Blocking certain epigenetic proteins prevents breast cancer: Study

Blocking certain epigenetic proteins prevents breast cancer: Study

Overview

  • Post By : Bhawana Jain
  • Source: Medical News Today
  • Date: 21 June, 2018

Scientists from the Princess Margaret Cancer Centre in Toronto, Canada identified that blocking key proteins that respond to the hormone progesterone may prevent breast cancer in the women who carry high-risk genes.

These proteins known as epigenetic proteins when get exposed to the hormone progesterone cause "mammary gland stem cell" numbers to expand.

The research describing the discovery in a paper is due to be published in the Journal of Cell Biology.

The findings of the study would help in taking the next step towards the development of "chemoprevention" for those at high risk for breast cancer.

The senior author Rama Khokha, a senior scientist at Princess Margaret Cancer Centre and professor of biophysics at the University of Toronto says that, "Currently, there are no standard of care preventative interventions for women at high risk of breast cancer."

Previous research has showed that certain gene mutation raises the risk of developing cancer. For example, specific mutations in the tumor suppressor genes BRCA1 and BRCA2, greatly raise the risk of developing breast cancer.

Breast cancer and its link with stem cells

Breast cancer starts when abnormal cells in breast tissue begin to grow uncontrollably and spread to surrounding areas. Although the majority of cases occur in women, sometimes men can also get it as they too have breast tissue.

In the United States, it is expected that during 2018 an estimate of 330,080 new cases of breast cancer will be diagnosed in women while about 2,550 new cases will be diagnosed in men.

New drug attacks cancer-causing genes

A new class of drugs discovered a decade ago called BET inhibitors may help to improve survival rates in breast and other cancers by targeting cancer-causing genes.

Previous research has showed that certain gene mutation raises the risk of developing cancer. For example, specific mutations in the tumor suppressor genes BRCA1 and BRCA2, greatly raise the risk of developing breast cancer.

Mammary gland stem cells are highly specialized and self renewing. They give rise to mammary gland lineages. They act as progenitor cells that mature into luminal and basal cells, the two cell types that form the mammary gland, organ responsible for producing milk in the breast.

During menstruation and pregnancy, an increase in progesterone levels triggers an increase in basal and luminal stem cells thus causing the mammary glands to expand. This expansion is the result of epigenetic proteins that act as switches triggering the stem cell proliferation in response to progesterone.

However, the expansion of mammary gland stem cells and exposure to progesterone are also linked to breast cancer. It was found that the women who carry certain high-risk genes for breast cancer often have increased numbers of mammary gland stem cells.

Progesterone induces epigenome changes

For the research, Prof. Khokha and her team first observed how mammary gland cells isolated from mice responded when exposed progesterone. They also thoroughly checked the changes in the proteins and epigenomes of the cells.

The epigenome is a group of chemical compounds surrounding DNA that acts by switching genes on and off in the cell. It plays a key role in determining which genes are active in a particular cell by modifying the genome without altering the DNA sequences.

It was discovered that when mammary gland stem cells were exposed to increased progesterone levels, a massive switch-on of genes was triggered in the mammary gland stem cells, particularly responsible for making luminal cells.

Finally, on the basis of the above observations, the lead researcher Prof. Khokha claimed that "drugs that inhibit these epigenetic regulatory proteins might suppress the proliferation of stem and progenitor cells in response to progesterone."

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Bhawana Jain

Bhawana Jain