
                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: FRIDAY, March 15, 1991                   TAG: 9103150017
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A-2   EDITION: METRO 
SOURCE: Associated Press
DATELINE: WASHINGTON                                LENGTH: Medium

RESEARCHERS IDENTIFY KEY COLON CANCER GENE

Researchers said Thursday they have identified a gene that is a "smoking gun" link to an early stage of colon cancer, advancing the prospect of developing a test to identify people at high risk for one of the major cancer killers.

Kenneth Kinzler of the Johns Hopkins Oncology Center in Baltimore said a team of researchers identified the gene by finding genetic mutations in cells that produce abnormal growth early in colon cancer development.

The gene they found has been called MCC, for "Mutated in Colon Cancer."

"We have several lines of evidence to suggest that [the mutation of the gene] is one abnormal cell growth," Kinzler said. "Other genes, called tumor suppressors, normally prevent the abnormal growth. When mutation causes the tumor suppressors to not work normally, then a natural control on cell growth is removed."

Evidence suggests that it may take one or more oncogenes, plus the mutation of one or more suppressor genes for a tumor to develop. Kinzler said that MCC appears to be a suppressor gene. In addition to its mutation, he said, "We think there are four to six changes that have to occur before it can become a cancer cell."

The Hopkins researchers in earlier studies identified two other suppressor genes, called p53 and DCC, and one oncogene, called RAS, that play a role in colon cancer.

Colon and rectum cancer is diagnosed annually in about 140,000 Americans and is responsible for about 60,000 deaths a year, according to the National Cancer Institute.

Kinzler said the Hopkins group found the MCC gene by searching through hundreds of colon tumor specimens. Finally, he said, they found a gene that was mutated in the cancerous cells of a patient, but not in the normal cells.

Though the research points strongly at MCC, the scientist said that it should be considered only as a "candidate gene" until other studies confirm its role in colon cancer.

Science, which published the study, is the journal of the American Association for the Advancement of Science.

by CNB