ESTROGEN-RECEPTOR IN HAMSTER-KIDNEY DURING ESTROGEN-INDUCED RENAL TUMORIGENESIS

Specific binding of [3H]-estradiol to isolated cytosol and to nuclei in tissue slices was determined in hamster kidney before and during estrogen-induced renal tumorigenesis and in the kidney of normal rats, a species which does not develop the tumor. At 10-9M [3H]-estradiol, cytosol from normal hamster kidney bound 6.48 ± 0.3 × 10-15 mol/mg protein, which was significantly less than the 15.8 ± 1.1 × 10-15mol/mg bound by the rat. The apparent dissociation constant for estradiol was not significantly different (0.50 ± 0.08 nM in hamster and 0.66 ± 0.14 nM in rat). Cytosol binding increased after hamsters were implanted with estrogen pellets for 6 months (9.23 ± 0.2 × 10-15 mol/mg) or had developed tumors (13.7 ± 3.5 × 10-15 mol/mg). In tissue slices, the amount of [3H]-estradiol translocated to nuclei was greater in the rat (21.8 ± 0.8 × 10-14mol/mg nuclear protein) than in the normal hamster (3.28 ± 0.96 × 10-14 mol/mg) and was greater in tumor-bearing hamsters (6.70 ± 0.86 × 10-15 mol/mg DNA) than in normal hamsters (3.19 ± 0.63 × 10-15mol/mg DNA). We conclude: (1) the kidney of the tumor prone hamster does not contain an estrogen receptor of excessive quantity or unusual affinity and (2) the estrogen-receptor complex in estrogen-induced tumors can be translocated to cellular nuclei. © 1979.