Hwang Tsong-Long, Wu Chin-Chung, Guh Jih-Hwa, Teng Che-Ming
Graduate Institute of Natural Products, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, ROC.
Biochem Pharmacol. 2003 Jul 1;66(1):149-56. doi: 10.1016/s0006-2952(03)00202-8.
Using cultured rat alveolar NR 8383 macrophages, this study investigated the effect of YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole], a soluble guanylyl cyclase (sGC) activator, on the production of tumor necrosis factor-alpha (TNF alpha). YC-1 enhanced lipopolysaccharide and interferon-gamma (LPS/IFN gamma)-induced TNF alpha formation in a concentration- and time-dependent fashion. YC-1 also caused an increasing effect on the TNF alpha mRNA level, suggesting that the transcriptional process was involved. However, further studies suggested that cyclic GMP did not mediate the potentiation of YC-1 on TNF alpha release, because (a) the sGC inhibitor and the protein kinase G inhibitor failed to block the effect; and (b) the cyclic GMP analogues, on the contrary, concentration-dependently diminished LPS/IFN gamma-induced TNF alpha synthesis. In agreement with this finding, YC-1 produced changes in cell function but no changes in cyclic GMP and cyclic AMP levels or sGC activity. Pretreatment of the cells with cyclooxygenase inhibitors, a p38 mitogen-activated protein kinase inhibitor, a mitogen-activated protein kinase kinase (MEK) inhibitor, and a tyrosine kinase inhibitor did not attenuate the potentiation of TNF alpha release by YC-1. Cycloheximide prevented the YC-1-enhanced TNF alpha formation, implying that new protein synthesis was required. Interestingly, protein kinase C inhibitors enhanced the potentiation of YC-1 to a greater extent. Nevertheless, a protein kinase C activator, phorbol 12-myristate 13-acetate, failed to suppress the potentiation of TNFalpha production by YC-1. In summary, potentiation of TNF alpha release by YC-1 in LPS/IFN gamma-activated alveolar macrophages is an additional mode of action of this compound that is independent of the elevation of cyclic GMP. Thus, caution needs to be used in attributing the YC-1-mediated response to the activation of sGC.
本研究利用培养的大鼠肺泡NR 8383巨噬细胞，探讨可溶性鸟苷酸环化酶（sGC）激活剂YC-1 [3-(5'-羟甲基-2'-呋喃基)-1-苄基吲唑] 对肿瘤坏死因子-α（TNFα）产生的影响。YC-1以浓度和时间依赖性方式增强脂多糖和干扰素-γ（LPS/IFNγ）诱导的TNFα形成。YC-1还对TNFα mRNA水平产生增加作用，提示涉及转录过程。然而，进一步研究表明，环磷酸鸟苷（cGMP）并不介导YC-1对TNFα释放的增强作用，原因如下：（a）sGC抑制剂和蛋白激酶G抑制剂未能阻断该作用；（b）相反，环磷酸鸟苷类似物以浓度依赖性方式减少LPS/IFNγ诱导的TNFα合成。与此发现一致，YC-1引起细胞功能变化，但cGMP、环磷酸腺苷（cAMP）水平或sGC活性无变化。用环氧合酶抑制剂、p38丝裂原活化蛋白激酶抑制剂、丝裂原活化蛋白激酶激酶（MEK）抑制剂和酪氨酸激酶抑制剂对细胞进行预处理，并未减弱YC-1对TNFα释放的增强作用。放线菌酮可阻止YC-1增强的TNFα形成，这意味着需要新的蛋白质合成。有趣的是，蛋白激酶C抑制剂更大程度地增强了YC-1的增强作用。尽管如此，蛋白激酶C激活剂佛波醇12-肉豆蔻酸酯13-乙酸酯未能抑制YC-1对TNFα产生的增强作用。总之，YC-1在LPS/IFNγ激活的肺泡巨噬细胞中增强TNFα释放是该化合物的一种额外作用模式，且独立于cGMP升高。因此，在将YC-1介导的反应归因于sGC激活时需谨慎。
