THURSDAY, Feb. 28, 2002 (HealthDayNews) -- A mouse study has turned up a gene that appears to play a pivotal role in the onset of cancer of the colon and rectum.
The gene, designated Muc2, codes for a protein that is the principal ingredient in the layer of mucus that lines the intestinal tract. Intestinal cells of mice that were genetically engineered to lack the Muc2 gene developed a number of abnormalities and eventually became cancerous, says a report in tomorrow's issue of Science.
"We already knew that alterations in the expression of this gene are involved in colorectal cancer," says Anna Velcich, an associate professor of medicine at Albert Einstein College of Medicine and lead author of the report. "The question was whether there is a role for this gene in the early stages of tumor development, as opposed to when you already have cancer."
The answer to that question is "yes," Velcich says, but that answer raises other questions.
"It is important to understand the mechanism by which this happens," she says. "We don't know why absence of the gene affects the intestine in such a way as to cause the mice to develop tumors. Understanding the mechanism will open a window of opportunity for intervening."
One challenge is to fit the Muc2 gene into the emerging picture of the genetics of colorectal cancer, says Leonard Augenlicht, professor of cell biology and medicine at Albert Einstein and another member of the research team.
"We need to understand how it initiates tumors all by itself when the gene is deleted," Augenlicht says. "There are other genes that initiate colon cancer, and we know a lot about what they do. We have no idea about Muc2, whether it represents a distinct pathway or recruits other genes."
For example, mutations in a gene designated APC are known to be involved in colorectal cancer, Augenlicht says. "We have no idea whether Muc2 represents a distinct path or whether it recruits other genes, such as APC."
One focus of study now will be the cells in which Muc2 activity is altered, Augenlicht says. The protein produced by the Muc2 apparently plays a protective role, preventing cells from turning cancerous. It appears there are distinctive groups of cells in which Muc2 stops providing that protection, and "it is possible that this will define those areas that are more probable to progress to colon cancer."
It is much too early to know how the discovery will be used to fight cancer, Velcich and Augenlicht say. What is clear now is that what happens in the laboratory mice almost certainly happens in humans.
"This work suggests that analysis of Muc2 expression may provide clinically useful information for prognosis and prevention of human colorectal cancer," the journal report says.
What To Do
Colorectal cancer kills more Americans than any other form of cancer except that of the lung. However, it is curable if detected early, and the most effective detection technique is colonoscopy.
For detailed information about colorectal cancer, consult the National Cancer Institute or the American Gastroenterological Association.
