Mirk/Dyrk1B maintains the viability of quiescent pancreatic cancer cells by reducing levels of reactive oxygen species.
Mirk/Dyrk1B maintains the viability of quiescent pancreatic cancer cells by reducing levels of reactive oxygen species.
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DOI：
10.1158/0008-5472.can-08-2903
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发表时间：
2009-04-15
期刊：
影响因子：
11.2
通讯作者：
Friedman E
中科院分区：
文献类型：
--
作者：
Deng X;Ewton DZ;Friedman E
在早期的研究中，Mirk/dyrk1B激酶介导胰腺癌细胞的克隆生长。现在显示，当超过三分之一的细胞积聚在静止的G0状态时，SU86.86胰腺癌细胞中的Mirk水平增加了7倍，由Hoechst/Pyronin Y染色定义。多西环素诱导的短发夹RNA使Mirk的G0部分增加到50%左右，表明Mirk在G0中发挥了一定的功能。Mirk通过增加抗氧化基因铁氧化酶、超氧化物歧化酶2 （SOD2）和超氧化物歧化酶3 （SOD3）的转录，降低了SU86.86细胞和Panc1细胞静止培养中的活性氧（ROS）水平。这些基因在胰腺癌细胞中是功能性抗氧化基因，因为在mirk缺失的细胞中异位表达SOD2和氧化铁酶会降低ROS水平。由于ROS水平升高，当Mirk耗尽时，静止的胰腺癌细胞迅速失去活力，集落形成活性降低4倍，染料排除能力降低4倍。结果，n -乙酰半胱氨酸减少ROS导致更多的活细胞。Mirk还破坏了静止细胞中的细胞周期蛋白D1和D3的稳定性。因此，缺乏Mirk的处于静止状态的胰腺癌细胞变得不那么有活力，因为它们受到ROS的破坏，G1细胞周期蛋白水平升高，从而使原始细胞摆脱了静止状态。
The kinase Mirk/dyrk1B mediated the clonogenic growth of pancreatic cancer cells in earlier studies. It is now shown that Mirk levels increased 7-fold in SU86.86 pancreatic cancer cells when over a third of the cells were accumulated in a quiescent G0 state, defined by Hoechst/Pyronin Y staining. Depletion of Mirk by a doxycycline-inducible short hairpin RNA increased the G0 fraction to about 50%, suggesting that Mirk provided some function in G0. Mirk reduced the levels of reactive oxygen species (ROS) in quiescent cultures of SU86.86 cells and of Panc1 cells by increasing transcription of the antioxidant genes ferroxidase, superoxide dismutase 2 (SOD2), and superoxide dismutase 3 (SOD3). These genes were functional antioxidant genes in pancreatic cancer cells because ectopic expression of SOD2 and ferroxidase in Mirk-depleted cells lowered ROS levels. Quiescent pancreatic cancer cells quickly lost viability when depleted of Mirk because of elevated ROS levels, exhibiting up to 4-fold less colony forming activity and 4-fold less capability for dye exclusion. As a result, reduction of ROS by N-acetyl cysteine led to more viable cells. Mirk also destabilizated cyclin D1 and D3 in quiescent cells. Thus quiescent pancreatic cancer cells depleted of Mirk became less viable because they were damaged by ROS, and had increased levels of G1 cyclins to prime cells to escape quiescence.