Produced in the brain's pineal gland, melatonin is called the sleep hormone because it helps regulate your sleep and wake cycles. Researchers at Michigan State University have found, however, that melatonin can do much more than help your body catch some Zs. It may be able to suppress the growth of breast cancer tumors.
The pineal gland manufactures melatonin at night to regulate sleep cycles. According to WebMD, levels begin to rise in the evening, remain high for most of the night and begin to drop in the morning. "Light affects how much melatonin your body produces," reports WebMD. Shorter winter days can disrupt when exactly your body produces the hormone, which can lead to sleep-related issues and seasonal affective disorder (SAD).
But in addition to establishing a link between melatonin and sleep, epidemiologists and experimentalists have speculated that the lack of melatonin puts women at higher risk for breast cancer. The latest MSU study shows that melatonin suppresses the growth of breast cancer stem cells, providing scientific proof to support the growing body of anecdotal evidence on sleep deprivation.
The MSU team published its findings in the current issue of Genes and Cancer, and note that, while treatments based on this key discovery are still years away, the results give scientists a key foundation on which to build future research.
"Understanding the expression of genes in their natural environment reveals how they interact in disease settings," explains David Arnosti, MSU biochemistry professor, director of MSU's Gene Expression in Development and Disease Initiative and co-author of the study. "That's what is so special about this work."
The research team was led by Juliana Lopes, a visiting researcher from Sao Paolo, Brazil. Before the team could test its theory, the scientists had to grow tumors from stem cells, known as "mammospheres," a method perfected in the laboratory of James Trosko at MSU.
The growth of these mammospheres was enhanced with chemicals known to fuel tumor growth, namely, the natural hormone estrogen, and estrogen-like chemical Bisphenol A, or BPA, found in many types of plastic food packages.
Melatonin treatment significantly decreased the number and size of mammospheres when compared with the control group. Furthermore, when the cells were stimulated by estrogen or BPA and treated with melatonin at the same time, there was a greater reduction in the number and size of mammospheres.
"This work establishes the principal by which cancer stem cell growth may be regulated by natural hormones, and provides an important new technique to screen chemicals for cancer-promoting effects, as well as identify potential new drugs for use in the clinic," Trosko said.