PMH cancer researchers link ovarian hormone to breast stem cells growth

May 5, 2010

Cancer researchers at Princess Margaret Hospital (PMH) have discovered that the ovarian hormone progesterone plays a pivotal role in altering breast stem cells, a finding that has important implications for breast cancer risk.

The findings, published online today in Nature, are significant because reproductive history is among the strongest risk factors for , says principal investigator Rama Khokha, a molecular biologist at Ontario Cancer Institute and the Campbell Family Cancer Research Institute, PMH. Other major known risk factors are age, genetics and .

"Our study shows how and when hormones affect breast stem cells during the natural . There are well accepted links between ovarian hormones and breast cancer, and there is mounting evidence that stem cells are seeds for breast cancer. We now show a direct connection between hormones and breast stem cells. "

Lead author Purna Joshi adds: "Our research demonstrates that when progesterone peaks during the second half of the menstrual cycle, it starts a cross-talk between stem cells and neighbouring cells that propels normal breast stem cells to expand in number, and may trigger an environment where cancer can begin."

Until now, breast stem cells were thought to be generally inactive in the adult female breast, says Dr. Khokha, whose speciality is modelling human cancer in the laboratory. In this study, the research team replicated the human natural reproductive cycle in mice to determine the impact of hormones on breast stem cells.

How hormones change these stem cells opens a new pathway to understanding the cell growth that begins breast cancer, and, with further research, will open new ways of targeting .

"It is the first evidence, to our knowledge, for progesterone-driven dynamic shifts in the mammary stem cell pool. This activation provides an opportunity to start the process of cell transformation leading to breast cancer."

Explore further: Clues to breast cancer hidden inside stem cells

More information: DOI:10.1038/nature09091

Related Stories

Study questions 'cancer stem cell' hypothesis in breast cancer

March 12, 2007

A Dana-Farber Cancer Institute study challenges the hypothesis that "cancer stem cells" – a small number of self-renewing cells within a tumor – are responsible for breast cancer progression and recurrence, and that wiping ...

Herceptin targets breast cancer stem cells

July 9, 2008

A gene that is overexpressed in 20 percent of breast cancers increases the number of cancer stem cells, the cells that fuel a tumor's growth and spread, according to a new study from the University of Michigan Comprehensive ...

Therapy may block expansion of breast cancer cells

November 5, 2008

Breast cancer stem cells are known to be involved in therapy resistance and the recurrence of cancerous tumors. A new study appearing in Clinical and Translational Science shows the mechanisms governing stem cell expansion ...

Broccoli component limits breast cancer stem cells

May 3, 2010

A compound derived from broccoli could help prevent or treat breast cancer by targeting cancer stem cells -- the small number of cells that fuel a tumor's growth -- according to a new study from researchers at the University ...

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

Machine Translates Thoughts into Speech in Real Time

December 21, 2009

( -- By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" process ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.