The human TDE gene homologue: localization to 20q13.1-13.3 and variable expression in human tumor cell lines and...

Expression of the mouse testicular tumor differentially expressed (TDE) gene is increased in testicular tumors as well as in testicular tumor cell lines derived from transgenic mice carrying the polyomavirus large-T antigen under the control of the metallothionein-1 promoter. To determine whether the TDE gene has a role in the development of human cancers, we used the mouse TDE cDNA sequence to screen a human placental cDNA library. The human TDE cDNA homologue coded for a protein that was 78% homologous to the mouse TDE amino acid sequence. Like the mouse TDE protein, the human TDE protein had several predicted hydrophobic alpha-helices characteristic of transmembrane proteins. The human TDE gene was expressed in all cell lines and tissues examined. Four mRNA species were observed in placenta, where we identified an alternate splicing pattern and the use of two different polyadenylation sites. Using fluoresence in situ hybridization analysis, we localized the human TDE gene to the q13.1-13.3 region of chromosome 20, a region known to be amplified in several types of human cancers. We then observed, by northern blot analysis, that human TDE expression was increased in three of five lung tumors examined.