[Separation and characterization of estrogen independent endometrial cancer cell line originated from Ishikawa...

An estrogen independent sub-clone of human endometrial carcinoma Ishikawa was established by culturing the mother cells in the absence of estrogen over a year. The daughter cells (designated as EIIL) possessed truncated estrogen receptors of an apparent size of 43Kd as well as normal 65Kd receptors and had lost sensitivity to estrogen or tamoxifen but remained sensitive to ICI 164,384. Analysis of the expression of the estrogen responsive element binding protein showed the presence of variant proteins which can recognize ERE. These observations indicate that long time estrogen deprivation may alter the expression of ER and this, in turn, alters cell response to estrogen as well as antiestrogens.