The reduced expression of E-cadherin, alpha-catenin and gamma-catenin but not beta-catenin in human lung cancer

Cadherins are Ca2+-dependent cell-cell adhesion molecules, and are involved in the formation and maintenance of the histo-architecture. Using a combin ation of biochemical and immunohistochemical methods, we analyzed the expre ssion of cadherin-catenin complexes in 37 nonsmall cell lung carcinomas. In 19 cases, decreased expression of E-cadherin protein was observed. In 12 o f them, decreased expression of alpha-catenin protein was also observed. Th us, decreased expression of alpha-catenin was apparently preceded by decrea sed expression of E-cadherin. In no cases was decreased expression of beta- catenin observed. In the 12 cases in which mRNA expression was analyzed by Northern blot analysis, decreased expression of mRNAs for E-cadherin and al pha-catenin was observed in 11 and 9 cases, respectively. In cases with red uced E-cadherin and alpha-catenin expression, immunohistochemistry revealed two types of staining pattern for the proteins. In the first type, almost all the cells in a tumor were stained weakly (homogeneous pattern). In the second type, different percentages of cells were stained strongly, the rest being almost negative for the staining (heterogeneous pattern).