Regulation of growth and tumorigenicity of breast cancer cells by the low molecular weight GTPase Rad and nm23.
Regulation of growth and tumorigenicity of breast cancer cells by the low molecular weight GTPase Rad and nm23.
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发表时间：
2001-03
期刊：
影响因子：
11.2
通讯作者：
Yu-Hua Tseng;David Vicent;Jianhua Zhu;Y. Niu;A. Adeyinka;J. Moyers;Peter H Watson;C. Kahn;Y-H T
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作者：
Yu-Hua Tseng;David Vicent;Jianhua Zhu;Y. Niu;A. Adeyinka;J. Moyers;Peter H Watson;C. Kahn;Y-H T
Rad是一个新的Ras相关GTP酶家族的原型成员，该家族通常在心脏、骨骼肌和肺中表达，并且已显示出与nm 23转移抑制因子具有双向相互作用的新形式。在本研究中，我们研究了Rad在正常和肿瘤性乳腺组织中的表达，通过Western blot和免疫组化以及改变Rad在乳腺癌细胞系中表达的功能效应。我们发现，尽管Rad在正常乳腺组织中频繁表达（23/30 Rad+ve），但在邻近的浸润性癌中通常表达缺失（8/30 Rad+ve; P < 0.0001）。然而，在小部分肿瘤中Rad表达持续存在的情况下，其与较高级别、较大尺寸和广泛腋窝淋巴结受累相关（n = 48;分别为P = 0.035、P = 0.016、P = 0.022）。此外，Rad还在具有高致瘤性和转移潜能的乳腺癌细胞系（MDA-MB 231）中高度表达。为了进一步研究Rad在乳腺癌中的作用，我们稳定转染了Rad-ve乳腺癌细胞系（MDA-MB 435）。体外软琼脂集落形成率显著增加（P < 0.05），裸鼠移植瘤生长率显著增加（P < 0.05）。此外，nm 23与野生型拉德的共表达抑制了拉德对这些细胞在培养中的生长的影响，并显着抑制体内肿瘤的生长。用突变的Rad cDNA进行的其他转染研究显示，Rad的生长促进作用似乎是通过其NH 2-和COOH-末端区域介导的，而不是其GT3结构域，并且可能涉及加速细胞周期转换。这些结果表明，Rad可能作为一个致癌蛋白在乳腺组织中，并证明了一个潜在的机制，Rad和nm 23之间的相互作用可能会调节乳腺癌的生长和致瘤性。
Rad is the prototypic member of a family of novel Ras-related GTPases that is normally expressed in heart, skeletal muscle, and lung and that has been shown to exhibit a novel form of bi-directional interaction with the nm23 metastasis suppressor. In the present study, we have investigated the expression of Rad in normal and neoplastic breast tissues by Western blot and immunohistochemistry and the functional effect of altered Rad expression in breast cancer cell lines. We found that, although Rad is frequently expressed in normal breast tissue (23/30 Rad+ve), expression is usually lost in adjacent invasive carcinoma (8/30 Rad+ve; P < 0.0001). However, where Rad expression persists in a small proportion of tumors, it is associated with higher grade, larger size, and extensive axillary nodal involvement (n = 48; P = 0.035, P = 0.016, P = 0.022, respectively). Furthermore, Rad is also highly expressed in a breast cancer cell line with high tumorigenic and metastatic potential (MDA-MB231). To further examine the role of Rad in breast cancer, we stably transfected a Rad-ve breast cancer cell line (MDA-MB435). We observed an increase in growth and marked increased colony formation in soft agar in vitro (P < 0.05) and an increase in tumor growth rate in nude mice (P < 0.05). Moreover, coexpression of nm23 with wild-type Rad inhibited the effect of Rad on growth of these cells in culture and markedly inhibited tumor growth in vivo. Additional transfection studies with mutated Rad cDNAs revealed that the growth-promoting effects of Rad appeared to be mediated through its NH2- and COOH-terminal regions, rather than its GTPase domain, and might involve acceleration of cell cycle transition. These findings suggest that Rad may act as an oncogenic protein in breast tissues and demonstrate a potential mechanism by which interaction between Rad and nm23 may regulate growth and tumorigenicity of breast cancer.