Expression of aberrant estrogen receptor mRNA in endometrial cancers in comparison with normal endometria

In endometrial cancers, some overexpression of estrogen receptor (ER) mRNA occurred in comparison with the ER mRNA level in normal endometria. DNA binding domains (DBDs) of ER mRNA were detected in 100% (13/13) of the endometrial cancers, and a mutated ER-DBD mRNA was found in 3 of the 13 by S1 nuclease protection analysis. It is suggested that estrogen might lead to disorder in the promotion of estrogen-inducible proteins in these 3 endometrial cancers, which seem to have a point-mutated DBD of the ER and a functional steroid-binding domain, resulting in the dedifferentiation of the original cells, and that the development and growth of cancer cells might, in part, be driven by estrogen.