LACK OF MUTATIONS OF THE ADENOMATOUS POLYPOSIS-COLI GENE IN ESOPHAGEAL AND GASTRIC CARCINOMAS

The adenomatous polyposis coli (APC) gene is the target of the loss of chromosome 5q heterozygosity observed frequently in gastrointestinal tract carcinomas and is inactivated in these carcinomas. We screened 9 4 gastrointestinal tract carcinomas for APC mutations, by polymerase c hain reaction single-strand conformation polymorphism (SSCP) analysis. Mutations were detected in 8 of 21 (38%) colorectal carcinomas in the mutation cluster region of the APC gene whereas no mutation was detec ted in any of 49 oesophageal and 24 gastric carcinomas, even though SS CP analysis was extended to in elude the 5' half of the APC gene exon 15. Direct DNA sequencing revealed that six of eight (75%) mutations i n colorectal carcinomas resulted in truncated gene products. These fin dings confirm the significance of APC gene mutations in colorectal, bu t not oesophageal or gas tric carcinomas. Some other tumour suppressor genes near the APC gene may be the target of the frequent allelic los s of chromosome 5q in oesophageal and gastric carcinomas.