Brett Smith for redOrbit.com – Your Universe Online
Produced by the brain in response to darkness and often taken as a sleep aid supplement, melatonin could be effective in slowing the growth of certain breast cancer tumors, according to a new report published in the open-access journal PLOS ONE.
More specifically, melatonin may stunt tumor growth and tumor cell production, as well as obstruct the generation of new blood vessels in breast cancer cells that test negative for estrogen receptors, referred to as ER-negative.
“These early stage research results with the melatonin drug in a triple-negative breast cancer animal models achieved in our lab has not been seen anywhere else,” said study author Adarsh Shankar, a radiology researcher at Henry Ford Hospital in Detroit. “The key finding of the study is that we now know that we can trace this drug and its effect on tumor growth, which opens the door for more research on this topic.”
A promising approach in reducing cancer progression is finding a way to mitigate angiogenesis, the tumor’s development of new arteries. Once a tumor exceeds several millimeters in diameter, a lack of oxygen triggers a series of events that enable angiogenesis and tumor growth.
To determine the effectiveness of melatonin on tumor expansion, the international team of study researchers evaluated the action of the naturally produced substance on angiogenesis in ER-negative breast cancer using both in vitro and in vivo using cell and mouse models respectively.
The mice were randomly assigned to either melatonin or control groups. The melatonin group was treated every night for 21 days. Melatonin was administered at a pharmacologic dose one hour before the lights in lab were turned off. Melatonin is thought to be more effective before sleep because tissues are most sensitive to the hormone at this time.
At the end of the 21-day regimen, scientists used single photon emission computed tomography (SPECT) to establish whether melatonin therapy properly decreased the size of human triple negative breast cancer in the rodents and if there was any modifications in the development of new blood vessels. The researchers also measured tumor volume each week. Tumor tissue was analyzed at the end of the 21-day period.
The study said none of the treated mice showed any loss of weight or energy during the 21-day treatment — in fact, most showed excessive movement, yet no irritability or hostile behavior.
Those treated showed considerably smaller tumors after 21 days while the mean tumor volume heightened noticeably in the control group. The researcher also found less vascular growth in the tumors of the treated group.
The study team said they found similar results in their cellular models.
The scientists called for more research on this potential treatment – particularly on how melatonin affects angiogenesis in various cancers – before human trials can be carried out.
In another study investigating the link between cancer and sleep, a team of American researchers found that disrupted sleep patterns can accelerate the progression of cancer.