Alpha-adrenergic inhibition of proliferation in HepG2 cells stably transfected with the alpha1B-adrenergic receptor through a p42MAPkinase/p21Cip1/WAF1-dependent pathway.
Alpha-adrenergic inhibition of proliferation in HepG2 cells stably transfected with the alpha1B-adrenergic receptor through a p42MAPkinase/p21Cip1/WAF1-dependent pathway.
复制标题
通过 p42MAPkinase/p21Cip1/WAF1 依赖性途径稳定转染 α1B 肾上腺素受体的 HepG2 细胞中，α 肾上腺素能抑制增殖。
DOI：
10.1016/s0014-5793(98)01074-6
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发表时间：
1998
期刊：
影响因子：
3.5
通讯作者：
Kunos,G
中科院分区：
文献类型：
--
作者：
Auer,KL;Spector,MS;Tombes,RM;Seth,P;Fisher,PB;Gao,B;Dent,P;Kunos,G
在原代培养的肝细胞中，α 1badren能受体（α1BAR）的激活促进了DNA的合成，但在增殖事件中，肝细胞中α1BAR的表达迅速下降。不表达α1BAR的HepG2人肝癌细胞稳定转染大鼠α1BAR cDNA （TFG2细胞），研究维持α1BAR表达对肝癌细胞增殖的影响。与模拟转染的HepG2细胞相比，TFG2细胞的生长速度下降，这是由[3H]胸苷结合到DNA中的减少所揭示的。用苯肾上腺素刺激α1BAR可进一步显著降低TFG2细胞的生长，而在模拟转染细胞中未观察到对细胞生长的影响。细胞生长减少与细胞周期G0/ g1和G2/M期细胞百分比增加相关。在TFG2细胞中，苯肾上腺素将p42MAP激酶活性提高1.5 - 2.0倍，持续24小时，并增加细胞周期蛋白依赖性激酶抑制剂蛋白p21Cip1/WAF1的表达。用特异性MEK1抑制剂PD98059处理TFG2细胞，或感染−/−MEK1重组腺病毒，可使苯肾上腺素增加而不是减少[3H]胸腺嘧啶的掺入。此外，PD98059或MEK1−/−对MAP激酶信号的抑制减弱了苯肾上腺素增加p21Cip1/ waf1表达的能力。表达反义p21Cip1/WAF1mRNA的重组腺病毒感染TFG2细胞，阻断了苯肾上腺素增加p21Cip1/ waf1表达和抑制DNA合成的能力，这与p21Cip1/ waf1表达增加在导致生长停滞中的作用一致。反义p21Cip1/ waf1允许苯肾上腺素刺激TFG2细胞的DNA合成，并消除生长停滞。这些结果表明，转化的肝细胞可能会关闭α1BARs的表达，从而阻止生长抑制途径的激活。通过α1BAR激活该抑制途径似乎依赖于p42MAP激酶和p21Cip1/ waf1。
Activation of α1Badrenergic receptors (α1BAR) promotes DNA synthesis in primary cultures of hepatocytes, yet expression of α1BAR in hepatocytes rapidly declines during proliferative events. HepG2 human hepatoma cells, which do not express α1BAR, were stably transfected with a rat α1BAR cDNA (TFG2 cells), in order to study the effects of maintained α1BAR expression on hepatoma cell proliferation. TFG2 cells had a decreased rate of growth compared to mock transfected HepG2 cells as revealed by a decrease in [3H]thymidine incorporation into DNA. Stimulation of α1BAR with phenylephrine caused a further large reduction in TFG2 cell growth, whereas no effect on growth was observed in mock transfected cells. Reduced cell growth correlated with increased percentages of cells found in G0/G1and G2/M phases of the cell cycle. In TFG2 cells, phenylephrine increased p42MAP kinaseactivity by 1.5‐ to 2.0‐fold for up to 24 h and increased expression of the cyclin dependent kinase inhibitor protein p21Cip1/WAF1. Treatment of TFG2 cells with the specific MEK1 inhibitor PD98059, or infection with a −/− MEK1 recombinant adenovirus permitted phenylephrine to increase rather than decrease [3H]thymidine incorporation. In addition, inhibition of MAP kinase signaling by PD98059 or MEK1 −/− blunted the ability of phenylephrine to increase p21Cip1/WAF1expression. In agreement with a role for increased p21Cip1/WAF1expression in causing growth arrest, infection of TFG2 cells with a recombinant adenovirus to express antisense p21Cip1/WAF1mRNA blocked the ability of phenylephrine to increase p21Cip1/WAF1expression and to inhibit DNA synthesis. Antisense p21Cip1/WAF1permitted phenylephrine to stimulate DNA synthesis in TFG2 cells, and abrogated growth arrest. These results suggest that transformed hepatocytes may turn off the expression of α1BARs in order to prevent the activation of a growth inhibitory pathway. Activation of this inhibitory pathway via α1BAR appears to be p42MAP kinaseand p21Cip1/WAF1dependent.