Comparison of estrogen receptors in hormone-dependent and hormone-independent Grunder strain mouse mammary tumors (original) (raw)

Hormone-dependent (HD) Grunder strain mouse mammary carcinomas contain a 65-kDa estrogen receptor (ER) with minor amounts of 50- and 35-kDa components which apparently still contain the intact hormone-binding (COOH-terminal) domain. When the HD tumors lose their hormonal dependence during serial transplantation, the hormone-independent (HI) transplants show an increase in 50- and 35-kDa components relative to 65-kDa ER. In HI transplants of three of five tumor lines studied (TSl 85, 86, and 106), the 65-kDa receptor was entirely replaced by 50- and 35-kDa receptors, whereas in the two other lines (TSl 101 and 104) there usually were about equal amounts of 65- and 50-kDa ERs. No difference was found between ERs of HD and HI tumors in affinity for estradiol, steroid specificity, or immunoreactivity for the monoclonal antibody JS34/32. Estrogen stimulation of HI tumors did not increase the concentration of progesterone receptor in the tumor tissue, indicating that ER in these tumors wa...

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