ABUNDANT EXPRESSION OF THE INTESTINAL PROTEIN VILLIN IN BARRETTS METAPLASIA AND ESOPHAGEAL ADENOCARCINOMAS

Villin is a cytoskeletal protein that is involved in the formation of brush-border microvilli in normal small intestine and colon epithelium . This protein is present in Barrett's metaplasia but is reported not to be expressed in Barrett's adenocarcinoma. In this study, we analyze d villin protein expression in Barrett's metaplasia and in both Barret t's adenocarcinomas and tumors of the gastric cardia. Immunohistochemi cal analysis was used to evaluate the expression and cellular localiza tion of the villin protein in 21 cases of Barrett's metaplasia, 30 cas es of Barrett's adenocarcinoma, 16 cases of gastric cardia adenocarcin oma, and eight cases of adenocarcinoma of the distal esophagus. Southe rn, northern, and western blot analyses were used to evaluate the pote ntial mechanisms for regulation of villin protein expression. Villin p rotein expression was observed in 21 of 21 cases (100%) of intestinal- type Barrett's metaplasia and in 28 of 30 cases (93%) of Barrett's ade nocarcinoma and was thus highly expressed in these tumors. Northern bl ot analysis demonstrated villin mRNA (3.5 and 2.7 kb) in both villin-p ositive Barrett's metaplasia and adenocarcinomas. Western blot analysi s with the antibody used for immunohistochemical analysis confirmed th e presence of a single villin protein band of 95 kDa. Abundant villin expression also was present in both adenocarcinoma of the gastric card ia (13 of 16 cases; 81%) and distal esophageal adenocarcinomas of unkn own origin (six of eight cases; 75%). The intestinal brush border enzy me sucrase isomaltase was found to be present in only 22 of 46 cases ( 48%) of the adenocarcinomas that expressed villin. We concluded that t he protein villin is highly expressed in Barrett's adenocarcinomas and is well maintained in these and other esophageal tumors. Mol. Carcino g. 22:182-189, 1998. (C) 1998 Wiley-Liss, Inc.