The major project of the laboratory is to determine the identity, nature, and cause of genetic rearrangements in esophageal adenocarcinoma and its premalignant condition known as Barrett's esophagus. Even though this cancer is moderately common (about 5,000 cases and deaths a year), there is relatively little known about its molecular biology, and there are no cell lines of it available. Mutations involving p53, the adenomatous polyposis coli gene, and the retinoblastoma gene are known to occur in this type of cancer, although the relationship of these mutations to the prognosis of the cancer is not known. In addition, it is known that there are several other gross rearrangements in this type of cancer, but the extent of rearrangements or the genes involved have not been determined. Four clinical protocols to obtain patient material have been approved at the Cooperative Human Tissue Network (CHTN), NIH, the National Naval Medical Center, and Georgetown University. Through the CHTN, about two dozen snap-frozen surgical specimens have been obtained, most accompanied by normal or Barrett's esophagus as well as malignant tissue. Two fresh biopsy specimens of Barrett's esophagus and two of esophageal cancer have been used to establish primary cultures, all of which have been maintained for several months. Although the cells have not proliferated to any great extent, they are viable, and should be able to serve as a source of cells for tranfection experiments to establish immortalized cell lines. In addition, lymphoblastoid lines have been established from blood of the same patients that provided the biopsy specimens and this will be the source of high quality DNA necessary to fully use several powerful new molecular biology techniques. In the time that the lab has been accumulating the esophageal patient material, laboratory experiments involving the molecular biology of the similar disease of gastric adenocarcinoma have been proceeding. Fourteen cell lines have each been genotyped at 400 evenly spaced loci. These experiments have located new genetic sites that are commonly amplified or deleted in these tumors, and provide genetic """"""""road maps"""""""" for quiding experiments to confirm and extend observations made in other types of tumors. In addition, representational difference analysis has been applied to one cell line, and clones have been obtained that likely are part of amplified regions of these tumors. RecA protein techniques developed in the lab are particularly well suited for mapping and cloning these large rearranged regions. In the short term, it is hoped that the knowledge from this project will allow predicting which patients with Barrett's esophagus will proceed to adenocarcinoma (currently, about half a million Americans have Barrett's esophagus, but only 10% will proceed to cancer). The long term goal of the project is two- fold. One goal is to find new tumor suppressor genes and oncogenes that shed light on the pathogenesis of this and other adenocarcinomas, which account for about half of all cancer deaths. The second is to determine the genetic breakpoints and the enzymatic machinery that generates them in an effort to understand the genetic instablility that characterizes cancer and its ability to evade natural and pharmacological defenses.
