Rudland P S, Davies A T, Warburton M J
J Natl Cancer Inst. 1982 Nov;69(5):1083-93.
Differentiation of the rat mammary stem cell line Rama 25 to alveolar-like cells was monitored both by the increased production of domes (hemispherical blisters) in the cell monolayer and by immunoreactive casein in the tissue culture medium. In addition to the synthetic inducer dimethyl sulfoxide (DMSO), prostaglandin (PG)E1, and to a lesser extent PGE2 and PGF2 alpha (concentration range, 50--500 ng/ml) in the presence of the hormones prolactin (Pr), hydrocortisone (HC), insulin (I), and 17 beta-estradiol (E) also accelerated this step. A combination of PGE1, HC, and I was active in promoting doming even in serum-free medium, whereas PGE1, all four hormones, and serum were required for maximum production of immunoreactive casein. The DNA synthetic rate was concomitantly reduced during this differentiation step. Rama 25 readily formed tumors in young, female nu/nu mice. When Rama 25 cells were treated with PGE1 or DMSO and the four hormones yielding the droplet and doming cultures, subsequent injection of these cultures into nu/nu mice led to a reduced incidence of tumors compared with injections of untreated cultures. Variant cell lines were selected from a subclone of elongated, myoepithelial-like Rama 29 cells that had been derived from Rama 25 and directly from Rama 25 itself. The former were elongated cells and termed "Rama 521," and the latter were cuboidal epithelial cells and termed "Rama 259." Both these variants were resistant to the actions of PGE1 or DMSO and to the mammotropic hormones in accelerating the rate of formation of domes, producing immunoreactive casein, in substantially reducing the DNA synthetic rate, and in reducing the incidence of tumors when injected into nu/nu mice. We have therefore shown that conversion of Rama 24 stem cells to alveolar-like cells in culture is specifically accompanied by a reduction in their neoplastic potential in nu/nu mice.
通过细胞单层中穹顶（半球形水泡）产量的增加以及组织培养基中免疫反应性酪蛋白的产生，监测大鼠乳腺干细胞系Rama 25向肺泡样细胞的分化。除了合成诱导剂二甲基亚砜（DMSO）外，在催乳素（Pr）、氢化可的松（HC）、胰岛素（I）和17β-雌二醇（E）存在的情况下，前列腺素（PG）E1以及程度较轻的PGE2和PGF2α（浓度范围为50 - 500 ng/ml）也加速了这一步骤。PGE1、HC和I的组合即使在无血清培养基中也能促进穹顶形成，而免疫反应性酪蛋白的最大产量则需要PGE1、所有四种激素和血清。在这个分化步骤中，DNA合成速率随之降低。Rama 25在年轻的雌性裸鼠中很容易形成肿瘤。当用PGE1或DMSO以及四种激素处理Rama 25细胞，使其产生液滴和穹顶培养物时，与注射未处理的培养物相比，随后将这些培养物注射到裸鼠中导致肿瘤发生率降低。从细长的、肌上皮样的Rama 29细胞亚克隆中选择变异细胞系，Rama 29细胞源自Rama 25，也直接来自Rama 25本身。前者是细长细胞，称为“Rama 521”，后者是立方形上皮细胞，称为“Rama 259”。这两种变异细胞对PGE1或DMSO以及促乳腺激素的作用均有抗性，在加速穹顶形成速率、产生免疫反应性酪蛋白、大幅降低DNA合成速率以及注射到裸鼠中时降低肿瘤发生率方面均表现出抗性。因此，我们已经表明，在培养中Rama 24干细胞向肺泡样细胞的转化特别伴随着它们在裸鼠中的肿瘤形成潜能的降低。
