Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

BRCA1 gene found to inhibit two sex hormones, not just one

27.01.2006


Could help explain why women who have mutations in their BRCA1 gene are susceptible to ’hormone-dependent’ cancers including breast, endometrial and cervical cancers



It’s been known that the breast cancer susceptibility gene BRCA1 regulates use of estrogen in breast and other cells, but now researchers at Georgetown University Medical Center have discovered that it also controls activity of a second sex steroid hormone, progesterone.

The findings, conducted in cell culture and in mice and reported by the researchers in the January issue of Molecular Endocrinology, could help explain why women who have mutations in their BRCA1 gene are susceptible to a number of different "hormone-dependent" cancers, including those of the breast, endometriun and cervix.


It also has implications for ordinary cancers that arise because a normal BRCA1 gene is under-expressed, said the study’s principal investigator, Eliot Rosen, MD, PhD, professor of oncology, cell biology, and radiation medicine at the Lombardi Comprehensive Cancer Center.

For example, he says that up to 40 percent of breast tumors are deficient in BRCA1, "and it may be that some patients could benefit not only from an anti-estrogen therapy, like tamoxifen, but also from an anti-progesterone agent.

"We don’t know if that is true yet, of course, but it is certainly worth investigating, given our findings," Rosen said.

The BRCA1 gene and a second gene, BRCA2, were discovered to be breast cancer susceptibility genes in 1994 and 1995, respectively. Women who inherit faulty copies of one of these genes have up to an 80 percent increased risk of developing breast cancer by age 70, and are also more likely to be diagnosed with ovarian cancer.

Rosen and his research team undertook the study to understand why loss of the BRCA1 gene results in cancers in tissues that are dependent on hormones. They focused on the progesterone hormone, in part, because of the observation that women who use hormone replacement therapy that includes both estrogen and progestin (a synthetic form of progesterone) are at greater risk of developing breast cancer than women who use only estrogen replacement.

The use of progesterone in the breast is tightly regulated and is primarily activated when growth in cells is needed, such as during the female menstrual cycle and to support a pregnancy. A cell’s use of progesterone and other such hormones is controlled by specific receptor proteins, located inside cells, which bind on to the hormone. This process activates the receptor, which then migrates to the cell nucleus to stimulate gene expression.

To find out what role BRCA1 played in progesterone receptor signaling, the Lombardi research team conducted a series of experiments. In one set of cell culture studies in the laboratory, they used breast cancer cells that were responsive to progesterone, and then genetically manipulated them to either over or under-express the BRCA1 gene in order to assess the gene’s effect on progesterone receptor signaling.

They also used mice in which the BRCA1 gene was partially deleted, but only in breast tissue. The animals were treated with estrogen, or progesterone, or both, and response of the mammary gland was compared with that of normal mice.

In this way, the researchers concluded that BRCA1 interacts physically with the progesterone receptor, and stops it from activating other genes. It does this even in the absence of the progesterone hormone, and, thus, acts as a strong check on errant growth.

"But in mice deficient in BRCA1, we found that estrogen plus progesterone has a particularly large effect in stimulating the growth of mammary epithelial cells − an effect much greater than the effects of either hormone used alone," Rosen said.

Liz McDonald | EurekAlert!
Further information:
http://www.georgetown.edu

More articles from Life Sciences:

nachricht New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>