Reduction to homozygosity involving p53 in esophageal cancers demonstrated by the polymerase chain reaction.

Abstract

Loss of heterozygosity affecting chromosome 17p has been detected at high frequencies in a variety of human tumors, including cancers ofthe colon, breast, lung, and brain. One presumed target of these losses is p53, a tumor suppressor gene located on 17p. To our knowledge, loss of heterozygosityhas not yet been reported at any locus, including p53, in human esophageal cancer. Moreover, current methods of detecting loss of heterozygosity depend on the availability of large amounts of high molecular weight DNA, making the study of small biopsy specimens or paraffin-embedded tissues problematic. We examined 52 primary human esophageal neoplasms for loss of heterozygosity affecting the p53 gene by using the polymerase chain reaction. Loss of one allele was detected in 52% of informative cases and was more common in squamous carcinomas than in adenocarcinomas. Southern blot analysis was used to confirm polymerase chain reaction-derived data.The identification of allelic loss in approximately half of the tumors analyzed supports the hypothesis that inactivation of p53 is involved in the pathogenesis of esophageal cancer.Esophageal carcinoma is a major cancer worldwide, ranked among the leading causes of cancer death (1). There are two main forms of this disease, squamous cell carcinoma and adenocarcinoma. Squamous esophageal cancer is associated with ethanol and tobacco consumption (1), whereas primary esophageal adenocarcinoma usually accompanies Barrett esophagus (2). Barrett esophagus denotes replacement of the normal squamous esophageal lining by metaplastic columnar mucosa in response to chronic gastroesophageal reflux (3). Patients with this condition are at increased risk of developing esophageal adenocarcinoma (4, 5). Despite the clinical importance of esophageal cancer, its molecular basis is not well understood. Recent studies have addressed the role of ras family protooncogene activation in this disease, but ras mutations were found rarely or not at all (6-9). Amplification of several protooncogenes has also been reported (6, 10-13).Loss of heterozygosity (LOH) occurring frequently at a specific locus is widely assumed to imply the existence of a tumor suppressor gene at or near that locus. The p53 gene encodes an evolutionarily conserved 53-kDa cellular protein implicated in the control of cell proliferation and tumor formation/progression (14)(15)(16)(17)(18)(19)(20)(21)(22). LOH at or near the p53 gene locus, shown to occur frequently in a variety of human tumor types (18,(23)(24)(25)(26)(27)(28)(29), is believed to favor malignancy by removing a normal copy of this tumor suppressor gene (30). The remaining p53 allele is often inactivated by point mutation (18)(19)(20)(31)(32)(33)(34). It is believed that this mutant p53 may exert a dominant negative effect by complexing with wild-type product (35,36). A recent study suggests involvement of the p53 gene by point mutation in esophageal cancers (34). LOH at any locus, including 17p, has not to our knowledge been reported in esophageal cancer.Curren...

The antiapoptotic decoy receptor TRID/TRAIL-R3 is a p53-regulated DNA damage-inducible gene that is overexpressed in primary tumors of the gastrointestinal tract

“…(c) Representative Southern blots showing TRID gene structure in esophageal tumors and their matching normal tissues. DNA extraction and Southern blot hybridization were performed as previously described (Meltzer et al, 1991). In brief, genomic DNA was digested to completion with EcoRI restriction enzyme and electrophoresed onto a 0.8% agarose gel and transferred to a supported Nylon membrane (Schleicher and Schuell, Keene, NH, USA).…”

Metallothionein expression correlates with metastatic and proliferative potential in squamous cell carcinoma of the oesophagus

“…Recently, genetic mechanisms underlying metastasis and pathogenesis of oesophageal SCC have been explored in several studies: int-2/hst-1 co-amplification correlated with high incidence of metastasis in distant organs (Kitagawa et al, 1991), loss of heterozygosity of the DCC gene associated with the degree of lymph node metastasis (Miyake et al, 1994), and mutation of the p53 gene in the pathogenesis (Hollstein et al, 1990;Meltzer et al, 1991) of SCC. However, there are only a limited number of reports on the prognostic indicators for invasion and metastasis of oesophageal SCC.…”

Molecular Alterations of Barrett's Esophagus on Microdissected Endoscopic Biopsies

“…Allelic losses at multiple chromosomal loci corresponding to diverse tumor suppressor genes have been demonstrated in esophageal adenocarcinoma (Barrett et al, 1996;Hammoud et al, 1996;Huang et al, 1992;Meltzer, 1996;Ying et al, 1992). In particular 17p LOH, corresponding to p53 locus, has been implicated in most adenocarcinomas at a rate ranging from 50% to 90% Meltzer et al, 1991;Montesano et al, 1996). Other loci and corresponding tumor suppressor genes such as 5q, the adenomatous polyposis coli (APC) locus, 13q, the retinoblastoma (Rb) locus, and 18q, the deleted in colon cancer (DCC) locus, have been proposed to have a causative role in esophageal adenocarcinogenesis ( Blount et al, 1993;Boynton et al, 1991;Gonzalez et al, 1997;Zhuang et al, 1996).…”