Gene silencing in colorectal cancer may prove useful
New finding suggests an easy test to see who needs further screening
By Nathan Seppa
A gene that is frequently switched off in colorectal cancer cells seems to help the cancer but may also make it easy to detect, scientists say. Conveniently, the modification that silences the NDRG4 gene can often be spotted in stool samples, providing an inexpensive test, the researchers report in the July 1 Journal of the National Cancer Institute.
What’s more, the molecular change sometimes shows up in growths called polyps, which can be precancerous. If further research shows that the genetic aberration in polyps is also detectable in stool samples, doctors might one day be able to screen vast numbers of people for colorectal cancer risk before resorting to more expensive colonoscopies, says study coauthor Manon van Engeland, a molecular biologist at Maastricht University in the Netherlands.
“Colonoscopy remains the gold standard” for detecting precancerous polyps and colorectal cancer itself, she says. But in developing countries where few people receive any form of screening, she says, “you could use this biomarker to preselect those people needing to undergo a colonoscopy, and that could be very quick and cost-effective.”
While the role of NDRG4 is poorly understood, two other genes in the NDRG family are known tumor suppressors. In some cancers, these genes are bogged down or silenced altogether by a chemical process called promoter methylation. This process adds a methyl molecule to the gene’s promoter region, DNA that switches on the gene as needed. Methylating the promoter can silence the gene and thwart production of the protein it encodes.