Scientists at Johns Hopkins have devised a new technique to fight colorectal cancer by harnessing the ability of tiny molecules to deliver potent barrages of radiation inside cancer cells.
Current treatments bind to the surface of cells, attack from the outside, and may cause unwanted side effects.
Colorectal cancer specialists Dr. John Abraham and Dr. Stephen Meltzer say that the new radiation delivery system has been found to have the potential to specifically target colon cancer cells in laboratory studies with normal and cancer cells.
The researchers say that the delivery system's molecules are so small that the kidneys may easily filter out their left over.
Considering that small molecules generally make better treatment packages, the researchers designed small bits of protein as the foundation for their drugs.
Whereas, antibodies used to deliver radiation or chemicals can be over one thousand amino acids long, the bits of proteins designed by Hopkins scientists are only 10 amino acids long.
Dr. Abraham revealed that his team attached radioactive phosphorous, P32, as a test of how well their peptides worked.
'To our surprise, our first tests showed that cells were ingesting these molecules, thus transferring the radiation inside and killing them by breaking up their DNA and proteins,' he said.
He further revealed that P32 gave off high energy that could penetrate through 5 millimetres of human tissue, a reason behind it being a good candidate to tackle colon cancer. He corroborated this suggestion with the fact that colon cancer cells often form large, thick tumours into which drugs may not penetrate very well.
Dr. Abraham also said that P32-labeled peptides might be helpful in finding small metastases or recurrences of colon tumours, while they are still small enough to treat.
He also revealed that tests with a variety of P32-peptides on 18 normal and cancerous human cell samples showed that the most potent peptide, MA5, could bind to adenocarcinoma cells that make up 95 percent of all colon cancers 150 times more strongly than other cell types. It could be transferred inside cells within two hours, the researcher added.
The study has been reported in online in PLoS One.