Genetic alterations in the transforming growth factor receptor complex in sporadic endometrial carcinoma.

Cellular responses to the transforming growth factor beta (TGFbeta) ligand, including inhibition of cell proliferation, are mediated by a heteromeric receptor complex composed of TGFbeta types I and II receptors (TbetaR-I and TbetaR-II). Loss of responsiveness to TGFbeta, attributed to inactivation of the TbetaR complex, has been implicated in the development of tumors in a number of human epithelial and lymphoid tissues. To gain a better understanding of TGFbeta signal transduction pathways in endometrial carcinogenesis, we have investigated the role of the TbetaR complex by evaluating the TbetaR-I and TbetaR-II genes for mutations throughout the entire coding region in human sporadic endometrial tumors. Using reverse transcription-PCR, "Cold" single-strand conformation polymorphism analysis, and direct DNA sequencing, it was found that 1 of 39 (2.6%) and 7 of 42 samples (17%) contained code-altering changes in the kinase domain of TbetaR-I and TbetaR-II, respectively. In 7betaR-I, a 3-bp deletion was found resulting in replacement of Arg and Glu at codon 237 and 238 by Lys. With TbetaR-II, mutations were found in the kinase, the extracellular, and the C-terminal domains. No frameshift mutations were detected; however, a silent population polymorphism (AAC-->AAT at codon 389) in TbetaR-II was found in 19 of 42 (44%) tumor samples. These results suggest that alteration in TbetaR-II, but not TbetaR-I, has an important role in the development of endometrial carcinoma.