Accumulation of genetic alterations during esophageal carcinogenesis

Using polymerase chain reaction amplification of microsatelliteregions in DNA from 11 epithelial dysplasias of the esophagusand 21 early squamous cell carcinomas, we were able to detectfrequent loss of heterozygosity (LOH) on chromosomes 3p21.3and 9q31 even in low-grade dysplasias. In contrast, we observedfrequent LOHs on chromosomes 9p22 and 17p13 (TP53 locus) onlyin high-grade dysplasias and carcinomas, but not in any low-gradedysplasias. Analysis of LOH at the same four chromosomal regionsIn DNA of five additional minimal carcinomas and accompanyingdysplastic lesions revealed loss of alleles at the loci on 3p21.3and 9q31 throughout various degrees of dysplasia and carcinoma;again, LOHs on 9q22 and 17p13 occurred only in high-grade dysplasiaand carcinoma in situ. Our results indicated that Inactivationof putative tumor suppressor genes on 3p21.3 and 9q31 may beearly genetic events during esophageal carcinogenesis, and thatadditional genetic alterations on 9p22 and 17p13 probably playroles in progression.