Rahman N A, Huhtaniemi I
Department of Physiology, University of Turku, Finland.
Mol Cell Endocrinol. 1999 Mar 25;149(1-2):9-17. doi: 10.1016/s0303-7207(99)00004-0.
We have produced a transgenic (TG) mouse model expressing the Simian Virus 40 T-antigen (Tag) gene, driven by a 6-kb fragment of the mouse inhibin-alpha subunit promoter (inh-alpha). The mice develop gonadal tumors with 100% penetrance by the age of 5-8 months, of granulosa cell origin in the ovary, and of Leydig cell origin in the testis. In the present study, we characterized the hormonal regulation of proliferation of two immortalized cell lines, BLT-1, originating from a Leydig cell tumor, and NT-1, originating from a granulosa cell tumor. [3H]-thymidine incorporation in both types of cells was stimulated by activin (> or = 10-30 microg/l), while inhibin had no effect. Transforming growth factor (TGF)-beta, at > or = 0.01 microg/l, stimulated proliferation of the granulosa tumor cells, but no effect was found on the Leydig tumor cells. Progesterone inhibited the proliferation of both cell lines, although the granulosa tumor cells were clearly less sensitive than the Leydig cells to this effect ( > or = 3 micromol/l vs. > 10 nmol/l, respectively). hCG had no effect on the Leydig tumor cell DNA synthesis whereas at high concentration (100 microg/l) it stimulated that of the granulosa cells. We also investigated in BLT-1 and NT-1 cells whether the proliferative changes were related to concomitant changes in Tag expression. In BLT-1 cells, this was stimulated by activin, progesterone and hCG, even though the latter substance did not affect cell proliferation. In contrast, TGF-beta inhibited Tag expression. In NT-1 cells, the expression of Tag was stimulated by activin, while hCG had no effect. In contrast, it was reduced by progesterone, inhibin and TGF-beta. In conclusion, our results indicate that the granulosa and Leydig tumor cells, despite similar mechanism of immortalization, respond differently to several mitotic stimuli. The responses in the level of Tag expression in these cells did not always correlate with the changes observed in cell proliferation, indicating the independence of these two phenomena.
我们构建了一种转基因（TG）小鼠模型，该模型表达由小鼠抑制素α亚基启动子（inh-α）的6 kb片段驱动的猿猴病毒40 T抗原（Tag）基因。这些小鼠在5至8月龄时100%发生性腺肿瘤，卵巢中的肿瘤起源于颗粒细胞，睾丸中的肿瘤起源于睾丸间质细胞。在本研究中，我们对两种永生化细胞系（BLT-1，源自睾丸间质细胞瘤；NT-1，源自颗粒细胞瘤）增殖的激素调节进行了表征。两种类型细胞中的[3H] - 胸腺嘧啶核苷掺入均受到激活素（≥10 - 30 μg/l）刺激，而抑制素无作用。转化生长因子（TGF）-β在≥0.01 μg/l时刺激颗粒细胞瘤细胞增殖，但对睾丸间质瘤细胞无作用。孕酮抑制两种细胞系的增殖，尽管颗粒细胞瘤细胞对此作用的敏感性明显低于睾丸间质细胞（分别为≥3 μmol/l对＞10 nmol/l）。人绒毛膜促性腺激素（hCG）对睾丸间质瘤细胞的DNA合成无作用，而在高浓度（100 μg/l）时刺激颗粒细胞的DNA合成。我们还在BLT-1和NT-1细胞中研究了增殖变化是否与Tag表达的相应变化相关。在BLT-1细胞中，激活素、孕酮和hCG刺激Tag表达，尽管后一种物质不影响细胞增殖。相反，TGF-β抑制Tag表达。在NT-1细胞中，激活素刺激Tag表达，而hCG无作用。相反，孕酮、抑制素和TGF-β降低其表达。总之，我们的结果表明，颗粒细胞瘤细胞和睾丸间质瘤细胞尽管永生化机制相似，但对几种有丝分裂刺激的反应不同。这些细胞中Tag表达水平的反应并不总是与细胞增殖中观察到的变化相关，表明这两种现象相互独立。
