The proto‐oncogene/translation factor eIF4E: A survey of its expression in breast carcinomas

The eukaryotic translation initiation factor elF‐4E binds to the cap structure of mRNAs as one component of the elF‐4 translation initiation complex, which mediates the recruitment of mRNA to the ribosomes. Overexpression of elF‐4E can result in oncogenic transformation and uncontrolled growth of mammalian cells, presumably by facilitating the expression of growth‐control gene products which are normally translationally repressed. Whereas the mechanism of elF‐4E‐mediated transformation is being actively pursued, clinical investigations into the expression of elF‐4E in prevalent human cancers are lacking. We have recently initiated a screen of breast carcinomas by probing with elF‐4E antiserum. Using Western blots, we have analyzed the level of elF‐4E in 38 carcinomas, 7 normal samples and 3 fibroadenomas. We found that elF‐4E was elevated 3‐ to 10‐fold in virtually all the carcinomas we analyzed, but not in fibroadenomas. This analysis was also confirmed by immunohistological staining in situ, showing that overexpression of elF‐4E can be readily identified at the single‐cell level. Our results suggest that an elevation of elF‐4E may be an essential component in the development of breast cancer. © 1995 Wiley‐Liss, Inc.