In vitro analysis of cultured Barrett's esophagus cells: insights into mechanisms of genomic instability and possible therapeutic strategies

Abstract

Barrett's esophagus is a human premalignant condition in which the normal squamous epithelial lining of the esophagus is replaced by a metaplastic columnar epithelium. Patients with Barrett's esophagus are at increased risk for the subsequent development of esophageal cancer. While some of the genetic and cell cycle abnormalities that occur in progression to cancer in Barren's esophagus have been delineated through the analysis of patient tissue samples, there has been no relevant in vitro or animal model that has been developed in which to investigate the mechanisms contributing to carcinogenesis in this condition. We describe the development of a cell culture protocol that allows the establishment of Barrett's esophagus and normal squamous esophagus epithelial cultures from endoscopic biopsies. Through these methods, we have been able to establish the first long-term Barrett's epithelial cultures that contain the same genetic and cell cycle abnormalities present in vivo , including the inactivation of the p53 and p16 tumor suppressor genes and the elevation of the 4N DNA content fraction. We used four of the Barrett's cell strains to study the contribution of centrosome abnormalities, tetraploidization, and telomerase activation to neoplastic progression in Barrett's esophagus, focusing on the effect that these factors may have on genomic instability. The establishment of Barrett's cell strains provides an in vitro model in which to test promising therapeutics in the treatment or prevention of esophageal cancer. We performed a series of experiments testing the efficacy of chemotherapeutic drugs and a mutant E1B adenovirus in selectively killing Barrett's cells lacking p53 function. The results show the feasibility of using the Barrett's cell strains for in vitro therapeutic screening purposes.