A MUTATION IN THE TRANSFORMING GROWTH-FACTOR-BETA TYPE-II RECEPTOR GENE PROMOTER ASSOCIATED WITH LOSS OF GENE-EXPRESSION

Expression of transforming growth factor beta type II receptors (T bet a R-IIs) is either greatly decreased or absent in many tumors, implyin g that the loss of T beta R-II function is one of the mechanisms leadi ng to tumor development. In this report, we examine the expression of the T beta R-II receptor in a squamous carcinoma cell line that expres sed reduced levels of T beta R-II mRNA, We found an A --> G mutation a t position -364 of the 5' untranslated region of the T beta R-II gene, This mutation results in significantly decreased transcriptional acti vity by the T beta R-II gene promoter, suggesting that it is a primary mechanism of loss of T beta R-II expression in this tumor cell line.