Molecular basis for the antiproliferative effect of agmatine in tumor cells of colonic, hepatic, and neuronal origin
Molecular basis for the antiproliferative effect of agmatine in tumor cells of colonic, hepatic, and neuronal origin
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DOI：
10.1124/mol.106.028449
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发表时间：
2007-01-01
影响因子：
3.6
通讯作者：
Molderings, G. J.
中科院分区：
文献类型：
--
作者：
Wolf, C.;Bruess, M.;Molderings, G. J.
本研究的目的是挑战胍丁胺抑制肿瘤细胞增殖的潜在作用机制。胍丁胺抑制人肝癌细胞HepG2、人腺癌细胞HT29、大鼠肝癌细胞McRH7777和大鼠嗜铬细胞瘤细胞PC-12的增殖。 HepG2 细胞增殖的抑制与鸟氨酸脱羧酶 (ODC) 蛋白表达的消除和编码 ODC 的 mRNA 含量加倍有关。在 HepG2 细胞中，通过 RNA 干扰沉默 ODC-antizyme-1，但不沉默抗酶抑制剂，导致胍丁胺的抗增殖作用增强。因此，胍丁胺引起的细胞内多胺含量的明显降低是由于合成蛋白ODC的翻译减少所致，但本质上并不是由ODC抗酶的诱导或抗酶抑制剂的阻断介导的。在相互作用实验中，1 mM L-精氨酸、1 mM D-精氨酸、1 mM 瓜氨酸、100 μM N-omega-硝基-L-精氨酸甲酯、1 和 10 μM 硝普钠以及 1 μM N-1-鸟苷酸-1,7-二氨基庚烷未能改变胍丁胺的抗增殖作用。因此，胍丁胺在 HT29 和 HepG2 细胞中的抗增殖作用既不是由于与 NO 合酶、eIF5A 的兴奋性相互作用，也不是由于胍丁胺诱导的细胞内 L-精氨酸可用性减少。 L-精氨酸和瓜氨酸本身抑制肿瘤细胞增殖，但 D-精氨酸则不然。通过 RNA 干扰沉默精氨酸脱羧酶 (ADC) 表达后，它们的抑制作用被消除，表明 ADC 转化为胍丁胺。最后，在所研究的四种细胞系中，胍丁胺诱导的细胞增殖抑制与细胞内 caspase-3 活性的增加同时发生，表明细胞凋亡得到促进。
The aim of the present study was to challenge potential mechanisms of action underlying the inhibition of tumor cell proliferation by agmatine. Agmatine inhibited proliferation of the human hepatoma cells HepG2, the human adenocarcinoma cells HT29, the rat hepatoma cells McRH7777, and the rat pheochromocytoma cells PC-12. Inhibition of proliferation of HepG2 cells was associated with an abolition of expression of ornithine decarboxylase (ODC) protein and a doubling of mRNA content encoding ODC. In HepG2 cells, silencing of ODC-antizyme-1, but not of antizyme inhibitor, by RNA interference resulted in an increase of agmatine's antiproliferative effect. Thus, the distinct decrease in intracellular polyamine content by agmatine was due to a reduced translation of the synthesizing protein ODC but was not essentially mediated by induction of ODC-antizyme or blockade of antizyme inhibitor. In interaction experiments 1 mM L-arginine, 1 mM D-arginine, 1 mM citrulline, 100 mu M N-omega-nitro-L-arginine methyl ester, 1 and 10 mu M sodium nitroprusside, and 1 mu M N-1-guanyl-1,7-diaminoheptane failed to alter agmatine's antiproliferative effect. Hence, the antiproliferative effect of agmatine in HT29 and HepG2 cells is due to an interaction with neither the NO synthases, the hypusination of eIF5A, nor an agmatine-induced reduction in availability of intracellular L-arginine. L-Arginine and citrulline, but not D-arginine, inhibited tumor cell proliferation by themselves. Their inhibitory effect was abolished after silencing of arginine decarboxylase (ADC) expression by RNA interference indicating the conversion to agmatine by ADC. Finally, in the four cell lines under study, agmatine-induced inhibition of cell proliferation was paralleled by an increase in intracellular caspase-3 activity, indicating a promotion of apoptosis.