Brest Stem cell
Chris - Jane Visvader and Connies Eaves have independently discovered the breast stem cell. This is important because if you take that cell and place it elsewhere in the body, it ca make an entirely new breast. That must have have very important cosmetic applications because if you needed to have a new breast after maybe losing one for various disease processes, it could be very handy. But this stem cell may also hold the key to controlling breast cancer. It's becoming increasingly clear that these stem cells play a role in triggering cancers in the first place, but also that chemotherapy which we use to treat cancers doesn't hit those cells very efficiently. They're always loitering there ready to cause the recurrence of the disease. Now we know how to track them down, we may be in a much better position to treat breast cancer properly. First of all, let's talk to Jane Visvader, who is at the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia.
Jane - We've isolated and identified the breast stem cell, and shown that a single cell, when implanted into its correct environment, can in fact give rise to the entire ductal tree that typifies the breast tissue.
Chris - How did you actually track the stem cell down?
Jane - It was years of work by two very talented people in the lab, and by using a whole series of markers that are expressed on the cell surface, went through one by one and eventually found a population among breast tissue that expresses these specific markers. By using these markers, they could actually isolate the cells. They could purify them and then implant them into a mouse model in the fat pad or 'mouse breast' where it normally grows.
Chris - That was Jane Visvader describing how the breast stem cell can give rise to all of the normal tissues in the breast. But the findings also point to one way in which these stem cells could contribute to the formation of abnormal tissues within the breast too; in other words, cancers. Connie Eaves from the Terry Fox Laboratory at the British Columbia Cancer Agency in Vancouver explains.
Connie - One of the most fascinating observations in our paper is that this cell is not what everybody thought would be the case. It is not lying there mostly asleep. It is a very actively dividing cell. But because they are diving all the time, that means that they must be very prone to developing mutations and some of those mutations by chance would be mutations that would give you a cancer. So this may explain why the breast is a tissue where the development of cancer is very prevalent amongst women.
Chris - Now presumably, given that you've identified this cell, you can now look for any markers that distinguish it from other cells or gives it its individuality.
Connie - Yes, well part of this paper is about the identification of certain adhesion molecules that are expressed at very high levels on these cells, more so than any other cells in the breast tissue. That what makes it possible for us to isolate these cells.
Chris - That was Connie Eaves describing how breast stem cells might contribute to the formation of breast cancers, and how the unique molecular fingerprint that they express on their surfaces allows them to be singled out from other cells in the breast. But what are the implications of these findings for the ability to treat breast cancers?
Jane - There is growing evidence that many cancers contain a very rare population of stem cells that actually drive tumour formation. They're very difficult to eradicate because they have different properties, so many chemotherapies available now do not target these cells. So in the context of breast cancer, we've characterised the normal breast stem cell, which will share characteristics with this and so our future studies will certainly go in the direction of trying to identify these stem cells that exist in proportions of breast cancers.