MR‐detectable metabolic consequences of mitogen‐activated protein kinase kinase (MEK) inhibition

Metabolic reprogramming is increasingly being viewed as a hallmark of cancer. Accordingly, metabolic readouts can serve as biomarkers of response to therapy. The goal of this study was to investigate some of the MRS‐detectable metabolic consequences of mitogen‐activated protein kinase kinase (MEK) inhibition. We investigated PC3 prostate cancer, MCF‐7 breast cancer and A375 melanoma cells, and determined that, consistent with previous studies, MRS‐detectable levels of phosphocholine decreased significantly in all cell lines (to 63%, 50% and 18% of the control, respectively) following MEK inhibition with U0126. This effect was mediated by a decrease in the expression of choline kinase α, the enzyme that catalyzes the phosphorylation of choline. In contrast, the impact of MEK inhibition on glycolysis was cell line dependent. A375 cells, which express mutant BRAF, demonstrated significant decreases in glucose uptake (to 36% of control) and lactate production (to 42% of control) in line with positron emission tomography data. In contrast, in PC3 and MCF‐7 cells, increases in glucose uptake (to 198% and 192% of control, respectively) and lactate production (to 177% and 212% of control, respectively) were observed, in line with a previous hyperpolarized ¹³C MRS study. This effect is probably mediated by the activation of the phosphoinositide 3‐kinase pathway and AMP‐activated protein kinase. Our findings demonstrate the value of translatable non‐invasive MRS methods for the provision of information on cellular metabolism as an indication of the activation of potential feedback loops following MEK inhibition. Copyright © 2014 John Wiley & Sons, Ltd.     

MEK–ERK signaling in adult newt retinal pigment epithelium cells is strengthened immediately after surgical induction of retinal regeneration

Adult newt retinal pigment epithelium (RPE) cells are mitotically quiescent in the physiological condition, but upon a traumatic injury of the neural retina (NR) they re-enter the cell-cycle and eventually regenerate the missing NR. Here, to understand the mechanism underlying the cell-cycle re-entry of RPE cells following NR injury, we first investigated changes in MEK–ERK signaling activity in RPE cells upon removal of the NR (retinectomy) from the eye of living animals, and found that ERK-mediated signaling activity is elevated quickly (in 30 min) upon retinectomy. In addition, we found, in in vitro analyses, that immediate early activation of MEK–ERK signaling may occur in RPE cells upon NR injury, intensifying the MEK–ERK signaling itself through up-regulation of the expression of constituent molecules in the pathway, and that 1-h blockade of such early MEK–ERK signaling interferes with the cell-cycle re-entry, which occurs 5–10 days later. Together, these results provide us with insight that elevation of MEK–ERK signaling activity upon NR injury may be a key process for mitotically quiescent RPE cells to re-enter the cell-cycle, leading to retinal regeneration.     

MEK5/ERK5在大鼠脊髓损伤修复过程中表达水平动态变化及临床意义

目的 以大鼠为模型观察脊髓损伤修复过程中MEK5/ERK5(mitogen extracellular signal-regulated kinase 5/extracellular signal kinase 5)表达水平变化及临床指导意义.方法 将成年健康雄性大鼠随机分为实验组和假手术组,应用western-blotting蛋白质印迹技术和Real-Time PCR实时荧光定量检测技术分别检测脊髓损伤后1天,3天,7天,14天后MEK5、ERK5两种蛋白及其mRNA表达水平动态变化情况,通过考察P-ERK(phosphorylated extracellular signal kinase 5)表达水平考察ERK5激活情况.结果 RT-PCR显示实验组组MEK5 mRNA和ERK5 mRNA表达水平均随时间呈逐渐增加的动态变化规律,且与假手术组相比表达水平明显增加;Western blotting显示实验组MEK5表达水平随时间先增加后回落,ERK5表达水平随时间逐渐增加,P-ERK表达水平随时间增加.结论 ERK5表达水平与脊髓损伤修复过程呈正相关,ERK5的促组织细胞分裂增殖的功能可能有助于脊髓损伤加速修复.     

Hyperbaric oxygen-stimulated proliferation and growth of osteoblasts may be mediated through the FGF-2/MEK/ERK 1/2/NF-κB and PKC/JNK pathways

We investigated whether the hyperbaric oxygen (O₂) could promote the proliferation of growth-arrested osteoblasts in vitro and the mechanisms involved in this process. Osteoblasts were exposed to different combinations of saturation and pressure of O₂ and evaluated at 3 and 7 days. Control cells were cultured under ambient O₂ and normal pressure [1 atmosphere (ATA)]; high-pressure group cells were treated with high pressure (2.5 ATA) twice daily; high-O₂ group cells were treated with a high concentration O₂ (50% O₂) twice daily; and high pressure plus high-O₂ group cells were treated with high pressure (2.5 ATA) and a high concentration O₂ (50% O₂) twice daily. Hyperbaric O₂ significantly promoted osteoblast proliferation and cell cycle progression after 3 days of treatment. Hyperbaric O₂ treatment stimulated significantly increased mRNA expression of fibroblast growth factor (FGF)-2 as well as protein expression levels of Akt, p70^S6K, phosphorylated ERK, nuclear factor (NF)-κB, protein kinase C (PKC)α, and phosphorylated c-Jun N-terminal kinase (JNK). Our findings indicate that high pressure and high O₂ saturation stimulates growth-arrested osteoblasts to proliferate. These findings suggest that the proliferative effects of hyperbaric O₂ on osteoblasts may contribute to the recruitment of osteoblasts at the fracture site. The FGF-2/MEK/ERK 1/2/Akt/p70^S6K/NF-κB and PKC/JNK pathways may be involved in mediating this process.     

微载体培养MEK和Vero细胞试制甲肝灭活疫苗

目的探索微载体培养细胞大量制备甲肝病毒抗原及其灭活疫苗的可行性。方法使用 Cytodex- 1培养恒河猴胚肾细胞和 Vero细胞制备 HAV ,经过初步纯化、甲醛灭活、吸附佐剂 ,制成甲肝灭活疫苗 ,免疫昆明种小白鼠 ,测定免疫原性。结果 HAV X株和 W株抗原滴度分别为 1∶ 2 5 6、1∶ 12 8,感染滴度 (log TCID5 0 / m l)分别为 8.5 0、8.17,与静止培养获得的滴度相当。小鼠抗 HAV抗体第 45 d达到峰值 ,滴度分别为 1∶ (96 .0± 78.4)、1∶ (12 8.0± 70 .1)。结论实验性甲肝灭活疫苗具有良好的免疫原性 ,应用微载体培养细胞制备甲肝灭活疫苗是可行的。     

Psychotic disorder induced by a combination of sorafenib and BAY86-9766

The Ras-Raf-mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)-ERK cascade is important in the intra-cellular transduction of neurotransmitters, such as dopamine and glutamate. Sorafenib (Nexavar), a multi-kinase inhibitor targeting Raf kinase, vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor, has shown promising results in the treatment of malignancies. BAY86-9766, a novel selective MEK 1/2 inhibitor, is being evaluated in clinical trials as an anticancer drug. We describe herein a hepatocellular carcinoma patient presenting with recurrent psychotic symptoms in the course of the BASIL trial (assessing BAY86-9766 plus sorafenib for the treatment of liver cancer). In this case, VEGFR inhibition caused by sorafenib alone may have contributed to the development of psychosis. A change in ERK activity might also have been involved. However, whether single or combination use of the two drugs is responsible for inducing the psychotic symptoms remains unclear. In summary, the role of the ERK pathway in psychosis is still vague. Further investigation of the ERK activity in patients with psychotic disorders may disclose its role in the pathophysiology of psychosis.     

MEK/ERKs signaling is essential for lithium-induced neurite outgrowth in N2a cells

Lithium, a drug used for the treatment of bipolar disorder, has been shown to affect different aspects of neuronal development such as neuritogenesis, neurogenesis and survival. The underlying mechanism responsible for lithium's influence on neuronal development, however, still remains to be elucidated. In the present study, we demonstrate that lithium increases the phosphorylation of extracellular-signal regulated kinases (ERKs) and protein kinase B (Akt) and promotes neurite outgrowth in mouse N2a neuroblastoma cells (N2a). The inactivation of mitogen-activated protein kinase kinase (MEK)/ERKs signaling with a MEK inhibitor inhibits neurite outgrowth, but it enhances Akt activation in lithium-treated N2a cells. Furthermore, the inactivation of phosphoinositide-3-kinase (PI3K)/Akt signaling with a PI3K inhibitor increases both lithium-induced ERKs activation and lithium-induced neurite outgrowth. Taken together, our study suggests that lithium-induced neurite outgrowth in N2a cells is regulated by cross-talk between the MEK/ERKs and PI3K/Akt pathways and requires the activation of the MEK/ERKs signaling.     

整合药理学方法的心可舒片干预动脉粥样硬化作用网络机制探讨

目的探究心可舒片干预动脉粥样硬化(AS)作用的分子机制,对于心可舒片二次开发和临床应用提供参考。方法用整合药理学平台对心可舒片干预AS的关键靶点和通路进行预测,探究其干预AS的分子机制。结果通过建立心可舒片"中药-成分-靶点-通路"网络进行预测和分析,得到相关有效成分80个,确定了B4GALT4、B4GALT2、PRKCD、GCK、GNB1等关键靶点,明确了内分泌系统、甲状腺激素、神经系统、雌性激素和趋化因子等富集通路与其抗AS作用相关。结论心可舒片通过对PI3K/Akt/eNOS和Raf/MEK/ERK途径的共同调节,保护血管内皮细胞,从而达到干预AS的效果。