Picky. peptide latches onto the receptors on the wall of a blood vessel of the prostate (above), but does not appear on the skin (bottom).
a rare experience with a man of brain death has added weight to the idea that the blood vessels in different parts of the body are separate. A team of biologists infused 1 billion different peptides in humans to determine which blood vessels, they went to. Their findings suggest the possibility of designing cancer drugs that target specific tissues.
whereas cancers are often localized in specific tissues, drugs to treat the disease are rarely selective. One solution might be to exploit differences in the molecular signatures of blood vessels that feed tumors in various body parts. For example, a drug designed to target peptides - small chains of amino acids - in the walls of tumor feeding vessels in the liver could stifle tumor blood supply without affecting the healthy tissues in the body. But scientists are only beginning to identify home peptides on which the blood vessels in mice, and some fear the results may not translate into humans.
Wadih Arap and Renata Pasqualini, a husband and wife team of biologists cancer MD Anderson Cancer Center in Houston, Texas, learned about a 48-year-old brain-dead man in the unity of ICU of the hospital. The family of the man wanted to donate his organs, but his advanced cancer made it impossible. Instead, the family agreed to let Arap and Pasqualini infuse their entire library of peptides in human body. The study underwent ethical review by several groups before being approved.
Before the man was kidnapped on life support, the researchers took samples of his muscle, skin, bone marrow, prostate, and fat. They then sequenced hundreds of peptides of each tissue type. To double-check that the peptides were injected demanding tissues, they related - key if they are to be useful therapeutically - the team focused on a peptide that has turned into the blood vessels of the prostate. This peptide thus bound to the tissue of the prostate, but not in skin samples. The reverse is true for a peptide found on blood vessels in the skin, they report in the February issue of Nature Medicine .
By setting a specific peptide known to migrate to certain blood vessels in a cancer-killing drugs, you can "get your smart drug to a particular site," said Bruce Zetter, a cancer biologist at the children's hospital Boston. the work is very promising, he says, but it can move slowly until experiments with brain-dead patients gain greater acceptance among clinicians.
Related Sites
house Renata Pasqualini page
home page of Wadih Arap
Background of angiogenesis
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