Cyclic AMP enhances resolution of allergic pleurisy by promoting inflammatory cell apoptosis via inhibition of PI3K/Akt and NF-κB

Selective and timely induction of apoptosis is an effective means of resolving inflammation. The effects and putative mechanisms by which cyclic AMP (cAMP) modulates leukocyte apoptosis in vivo are still unclear. The present study aims at identifying intracellular pathways underlying the ability of cAMP elevating agents to resolve eosinophilic inflammation in a model of allergic pleurisy in mice. Ovalbumin (OVA) challenge of immunized mice induced eosinophil recruitment that peaked at 24 h and persisted till 48 h. Treatment with the PDE4 inhibitor rolipram, cAMP mimetic db-cAMP or adenylate cyclase activator forskolin, at 24 h after antigen-challenge resulted in profound resolution of eosinophilic inflammation, without a decrease of mononuclear cell numbers. There was a concomitant increase in number of apoptotic cells in the pleural cavity. The effects of rolipram and db-cAMP were inhibited by the PKA inhibitor H89. Inhibition of PI3K/Akt or NF-κB induced resolution of inflammation that was associated with increased apoptosis. OVA-challenge resulted in a time-dependent activation of Akt and NF-κB, which was blocked by treatment with rolipram or PI3K/Akt pathway inhibitors. Thus, cAMP elevating agents resolve established eosinophilic inflammation by inducing leukocyte apoptosis. Mechanistically, the actions of cAMP are dependent on PKA and target a PI3K/Akt-dependent NF-κB survival pathway.     

Neuroprotective effects of sodium orthovanadate after hypoxic-ischemic brain injury in neonatal rats

Sodium orthovanadate (SOV), a competitive inhibitor of protein tyrosine phosphatases, is neuroprotective in adult animals following an ischemic event. The present study evaluated whether SOV might be protective in a rat pup hypoxic-ischemic (HI) model. Seven-day-old rat pups had the right carotid artery permanently ligated followed by 140 min of hypoxia (8% oxygen). SOV 1.15, 2.3, 4.6, 9.2 or 18.4 mg/kg and vehicle were administered by i.p. injection at 5 min after reoxygenation. Brain damage was evaluated by weight loss of the right hemisphere at 22 days after hypoxia and by gross and microscopic morphology. SOV lowered blood glucose at doses of 1.15, 2.3 and 4.6 mg/kg and induced toxic effects at 9.2 mg/kg. The doses of 2.3 and 4.6 mg/kg of SOV significantly reduced brain weight loss (p < 0.05), but treatment with 1.15 or 9.2 mg/kg did not. SOV 4.6 mg/kg also improved the histopathologic score and diminished the HI induced reduction of Akt and ERK-1/2 phosphorylation in the cortex (p < 0.05) and increased the density of BrdU-positive cells in the subventricular zone (p < 0.01). In conclusion, SOV has neuroprotective effects in the neonatal rat HI model partially mediated by activating Akt and ERK-1/2 pathways.     

Focal adhesion kinase: a potential target in cancer therapy

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that plays an important role in signal transduction pathways that are initiated at sites of integrin-mediated cell adhesions and by growth factor receptors. FAK is a key regulator of survival, proliferation, migration and invasion: processes that are all involved in the development and progression of cancer. FAK is also linked to oncogenes at both a biochemical and functional level. Moreover, overexpression and/or increased activity of FAK is common in a wide variety of human cancers, implicating a role for FAK in carcinogenesis. Given the important role of FAK in a large number of processes involved in tumorigenesis, metastasis and survival signalling FAK should be regarded as a potential target in the development of anti-cancer drugs. Therefore, selective inhibitors of FAK need to be developed. Combination of these selective FAK inhibitors with cytotoxic agents could be a very promising anti-cancer therapy.     

Rationale and clinical application of alkylphospholipid analogues in combination with radiotherapy

Concurrent treatment with radiotherapy and chemotherapy has emerged as an effective strategy to improve clinical outcome of cancer. In addition to combining radiation with classical anticancer agents, several new biological response modifiers are under investigation in pre-clinical and clinical studies. Synthetic alkylphospholipids are anticancer agents that in contrast to most anticancer drugs, do not target DNA, but insert in the plasma membrane and subsequently induce a broad range of biological effects, ultimately leading to cell death. Alkylphospholipids kill tumor cells directly by induction of both apoptotic and non-apoptotic cell death, and indirectly by interference with critical signal transduction pathways involved in phospholipid metabolism and survival. Due to their distinct mode of action, these drugs are considered as attractive candidates to combine with radiotherapy. In this review, we will discuss several alkylphospholipids that reached clinical application. These include first-generation alkyl-lysophospholipids edelfosine and ilmofosine, second-generation alkylphosphocholine-prototype miltefosine and more recently developed analogues perifosine and erucylphosphocholine. We focus on mechanisms of action and the rationale to combine these agents with radiotherapy. The preclinical results on molecular targeting underlying this approach will be reviewed, concluded with first clinical data on combined treatment of radiotherapy with perifosine.     

茶多酚对卵巢癌SKOV3细胞自噬水平的影响及相关机制研究

目的研究茶多酚(EGCG)对人卵巢癌SKOV3细胞自噬水平的影响及相关机制。方法用EGCG处理SKOV3细胞,Western blot检测自噬相关蛋白LC3-II及蛋白激酶B(PKB)信号通路相应蛋白表达变化。结果 EGCG处理SKOV3细胞后,自噬相关蛋白LC3-II表达上调,并呈一定的时间浓度依赖性。EGCG处理SKOV3细胞后,AKT的磷酸化水平下调,AKT激活剂胰岛素样生长因子1(IGF-1)预处理后,自噬相关蛋白LC3-II高表达被抑制。结论 EGCG通过AKT介导的信号通路诱导SKOV3细胞自噬水平升高。     

IGF信号通路关键蛋白IGF1、IGF1R和AKT在原发性肺腺癌中的表达及意义

目的检测IGF信号通路关键蛋白IGF1，IGF1R和AKT在原发性肺腺癌中的表达，探讨其与临床病理学特征和生存时间的关系。方法采用免疫组化方法和免疫印迹技术检测IGF1，IGF1R和AKT在31例原发性肺腺癌及12例良性肺病变组织中的表达。结果IGF1、IGF1R和AKT在肺腺癌中的表达率分别为41．9％（13／31）、67．7％（21／31）和51．6％（16／31），显著高于良性肺组织（P值分别为0．0252、0．0016和0．0071）。IGF1和IGF1R及IGF1和AKT在肺腺癌中表达呈显著相关（P值分别为0．0344和0．0179）。晚期肺癌（Ⅲ＋Ⅳ）IGF1和IGF1R表达显著高于早期（Ⅰ＋Ⅱ）（P值分别为0．0109和0．0303）。IGF1、IGF1R和AKT在伴有淋巴结转移肺癌中的表达显著高于无淋巴结转移肺癌（P值分别为0．0468、0．0490和0．0443）。低分化肺癌中IGF1和IGF1R表达显著高于中或高分化肺癌（P值分别为0．0484和0．0291）。IGF1和IGF1R阳性患者的生存时间显著短于阴性者（IGF1：10比14个月，P=0．0103；IGF1R：13比26个月，P=0．0056）。IGF1和IGF1R是肺腺癌预后的影响因素，AKT无预后意义。结论IGF信号通路关键蛋白IGF1、IGF1R和AKT表达在肺腺癌的发生和发展中可能起重要作用，进一步的研究有望展示其在肺癌预后和治疗方面的意义。     

自噬基因Beclin 1在SKOV3细胞中的表达及其调控相关信号传导途径的研究

目的探讨自噬基因Beclin 1在人卵巢癌SKOV3细胞中过表达后自噬相关信号调控通路PI3K/PKB途径中ClassⅠPI3K（p110α）、p-PKB和ClassⅢPI3K（hvps34）的表达变化以及对肿瘤细胞的自噬活性的影响.方法将自噬基因Beclin 1的真核表达载体pcDNA3.1/Beclin1转染SKOV3细胞;分别用荧光定量RT-PCR和Western blot在mRNA和蛋白水平检测用流式细胞仪检测Beclin1、p110α、hvps34和p-PKB的表达;在电镜和荧光显微镜下观察自噬现象,用流式细胞仪检肿瘤细胞自噬情况.结果 pcDNA3.1/Beclin1转染后SKOV3细胞Beclin1表达在mRNA和蛋白质水平明显高于转染空质粒pcDNA3.1和未转染细胞;PcDNA3.1/Beclin1转染后hvps34表达上调,而p110α、p-PKB的表达下调.PcDNA3.1/Beclin1转染SKOV3细胞后在在电镜下可见大量自噬囊泡形成.在荧光显微镜下见pcDNA3.1/Beclin1转染后SKOV3细胞中MDC阳性细胞明显增加.流式细胞仪检测pcDNA3.1/Beclin1转染后SKOV3细胞MDC平均荧光强度高于pcDNA3.1转染组和未转染组.Beclin 1在SKOV3中的过表达后抑制肿瘤细胞在体外的生长,抑制率为58.68%.结论自噬基因Beclin1在人卵巢癌细胞SKOV3中过表达可使ClassⅢPI3K（hvps34）表达上调,ClassⅠPI3K（p110α）及其下游的p-PKB表达下调,诱导肿瘤细胞自噬活性增加,抑制SKOV3在体外的增殖.     

Human adenosine A(3) receptor leads to intracellular Ca(2+) mobilization but is insufficient to activate the signaling pathway via phosphoinositide 3-kinase gamma in mice

Selective antagonists for the adenosine A(3) receptor (A3AR), a member of the G protein-coupled receptors, have been indicated as potential drugs for anti-asthma or anti-inflammation. However, potent antagonists for the rodent A3AR have not been identified. To evaluate the pharmacological effects of human A3AR antagonists in mice, we here generated A3AR-humanized mice, in which the mouse A3AR gene was replaced by its human counterpart. The expression levels of human A3AR in the A3AR-humanized mice were equivalent to those of mouse A3AR in wild-type mice. Elevation of the intracellular Ca(2+) concentration induced by an A3AR agonist was observed in bone marrow-derived mast cells from the A3AR-humanized mice and this Ca(2+) mobilization was completely antagonized by a human A3AR antagonist. However, antigen-dependent degranulation was not potentiated by the A3AR agonist in the mast cells from A3AR-humanized mice. The agonist-stimulated human A3AR did not lead to the phosphorylation of either extracellular signal-regulated kinase 1/2 or protein kinase B in A3AR-humanized mice. The rate of human A3AR internalization in the mast cells was also markedly decreased compared with that of mouse A3AR in the mast cells. These results demonstrate that the human A3AR is insufficient to activate phosphoinositide 3-kinase gamma-dependent signaling pathways in mice, probably due to the uncoupling of member(s) of the G proteins, which are capable of activating phosphoinositide 3-kinase gamma, to the human A3AR, despite the mouse G protein(s) responsible for the Ca(2+) elevation are coupled with the human A3AR.