# Presentation: 650818

## Molecular Imaging of Cancer

## Photinus pyralis

*Photinus pyralis*

- Shown here are pictures of the firefly, known to scientists as *Photinus pyralis*.  Have you ever noticed how bright a signal they create, especially on a dark summer night?  Well molecular biologists also wondered why they glow.  But more importantly, for those who worked on cancer, they wondered if they could harness the intensity of this bright signal to help in their studies.  The answer is yes, and several scientists won Nobel Prize awards in 2008 for a similar technique, describing the use of the gene that causes the jellyfish to glow green, to study normal and abnormal human functions.

## Make firefly DNA

**In the laboratory, we can make firefly DNA.**
- Shown in the picture is Jennifer Jackson, previously  a research technician at the NIH, who went on to earn her Masters Degree and is now a dietician.

## Isolate the glowing part of firefly DNA

**We then isolate the part of the firefly DNA that makes it glow.  **
- Seth Cohen, who joined Dr. Helman’s laboratory between his 3rd and 4th years of medical school.  He is currently completing a surgery resident at the University of California at San Diego.

## Put Glowing Firefly DNA into Cancer Cells

**We then add the glowing firefly gene into a cancer cell line.**
- Sarah Herby, now a fourth year medical student at the University of Nebraska.

## Cells without firefly DNA

- Shown here, is a plate of cells,
- that do not contain firefly DNA.

## Cells without firefly DNA

**Cells with firefly DNA**

- Shown now is a plate of cells,
- that contain firefly DNA.

## Imaging mice with firefly DNA

- After injecting mice with tumor cells that contain firefly DNA, we can image them using the system shown above, to detect a small number of tumor cells.

## Control Mice

- Day 8

- Day 15

- Treated Mice

- Mice were injected into a vein with tumor cells known to spread to the lungs (metastasis) that were modified with firefly DNA.  Mice on the left (Control) were not treated and mice on the right (Treated) received an experimental agent.  All mice were imaged once a week to detect a glowing signal.  Mice lined up horizontally (#1, 2, 3, 4, 11, 12, 13, 14) are different mice.  Mice lined up vertically (days 1, 8 and 15) are the same mice, imaged on different days.  All of the control (not treated) mice showed a signal in the lungs by day 8 that increased in intensity by day 15.  In contrast, none of the mice that were treated with the experimental agent showed a signal in the lungs by day 8 and only one treated mouse had a weak signal by day 15 (mouse #14).

- 1       2        3       4                     11      12     13     14

## Control Mice

- Treated Mice

- At the conclusion of this experiment, all of the mice were euthanized and their lungs were harvested.  Shown on the left are the lungs of two control (non-treated) mice.  The pink areas are normal lung.  The big white patches are tumor nodules.  In contrast, shown on the right is a lung from a mouse treated with the experimental agent.  Notice that this lung is smooth and red and lacks the white tumor nodules.  This was one of many studies that demonstrated that this experimental agent was effective in preventing the spread of a bone cancer to the lungs in mice.