Hypoxia-inducible factor-1α inhibition by a pyrrolopyrazine metabolite of oltipraz as a consequence of microRNAs 199a-5p and 20a induction
Hypoxia-inducible factor-1α inhibition by a pyrrolopyrazine metabolite of oltipraz as a consequence of microRNAs 199a-5p and 20a induction
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DOI：
10.1093/carcin/bgr320
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发表时间：
2012-03-01
期刊：
影响因子：
4.7
通讯作者：
Kim, Sang Geon
中科院分区：
文献类型：
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作者：
Kang, Seul Gi;Lee, Woo Hyung;Kim, Sang Geon
Oltipraz是一种癌症化学预防剂，具有抗肿瘤和抗血管生成的作用。在动物模型和临床研究中，相当数量的oltipraz被代谢为pyrolopyrazines，包括M2, 7-甲基-6,8-双（甲基硫）pyrrolo[1,2-a]pyrazine；M3, 7-甲基-8-（甲基亚砜基）-6-（甲基硫代）吡咯[1,2-a]吡嗪和M4, 7-甲基-6,8-双（甲基亚砜基）吡咯[1,2-a]吡嗪。鉴于缺氧诱导因子-1 (hypoxia-inducible factor-1, HIF-1) α在肿瘤生长和血管生成中的作用，本研究探讨了oltipraz的pyrolopyrazine代谢物是否抑制HIF-1 α的诱导，如果抑制，其分子基础是什么。M2处理可以抑制HCT116细胞中胰岛素、缺氧、CoCl2和过氧化氢等多种刺激对HIF-1 α的诱导，而M3或M4则没有作用。M2一致地阻止HIF-1 α靶基因的诱导。此外，它还能抑制癌细胞的侵袭和迁移。M2没有引起HIF-1 α转录物表达的变化，但增加了microRNAs （miRNAs）的前体形式199a-5p和20a的表达水平，但没有增加初级形式的表达水平，表明M2促进了miRNAs的成熟过程。使用模拟物的实验结果表明，mirna水平的增加有助于抑制HIF-1 α。与此一致的是，M2处理抑制了HIF-1 α的从头合成，这是由[S-35]-蛋氨酸掺入HIF-1 α减少而其泛素化或降解没有变化所支持的。7-乙基-6,8-双（甲基硫）吡咯[1,2-a]吡嗪是M2的合成类似物，具有类似的抑制作用。综上所述，具有吡洛吡嗪结构的M2及其7-乙基同源物具有阻止HIF-1 α诱导的能力，这可能是通过诱导miR-199a-5p和miR-20a介导的抑制HIF-1 α从头合成的结果。
Oltipraz, a cancer chemopreventive agent, has antitumor and antiangiogenic effects. In animal models and clinical studies, a considerable amount of oltipraz is metabolized to pyrrolopyrazines, including M2, 7-methyl-6,8-bis(methylthio)pyrrolo[1,2-a]pyrazine; M3, 7-methyl-8-(methylsulfinyl)-6-(methylthio)pyrrolo[1,2-a]pyrazine and M4, 7-methyl-6,8-bis(methylsulfinyl)pyrrolo[1,2-a]pyrazine. In view of the role of hypoxia-inducible factor-1 (HIF-1) alpha in tumor growth and angiogenesis, this study investigated whether pyrrolopyrazine metabolites of oltipraz inhibit HIF-1 alpha induction, and if so, what the molecular basis is. M2 treatment inhibited the induction of HIF-1 alpha by a variety of stimuli including insulin, hypoxia, CoCl2 and hydrogen peroxide in HCT116 cells, whereas M3 or M4 failed to do so. Consistently, M2 prevented HIF-1 alpha target gene induction. Moreover, it inhibited cancer cell invasion and migration. M2 caused no change in the expression of HIF-1 alpha transcript but increased the levels of precursor forms of microRNAs (miRNAs) 199a-5p and 20a, but not those of primary forms, indicating facilitation of the maturation process of the miRNAs by M2. Increased levels of the miRNAs contributed to HIF-1 alpha repression, as shown by the results of experiments using mimics. Consistently, M2 treatment inhibited de novo synthesis of HIF-1 alpha, as supported by decreased incorporation of [S-35]-methionine into HIF-1 alpha with no changes in its ubiquitination or degradation. 7-Ethyl-6,8-bis(methylthio)pyrrolo[1,2-a]pyrazine, a synthetic analog of M2, had a similar inhibitory effect. In conclusion, M2 with pyrrolopyrazine structure and its 7-ethyl congenor have the ability to prevent the induction of HIF-1 alpha, which may result from the inhibition of HIF-1 alpha de novo synthesis, as mediated by the induction of miR-199a-5p and miR-20a.