Lighting up tumors

Lawrence Marnett and his team from Vanderbilt University have found a way to visually tag cancer cells in the early stages before they become malignant.

Marnett and his colleagues created a fluorescent compound that binds to the enzyme cyclooxygenase-2 (COX-2). This was not a random choice. COX-2 is undetectable in normal cells, but is expressed in cancerous cells whether or not they are malignant. Unfortunately, most compounds that will bind COX-2 will also bind the related COX-1 enzyme, which is abundant in normal cells. The scientists synthesized and tested over 200 compounds before finding two that selectively bound to COX-2.

The next step was to see whether the compounds, named ‘fluorocoxibs’ (fluorescent COX inhibitors) could in fact target and light up tumors. The researchers injected the fluorocoxibs into mice suffering from a variety of tumors. In each case, the tumor glowed exactly as anticipated. You can see one such result below.

Fluorocoxib injection into mouse lights up an intestinal polyp.

Credit: Lawrence Marnett, Ph.D., and colleagues

According to Marnett:

Because COX-2 levels increase during cancer progression in virtually all solid tumors, we think these imaging tools will have many, many different applications.

In fact, he and his team are already working on attaching cancer-killing drugs rather than fluorescent dyes to the COX inhibitors. If this works, it could deliver the drugs directly into cancerous cells, killing them even before they become malignant.