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 (TbetaR-IIs) is either greatly decreased or absent in many tumors, implying that the loss of TbetaR-II function is one of the mechanisms leading to tumor development. In this report, we examine the expression of the TbetaR-II receptor in a squamous carcinoma cell line that expressed reduced levels of TbetaR-II mRNA. We found an A --> G mutation at position -364 of the 5' untranslated region of the TbetaR-II gene. This mutation results in significantly decreased transcriptional activity by the TbetaR-II gene promoter, suggesting that it is a primary mechanism of loss of TbetaR-II expression in this tumor cell line.