Showing How Breast Cancer Spreads

Photo: Small red point in the middle of green-blue tissue

Photoswitching principle: Changing
a cell from green to red colour, it
can easily be located; © Yeshiva

These movements are the first steps of the potentially deadly stage of cancer known as metastasis. The new method of viewing cancer cells over several days in their natural environment is considered significant by the researchers because prior methods of study only allowed cells to be viewed clearly for several hours at one time. Having a longer and clearer window into how cancer cells move during the early stages of metastasis may help scientists develop more effective cancer therapies.

Using intravital imaging, the researchers developed a “photoswitch” to mark cancer cells of their choosing within a tumour and observe how these tumour cells in mice move in their surrounding tissue. The technique allowed researchers to see individually labelled tumour cells move in real time and in living mice.

The new method involves the placement of a frame containing a small glass window onto the breast tumour of a mouse formed from cancerous cells that have a specific tag. Through the glass, individual breast tumour cells are targeted with a laser that ‘marks’ the cancer cells red. By viewing the cells through the window using a microscope, researchers can follow the cells as they spread. The mouse can move around and live normally with the glass plate and then be anesthetised briefly for observance under the microscope. The marked cancer cells are followed over a period of days until they lose their brightness.

Using this technique, investigators found that breast cancer cells closer to blood vessels were more aggressive and directed in their invasiveness than cancer cells farther from blood vessels. The cancer cells near blood vessels also appeared in the lung indicating that they are disseminated throughout the body.

This finding marks the first time a direct link was shown between the presence of blood vessels and the invasive ability of a cancer cell, which strengthens the growing theory that blood supply is crucial to effective metastasis. It also suggests that many cancer therapies currently in development, which are directed at cutting off blood supply to tumours, may be on the right track.; Source: Albert Einstein College of Medicine of Yeshiva University