly important with age.
The researchers believe these findings may eventually lead to new treatments. Instead of focusing only on cancer cells themselves, future therapies might target the communication pathways between muscles and tumors.
Treatments that restore healthy extracellular vesicles or increase beneficial molecules such as miR-7a-5p could potentially help reduce cancer risk in older adults.
The scientists now plan to study human samples to determine whether extracellular vesicles and the miR-7a-5p they carry could be used as biomarkers to identify older people who may face a higher risk of cancer associated with muscle loss.
In reviewing the findings, this study highlights that muscles are far more important than previously understood. They appear to act as communication organs that may help protect the body from cancer.
The discovery that exercise can restore some of these protective signals is especially encouraging because physical activity is a low-cost intervention that is accessible to many people. However, the study remains at an early stage, and more research in humans is needed before new treatments can be developed.
Even so, the findings add another compelling reason to preserve muscle health throughout life and suggest that maintaining strong muscles may play an unexpected role in healthy aging and cancer prevention.
If you care about cancer, please read studies that a low-carb diet could increase overall cancer risk, and vitamin D supplements could strongly reduce cancer death.
For more information about health, please see recent studies about how drinking milk affects the risks of heart disease and cancer and results showing higher intake of dairy foods linked to higher prostate cancer risk.
Source: Duke-NUS Medical School.
