Dorsey Waneene C, Tchounwou Paul B, Ford Byron D
Molecular Toxicology Research Laboratory, Grambling State University, Grambling, LA, USA.
Int J Environ Res Public Health. 2006 Mar;3(1):11-22. doi: 10.3390/ijerph2006030002.
Neuregulins are a family of growth factor domain proteins that are structurally related to the epidermal growth factor. Accumulating evidence has shown that neuregulins have cyto- and neuroprotective properties in various cell types. In particular, the neuregulin-1 Beta (NRG1-Beta) isoform is well documented for its antiinflammatory properties in rat brain after acute stroke episodes. Pentachlorophenol (PCP) is an organochlorine compound that has been widely used as a biocide in several industrial, agricultural, and domestic applications. Previous investigations from our laboratory have demonstrated that PCP exerts both cytotoxic and mitogenic effects in human liver carcinoma (HepG2) cells, primary catfish hepatocytes and AML 12 mouse hepatocytes. We have also shown that in HepG2 cells, PCP has the ability to induce stress genes that may play a role in the molecular events leading to toxicity and tumorigenesis. In the present study, we hypothesize that NRG1-Beta will exert its cytoprotective effects in PCP-treated AML 12 mouse hepatocytes by its ability to suppress the toxic effects of PCP. To test this hypothesis, we performed the MTT-cell respiration assay to assess cell viability, and Western-blot analysis to assess stress-related proteins as a consequence of PCP exposure. Data obtained from 48 h-viability studies demonstrated a biphasic response; showing a dose-dependent increase in cell viability within the range of 0 to 3.87 microg/mL, and a gradual decrease within the concentration range of 7.75 to 31.0 microg/mL in concomitant treatments of NRG1-Beta+PCP and PCP. Cell viability percentages indicated that NRG1-Beta+PCPtreated cells were not significantly impaired, while PCP-treated cells were appreciably affected; suggesting that NRG1-Beta has the ability to suppress the toxic effects of PCP. Western Blot analysis demonstrated the potential of PCP to induce oxidative stress and inflammatory response (c-fos), growth arrest and DNA damage (GADD153), proteotoxic effects (HSP70), cell cycle arrest as consequence of DNA damage (p53), mitogenic response (cyclin- D1), and apoptosis (caspase-3). NRG1-Beta exposure attenuated stress-related protein expression in PCP-treated AML 12 mouse hepatocytes. Here we provide clear evidence that NRG1-Beta exerts cytoprotective effects in AML 12 mouse hepatocytes exposed to PCP.
神经调节蛋白是一类生长因子结构域蛋白，在结构上与表皮生长因子相关。越来越多的证据表明，神经调节蛋白在多种细胞类型中具有细胞保护和神经保护特性。特别是，神经调节蛋白-1β（NRG1-β）亚型在大鼠急性中风发作后的大脑中的抗炎特性已有充分记录。五氯苯酚（PCP）是一种有机氯化合物，已广泛用作多种工业、农业和家庭用途的杀生物剂。我们实验室先前的研究表明，PCP在人肝癌（HepG2）细胞、原代鲶鱼肝细胞和AML 12小鼠肝细胞中具有细胞毒性和促有丝分裂作用。我们还表明，在HepG2细胞中，PCP能够诱导可能在导致毒性和肿瘤发生的分子事件中起作用的应激基因。在本研究中，我们假设NRG1-β将通过其抑制PCP毒性作用的能力，在PCP处理的AML 12小鼠肝细胞中发挥细胞保护作用。为了验证这一假设，我们进行了MTT细胞呼吸测定以评估细胞活力，并进行了蛋白质印迹分析以评估PCP暴露后与应激相关的蛋白质。从48小时活力研究中获得的数据显示出双相反应；在NRG1-β+PCP和PCP联合处理中，在0至3.87微克/毫升范围内细胞活力呈剂量依赖性增加，而在7.75至31.0微克/毫升浓度范围内逐渐降低。细胞活力百分比表明，NRG1-β+PCP处理的细胞没有受到明显损害，而PCP处理的细胞受到明显影响；这表明NRG1-β具有抑制PCP毒性作用的能力。蛋白质印迹分析表明，PCP具有诱导氧化应激和炎症反应（c-fos）、生长停滞和DNA损伤（GADD153）、蛋白毒性作用（HSP70）、DNA损伤导致的细胞周期停滞（p53）、促有丝分裂反应（细胞周期蛋白D1）和凋亡（半胱天冬酶-3）的潜力。NRG1-β暴露减弱了PCP处理的AML 12小鼠肝细胞中与应激相关的蛋白质表达。在这里，我们提供了明确的证据，表明NRG1-β在暴露于PCP的AML 12小鼠肝细胞中发挥细胞保护作用。
