The APC gene is responsible for familial adenomatous polyposis and is considered to be a tumor suppressor gene associated with development of sporadic colorectal tumors. Here we report the disruption of the APC gene caused by somatic insertion of a long interspersed repetitive element (LINE-1 sequence) into the last exon of the APC gene in a colon cancer. The inserted sequence was composed of a 3′ portion of the LINE-1 consensus sequence and nearly 180 base pairs of polyadenylate tract. Furthermore, since an 8-base pair target site duplication was observed, retrotranscriptional insertion of an active LINE-1 sequence is suspected as the cause of this insertion event. This is the first report of the disruption of a tumor suppressor gene caused by somatic insertion of a mobile genetic element.
↵1 This work was supported in part by a Grant-in-Aid from the Ministry of Education, Culture and Science, Japan, and Grants for the Vehicle Racing Commemorative Foundation, the Clayton Fund, and National Cancer Institute.
↵2 To whom requests for reprints should be addressed.
- Received September 4, 1991.
- Accepted November 13, 1991.
- ©1992 American Association for Cancer Research.