Up for the Challenge
Stimuli of enriched environment may curb cancer
An animal study led by researchers at the OSUCCC – James shows that living in an environment rich with physical, mental and social stimulation – a setting that causes mild stress – may curb cancer growth.
The researchers discovered that an enriched environment activates the hypothalamic-sympathoneuraladipocyte (HSA) axis, a nervous-system pathway that instructs fat cells to stop releasing leptin into the bloodstream. Overall, the study suggests that environmental or genetic activation of the HSA pathway leads to a marked drop in serum leptin levels, and that this inhibits tumor growth.
“People think cancer survivors should avoid stress, but our data suggest this is not completely true,” says study leader Matthew During, MD, PhD, professor of Neuroscience, of Neurological Surgery and of Molecular Virology, Immunology and Medical Genetics. “The anticancer effect we observed was not due simply to increased activity, but to social and physical challenges that cause mild stress.”
The most dramatic hormonal change observed was the drop in leptin from fat after enhanced housing conditions activated the HSA pathway. The HSA pathway is also present in humans and is likely to be activated by a complex and challenging lifestyle, During notes. The enriched environment created for this study housed 20 mice in large containers equipped with toys, hiding places and running wheels, along with unlimited food and water. Control mice were housed in groups of five in smaller laboratory containers with unlimited food and water.
The researchers injected human melanoma cells under the skin in both sets of animals. After three weeks, mice in enriched housing had tumors about half the size of those in control mice. After six weeks of enrichment, those tumors had dropped to one fifth the size of those in control animals, and almost 20 percent of enriched-group mice had no visible tumors. All control animals had visible tumors.
Published as the lead cover story in the journal Cell.