Women in Science: How the breast makes milk and what this tells us about breast cancer
I enjoy engaging with the public so when I was asked to stand on a Soapbox on South Bank and talk about my work, I immediately said yes. Then I wondered – would the public be interested in my work? As it turned out, they were and I was asked all sorts of interesting questions by people who stopped to listen. Soapbox Science is a great idea and much more fun than I had imagined.
For the past 15 years or so I have been studying cells in the breast. I am interested in finding out how the special cells in the breast that make milk develop during pregnancy. I am also interested in how these cells are induced to die after they are no longer needed, when the baby is weaned. My hope is that by understanding these processes, I will be able to find why they don’t work in breast cancers. One of the features of breast cancer cells is that they become resistant to cell death and so don’t respond to treatments that are designed to kill them. More aggressive breast cancer cells can also lose the ability to make milk.
The first topic we discussed was what happens to the breast during pregnancy. We have discovered a new gene that is a master controller of the milk-producing (alveolar) cells. This gene normally stops the alveolar cells from growing but it is switched off by pregnancy hormones and this allows cells to start dividing rapidly. They grow into round clusters of cells that are attached to a network of ducts that connect to the nipple, allowing the milk to be suckled.
We had made posters with diagrams to explain all of this but I think our bunch of grapes analogy worked much better! If you think of the grapes in a bunch as the milk producing clusters of cells and the twigs to which they are attached as the network of ducts, then you get a good idea of how a lactating breast is constructed. This topic stimulated good discussion. I was delighted that we had a mother of quadruplets in the audience who was proof that the breast can make as much milk as required. We even had a man who revealed he had four nipples – Scaramanga eat your heart out ! Such supernumerary nipples are not uncommon.
The other side of the coin is the removal of these cells when the milk is not needed. It makes sense to kill them off and grow new ones for the next baby. So, if we think about our bunch of grapes after we have eaten the grapes, we are left with the twigs and this is what happens to the breast during weaning. Only the network of branches remains ready for the next pregnancy.
There are many ways to kill cells but the most usual method is a process called apoptosis. However, we have found that another method kills the cells. This requires a rather strange structure called a lysosome. These are sometimes called garbage disposal centres as all the waste products and damaged parts of the cell get sent to the lysosomes for recycling. Lysosomes are full of enzymes that digest everything you find in a cell including DNA, proteins and sugars.
We have found that lysosomes become leaky after lactation stops and the enzymes that leak out break down essential components of the cell which then dies. We are trying to find ways of making lysosomes leak in cancer cells so that we can develop a new treatment for cancers that are resistant to other types of therapy.
This lead us on to talk about breast cancer, an emotive topic. What surprised the audience was that men can get breast cancer too. It is very rare but I don’t think most men realise that they have breast tissue! The good news for women is that survival rates are high compared to many other cancers but we still have a long way to go to find treatments for the aggressive types of breast cancer which often affect young women.
The other Soapbox scientists were inspiring and interesting people and the sponsors L’Oréal and The Zoological Society of London did a fantastic job organising the event. My graduate student Hayley Frend was a great help preparing for the event and on the day, holding up the posters. I hope the people who stopped to engage with us found it worthwhile and that young women who are thinking of a career in science decide to go for it. It’s a challenging but rewarding career.
Professor Christine Watson is a Professor of Cell and Cancer Biology at the University of Cambridge.
She is working with the L’Oréal-UNESCO For Women in Science Programme and The Zoological Society of London to encourage more young women to pursue careers in science. www.womeninscience.co.ukTagged in: Breast Cancer, breast milk, science, Soapbox
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