Tsuji Y, Kinoshita Y, Hato F, Lin B
Department of Physiology, Osaka City University Medical School, Abeno-ku, Osaka, Japan.
Cell Mol Biol (Noisy-le-grand). 1997 Mar;43(2):149-56.
Two kinds of thymus epithelial cell lines have been utilized: the TAD3 from lymphocyte-dominant rat thymoma and the IT-45R1 derived from normal rat thymus. In the preconfluent state, the percent increase of DNA synthetic activity of TAD3 cells stimulated by GH or IGF-I was significantly higher than that of IT-45R1 cells. In the confluent state, at the contrary, no any noticeable modification of the activity by GH could be detected and that in both cell lines. However, a treatment of the confluent TAD3 cells with IGF-I caused a significant increase of their DNA synthetic activity, whereas the confluent IT-45R1 cells treated with these molecules did not. It was observed that TAD3 cells in the preconfluent state proliferate markedly after stimulation by GH or IGF-I as compared with IT-45R1 cells and that the former is able to proliferate even in the confluent state, after an exposure of IGF-I, whereas the latter did not. Thymus epithelial cells treated with GH were reported to release more IGF-I molecules what had as a consequence a marked proliferative response of thymic lymphocytes. It is therefore assumed that the very particular nature of TAD3 cells treated with IGF-I, able of proliferating by crossing over the contact inhibition, might have a close relationship in the formation of the lymphocyte-dominant thymoma.
来自淋巴细胞占主导的大鼠胸腺瘤的TAD3和源自正常大鼠胸腺的IT-45R1。在汇合前状态下，生长激素（GH）或胰岛素样生长因子-I（IGF-I）刺激的TAD3细胞的DNA合成活性增加百分比显著高于IT-45R1细胞。相反，在汇合状态下，未检测到GH对两种细胞系的活性有任何明显改变。然而，用IGF-I处理汇合的TAD3细胞会导致其DNA合成活性显著增加，而用这些分子处理汇合的IT-45R1细胞则不会。据观察，与IT-45R1细胞相比，汇合前状态的TAD3细胞在受到GH或IGF-I刺激后增殖明显，并且前者在暴露于IGF-I后即使在汇合状态下也能增殖，而后者则不能。据报道，用GH处理的胸腺上皮细胞会释放更多的IGF-I分子，这导致胸腺淋巴细胞出现明显的增殖反应。因此可以推测，经IGF-I处理的TAD3细胞具有非常特殊的性质，能够通过克服接触抑制进行增殖，这可能与淋巴细胞占主导的胸腺瘤的形成密切相关。
