Epithelial Stromal Interaction 1, Breast (EPSTI1)

By differential display, Nielsen et al. (2002) identified EPSTI1 as a transcript that is induced by coculture of breast tumor cells and fibroblasts, and they generated the full-length cDNA by 5-prime RACE of normal breast or placenta RNA. The deduced 307-amino acid protein has a calculated molecular mass of about 35 kD. It contains no N-terminal signal sequence and no transmembrane domains; however, there are 3 coiled-coil regions. Northern blot analysis revealed a transcript size of 1.5 kb. Real-time PCR revealed highest expression in placenta; strong expression in small intestine, spleen, salivary gland, and testes; and low levels of expression in normal breast and several other tissues. The expression of EPSTI1 was upregulated up to 72 times (range 5.6-72.1) in all 14 breast carcinomas tested.