On Target
A new generation of drugs offers customized cures
Stopping cancer inside and out
Think of the cell as a fort. Many deadly cancers do their damage when normal cells go bad and take in too much growth factor, causing uncontrollable proliferation. Personalized drugs use different armaments to stop this unwelcome invasion.
THE INVASION
Human growth factor is a protein that's essential to life. However, cells can mutate and produce more than the normal number of receptors that "grab" this protein. The result is a very strong signal traveling into the cell to its nucleus, telling it to divide and divide. That's the signature of cancer.
[Drawing is not available]
[labels]
Growth factor
Receptor
Signaling molecules
Growing tumor
Nucleus
PERIMETER DEFENSE
The drug Herceptin aims to stop this invading protein by establishing a molecular moat outside a cell's walls, blocking a particular growth factor receptor. With the drug blocking the receptor, the growth factor can't attach. Therefore, it can't send its "grow and divide" signal into the cell, and the cell remains stable.
[Drawing is not available]
[labels]
Growth factor
Receptor
Signaling molecules
Herceptin
Nucleus
INTERIOR DEFENSE
The pill Iressa, by contrast, goes deeper. It homes in on the receptor but dives beyond it, inside the cell wall. Here it lies in wait, blocking messenger molecules within the cell that ordinarily would carry the growth command to the cell nucleus. Again, the goal is to stabilize the cell and keep it from growing out of control.
[Drawing is not available]
[labels]
Growth factor
Receptor
Iressa
Signaling molecules
Nucleus
Sources: Genentech, AstraZeneca; Rod Little
advertisement
