Melatonin May Potentially Slow Tumor Growth in Estrogen Receptor–Negative Breast Cancers
An early-stage study shows melatonin may have the potential to help slow the growth of certain breast cancer tumors, according to researchers from Henry Ford Hospital in Detroit and Foundation for Research Support of the State of São Paulo. The study, published online in the journal PLoS One, found that melatonin may inhibit tumor growth and cell production, as well as block the formation of new blood vessels in estrogen receptor–negative breast cancer models.
"These early-stage research results with the melatonin drug in triple-negative breast cancer animal models achieved in our lab has not been seen anywhere else," said study coauthor Adarsh Shankar, a research assistant in the Department of Radiology at Henry Ford Hospital. "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."
Because of melatonin's suspected antioxidant properties, some believe it may suppress the growth of some types of cancer cells, especially when combined with certain anticancer drugs, according to the American Cancer Society.
Study Details
To determine the therapeutic effectiveness of melatonin on tumor growth, researchers evaluated the action of melatonin on angiogenesis in estrogen receptor–negative breast cancer in vitro and in vivo using cell and mouse models, respectively.
The mice were randomly assigned to either the melatonin or control groups. The melatonin group received treatment each night for 21 days; melatonin was administered at pharmacologic concentration 1 hour before room lighting was switched off. Melatonin administered prior to the nocturnal phase is believed to be more effective because tissues are most sensitive to the hormone at this time.
At the end of the 21-day treatment, researchers used single-photon emission computed tomography to determine whether melatonin therapy effectively decreased the size of implanted human triple-negative breast cancer in the mouse models as well as whether there were any changes in the formation of new blood vessels. Additionally, tumor volume was measured each week, and tumor tissue was analyzed at the end of treatment.
Outcomes
The study found that none of the treated mice showed any loss of weight and lethargy during the 21-day treatment; instead, most showed excessive movement but no irritability or aggressive behavior. Those treated showed significantly smaller tumors after 21 days while the mean tumor volume increased significantly in the control group. In addition, there was less vascular growth in the tumors of the treated group. The results were replicated in cell models.
The study demonstrated that melatonin administered at pharmacologic concentration was able to reduce estrogen receptor–negative breast cancer cell viability in vitro. These results suggest that melatonin has potential as a therapeutic agent for breast cancer.
The study's authors caution, however, that this research is still in its very early stages and results are not yet ready to be translated for patient use. More basic research is needed on this topic—particularly on how melatonin acts on angiogenesis in various cancers—before clinical trials in humans can be planned.
Debora Aparecida Pires de Campos Zuccari, of Faculdade de Medicina de São José do Rio Preto, Brazil, is the corresponding author for the PLoS One study.
The study was funded by the Foundation for Research Support of the State of São Paulo.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
