Effects of estradiol on estrogen receptor, progesterone receptor, and tyrosinase in hamster melanoma transplanted into athymic mice.
Effects of estradiol on estrogen receptor, progesterone receptor, and tyrosinase in hamster melanoma transplanted into athymic mice.
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发表时间：
1988-07
期刊：
影响因子：
11.2
通讯作者：
M. H. Hitselberger;R. Schleicher;C. Beattie
中科院分区：
文献类型：
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作者：
M. H. Hitselberger;R. Schleicher;C. Beattie
HM-1是一种恶性仓鼠黑色素瘤细胞系，在急性、亚慢性和慢性注射雌二醇后，移植到雄性和雌性无瘤小鼠体内，其核雌激素结合的特征。核结合是饱和的，高亲和力(10(10)M-1)，易溶于低盐缓冲液。饱和分析显示，超过5.0 nM的[~3H]雌二醇明显与第二类低亲和力(10(9)M-1)、较高容量的胞浆结合。用针对人雌激素受体蛋白的特异性单抗(H_(22)Sp-γ)进行酶联免疫分析，结果与用羟基磷灰石分离结合和游离基的结果非常一致(r=0.93)。HM-1细胞雌激素核受体含量在急性SC后1h最高。注射小剂量(0.1微克)的雌二醇。随着核受体含量的增加，胞浆结合明显迅速减少。亚慢性(3天)和长期(35天)雌激素暴露也可显著增加肿瘤细胞核雌激素受体的含量，且与剂量相关。在未暴露于雌二醇的HM-1异种移植瘤中，细胞液对孕激素的结合率很低(小于或等于2fmoL)或不存在。雌二醇亚慢性和慢性暴露可诱导雄性和雌性裸鼠HM-1异种移植瘤细胞浆中孕激素结合蛋白(S)产生剂量相关的、特异的、高亲和力(10(9)M-1)结合蛋白。相反，在雌激素刺激的动物中，孕激素与核受体的结合没有增加，急性注射孕酮(100微克S.C.)也没有增加。增加可饱和的、高亲和力的(10(9)M-1)核孕激素受体在对照组或雌二醇诱导的裸鼠中的数量。与孕激素结合的诱导相反，当在饱和浓度的酪氨酸下进行检测时，酪氨酸酶活性不会因类似的雌二醇暴露而改变。这些观察表明，HM-1细胞中的雌激素受体可能具有功能，但在哺乳动物中观察到的雌激素长期暴露后的色素变化可能不是通过直接影响黑色素合成的限速酶来调节的。
Nuclear estrogen binding was characterized in HM-1, a malignant hamster melanoma cell line transplanted into male and female athymic mice following acute, subchronic, and chronic injection of estradiol. Nuclear binding was saturable, of high affinity (10(10) M-1) and readily soluble in low salt buffer. Saturation analyses revealed that [3H]estradiol in excess of 5.0 nM apparently bound to a second class of lower affinity (10(9) M-1), higher capacity cytosol sites. Enzyme-linked immunoassay with a specific monoclonal antibody (H222 Sp gamma) directed against the human estrogen receptor protein was in excellent agreement (r = 0.93) with values obtained using hydroxyapatite to separate bound from free ligand. Nuclear estrogen receptor content in HM-1 cells was increased maximally 1 h after acute s.c. injection of a low dose (0.1 microgram) of estradiol. The increase in nuclear receptor content was accompanied by an apparent rapid reduction in cytosol binding. Subchronic (3 days) and chronic exposure (35 days) to estradiol also produced a significant, dose-related increase in tumor nuclear estrogen receptor content. Cytosol binding for progestin was low (less than or equal to 2 fmol) to absent in HM-1 xenografts not exposed to estradiol. Subchronic and chronic exposure to estradiol induced a dose-related, specific, high affinity (10(9) M-1) cytosol binding protein for progestin(s) in HM-1 xenografts carried in male and female athymic mice. In contrast, progestin binding to nuclear receptor was not increased in estrogen-primed animals, nor did acute injection of progesterone (100 micrograms s.c.) increase the amount of saturable, high affinity (10(9) M-1) nuclear progestin receptor in control or estradiol-primed athymic mice. In contrast to the induction of progestin binding, tyrosinase activity was not altered by a similar exposure to estradiol when assayed at a saturating concentration of tyrosine. These observations suggest that the estrogen receptor in HM-1 cells may be functional but that pigmentary changes observed in mammals following chronic exposure to estradiol may not be mediated by a direct effect on the rate limiting enzyme of melanin synthesis.