(Philadelphia, PA) - In the pursuit of novel cancer therapies, researchers at the University of Pennsylvania School of Medicine describe new mechanisms by which the hormone prolactin induces the growth and spread of breast cancer, a disease that affects one in nine women.

As a hormone, prolactin is necessary for the production of breast milk. However, its role in stimulating the growth of breast cancer has been only recently recognized in humans, as recent studies have found that prolactin is made by human breast cancer and that elevations in prolactin levels in the blood significantly increase the risk of developing this disease.

In the report, appearing this month in the Proceedings of the National Academy of Sciences, researchers describe that the alteration of the structure of one protein that binds prolactin results in a dramatic inhibition of the growth of breast cancer in the lab. This finding challenges the current dogma of how protein hormones like prolactin function and also provides researchers with new strategies in their therapeutic attack on breast cancer.

"Traditionally, it was thought that protein hormones, like prolactin, only work on the outside of cells - as if their only job was just to hit the 'on' switch," said Charles V. Clevenger, MD, PhD, associate professor in the Penn Department of Pathology and Laboratory Medicine.

"Contrary to established theory, our research has shown that prolactin combines with another protein called cyclophilin B to physically enter the cell and directly activate the process that turns on genes and trigger the growth of breast cancer cells."

"Here we show that prolactin clearly works inside the cell to turn on genes", said Michael Rycyzyn, a postdoctoral fellow in the Clevenger lab and co-author of this study, "and by using modified forms of cyclophilin B we can stop this process and block the growth of breast cancer." In doing this, their lab has uncovered a new pathway through which hormones work, and in turn, discovered a target-rich environment for cancer researchers to explore.

The research presented in this study was provided by grants from the National Institutes of Health and the American Cancer Society.


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Editor's Note:
You can find the original article online at www.pnas.org


 


 

 

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Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System, which together form a $6.7 billion enterprise.

The Perelman School of Medicine has been ranked among the top five medical schools in the United States for the past 20 years, according to U.S. News & World Report's survey of research-oriented medical schools. The School is consistently among the nation's top recipients of funding from the National Institutes of Health, with $392 million awarded in the 2016 fiscal year.

The University of Pennsylvania Health System's patient care facilities include: The Hospital of the University of Pennsylvania and Penn Presbyterian Medical Center -- which are recognized as one of the nation's top "Honor Roll" hospitals by U.S. News & World Report -- Chester County Hospital; Lancaster General Health; Penn Wissahickon Hospice; and Pennsylvania Hospital -- the nation's first hospital, founded in 1751. Additional affiliated inpatient care facilities and services throughout the Philadelphia region include Good Shepherd Penn Partners, a partnership between Good Shepherd Rehabilitation Network and Penn Medicine.

Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2016, Penn Medicine provided $393 million to benefit our community.

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