Scattered Light Detects Tumour Response

Photo: Breast cancer cell under the microscope

Within hours, researchers were able
to tell whether or not a cancer cell
was reacting to treatment; © NCI

Most chemotherapy drugs work by forcing cancer cells to commit cellular suicide, a process known as apoptosis. As cells undergo this process, bodies within the cell, such as the nucleus or mitochondria, go through structural changes.

Using the new approach, researchers can analyse the light scattered by these bodies to detect the apoptotic changes in real time. "Now, oncologists typically judge if an agent is working by looking for shrinkage in the tumour using imaging techniques, or pathological response at time of surgery" said Julie Ostrander, one of the paper's first authors. "Currently, it can take between six and eight weeks to detect the changes of apoptosis clinically,” adds Adam Wax of the research team.

The light-scattering technology is known as angle-resolved low coherence interferometry (a/LCI). Light is shined into a cell sample and sensors capture and analyse the light as it is scattered back. The technique is able to provide representations of sub-cellular structure without disrupting the cells, and can be used to scan a large number of cells in a short time.

For their experiments, the team studied a well-known cell culture line of human breast cancer. The cells were exposed to two common chemotherapy drugs. Using the a/LCI technology, the researchers looked for specific patterns, which indicate that structural changes have occurred.

The researchers found that when compared to control cells, the treated cells began showing significant increases in a pattern called fractal dimension within 90 minutes respectively three hours, depending on the drug. Interestingly, the fractal dimensions began decreasing at six hours, only to increase again within twelve hours of treatment.

"The fact that the changes in structure appear over two distinct time scales suggests that multiple mechanisms are involved in these early events in apoptosis," Wax said. "Further analysis showed the early changes were taking place in the mitochondria, while the changes in the structure of the nucleus were responsible for the later ones." Further studies will be carried out in animals.

MEDICA.de; Source: Duke University