Hsu S, Huang F, Ossowski L, Friedman E
Laboratory of Gastrointestinal Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
Carcinogenesis. 1995 Sep;16(9):2259-62. doi: 10.1093/carcin/16.9.2259.
nm23H1 has properties of a metastasis suppressor gene. Although its mechanism of action is unknown, nm23 has been implicated in transforming growth factor beta 1 (TGF beta 1) signal transduction. In an earlier study we decreased nm23 mRNA levels 2- to 8-fold by antisense phosphorothiolated oligonucleotides in two HT29 colon carcinoma sublines at different stages in tumor progression with different responses to TGF beta 1: the HD3 subline, which shows TGF beta 1-induced growth arrest and differentiation; and the more tumorigenic U9 subline, whose growth and invasion are stimulated by TGF beta 1. Only TGF beta 1-mediated responses in HD3 cells were inhibited by nm23 antisense oligos, suggesting that nm23 functions in only one TGF beta 1 signaling pathway. In the current report we have extended this study to cell motility. HD3 motility was increased by nm23 phosphorothiolated antisense oligos which decrease nm23 mRNA levels, while HD3 cell motility was conversely decreased by TGF beta 1 which increases nm23 mRNA levels. HD3 motility was not increased by basic FGF, TGF beta 1 or TGF alpha, while the 13-fold higher basal motility of U9 cells was stimulated 3-fold by basic FGF, 4-fold by TGF beta 1 and 5-fold by TGF alpha, but not by scatter factor. Differences in motility and response to motility factors could not be ascribed to differences in either basal levels of proteases or modulation of their levels by TGF beta 1. Both HD3 and U9 cells displayed equal levels of urokinase activity and mRNA, equal expression of the metalloproteinase inhibitor TIMP-1, and no detectable collagenases by zymography. No differential response to TGF beta 1 was seen in any of these assays. Thus limited cell motility and lack of response to motility factors in HD3 colon cancer cells could be correlated with expression of nm23 active in signal transduction.
nm23H1具有转移抑制基因的特性。尽管其作用机制尚不清楚，但nm23已被认为与转化生长因子β1（TGFβ1）信号转导有关。在早期的一项研究中，我们用反义硫代磷酸寡核苷酸使两个处于肿瘤进展不同阶段、对TGFβ1有不同反应的HT29结肠癌细胞亚系中的nm23 mRNA水平降低了2至8倍：HD3亚系，其表现出TGFβ1诱导的生长停滞和分化；以及致瘤性更强的U9亚系，其生长和侵袭受到TGFβ1的刺激。只有HD3细胞中TGFβ1介导的反应被nm23反义寡核苷酸抑制，这表明nm23仅在一条TGFβ1信号通路中发挥作用。在本报告中，我们将这项研究扩展到了细胞运动性方面。降低nm23 mRNA水平的nm23硫代磷酸反义寡核苷酸可增加HD3细胞的运动性，而增加nm23 mRNA水平的TGFβ1则会使HD3细胞的运动性相反地降低。碱性成纤维细胞生长因子（bFGF）、TGFβ1或TGFα不会增加HD3细胞的运动性，而U9细胞比HD3细胞高13倍的基础运动性会被bFGF刺激3倍、被TGFβ1刺激4倍、被TGFα刺激5倍，但不会被分散因子刺激。运动性和对运动因子反应的差异不能归因于蛋白酶基础水平的差异或TGFβ1对其水平的调节差异。HD3和U9细胞都表现出相同水平的尿激酶活性和mRNA、金属蛋白酶抑制剂TIMP-1的相同表达，并且通过酶谱分析未检测到胶原酶。在任何这些检测中都未观察到对TGFβ1的差异反应。因此，HD3结肠癌细胞中有限的细胞运动性和对运动因子缺乏反应可能与nm23在信号转导中的活性表达相关。
