Proteins may act as flags for cancer drugs

PROTEINS found on the outside of cancer cells could be targeted by a drug “guidance system” which seeks out and destroys the disease, scientists said yesterday.

Researchers from the University of Texas said the stress response proteins could be used to target drug treatments where they would have the most effect.

Their research showed how protein tags unique to cancer could be found, allowing the drug delivery system to be “tweaked” to zero in on the tags and destroy the cells.

The study, published in the journal Cancer Cell, showed that this strategy had already worked on breast and prostate cancer cell lines in animal trials and lab tests using patient samples. The researchers said they planned to test the method on human tumours.

Researcher Renata Pasqualini, a professor of medicine and cancer biology, said: “It’s been very effective so far and we think targeting this protein might also work in other tumour types”.

The latest findings follow work by Prof Pasqualini and Prof Wadih Arap, who together pioneered the “zip code” approach to designing drugs.

This involves finding proteins that are specific to different tissue sites in the body - or “addresses” - which can be used as targets for drugs.

In other research last year, the scientists found that a protein in prostate cancer cells appeared to be linked to poor prognosis and advanced disease.

This protein - identified as glucose-regulated protein-78 (GRP78) - is part of a group of stress response proteins that appear when a cell is in trouble.

The researchers said that stress could be due to problems such as chemotherapy, radiation damage or lower oxygen levels which occur when cancer developed.

“These stress proteins do many things that give cells a better fighting chance to survive such as chaperoning misfolded proteins that arise under stress for destruction as needed,” Prof Arap said.

The latest study showing that these proteins could be found on the outside of cancer cells was “a major finding because it means that the protein could be accessible to a drug that is designed to stick onto it”, Prof Arap said.