地塞米松增强L02细胞P-糖蛋白的表达作用机制的初步研究

目的 探讨地塞米松对人正常肝细胞株L02细胞P-糖蛋白(P-gp)表达的影响,以及磷酸肌醇-3激酶(PI3K)/蛋白激酶B(Akt)途径在调控P-gp表达中的作用.方法 采用Western blot检测体外培养L02细胞P-gp与Akt的表达水平,比较经地塞米松、PI3K/Akt酶抑制剂LY294002及两者联合处理24 h前后L02细胞P-gp表达水平的变化及地塞米松处理24 h前后L02细胞Akt表达水平的差异,分析L02细胞P-gp表达与PI3K/Akt表达之间的关系.结果 10 μmol/L地塞米松刺激24 h后L02细胞P-gp及Akt表达水平较刺激前分别显著增加60.8％ (P =0.026 7)和25.0％ (P =0.035 8);L02细胞中P-gp表达水平与Akt表达水平之间呈显著正相关(Pearson系数=0.87,P＜0.01);LY294002(20 μmol/L)处理组L02细胞P-gp表达水平较对照组(未处理组)显著降低33.8％ (P =0.018 4);地塞米松单独处理组和地塞米松与LY294002联合处理组L02细胞P-gp表达水平分别是对照组的(163.5±18.4)％和(130.1±22.0)％,两者间相差显著(P =0.031 3).结论 地塞米松可能通过激活PI3 K/Akt途径诱导L02细胞P-gp增强表达.     

Immunohistochemical Expression of Components of the Akt-mTORC1 Pathway is Associated with Hepatocellular Carcinoma in Patients with Chronic Liver Disease

Activation of the Akt-mTORC1 signaling pathway was evaluated in premalignant and hepatocellular carcinoma (HCC) lesions by assessing the expression of pS6, an Akt effector, and PTEN, an Akt suppressor. Methods: Immunohistochemical staining for pS6 and PTEN was performed on liver tissue from 52 patients with cirrhosis, with and without HCC. Two pathologists independently evaluated pS6 staining on a semiquantitative scale and categorized PTEN staining as present or absent. Results: In the HCC group, pS6 staining was greatest in HCC, followed by dysplasia, and benign cirrhotic tissue (P < 0.001). pS6 staining was greater in cirrhotic tissue from patients with HCC compared to cirrhosis in patients without HCC (P = 0.03). PTEN staining in tumor was absent in 8/33 (24%) cases. Loss of PTEN expression was more common in patients with higher tumor stage, compared to those with stage 1 tumors (P = 0.04). Conclusion: Immunohistochemical evidence of activation of the Akt-mTORC1 pathway is associated with HCC.     

FGF21 protects human umbilical vein endothelial cells against high glucose-induced apoptosis via PI3K/Akt/Fox3a signaling pathway

Aims

Diabetic macroangiopathy is the main cause of morbidity and mortality in patients with diabetes. Endothelial cell injury is a pathological precondition for diabetic macroangiopathy. Fibroblast growth factor 21 (FGF21) is a key metabolic regulator which has recently been suggested to protect cardiac myocytes and vascular cells against oxidative stress-induced injury in vitro and vivo. In this study, we aimed to investigate the protective capacity of FGF21 in human umbilical vein endothelial cells (HUVECs) against high glucose (HG)-induced apoptosis via phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt)/FoxO3a pathway.

Shikonin protects chondrocytes from interleukin-1beta-induced apoptosis by regulating PI3K/Akt signaling pathway

Chondrocyte apoptosis is mostly responsible for the development and progression of osteoarthritis. IL-1β is generally served as an agent that induces chondrocyte apoptosis. Shikonin exerts its anti-inflammatory effect on cartilage protection in vivo. We aimed to explore the protective effect of shikonin on interleukin-1beta (IL-1β)-induced chondrocyte apoptosis and the potential molecular mechanisms. Chondrocytes were isolated from the joints of newborn Sprague-Dawley rats. The MTT assay and LDH cell death assay were used to determine the cell viability and chondrocyte apoptosis was detected by Annexin-V/PI staining and nucleosomal degradation. The contents of phosphorylated-PI3K (p-PI3k), phosphorylated-Akt (p-Akt), Bcl-2, Bax, and cytochrome c were detected by Western blotting. A quantitative colorimetric assay was used to detect the caspase-3 activity. Our results showed that pretreatment with shikonin (4 μM) inhibited cytotoxicity and apoptosis induced by IL-1β (10 ng/ml) in chondrocytes. Shikonin pretreatment also decreased the activity of IL-1β that decreased Bcl-2 expression and levels of p-PI3K and p-Akt, and increased Bax expression, cytochrome c release, and caspase-3 activation. It also reversed the activity of IL-1β that promoted the synthesis of matrix metalloproteinase-13 and inhibited the expression of tissue inhibitor of metalloproteinase-1 expression, with the net effect of suppressing extracellular matrix degradation. These data suggested that shikonin may protect chondrocytes from apoptosis induced by IL-1β through the PI3K/Akt signaling pathway, by deactivating caspase-3.     

Mesenchymal stem cells suppress lung inflammation and airway remodeling in chronic asthma rat model via PI3K/Akt signaling pathway

Background: Mesenchymal stem cells (MSCs) came out to attract wide attention and had become one of the hotspots of most diseases’ research in decades. But at present, the mechanisms of how MSCs work on chronic asthma remain undefined. Our study aims at verifying whether MSCs play a role in preventing inflammation and airway remodeling via PI3K/AKT signaling pathway in the chronic asthma rats model. Methods: First, an ovalbumin (OVA)-induced asthma model was built. MSCs were administered to ovalbumin-induced asthma rats. The total cells in a bronchial alveolar lavage fluid (BALF) and inflammatory mediators in BALF and serum were measured. Histological examination of lung tissue was performed to estimate the pathological changes. Additionally, the expression of phosphorylated-Akt (p-Akt) in all groups was measured by western blot and immunohistochemistry (IHC). Results: Compared to normal control group, the degree of airway inflammation and airway remodeling was significantly increased in asthma group. On the contrary, they were obviously inhibited in MSCs transplantation group. Moreover, the expression of p-Akt was increased in lung tissues of asthmatic rats, and suppressed by MSCs transplantation. Conclusion: Our results demonstrated that MSCs transplantation could suppress lung inflammation and airway remodeling via PI3K/Akt signaling pathway in rat asthma model.     

ShcC proteins: Brain aging and beyond

To date, most studies of Shc family of signaling adaptor proteins have been focused on the near-ubiquitously expressed ShcA, indicating its relevance to age-related diseases and longevity. Although the role of the neuronal ShcC protein is much less investigated, accumulated evidence suggests its importance for neuroprotection against such aging-associated conditions as brain ischemia and oxidative stress. Here, we summarize more than decade of studies on the ShcC expression and function in normal brain, age-related brain pathologies and immune disorders with a focus on the interactions of ShcC with signaling proteins/pathways, and the possible implications of these interactions for changes associated with aging.     

风药、补虚药对脑缺血大鼠海马PI3K/Akt信号通路的影响

目的探讨侯氏黑散方中风药、补虚药、风药补虚药联用(以下简称联用药)抗脑缺血损伤的作用机制。方法利用线栓法制备永久性大脑中动脉栓塞(p MCAO)模型。SPF级雄性SD大鼠随机被分为假手术组、模型组、风药组、补虚药组及联用药组。脑缺血72 h后分离缺血侧海马组织,运用双抗体夹心法测定缺血侧海马组织中脑源性神经营养因子(BDNF)的表达,Western blot检测磷脂酰肌醇3-激酶(PI3K)、蛋白激酶B(PKB又称Akt)、环磷酸腺苷反应元件结合蛋白(CREB)蛋白的表达。结果侯氏黑散方中风药对脑缺血大鼠缺血侧海马BDNF、PI3K、Akt及CREB的蛋白表达无明显影响;补虚药可以明显上调脑缺血大鼠缺血侧海马BDNF和Akt蛋白的表达(P0.05);联用药可以明显降低脑缺血大鼠神经功能评分(P0.05),显著上调脑缺血大鼠缺血侧海马BDNF、PI3K、Akt及CREB蛋白的表达(P0.05)。结论风药可以佐助补虚药通过对PI3K/Akt信号通路中关键信号分子进行调控,减轻缺血性脑损伤。     

PI3K/Akt信号通路对肝癌细胞系HepG2中SP细胞的影响

[目的]探讨PI3K/Akt信号通路对肝癌细胞系HepG2中肿瘤干细胞比例及干细胞特性的影响.[方法]使用PI3K/Akt通路抑制剂处理HepG2细胞后,使用流式技术分析HepG2细胞系中的侧群（SP）细胞的变化.软琼脂克隆形成实验检测PI3K/Akt抑制剂对HepG2细胞中SP细胞和非SP细胞成克隆能力的影响.[结果]HepG2细胞中存在SP细胞,经过LY294002处理后,SP细胞比例下降.LY294002可以显著降低SP细胞的软琼脂成克隆能力,对非SP细胞的软琼脂成克隆能力影响不明显.[结论]HepG2细胞中的SP细胞具有干细胞特性,PI3K/Akt信号通路对HepG2细胞中SP细胞的维持起重要作用,抑制PI3K/Akt信号通路后HepG2细胞中的SP细胞比例明显减低,并能显著抑制SP细胞的增殖速度、软琼脂成克隆能力,增加SP细胞对化疗药物的敏感性,为更加深入地了解肝癌干细胞的特性以及探索针对肿瘤干细胞的治疗提供理论依据.     

鼻咽癌复发的分子标志物Jab1 和Akt1 蛋白表达的差异*

 目的：通过筛查鼻咽癌病人复发组织与鼻咽癌初发组织分子标志物表达的差异,探讨差异表达的蛋白与鼻咽癌复发的关系,为干预鼻咽癌复发提供新的靶点。方法：免疫组织化学SABC 法检测Jab1、p-STAT3、 CHOP 和Akt1 在复发和初发病人鼻咽癌组织中的表达;Western blotting 法检测鼻咽癌细胞CNE-1、CNE-2、CNE-2R 和HONE1 中Jab1 和Akt1 蛋白的表达。结果：复发病人鼻咽癌组织Jab1和Akt1核表达水平均高于初发鼻咽癌组织（P<0.05）;Jab1 和Akt1 在CNE-1、CNE-2R 和HONE1细胞中的表达高于在CNE-2细胞中的表达,电离辐射能促进CNE-1、CNE-2、CNE-2R 和HONE1细胞中Jab1 蛋白的表达。结论：复发病人鼻咽癌组织或辐射抗拒鼻咽癌细胞中Jab1 和Akt1 核表达均高于初发鼻咽癌组织或辐射相对敏感的鼻咽癌细胞;电离辐射促进鼻咽癌细胞中Jab1 过表达。