Loss of heterozygosity on the long arm of chromosome 11 in colorectal tumours.
We have examined a series of human colorectal adenomas, carcinomas and cell lines derived from human colorectal cancer for loss of heterozygosity (LOH) on chromosome 11q22-23 by polymerase chain reaction (PCR) amplification of a microsatellite polymorphism of the dopamine D2 receptor (DRD2) locus. LOH was demonstrated in 5/30 (16.7%) adenomas and 23/68 (33.8%) carcinomas. Only 2/20 (10%) cell lines showed homozygosity which could potentially be as a consequence of LOH. This moderate level of loss in the tumour samples was probably not an underestimation as a result of excessive stromal contamination because high rates (68-77%) have been detected in the same samples on chromosomes 17 and 18. In contrast to a previous report, LOH in carcinomas at 11q22-23 occurred at a lower frequency and was not associated with Dukes' stage, degree of differentiation, mucin production or the location of the cancer. However, a significant association was found between LOH on chromosome 11 and chromosome 14. Thus, inactivation of any putative tumour-suppressor gene at 11q22-23 by LOH is not a very common event in the development of colorectal tumours, but may be biologically significant if accompanied by chromosome 14 deletions.
Gustafson
C E
CE
Queensland Institute of Medical Research, Brisbane, Australia.
Young
J
J
Leggett
B
B
Searle
J
J
Chenevix-Trench
G
G
D000236:Adenoma / Q000235:genetics; D000368:Aged; D000483:Alleles; D002880:Chromosomes, Human, Pair 11; D015179:Colorectal Neoplasms / Q000235:genetics*; D005260:Female; D017353:Gene Deletion; D014644:Genetic Variation; D006579:Heterozygote; D006801:Humans; D008297:Male; D009154:Mutation; D016133:Polymerase Chain Reaction; D017448:Receptors, Dopamine D2 / Q000235:genetics; D014407:Tumor Cells, Cultured
D017448:Receptors, Dopamine D2