Featured Research

from universities, journals, and other organizations

Researchers Discover New Risk Factor For Colon Cancer

Date:
September 20, 2002
Source:
Howard Hughes Medical Institute
Summary:
A combination of mouse and human studies have revealed that people who are carriers of the rare disease Bloom syndrome are at increased risk for developing colorectal cancer.

A combination of mouse and human studies have revealed that people who are carriers of the rare disease Bloom syndrome are at increased risk for developing colorectal cancer.

In two studies, published in the September 20, 2002, issue of the journal Science, collaborative teams of scientists present evidence that a mutation in one of two copies of the Bloom syndrome gene (BLM) is sufficient to raise the risk of cancer in mice and humans. The results are the first to show that being a carrier of a recessive cancer syndrome gene can raise the risk of cancer, even if that individual does not have the disease itself.

"The findings remind us that knowing your family history of disease is very important," said Howard Hughes Medical Institute investigator Joanna Groden, who led the team that conducted the experiments in mice. "Even cancers that we think of as common and age-related can have a hereditary component."

In the case of Bloom syndrome, people who have two defective copies of the BLM gene are generally of short stature and have a variety of physical defects and a predisposition to developing many types of cancer. Bloom syndrome occurs in all ethnic populations, but it is more common in Jewish people of European descent (Ashkenazi Jews).

The BLM protein plays a role in helping ensure that chromosomes are copied properly during cell division. When the BLM protein is defective or missing, cells are more likely to acquire or keep DNA-copying errors that result in mutation. The chromosomes in cells without BLM also may have trouble getting untangled during cell division, sometimes causing pieces of chromosomes to break off.

Groden and her colleagues at the University of Cincinnati conducted a series of experiments in mice that were engineered to carry a single copy of the mutant Blm gene. These mice, which also had one normal copy of the gene, made about half the normal amount of BLM protein.

"Our hypothesis was that if there is less protein present, cells may be less competent at repairing breaks or carrying out replication," said Groden.

To test their idea, the scientists mated the BLM mice with another type of mouse that is prone to developing intestinal cancer. When they counted the number of intestinal tumors in the offspring, they found that mice carrying one Blm gene mutation developed twice as many tumors as mice without the mutation.

In another experiment, the researchers examined lung cells from the BLM mice that were cultured in the laboratory. After adding a chemical that increases the usually low rate of DNA damage during cell division, they compared DNA damage in normal cells with DNA damage in the BLM mouse cells. The experiments showed that there were twice as many fragments of broken chromosomes, counted as micronuclei, in the BLM mouse cells as there were in normal mouse cells.

"There were subtle increases in the number of micronuclei," said Groden. "This suggests that perhaps there is a reduction in the ability of the helicase to maintain or repair DNA that accompanies its reduction in amount."

The results of the mouse study spurred an investigation of the role of BLM in colon cancer incidence among Ashkenazi Jews, an ethnic group in which one percent of the population carries the gene mutation that causes Bloom syndrome. A collaborative team of investigators from Memorial Sloan-Kettering Cancer Center, the University of Michigan, and the Technion Faculty of Medicine in Haifa, Israel, studied 1,224 Ashkenazi Jews who developed colon cancer and 1,839 normal controls.

They found that carriers of the Bloom disease gene were nearly three times as likely to have developed colon cancer.

"This study shows that genes that are relatively common in the population can change a person's risk for colorectal cancer," said Groden. "This is one step toward understanding a complex disease and identifying the combination of factors that may increase risk."

Groden points out that in a disease like colon cancer, knowing risk factors is especially important because screening is available that can catch the disease early and greatly increase the chances of a cure. According to the American Cancer Society, there will be 148,300 new cases of colon cancer in the United States in 2002, and 56,600 deaths, making colon cancer the third most common cancer for both men and women.

"This is the kind of study that shows the power of using the mouse as a model for human disease," said Groden. "It is always the hope of those of us in the mouse modeling community to study genes that will improve how we treat diagnose and counsel people. If these discoveries encourage even a few people in the Ashkenazi Jewish population to learn their family history and go for early colon cancer screening then that's terrific."


Story Source:

The above story is based on materials provided by Howard Hughes Medical Institute. Note: Materials may be edited for content and length.


Cite This Page:

Howard Hughes Medical Institute. "Researchers Discover New Risk Factor For Colon Cancer." ScienceDaily. ScienceDaily, 20 September 2002. <www.sciencedaily.com/releases/2002/09/020920071937.htm>.
Howard Hughes Medical Institute. (2002, September 20). Researchers Discover New Risk Factor For Colon Cancer. ScienceDaily. Retrieved August 23, 2014 from www.sciencedaily.com/releases/2002/09/020920071937.htm
Howard Hughes Medical Institute. "Researchers Discover New Risk Factor For Colon Cancer." ScienceDaily. www.sciencedaily.com/releases/2002/09/020920071937.htm (accessed August 23, 2014).

Share This




More Health & Medicine News

Saturday, August 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Newsy (Aug. 21, 2014) An experimental drug used to treat Marburg virus in rhesus monkeys could give new insight into a similar treatment for Ebola. Video provided by Newsy
Powered by NewsLook.com
Two US Ebola Patients Leave Hospital Free of the Disease

Two US Ebola Patients Leave Hospital Free of the Disease

AFP (Aug. 21, 2014) Two American missionaries who were sickened with Ebola while working in Liberia and were treated with an experimental drug are doing better and have left the hospital, doctors say on August 21, 2014. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
Cadavers, a Teen, and a Medical School Dream

Cadavers, a Teen, and a Medical School Dream

AP (Aug. 21, 2014) Contains graphic content. He's only 17. But Johntrell Bowles has wanted to be a doctor from a young age, despite the odds against him. He was recently the youngest participant in a cadaver program at the Indiana University NW medical school. (Aug. 21) Video provided by AP
Powered by NewsLook.com
American Ebola Patients Released: What Cured Them?

American Ebola Patients Released: What Cured Them?

Newsy (Aug. 21, 2014) It's unclear whether the American Ebola patients' recoveries can be attributed to an experimental drug or early detection and good medical care. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins