Navigation Links
New Research Shows Artificial Light at Night Stimulates Breast Cancer Growth in Laboratory Mice

Results from a new study in laboratory mice show that nighttime exposure to artificial light stimulated the growth of human breast tumors by suppressing the levels of a key hormone called melatonin. The study also showed that extended periods of nighttime darkness greatly slowed the growth of these tumors.

The study results might explain why female night shift workers have a higher rate of breast cancer. It also offers a promising new explanation for the epidemic rise in breast cancer incidence in industrialized countries like the United States.

The National Cancer Institute and the National Institute of Environmental Health Sciences, agencies of the federal National Institutes of Health, provided funding to researchers at the Bassett Research Institute of the Mary Imogene Bassett Hospital in Cooperstown, New York and The Thomas Jefferson University in Philadelphia, Pa. The results are published in the December 1, 2005 issue of the scientific journal Cancer Research.

“This is the first experimental evidence that artificial light plays an integral role in the growth of human breast cancer,?said NIEHS Director David A. Schwartz, M.D. “This finding will enable scientists to develop new strategies for evaluating the effects of light and other environmental factors on cancer growth.?/p>

“The risk of developing breast cancer is about five times higher in industrialized nations than it is in underdeveloped countries,?said Les Reinlib, Ph.D., a program administrator with the NIEHS?grants division. “These results suggest that the increasing nighttime use of electric lighting, both at home and in the workplace, may be a significant factor.?/p>

Previous research showed that artificial light suppresses the brain’s production of melatonin, a hormone that helps to regulate a person’s sleeping and waking cycles. The new study shows that melatonin also plays a key role in the development of cancerous tumors.

“We know that many tumors are large ly dependent on a nutrient called linoleic acid, an essential fatty acid, in order to grow,?said David Blask, M.D., Ph.D., a neuroendocrinologist with the Bassett Research Institute and lead author on the study. “Melatonin interferes with the tumor’s ability to use linoleic acid as a growth signal, which causes tumor metabolism and growth activity to shut down.?/p>

To test this hypothesis, the researchers injected human breast cancer cells into laboratory mice. Once these cells developed into cancerous tumors, the tumors were implanted into female rats where they could continue to grow and develop.

The researchers then took blood samples from 12 healthy, premenopausal volunteers. The samples were collected under three different conditions ?during the daytime, during the nighttime following 2 hours of complete darkness, and during the nighttime following 90 minutes of exposure to bright fluorescent light. These blood samples were then pumped directly through the developing tumors.

“The melatonin-rich blood collected from subjects while in total darkness severely slowed the growth of the tumors. “These results are due to a direct effect of the melatonin on the cancer cells,?said Blask. “The melatonin is clearly suppressing tumor development and growth.?/p>

In contrast, tests with the melatonin-depleted blood from light-exposed subjects stimulated tumor growth. “We observed rapid growth comparable to that seen with administration of daytime blood samples, when tumor activity is particularly high,?Blask said.

According to the researchers, melatonin exerts a strong influence on the body’s circadian rhythm, an internal biological clock that regulates sleep ?wake cycle, body temperature, endocrine functions, and a number of disease processes including heart attack, stroke and asthma. “Evidence is emerging that disruption of one’s circadian clock is associated with cancer in humans, and that interference with internal timekeeping can tip the balance in favor of tumor development,?said Blask.

“The effects we are seeing are of greatest concern to people who routinely stay in a lighted environment during times when they would prefer to be sleeping,?said Mark Rollag, Ph.D., a visiting research scientist at the University of Virginia and one of the study co-authors. “This is because melatonin concentrations are not elevated during a person’s normal waking hours.?/p>

“If the link between light exposure and cancer risk can be confirmed, it could have an immediate impact on the production and use of artificial lighting in this country,?said Richard Stevens, Ph.D., an epidemiologist with the University of Connecticut Health Center who has authored several papers on the subject. “This might include lighting with a wavelength and intensity that does not disrupt melatonin levels and internal timekeeping.?/p>

“Day workers who spend their time indoors would benefit from lighting that better mimics sunlight,?added Stevens. “Companies that employ shift workers could introduce lighting that allows the workers to see without disrupting their circadian and melatonin rhythms.?


'"/>

Source:NIH


Related biology news :

1. Researchers discover way to make cells in the eye sensitive to light
2. Quantum Dots Research Leads to New Knowledge about Protein Binding in Plants
3. Researchers find how protein allows insects to detect and respond to pheromones
4. Researchers Uncover Key Step In Manufacture of Memory Protein
5. Research advances quest for HIV-1 vaccine
6. Research on Worms Yields Clues on Aging
7. Researchers reveal the infectious impact of salmon farms on wild salmon
8. Researchers identify target for cancer drugs
9. Weill Cornell Research Reveals Secrets Of Trafficking Within Cells
10. Researchers discover molecule that causes secondary stroke
11. Researchers find missing genes of ancient organism
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:3/24/2017)... Research and Markets has announced the addition of the ... Forecast to 2025" report to their offering. ... The Global Biometric Vehicle Access System ... over the next decade to reach approximately $1,580 million by 2025. ... forecasts for all the given segments on global as well as ...
(Date:3/23/2017)... 2017 Research and Markets has announced the ... Trends - Industry Forecast to 2025" report to their offering. ... The Global ... of around 8.8% over the next decade to reach approximately $14.21 ... market estimates and forecasts for all the given segments on global ...
(Date:3/22/2017)... Optimove , provider of the ... as 1-800-Flowers and AdoreMe, today announced two new ... Using Optimove,s machine learning algorithms, these features allow ... recommendations to their customers based not just on ... intent drawn from a complex web of data ...
Breaking Biology News(10 mins):
(Date:7/24/2017)... ... July 24, 2017 , ... ... the stock market news outlet had initiated coverage on Interpace Diagnostics. Interpace ... and identifies exposure, progression and risk analysis from specific cancers in humans. ...
(Date:7/20/2017)... ... 20, 2017 , ... Resoundant, Inc. is pleased to introduce ... the U.S. that offer MR Elastography for liver fibrosis staging. MR Elastography ... staging liver fibrosis assessment. , “MRE:connect was created in response to an increasing ...
(Date:7/20/2017)... ... 20, 2017 , ... Litmus Health , a clinical ... advisory board. The board comprises leaders spanning business, technology, academia, and pharmaceutical research. ... of Engineering, to Chief Technology Officer. Crooks will lead strategy and development of ...
(Date:7/20/2017)... ... July 20, 2017 , ... Corista, a leader in integrated ... Tuesday, July 25, during the Association of Pathology Chairs’ Jubilee Meeting in Washington, ... Baras, Associate Director of Pathology Informatics, will present “The Digital Pathology Experience at ...
Breaking Biology Technology: