Involvement of PI3K/Akt pathway in rat condylar chondrocytes regulated by PTHrP treatment

Objective

The aim of this study was to explore the mutual communication of the parathyroid hormone-related peptide (PTHrP) and phosphatidylinositol 3-kinase/threonine protein kinase (PI3K/Akt) pathway on the proliferation and differentiation of condylar chondrocytes from Sprague-Dawley (SD) rats.

Methods

Condylar chondrocytes from the condylar cartilage were cultured and an organ culture system of mandibular condyles was employed. The distribution of PI3K, phospho-Akt (p-Akt), and PTHrP in condylar cartilage was detected by either immunohistochemistry or immunofluorescence. The second passage chondrocytes and condyle specimens in the organ culture system were treated with PTHrP, LY294002, PTHrP and LY294002 in combination, or dimethyl sulfoxide (DMSO), separately. The mRNA and protein levels of type II (Col II) and type X collagen (Col X) were investigated by real-time polymerase chain reaction (PCR) and Western blot analysis. The condyle growth in organ culture system was analysed by haematoxylin–eosin staining.

Results

PTHrP, PI3K, and p-Akt were mainly located in the proliferative and hypertrophic zones. PTHrP promoted the proliferation of condylar chondrocytes, while LY294002 limited this effect. The mRNA and protein levels of Col II and Col X in these cells were reduced by PTHrP and enhanced by LY294002. Organ culture showed a significant enhancement of condyle elongation with PTHrP treatment or a combination of PTHrP and LY294002 treatment. After treatment with LY294002, the length of condyles was reduced compared with the samples treated with DMSO.

Conclusions

We conclude that the PI3K/Akt pathway plays an essential role in the proliferation and differentiation of condylar chondrocytes and is a potential target for PTHrP in regulating chondrocyte differentiation at condylar cartilage.     

PI3 kinase／Akt通路对颌骨代谢的调节

胰岛素不仅在糖尿病中发挥重要的作用，在骨的代谢中也是关键的调节因子，胰岛素与胰岛素受体结合，促进胰岛素受体底物（IRS）发生酪氨酸磷酸化，进而激活PI3 kinase／Akt通路。PI3 kinase／Akt通路参与了多种细胞的增殖分化，越来越多的证据证明，PI3 kinase／Akt通路在骨细胞的增殖、分化起重要作用。本文就PI3 kinase／Akt通路对骨代谢的调节作一综述，希望能为骨代谢疾病患者种植牙的药物选择提供思路。     

胰岛素样生长因子1经PI3K/Akt信号通道对人牙髓细胞凋亡的抑制调控

目的 研究PI3K/Akt信号通路中相关蛋白Akt、pAkt在磷脂壁酸（lipoteichoic acid,LTA）和脂多糖(lipopolysaccharide,LPS)诱导引起的人牙髓细胞（human dental pulp cells,HDPCs）损伤中的表达情况及PI3K/Akt激活剂胰岛素样生长因子(IGF)-1对人牙髓细胞损伤的保护作用。方法 甲基噻唑基四唑（MTT）法检测LTA、LPS作用24、48、72 h后对HDPCs增殖的影响以及IGF-1对LTA、LPS引起的HDPCs增殖抑制的保护作用,蛋白免疫印迹法检测LTA、LPS刺激HDPCs 24 h后及使用IGF-1和脂磷壁酸、脂多糖共同处理HDPCs相关蛋白Akt、pAkt表达水平的变化。结果 LTA和LPS抑制HDPCs增殖具有浓度依赖性。IGF-1可降低LTA、LPS引起的HDPCs增殖抑制程度。使用IGF-1和脂磷壁酸、脂多糖共同处理HDPCs后pAkt（Ser473）蛋白表达上调,这种作用可被LY294002取消。结论 IGF-1对脂磷壁酸、脂多糖引起的hHDPCs增殖抑制有保护作用,这种保护作用可能通过激活PI3K/Akt信号通路发挥作用。     

Novel function of Porphyromonas gingivalis gingipains in the PI3K/Akt signaling pathway

Background

Porphyromonas gingivalis is s major oral bacterium closely associated with periodontal diseases including periodontitis and directly affects host cellular signaling. The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway plays multiple roles in various cell functions including cell survival and glucose metabolism. In this review, we describe the effect of gingipains on the PI3K/Akt signaling pathway in P. gingivalis infection.

PI3K/Akt/mTOR通路在头颈部鳞状细胞癌中的靶向治疗研究进展

头颈部鳞状细胞癌（HNSCC）在全球最常见的恶性肿瘤中位居第六,晚期患者转移并复发率高,预后较差,为患者家庭和社会经济带来严重损失。靶向药物结合经典放化疗的个性化方案有望提高治疗功效并延长生存期。磷脂酰肌醇3-激酶/蛋白激酶B/哺乳动物雷帕霉素靶蛋白（PI3K/Akt/mTOR）在HNSCC中普遍存在过度激活,是控制肿瘤发生、发展及研发靶向药物的重要通路。本文就PI3K/Akt/mTOR通路应用于HNSCC靶向治疗的个体性差异发生的潜在机制,以及临床试验取得的进展与目前所面临的困境进行探讨,拟为HNSCC的临床靶向治疗提供参考思路,从而提高患者的生存质量。     

甘草苷调控PI3K/Akt/m-TOR信号通路对口腔鳞状细胞癌细胞及裸鼠移植瘤小鼠的作用研究

目的:目的探讨甘草苷(Liquiritin,LIQ)对人口腔鳞状细胞癌细胞(OSCCs)的增殖抑制、凋亡诱导作用和分子机制并通过裸鼠模型进行验证。方法:CCK-8检测LIQ对口腔鳞状细胞癌细胞的增殖抑制作用;流式细胞术及TUNEL实验检测凋亡情况;Western blot检测蛋白表达变化;构建裸鼠瘤模型,连续给药20 d,绘制肿瘤生长曲线,并计算抑瘤率。结果:LIQ可以抑制口腔鳞状细胞癌细胞增殖及裸鼠瘤体积增长,并诱导细胞凋亡;LIQ抑制PI3K/Akt/m-TOR信号通路的过度激活。结论:LIQ能够在体内外对口腔鳞状细胞癌产生抗癌效果,其机制可能是通过抑制PI3K/AKT/m-TOR信号通路的过度激活。     

HBXIP对腺样囊性癌细胞株ACC-M生物学功能及PI3K/Akt信号通路的影响

目的:研究乙肝病毒X蛋白结合蛋白(hepatitis B X-interacting protein,HBXIP)对唾液腺腺样囊性癌肺高转移细胞株(ACC-M)增殖、迁移和侵袭的影响,及其对PI3K/Akt信号通路的影响.方法:将HBXIP质粒转染到ACC-M中,将细胞分为实验组(转染pEGFP-N1-HBXIP质粒)、对照组1(未转染组)和对照组2(vector组,pEGFP-N1).采用RT-PCR检测HBXIP在ACC-M中的表达;采用MTT实验、Transwell小室实验和划痕实验检测HBXIP过表达对ACC-M的增殖、迁移和侵袭的影响;Western印迹法检测HBXIP过表达对Akt、p-Akt、PI3K、p-PI3K及S100A4蛋白表达量的影响.采用SPSS18.0软件包对数据进行统计学分析.结果:MTT实验结果显示,实验组中存活的细胞数显著高于对照组(P＜0.05);划痕实验结果显示,实验组细胞迁移率显著高于对照组(P＜0.01);Transwell小室实验结果显示,实验组细胞侵袭个数显著高于对照组(P＜0.01);Western印迹法结果显示,相对于对照组,实验组随着HBXIP过表达,p-Akt、p-PI3K及S100A4表达量相对增高.结论:HBXIP基因过表达ACC-M增殖、迁移和侵袭具有影响,可能通过促进Akt、PI3K磷酸化及S100A4蛋白表达量增加,促进ACC-M的增殖、迁移和侵袭.     

Extrapancreatic roles of glimepiride on osteoblasts from rat manibular bone in vitro: Regulation of cytodifferentiation through PI3-kinases/Akt signalling pathway

Glimepiride, a third-generation sulfonylurea, has also been reported to have extrapancreatic functions including activation of PI3-kinase (PI3K) and Akt in rat adipocytes, skeletal muscle and endothelial cells. It is tempting to speculate that glimepiride would improve bone–implant contact in diabetic patients by mediating the activity of GLUT1 and 3 via the PI3K/Akt pathway. In this study, we investigated the effects of glimepiride on rat mandible osteoblasts cultured under two different levels of glucose. Cell proliferation was determined by the MTT assay. The supernatant was used to measure alkaline phosphatase (ALP) activity. Glucose uptake was determined by measuring the rate of 2-deoxy-d-glucose (2-DG) uptake. Western blotting was performed used to determine collagen I and PI3K/Akt expression. RT-PCR was performed used to determine osteocalcin (OCN) mRNA expression. We found that hyperglycemia down-regulated proliferation, ALP activity, OCN mRNA and GLUT3 protein expression in rat osteoblasts, and upregulated collagen I and GLUT1 protein expressions. Glimepiride enhanced the proliferation, ALP activity and OCN mRNA levels, and upregulated collagen I and GLUT1 and 3 protein expressions of rat osteoblasts at two different glucose concentrations. This study also provides the first evidence that glimepiride stimulates the phosphorylation of PI3K/Akt in osteoblasts and ameliorated the damage caused by high concentrations of glucose through the PI3K/Akt pathway.     

PI3K/AKT信号通路对体外人牙髓细胞增殖和成牙本质向分化能力的影响

目的 研究PI3K/AKT信号通路对人牙髓细胞（hDPC）体外增殖作用和成牙本质向分化能力的影响.方法 体外培养hDPC,采用PI3K通路抑制剂LY294002（LY）处理hDPC,CCK8法检测细胞增殖情况,Western blot蛋白印记检测PI3K/AKT通路下游蛋白AKT、磷酸化AKT（p-AKT）水平在6、12、24、48、72 h的改变,检测成牙本质向分化指标DSPP的蛋白水平变化;设立空白对照组、矿化诱导组、LY组、矿化诱导＋LY组共4组,成牙本质向矿化诱导14 d,茜素红染色检测矿化结节形成情况.结果 CCK8结果显示,LY294002在24、48和72 h可抑制hDPC的增殖（24 h：Z=-0.358,P＜ 0.05;48 h：t=11.674,P＜ 0.05;72 h：t=10.832,P＜ 0.05）;Western blot显示,LY294002抑制PI3K/AKT通路下游蛋白p-AKT活性,在24 h时作用最明显,成牙本质向分化指标DSPP蛋白水平降低;茜素红染色结果显示,矿化结节的数量B组最多、C组最少.结论 PI3K/AKT信号通路可促进hDPC的增殖和成牙本质向分化能力.     

The PI3K/Akt/mTOR axis in head and neck cancer: functions,aberrations, cross‐talk,and therapies

Head and neck squamous cell carcinoma (HNSCC) is one of the most morbid, mortal, and genetically diverse malignancies. Although HNSCC is heterogeneous in nature, alterations in major components of the PI3K/Akt/mTOR pathway are consistently observed throughout the majority of HNSCC cases. These alterations include genetic aberrations, such as mutations or DNA copy number variations, and dysregulation of mRNA or protein expression. In normal physiology, the PI3K/Akt/mTOR axis regulates cell survival, growth, and metabolism. However, alterations in this pathway lead to the malignant phenotype which characterizes HNSCC, among many other cancers. For this reason, both pharmaceutical companies and academic institutions are actively developing and investigating inhibitors of PI3K, Akt, and mTOR in preclinical and clinical studies of HNSCC. Many of these inhibitors have shown promise, while the effects of others are tempered by the mechanisms through which HNSCC can evade therapy. As such, current research aimed at elucidating the interactions between PI3K/Akt/mTOR and other important signaling pathways which may drive resistance in HNSCC, such as p53, NF‐κB, and MAPK, has become a prominent focus toward better understanding how to most effectively treat HNSCC.     

PI3K/AKT信号通路在2型糖尿病患者种植体骨结合中作用机制的研究进展

口腔种植治疗目前被认为是缺牙患者的首选治疗方案,但糖尿病仍然是种植治疗的相对禁忌证。糖尿病患者的高血糖环境以及微血管病变等可能会影响成骨细胞及破骨细胞的功能,影响骨代谢,导致种植失败。目前,对于糖尿病影响种植体骨结合的确切机制尚未阐明。PI3K/AKT信号通路在骨组织代谢中起重要作用,可促进成骨细胞的增殖和分化;此外,PI3K/AKT/mTOR也是响应胰岛素信号传导的经典途径。该文分别对PI3K/AKT信号通路在2型糖尿病和种植体骨结合中作用机制的研究进展进行综述,为今后促进糖尿病患者种植体周围骨再生等研究奠定基础。     

PI3K/Akt mediates expression of TNF‐α mRNA and activation of NF‐κB in calyculin A‐treated primary osteoblasts

Objective: The effect of calyculin A (CA), a serine/threonine protein phosphatase inhibitor, on tumor necrosis factor‐α (TNF‐α) in primary osteoblasts was investigated to determine whether protein phosphatases could affect primary osteoblasts and if so which signaling pathways would be involved. Materials and methods: Primary osteoblasts were prepared from newborn rat calvaria. Cells were treated with 1 nM CA for different time periods. The expressions of TNF‐α and GAPDH mRNA were determined by RT‐PCR. Cell extracts were subjected to SDS‐PAGE and the activation of Akt and NF‐κB were analyzed by western blotting. Results: Calyculin A‐treatment markedly increased the expression of TNF‐α mRNA and enhanced the phosphorylation level of Akt (Ser473) in these cells. Pretreatment with the PI3K inhibitor LY294002 suppressed the increase in TNF‐α mRNA expression and the phosphorylation of Akt in response to CA. Western blot analysis showed that CA stimulated the phosphorylation and nuclear translocation of NF‐κB in primary osteoblasts, and these responses were blocked by pretreatment with LY294002. Conclusion: Calyculin A elicits activation of PI3K/Akt pathway which leads to expression of TNF‐α mRNA and activation of NF‐κB. This NF‐κB activation involves both phosphorylation and nuclear translocation of NF‐κB.     

SOX2通过PI3K/AKT通路调控口腔鳞癌细胞迁徙的机制研究

目的:研究过表达SOX2通过PI3K/AKT通路促进口腔鳞癌(oral squamous cell carcinoma,OSCC)细胞迁移及上皮间质转化(epithelial mesenchymal transition,EMT)的作用及机制.方法:收集OSCC组织及正常口腔黏膜组织,培养OSCC细胞株Tca83、SC...