Lack of loss of heterozygosity at the c-erbA beta locus in gastrointestinal tumors.
The cellular homologues of the viral oncogene c-erbA encode for the nuclear thyroid hormone receptor c-erbA (TR). The gene for the human TR beta subtype is located on chromosome 3p24, and a loss of heterozygosity around this region has been reported in breast and small cell lung cancers, suggesting that TR beta might act as a tumor suppressor gene. In the present study, we used PCR-based restriction fragment length polymorphisms to examine the 3p24 region of 19 patients with gastrointestinal tumors for loss of heterozygosity (LOH). Interestingly, only 1 of the patients had an LOH at this locus, while 4 patients had a microdeletion of both alleles in the 3p24 region. These results suggest that, in contrast to previous reports on lung and breast cancers, a loss of heterozygosity of the TR locus at 3p24 is a rare event. A critical review of the literature, however, suggests, that some of the earlier studies have used markers whose location is only imprecisely mapped and may hence point to a tumor suppressor gene candidate other than TR beta. However, a selective microdeletion of both alleles was detected in the tumors of 4 of the 19 patients, indicating that this region on chromosome 3p may be genetically unstable in gastrointestinal tumors.
Huber-Gieseke
T
T
Division of Endocrinology, Massachusetts General Hospital, Boston, Mass., USA.
Pernin
A
A
Huber
O
O
Burger
A G
AG
Meier
C A
CA
D000368:Aged; D000369:Aged, 80 and over; D002872:Chromosome Deletion; D002893:Chromosomes, Human, Pair 3; D015342:DNA Probes; D004938:Esophageal Neoplasms / Q000235:genetics*; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000235:genetics*; D016147:Genes, Tumor Suppressor / Q000235:genetics*; D005814:Genes, Viral / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011988:Receptors, Thyroid Hormone / Q000235:genetics*
D015342:DNA Probes; D011988:Receptors, Thyroid Hormone