The conventional transforming growth factor-beta (TGF-beta) receptor type I is not required for TGF-beta 1 signaling in a human prostate cancer cell line, LNCaP.
The conventional transforming growth factor-beta (TGF-beta) receptor type I is not required for TGF-beta 1 signaling in a human prostate cancer cell line, LNCaP.
复制标题
人前列腺癌细胞系 LNCaP 中的 TGF-β 1 信号传导不需要传统的 I 型转化生长因子 (TGF-β) 受体。
DOI：
10.1006/excr.1998.4034
复制
发表时间：
1998
影响因子：
3.7
通讯作者：
Lee,C
中科院分区：
文献类型：
--
作者：
Kim,IY;Zelner,DJ;Lee,C
LNCaP是一种雄激素应答性人前列腺癌细胞系，其具有ALK-5（常规I型TGF-β受体）的缺陷基因。然而，这些细胞在适当浓度的双氢睾酮（DHT）下对外源性TGF-β1有反应。由于TGF-β信号传导需要由I型和II型受体组成的异聚体复合物，因此在以下浓度的DHT-0、0.1和100 nM下在LNCaP细胞中研究了这些受体的表达。选择这些浓度是因为它们分别代表其中LNCaP细胞对TGF-β1不敏感的零DHT对照、其中这些细胞对外源性TGF-β1敏感的DHT增殖剂量和其中LNCaP表现出TGF-β信号传导迹象但对外源性TGF-β1不敏感的DHT生长停滞剂量。Western blot分析结果显示，在0.1 nM DHT（TGF-β1敏感剂量）下，LNCaP细胞表达的II型受体水平增加。然而，竞争性定量RT-PCR结果表明，DHT没有显着改变II型受体mRNA的水平，表明DHT在转录后水平调节II型受体的水平。相比之下，在本研究中使用的所有浓度的DHT下，通过Western印迹分析或RT-PCR在这些细胞中均未检测到ALK-5。随后，检测了ALK-1、ALK-2和ALK-4在LNCaP细胞中的表达，因为这些蛋白在体外已显示与TGF-β 1结合。竞争性定量RT-PCR和Western blot分析表明，DHT对LNCaP细胞中ALK-1和ALK-2的表达水平无影响。这些观察结果共同表明，ALK-5不是TGF-β1信号传导所必需的，并且在某些系统中可能存在TGF-β1信号转导的替代机制。
LNCaP is an androgen-responsive human prostate cancer cell line that has a defective gene for ALK-5, the conventional TGF-β receptor type I. Yet, these cells respond to exogenous TGF-β1 under appropriate concentrations of dihydrotestosterone (DHT). Because a heteromeric complex composed of type I and type II receptor is required for TGF-β signaling, the expression of these receptors was investigated in LNCaP cells at following concentrations of DHT—0, 0.1, and 100 nM. These concentrations were selected because they represent the zero DHT control in which LNCaP cells are not sensitive to TGF-β1, the proliferative dose of DHT in which these cells are sensitive to exogenous TGF-β1, and the growth-arrest dose of DHT in which LNCaP exhibits signs of TGF-β signaling but are insensitive to exogenous TGF-β1, respectively. Results of Western blot analysis showed that LNCaP cells express an increased level of type II receptor at 0.1 nM DHT, the TGF-β1-sensitive dose. However, results of competitive quantitative RT-PCR demonstrated that DHT did not significantly change the level of type II receptor mRNA, suggesting that DHT modulates the level of type II receptor at the posttranscriptional level. In contrast, ALK-5 was not detected in these cells by either Western blot analysis or RT-PCR at all concentrations of DHT used in this study. Subsequently, the expression of ALK-1, -2, and -4 in LNCaP cells was examined because these proteins have been shown to bind TGF-β1in vitro.ALK-1 and -2 were detected in these cells. Further analysis by competitive quantitative RT-PCR and Western blot demonstrated that DHT did not affect the level of expression of ALK-1 and -2 in LNCaP cells. These observations, taken together, demonstrate that ALK-5 is not required for TGF-β1 signaling and that there may be alternative mechanism(s) for TGF-β1 signal transduction in some systems.