DELETION OF 1P36 AS A PRIMARY CHROMOSOMAL ABERRATION IN INTESTINAL TUMORIGENESIS

Cytogenetic analysis of short-term cultures from benign intestinal tum ors revealed clonal chromosome aberrations in rive colorectal adenomas , one adenoma of the papilla Vateri, and one hyperplastic polyp of the rectum. One adenoma had numerical aberrations only, but in all other tumors structural rearrangements were found that led to loss of geneti c material from 1p. In three of the cases, the deletion was restricted to the 1p36 band; the rest had lost larger 1p segments. The rearrange ment of chromosome 1 was the sole karyotypic anomaly in three adenomas , all with mild or moderate dysplasia, and in the hyperplastic polyp. Both adenomas that had additional aberrations beyond the lp loss showe d severe dysplasia. We conclude that cytogenetically detectable loss o f genetic information from 1p36 is an early, seemingly primary, premal ignant event in intestinal tumorigenesis. The fact that the adenomas w ith 1p- as the sole change showed only mild or moderate dysplasia and that the del(1p) was found also in the hyperplastic polyp suggests tha t this aberration is more related to the induction of hyperproliferati on than to differentiation disturbances in the intestinal mucosa.