吲哚美辛对慢性粒细胞白血病急变期CD34+细胞的影响研究

目的 探讨吲哚美辛(IN)对慢性粒细胞白血病(简称慢粒)急变期CD34+细胞凋亡和周期的影响,并从Wnt/β-catenin信号通路初步探讨其可能的分子机制.方法 采用免疫磁珠分选技术分选慢粒慢性期、急变期患者骨髓标本和正常脐带血标本中的CD34+细胞,流式细胞术鉴定其分选纯度,瑞氏染色观察其细胞形态,采用免疫荧光技术检测CD34+细胞中β-catenin和BCR/ABL的表达及定位.使用IN联合伊马替尼(IM)处理CD34+细胞,免疫荧光技术检测β-catenin蛋白变化,瑞氏染色和流式细胞术观察细胞凋亡及细胞周期,定量PCR检测靶基因c-myc和cyclin D1的mRNA水平,流式细胞术和免疫荧光技术检测BCR/ABL蛋白变化.结果 成功分选出CD34+细胞,纯度达90％以上;β-catenin和BCR/ABL均在慢粒急变期CD34+细胞中高表达,主要定位于胞质.IN与IM联用能够显著抑制慢粒急变期CD34+细胞中β-catenin的表达,使慢粒急变期CD34+细胞的细胞周期被阻滞在G0/G1期,明显增加细胞的凋亡,明显降低c-myc和cyclin D1的mRNA水平,并使BCR/ABL的蛋白水平显著下降,但对正常CD34+细胞没有影响.结论 IN通过影响细胞周期和细胞凋亡,增强IM对慢粒急变期CD34+细胞的杀伤力,其机制可能是与降低β-catenin的表达,抑制c-myc和cyclinD1的转录及BCR/ABL的蛋白水平有关.     

慢性粒细胞性白血病中SHIP1基因的表达变化及机制探讨

目的观察SHIP1基因在慢性粒细胞性白血病(CML)患者中的表达变化,并通过特异性小干扰RNA(siRNA)封闭K562细胞株BCR-ABL基因的表达,探讨BCR-ABL基因表达对SHIP1基因的影响。方法应用RQ-PCR方法检测CML患者骨髓、正常人外周血白细胞及白血病细胞株K562中SHIP1基因表达的差异。另取K562细胞分为3组:空白对照组(不加任何干扰成分);非特异性siRNA处理组(加非特异性siRNA);特异性siRNA处理组(加入特异性siRNA封闭BCR/ABL融合基因),应用RQ-PCR及Western blot方法分别检测3组中BCR/ABL、SHIP1基因的mRNA及其相应蛋白P210(BCR/ABL编码)、P145(SHIP1基因编码)的表达,并比较各组中表达水平的变化。结果CML患者骨髓白细胞和K562细胞中SHIP1基因的表达明显低于正常人的外周血白细胞。特异性siRNA处理组中BCR-ABL基因mRNA和P210蛋白的表达水平明显下降,SHIP1基因mRNA和P145蛋白表达水平随BCR-ABL表达下降而增加;非特异性siRNA处理组与空白组相比无明显差异。结论CML患者SHIP1基因的表达低于正常人;特异性siRNA能够抑制BCR-ABL基因的表达;BCR-ABL基因能抑制SHIP1基因及其蛋白表达。     

PI3KAktCOX-2途径在人宫颈癌HeLa细胞放射抗拒中的作用

目的 探讨PI3K/Akt/COX-2途径在人宫颈癌HeLa细胞放射抗拒中作用的分子机制。 方法 COX-2抑制剂塞来昔布单独及联合PI3K抑制剂LY294002作用HeLa细胞24 h,X射线不同剂量照射,利用克隆形成法计算细胞存活率,单击多靶模型拟合细胞存活曲线,计算D_q、D₀、SF₂值和放射增敏比(SER);应用Western blot方法检测Akt、磷酸化Akt、COX-2、Bad和磷酸化Bad蛋白的表达;应用RT-PCR检测COX-2和Bad mRNA的表达。结果 塞来昔布单独及联合LY294002作用HeLa细胞组D_q、D₀、SF₂明显低于单纯照射组;X射线照射后,能够活化HeLa细胞PI3K/Akt/COX-2途径,塞来昔布能够多靶点抑制PI3K/Akt/COX-2途径的活化。结论 PI3K/Akt/COX-2途径的活化是HeLa细胞放射抗拒的重要原因,PI3K/Akt与COX-2之间存在正反馈的调节,抑制PI3K/Akt/COX-2途径的活化能够提高HeLa细胞放射敏感性。     

间充质干细胞来源外泌体对视网膜光感受器细胞PI3K/AKT通路及Ang-1蛋白水平作用的研究

目的 探讨间充质干细胞(mesenchymal stem cell,MSC)下外泌体对视网膜光感受器细胞PI3K/AKT通路及Ang-1蛋白水平的影响。 方法 应用免疫印迹检测人脐带间充质干细胞(human umbilical cord derived mesenchymal stem cells,h UCMSCs)外泌体表面标志蛋白CD63及CD90 ,应用流式细胞仪检测光损伤661W细胞凋亡,应用免疫荧光检测Ang-1,应用免疫印迹检测PI3K、p-PI3K、AKT、p-AKT蛋白表达。 结果 形态学及免疫印迹检测CD63、CD90表达结果证实h UCMSCs外泌体。线粒体膜电位检测结果以及细胞形态学鉴定661W细胞建立光损伤模型成功。流式细胞仪、免疫荧光检测结果显示,与正常组比较模型组细胞凋亡率及Ang-1阳性表达增加,在经过h UCMSCs干预后有所降低,且呈现出明显的浓度依赖性（P<0.05）。免疫印迹结果显示,与正常组比较,模型组PI3K、AKT、p-PI3K、p-AKT表达降低,经过h UCMSCs干预后有所升高（P<0.05）,且高浓度组PI3K、AKT、p-PI3K、p-AKT表达水平与激动剂组比较无差异（P>0.05）,模型组PI3K、AKT、p-PI3K、p-AKT表达水平高于抑制剂组（P<0.05）。 结论 间充质干细胞下外泌体可能是通过激活PI3K/AKT通路,抑制了视网膜光感受器细胞的凋亡以及Ang-1的水平,从而对光损伤视网膜起保护作用。     

DNA双链断裂感应分子ATM能与PTC1相互作用

目的：研究DNA双链断裂感应分子ATM与原癌基因ret重排活化蛋白PTC1的相互作用。方法：用Flag抗体Western印迹检测，ATM免疫共沉淀真核细胞内过表达的PTC1；RET抗体检测ATM免疫共沉淀真核细胞内过表达的c-ret;用HA／myc抗体Western印迹检测，HA－ret TK myc-LZPR免疫共沉淀蛋白复合物；荧光蛋白标记的亚细胞定位。结果：PTC1可以与ATM激酶相互作用，此作用不依赖于电离辐射，且不被PI3K家族特异性抑制剂沃氏蓝霉素（wortmannin)所抑制，而野生型RET蛋白则不能同ATM结合；缺失体实验进一步证明两者的结合区段为ATM的LZPR结构域与PTC1的酪氨酸激酶结构域，构建PTC1绿色荧光蛋白表达质粒的亚细胞定位实验显示，PTC1以弥散形式分布于细胞质内。结论：胞浆蛋白PTC1可能借债某种途径使ATM在DNA损伤反应发生后重新定位，介导了细胞的恶性转化机制。     

表皮生长因子受体抑制剂联合放疗治疗肿瘤研究进展

表皮生长因子受体(EGFR)是原癌基因C-erbB-1的表达产物.EGFR家族包括4个成员:EGFR(ErbB-1/HER-1)、ErhB-2(HER-2/neu)、ErbB-3(HER-3)和ErbB-4(HER-4).这些受体与配体结合后引起细胞内信号转导,进而调节细胞的生长、分化、增殖等.EGFR在多种肿瘤中过度表达或突变.EGFR抑制剂主要包括EGFR单克隆抗体和酪氨酸激酶抑制剂,二者能通过阻断EGFR信号通路来提高肿瘤的辐射敏感性.     

PI3K/Akt与胶质瘤辐射抗性

恶性脑胶质瘤的术后治疗是患者预后生存期延长的关键,如何提高肿瘤组织的辐射敏感性,增强正常组织的辐射抗性是当前肿瘤放射生物学及临床放疗研究的热点。研究资料表明,PI3K/Akt抗细胞凋亡通路的激活提高了部分细胞的辐射抗性,特别在表皮细胞受紫外线照射的研究中提示,辐射产生的活性氧可能是该通路激活的原因之一;电离辐射可能诱导相关的细胞因子通过激活PI3K/Akt通路介导胶质瘤细胞的辐射抗性;PI3K及其相关酶可能通过DNA修复途径发挥抗辐射作用。PI3K/Akt通路的研究可为放射治疗胶质瘤提供新型的增敏药。     

空肠低度恶性间质瘤1例

胃肠道间质瘤（gastointestinal stromaltumor,GIST）是独立的来源于胃肠道原始间叶组织的非定向分化的肿瘤,可发生于从食管到肛门的整个消化道,也可发生于网膜、肠系膜、腹膜及后腹膜。目前研究发现,原癌基因c-kit突变是GIST形成的重要分子因素,c—kit的表达产物CD117（一种Ⅲ酪氨酸激酶生长激素受体）在GIST中有极高的敏感性和特异性,但不能作为判断良恶性的指标。     

U50,488H抑制缺氧/复氧心肌细胞线粒体分裂作用及机制

目的探讨外源性κ-阿片受体(κ-OR)激动剂U50,488H对缺氧/复氧(H/R) H9C2心肌细胞线粒体分裂的作用及机制。方法将H9C2心肌细胞随机分为常氧对照组(Control组)、H/R组、H/R+U50,488H组(H/R+U组)、H/R+κ-OR阻断剂(nor-BNI)+U50,488H组(H/R+N+U组)、H/R+磷脂酰肌醇3-激酶(PI3K)抑制剂wortmannin+U50,488H组(H/R+W+U组)、H/R+蛋白激酶B(Akt)抑制剂MK2206+U50,488H组(H/R+M+U组)。采用CCK8试剂盒检测细胞活力;流式细胞仪检测细胞凋亡率;激光共聚焦显微镜观察细胞线粒体形态;免疫印迹法检测细胞内PI3K、Akt、线粒体动力学分裂相关蛋白1(Drp1)的表达。结果与Control组比较,H/R组细胞活力降低,细胞凋亡率显著增加,线粒体分裂增加,磷酸化PI3K与Akt表达略增加,磷酸化Drp1 Ser637表达显著降低(P <0. 05);与H/R组比较,H/R+U组细胞活力增加,细胞凋亡率下降,线粒体分裂减少,磷酸化PI3K、Akt Ser473与Drp1 Ser637表达均显著增加(P <0. 05)。结论 H/R可引起心肌细胞凋亡及线粒体异常分裂,使用U50,488H激活κ-OR后,可通过PI3K-Akt通路促使Drp1 Ser637磷酸化,抑制H/R心肌细胞线粒体异常分裂,减少细胞凋亡。     

GDF11对糖尿病小鼠骨髓间充质干细胞细胞凋亡的影响及其信号机制

 目的 探讨生长分化因子11(GDF11)对糖尿病小鼠骨髓间充质干细胞(BMSCs)细胞凋亡的影响及其信号机制。方法 复苏BMSCs并将其分为4组:正常小鼠BMSCs组(Nor),糖尿病小鼠BMSCs组(DB),GDF11干预组(DB+GDF11;GDF11),抑制剂组(DB+GDF11+ LY294002;LY)。各组细胞培养3 d后,台盼蓝染色观察细胞凋亡率。Western blot检测凋亡相关蛋白Bax、Bcl-2和磷酸化(p)-PI3K、p-Akt的表达水平。结果 与正常小鼠BMSCs相比,糖尿病小鼠BMSCs细胞凋亡率显著升高[(36.2±3.3)% vs. (3.1±1.1)%,P＜0.05];GDF11可降低糖尿病小鼠BMSCs细胞凋亡率[(18.9±1.9)% vs. (36.2±3.3)%,P＜0.05],提高Bcl-2/Bax的蛋白表达比[(1.63±0.10) vs. (0.26±0.09);P＜0.05],同时激活PI3K[p-PI3K/PI3K:(0.98±0.08) vs. (0.42±0.11);P＜0.05]/Akt[p-Akt/Akt:(0.94±0.10) vs. (0.32±0.15);P＜0.05]信号通路。而且,当抑制PI3K/Akt信号通路后,GDF11抑制糖尿病小鼠BMSCs凋亡的作用明显减弱[细胞凋亡率:(41.1±3.9)% vs. (18.9±1.9)%,P＜0.05]。结论 GDF11可通过激活PI3K/Ak信号通路抑制糖尿病小鼠BMSCs细胞凋亡。     

PMA-enhanced neutrophil [18F]FDG uptake is independent of integrin occupancy but requires PI3K activity

OBJECTIVE: While respiratory burst enhances neutrophil glucose utilization, many neutrophil functions are critically influenced by extracellular matrix interaction and phosphoinositide-3-OH kinase (PI3K) signaling. We thus evaluated the role of RGD integrin occupancy and PI3K inhibition on respiratory burst and [(18)F]fluorodeoxyglucose ([(18)F]FDG) uptake of stimulated neutrophils. METHODS: Human neutrophils were stimulated by 100 ng/ml phorbol-myristate-acetate (PMA), and respiratory burst was measured by cumulative luminescence with lucigenin. [(18)F]FDG uptake and total hexokinase activity was measured 20 min after PMA stimulation in the presence or absence of soluble RGD peptides (200 microg/ml) and/or the PI3K inhibitor wortmannin (200 nM). RESULTS: Phorbol-myristate-acetate induced a 71.7+/-0.9 fold increase in neutrophil oxygen intermediate generation. [(18)F]FDG uptake was increased to 194.6+/-3.7% and hexokinase activity to 145.0+/-2.0% of basal levels (both P<.0005). RGD peptides attenuated respiratory burst activation to 35.6+/-0.2% (P<.005) but did not inhibit stimulated [(18)F]FDG uptake or hexokinase activity. In contrast, without affecting respiratory burst activation, wortmannin inhibited PMA-stimulated [(18)F]FDG uptake to 66.9+/-1.6% and hexokinase activity to 81.0+/-4.2% (both P<.0005), demonstrating its dependence on PI3K activity. Neither RGD nor wortmannin reversed the other's inhibitory effect on stimulated [(18)F]FDG uptake and hexokinase activity or respiratory burst, which suggests the involvement of distinct signaling pathways. CONCLUSION: Neutrophil [(18)F]FDG uptake is enhanced by PMA through a mechanism that requires PI3K activity but is independent of integrin receptor occupancy or respiratory burst activation.     

七氟醚上调PI3K/Akt/mTOR活性对小鼠心肌缺血再灌注损伤中自噬水平的影响

 目的 从PI3K/Akt/mTOR通路角度,探讨七氟醚对小鼠心肌缺血再灌注损伤中自噬水平的影响。方法 小鼠24只随机分4组(n=6):假手术组,只开胸不结扎;缺血再灌注组,戊巴比妥钠麻醉下结扎冠状动脉左前降支行缺血/再灌注手术;七氟醚组,七氟醚麻醉下手术;七氟醚+LY294002组,术前一周每日注射PI3K阻断剂LY294002,余同七氟醚组。收集血浆检测心肌损伤标志物肌酸激酶-MB(CK-MB)和心肌肌钙蛋白Ⅰ(cTnI)水平。心肌组织用免疫印迹法检测自噬标志物 LC3、Beclin1,及信号通路磷脂酰肌醇3-磷酸激酶(PI3K)、蛋白激酶B(Akt)、雷帕霉素(mTOR) 总蛋白及磷酸化蛋白水平。结果 与假手术组相比,其余3组的血浆CK-MB、cTnI、心肌自噬标志蛋白LC3和Beclin1水平均增高(P<0.05),磷酸化PI3K、Akt、mTOR与总蛋白比值降低(P<0.05)。与假手术组相比,七氟醚组的PI3K、Akt、mTOR总蛋白水平差异无统计学意义;而缺血再灌注组PI3K、Akt水平增高(P<0.05),且mTOR蛋白水平降低(P<0.05);七氟醚+LY294002组PI3K水平增高(P<0.05),且Akt、mTOR蛋白水平降低(P<0.05)。与缺血再灌注组相比,七氟醚组和七氟醚+LY294002组血浆CK-MB和cTnI、LC3和Beclin1水平均降低(P<0.05)。与缺血再灌注组相比,七氟醚组的磷酸化PI3K、Akt、mTOR蛋白与总蛋白比值升高(P<0.05)。与七氟醚组相比,七氟醚+LY294002组血浆CK-MB、cTnI降低,LC3和Beclin1水平均增高(P<0.05);七氟醚+LY294002组的磷酸化PI3K、Akt、mTOR蛋白与总蛋白比值均降低(P<0.05)。结论 七氟醚抑制了缺血再灌注引发的过度自噬,可能的机制是上调了PI3K/Akt/mTOR通路蛋白磷酸化水平。     

Nitric oxide stimulates 18F-FDG uptake in human endothelial cells through increased hexokinase activity and GLUT1 expression.

The endothelium constitutes a functionally active organ critically involved in angiogenesis. Nitric oxide (NO) is an important regulator of vascular homeostasis and angiogenesis and stimulates glucose metabolism in certain cells. We thus investigated the effect of exogenous NO on (18)F-FDG transport in human endothelial cells. METHODS: Human umbilical vein endothelial cells (HUVECs) were treated with the NO donors sodium nitroprusside (SNP) or diethylenetriamine (DETA), in concentrations of 1 micromol/L-1 mmol/L for up to 24 h. (18)F-FDG uptake levels corrected for protein content were determined by cellular radioactivity measured after 30-min incubation. Cells were evaluated for total hexokinase activity and plasma membrane glucose transporter 1 (GLUT1) levels, and involvement of potential signaling pathways was investigated by cotreatment with respective protein kinase inhibitors. RESULTS: Both SNP and DETA stimulated HUVEC (18)F-FDG uptake, which began at 16 h and peaked at 24 h. The increase in (18)F-FDG uptake was dose dependent, reaching 464.0% +/- 49.8% and 254.5% +/- 10.8% of control levels at 24 h with 1 mmol/L SNP and DETA, respectively. Exposure of HUVECs to 1 mmol/L SNP resulted in a 3.5 +/- 0.3-fold elevation in hexokinase activity (P < 0.01) and a significant increase in GLUT1 levels. SNP-stimulated (18)F-FDG uptake was abolished by cotreatment with cycloheximide, the tyrosine kinase inhibitor genistein, the phosphatidylinositol-3 kinase (PI3K) inhibitor wortmannin, or the protein kinase C inhibitor staurosporine. CONCLUSION: NO stimulates (18)F-FDG uptake in HUVECs through an increase in GLUT1 expression and hexokinase activity, which appears to involve both protein kinase C and PI3K pathways.     

An essential role of integrin-linked kinase in the cellular radiosensitivity of normal fibroblasts during the process of cell adhesion and spreading

PURPOSE: In addition to focal adhesion kinase (FAK), Paxillin and p130 Crk-associated substrate (p130Cas), integrin-linked kinase (ILK) mediates signals from beta integrins for controlling, e.g., survival, adhesion and spreading. To evaluate the role of ILK in the cellular radiosensitivity at different stages of cell adhesion and spreading, ILK(floxed/floxed (fl/fl)) and ILK(-/-) mouse fibroblasts were examined. MATERIALS AND METHODS: Cells were irradiated (0 - 4 Gy, X-rays) in suspension, after varying time periods on fibronectin (FN) or after 24 h on different matrix proteins. Irradiation was combined with phosphatidylinositol-3 kinase (PI3K) inhibition using Ly294002. Clonogenic radiation survival, cell adhesion, and kinetics of protein expression and phosphorylation during FN adhesion (ILK, v-akt murine thymoma viral oncogene homolog 1 (AKT), FAK, Paxillin, p130Cas) were examined. RESULTS: In suspension and during the first hour on FN, irradiated ILK(fl/fl) cells survived significantly better than ILK(-/-) cells in a PI3K- and serum-dependent manner. 24-h cell cultures on different matrix proteins showed no difference in radiosensitivity. During FN adhesion, which was slightly impaired in ILK(-/-) cells, protein kinetics uncovered differences in AKT, FAK, Paxillin and p130Cas phosphorylation in the two cell lines. Phosphorylation of FAK, Paxillin and p130Cas was downregulated upon exposure to ionizing radiation in an ILK-independent manner. CONCLUSIONS: These findings indicate a critical function of ILK in the cellular radiosensitivity during the early stages of adhesion to and spreading on FN. On the basis of the presented data, a precise correlation of adhesion-, serum- and PI3K-mediated changes in PI3K/AKT and FAK/Paxillin/p130Cas signaling cascades was not found. However, identifying the underlying mechanisms of adhesion- and spreading-related changes in the cellular radiosensitivity might be relevant for an optimization of radiotherapeutic strategies specifically targeting cells located at the invasive edge of a malignant tumor.     

Efficacy of indocyanine green and methylene blue mediated-photodynamic therapy on peri-implant outcomes among diabetics with peri-implant mucositis

BackgroundThis study aimed to assess the efficacy of indocyanine green (ICG)-mediated versus methylene blue (MB)-mediated photodynamic therapy (PDT) as an adjunct to conventional mechanical debridement (MD) on the peri‑implant clinical, radiographic, microbiological, and immunological outcomes among diabetics with peri‑implant mucositis (pi-M).MethodsFor this 3-month follow-up study, diabetics having pi-M were randomly divided into 3 groups: group-I (n = 20) subjects received only MD; group-II (n = 20) participants received ICG-mediated adjunct PDT; and group-III (n = 20) subjects received MB-mediated adjunct PDT. Peri-implant clinical (i.e., plaque index [PI], bleeding on probing [BOP], probing depth [PD]), radiographic (crestal bone loss [CBL]), microbiological (Fusobacterium nucleatum [F. nucleatum], Tannerella forsythia [T. forsythia], Prevotella intermedia [P. intermedia], Porphyromonas gingivalis [P. gingivalis], Aggregatibacter actinomycetemcomitans [A. actinomycetemcomitans]), and immunological (interleukin [IL]-6, IL-1β, tumor necrosis factor-alpha [TNF-α]) outcomes were assessed at baseline and 3-month follow-up.ResultsMean changes between baseline and 3-month follow-up in peri‑implant clinico-radiographic parameters were significantly different between control (PI: 12.42±21.80%; BOP: 12.10±19.30%; PD: 0.45±0.41 mm; CBL: 1.10±1.02 mm) and test groups (ICG-mediated PDT [PI: 26.55±25.80%; BOP: 28.77±29.24%; PD: 0.84±0.62 mm; CBL: 1.98±1.85 mm] and MB-mediated PDT [PI: 27.24±26.15%; BOP: 27.71±28.16%; PD: 0.85±0.63 mm; CBL: 1.95±1.80 mm]), however comparable differences were observed in peri‑implant PI, BOP, PD, and CBL between group-II and group-III participants (p>0.05). The proportions of T. forsythia were significantly reduced in group-II (4.78 × 10⁴ colony-forming unit per milliliter [CFU/mL]) and group-III (4.76 × 10⁴ CFU/mL) as compared to group-I (-4.40 × 10³ CFU/mL) at 3-month follow-up (p = 0.02). No statistically significant differences were observed between the study groups regarding the proportions of the other assessed target bacterial species. For IL-6 (group-I: 210±108; group-II: 298±165; group-III: 277±121 pg/mL; p = 0.03), IL-1β (group-I: 101±95; group-II: 84±98; group-III: 86±74 pg/mL; p = 0.02), and TNF-α (group-I: 336±121; group-II: 385±210; group-III: 366±198 pg/mL; p = 0.03) peri‑implant sulcular fluid [PISF] levels, all three study groups demonstrated statistically significant reduction at 3-month follow-up.ConclusionsICG-mediated and MB-mediated adjunctive PDT showed statistically significant improvements in peri‑implant clinical, radiographic, microbiological, and immunological parameters as compared to conventional MD alone at 3-month follow-up among diabetics with pi-M. However, comparable outcomes were demonstrated by ICG-mediated and MB-mediated adjunctive PDT regarding the assessed peri‑implant parameters.     

阻断PI3K信号通路显著抑制成骨前体细胞MC3T3-E1的分化

目的：研究PI3K信号通路对成骨前体细胞MC3T3-E1分化的调控作用。方法：首先通过Western印迹试验检测到PI3K信号通路参与成骨细胞分化的调控。应用PI3K激酶的特异性抑制剂LY294002药物阻断PI3K信号通路的活化，通过碱性磷酸酶(ALP)和von Kossa染色观察成骨前体细胞MC3T3-E1分化的改变。结果：Western印迹试验显示，成骨细胞分化过程中PI3K信号通路明显活化。阻断该信号通路的活化显著抑制成骨细胞碱性磷酸酶的活性，同时降低成骨细胞体外形成骨结节结构的能力。结论：PI3K信号通路参与了成骨细胞分化的调控，而这种调控作用是成骨细胞分化所必需的。     

Adaptive response and the influence of ageing: effects of low-dose irradiation on cell growth of cultured glial cells

PURPOSE: To examine the molecular mechanism of radiation adaptive response (RAR) for the growth of cultured glial cells and to investigate the influence of ageing on the response. MATERIALS AND METHODS: Glial cells were cultured from young and older rats (1 and 24 months). RAR for the growth of glial cells conditioned with a low dose of X-rays and subsequently exposed to a high dose of X-rays was examined for cell number and BrdU incorporation. Involvement of the subcellular signalling pathway factors in RAR was investigated using their inhibitors, activators, and mutated and knockout glial cells. RESULTS: RAR was observed in cells cultured from young rats but was not in cells from older animals. The inhibitors of protein kinase C (PKC) and DNA-dependent protein kinase (DNA-PK) or phosphatidylinositol 3-kinase (PI3K) suppressed RAR. The activators of PKC instead of low-dose irradiation also caused RAR. Moreover, glial cells cultured from severe combined immunodeficiency (scid) mice (CB-17 scid) and ataxia-telangiectasia mutated (Atm) knockout mice showed no RAR. CONCLUSION: The results indicated that PKC, ATM, DNAPK and/or PI3K were involved in RAR for growth and BrdU incorporation of cultured glial cells and RAR decreased with ageing.