ADAM8 is selectively up‐regulated in endothelial cells and is associated with angiogenesis after spinal cord injury in adult mice

Endothelial cell (EC) loss and subsequent angiogenesis occur over the first week after spinal cord injury (SCI). To identify molecular mechanisms that could be targeted with intravenous (i.v.) treatments, we determined whether transmembrane “a disintegrin and metalloprotease” (ADAM) proteins are expressed in ECs of the injured spinal cord. ADAMs bind to integrins, which are important for EC survival and angiogenesis. Female adult C57Bl/6 mice with a spinal cord contusion had progressively more ADAM8 (CD156) immunostaining in blood vessels and individual ECs between 1 and 28 days following injury. Uninjured spinal cords had little ADAM8 staining. The increase in ADAM8 mRNA and protein was confirmed in spinal cord lysates, and ADAM8 mRNA was present in FACS‐enriched ECs. ADAM8 colocalized extensively and exclusively with the EC marker PECAM and also with i.v.‐injected lectins. Intravenous isolectin B4 (IB4) labels a subpopulation of blood vessels at and within the injury epicenter 3–7 days after injury, coincident with angiogenesis. Both ADAM8 and the proliferation marker Ki‐67 were present in IB4‐positive microvessels. ADAM8‐positive proliferating cells were seen at the leading end of IB4‐positive blood vessels. Angiogenesis was confirmed by BrdU incorporation, binding of i.v.‐injected nucleolin antibodies, and MT1‐MMP immunostaining in a subset of blood vessels. These data suggest that ADAM8 is vascular selective and plays a role in proliferation and/or migration of ECs during angiogenesis following SCI. J. Comp. Neurol. 512:243–255, 2009. © 2008 Wiley‐Liss, Inc.     

大鼠压力负荷增加心肌肥厚模型中核仁素的表达

目的：探讨腹主动脉缩窄致压力负荷增加大鼠心肌肥厚模型中核仁素的表达情况。方法：采用体质量
180~220 g SD大鼠40只,随机分为假手术组和腹主动脉缩窄模型组,利用腹主动脉缩窄法制备压力负荷增加心肌肥
厚模型,分别于术后2周、4周观察心脏质量指数、左心室质量指数;采用RT-PCR检测心肌组织中-MHC mRNA的
表达;采用Western印迹检测心肌、脑、肾组织中核仁素的表达情况。结果：腹主动脉缩窄模型组4周以后心脏质量
指数、左心室质量指数较假手术组显著增加(P<0.01);4周以后心肌组织中-MHC mRNA的表达较假手术组显著升高
(P<0.05);2周以后心肌组织中核仁素蛋白的表达较假手术组显著升高(P<0.05),而在脑、肾组织中无明显升高。结论：
核仁素蛋白在大鼠压力负荷增加心肌肥厚模型中的表达上调,表明核仁素可能参与了压力负荷增加心肌肥厚的发生
发展。     

Interfering with the interaction between ErbB1, nucleolin and Ras as a potential treatment for glioblastoma

The three oncogenes, ErbB receptors, Ras proteins and nucleolin may contribute to malignant transformation. Previously, we demonstrated that nucleolin could bind both Ras protein and ErbB receptors. We also showed that the crosstalk between the three proteins facilitates anchorage independent growth and tumor growth in nude mice, and that inhibition of this interaction in prostate and colon cancer cells reduces tumorigenicity. In the present study, we show that treatment with Ras and nucleolin inhibitors reduces the oncogenic effect induced by ErbB1 receptor in U87-MG cells. This combined treatment enhances cell death, reduces cell proliferation and cell migration. Moreover, we demonstrate a pivotal role of nucleolin in ErbB1 activation by its ligand. Nucleolin inhibitor prevents EGF-induced receptor activation and its downstream signaling followed by reduced proliferation. Furthermore, inhibition of Ras by Salirasib (FTS), mainly reduces cell viability and motility. The combined treatment, which targets both Ras and nucleolin, additively reduces tumorigenicity both in vitro and in vivo. These results suggest that targeting both nucleolin and Ras may represent an additional opportunity for inhibiting cancers, including glioblastoma, that are driven by these oncogenes.     

热休克反应对氧化应激所致nucleolin裂解的影响

观察热休克反应对氧化应激（0.5 mmol/L H2O2）诱导细胞凋亡发生时 nucleolin(C23)裂解的影响并探讨其机制。方法： 采用caspase-3 活性定量分析及免疫印迹技术检测氧化应激诱导的原代心肌细胞、RAW 264.7巨噬细胞 及K562白血病细胞凋亡及C23的裂解;通过热休克反应观察热休克反应对C23裂解的影响。结果： 0.5 mmol/L H2O2处理细胞2 h caspase-3活性显著升高,12 h达高峰。免疫印迹结果显示上述各种细胞的C23蛋白均发生了裂解（有80 kD裂解片断出现）,而且最早出现裂解片段的时间都在H2O2处理30 min到1 h左右;同时热休克反应通过诱导HSP70,HSP25等应激蛋白表达而显著减少氧化应激所致C23的裂解。结论： 氧化应激诱导凋亡发生的同时也引起C23的裂解;热休克反应显著抑制氧化应激所致C23的裂解,其机制与热休克反应诱导多种热休克蛋白表达有关。     

Endostatin inhibits tumour lymphangiogenesis and lymphatic metastasis via cell surface nucleolin on lymphangiogenic endothelial cells

Endostatin has potent anti‐endothelial and anti‐angiogenic functions. Endostatin was reported to reduce lymphangiogenesis by down‐regulating the level of VEGF‐C in tumour tissues. However, there is little evidence for the direct function of endostatin on lymphangiogenic endothelial cells and lymphangiogenic vessels. Here, we report that cell surface nucleolin, which was reported as an endostatin receptor mediating its anti‐angiogenic and anti‐tumour functions, is also selectively expressed on the cell surface of lymphangiogenic endothelial cells both in vitro and in vivo. Treatment of primary mouse lymphatic endothelial cells (mLECs) by endostatin inhibits mLEC migration, tubule formation, and activation of the Erk pathway in mLECs, while neutralization of cell surface nucleolin or nucleolin knockdown results in loss of the anti‐lymphatic endothelial activities of endostatin. Also, anti‐nucleolin antibody or lentivirus delivered nucleolin siRNA abolishes the anti‐lymphangiogenic function of endostatin in the Matrigel plug assay. Endostatin remarkably inhibits tumour‐associated lymphangiogenesis, leading to reduced lymphatic metastasis. Systemic blockade of nucleolin notably abolishes the anti‐lymphangiogenic and anti‐lymphatic metastatic functions of endostatin. Importantly, endostatin does not affect quiescent lymphatics in normal organs, which is consistent with the lack of expression of cell surface nucleolin in quiescent lymphatics. Taken together, our results demonstrate that endostatin directly acts on lymphangiogenic endothelial cells via cell surface nucleolin, which provides a novel mechanism for the inhibition of tumour lymphangiogenesis and lymphatic metastasis by endostatin. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Evidence for an S-Phase checkpoint regulating DNA replication after heat shock: a review

Exposure of cells to heat inhibits a number of nuclear activities associated with semi-conservative replication of DNA including the incorporation of radiolabelled precursors into acid-insoluble DNA, the initiation of new replicons, the elongation of the DNA fibre at the replication fork, the synthesis and deposition of new histones into chromatin and the reorganization of nascent DNA into mature chromatin. These effects are likely to underlie the heat sensitivity of S-phase cells and may contribute to the radiosensitization observed in this phase of the cell cycle. While some of these effects may be explained as ‘passive’ consequences of heat-induced damage on chromatin structures, experiments reviewed here point to the activation of a checkpoint as a contributing factor to the observed inhibition of DNA replication. Activation of a heat responsive S-phase checkpoint targets the activity of RPA via interaction with nucleolin. Nucleolin, a major nucleolar protein, is found normally sequestered in the nucleolus. Exposure of cells to heat causes a rapid translocation of nucleolin from the nucleolus into the nucleoplasm that enables RPA/nucleolin interaction. This interaction inhibits functions of RPA associated with the initiation of DNA replication and contributes to the immediate inhibition of DNA synthesis observed after heat shock. The results suggest that the nucleolus serves as a sequestration centre for the temporary inactivation of regulatory molecules, such as nucleolin, capable of regulating essential cellular functions after heat shock. It is speculated that this regulatory process is integrated in the network of responses that determine cell sensitivity to heat and that it may be involved in heat radiosensitization to killing as well.     

XIAP overexpression promotes bladder cancer invasion in vitro and lung metastasis in vivo via enhancing nucleolin‐mediated Rho‐GDIβ mRNA stability

Our recent studies demonstrate that X‐linked inhibitor of apoptosis protein (XIAP) is essential for regulating colorectal cancer invasion. Here, we discovered that RhoGDIβ was a key XIAP downstream effector mediating bladder cancer (BC) invasion in vitro and in vivo. We found that both XIAP and RhoGDIβ expressions were consistently elevated in BCs of N‐butyl‐N‐(4‐hydroxybutyl)‐nitrosamine (BBN)‐treated mice in comparison to bladder tissues from vehicle‐treated mice and human BCs in comparison to the paired adjacent normal bladder tissues. Knockdown of XIAP attenuated RhoGDIβ expression and reduced cancer cell invasion, whereas RhoGDIβ expression was attenuated in BBN‐treated urothelium of RING‐deletion knockin mice. Mechanistically, XIAP stabilized RhoGDIβ mRNA by its positively regulating nucleolin mRNA stability via Erks‐dependent manner. Moreover, ectopic expression of GFP‐RhoGDIβ in T24T(shXIAP) cells restored its lung metastasis in nude mice. Our results demonstrate that XIAP‐regulated Erks/nucleolin/RhoGDIβ axis promoted BC invasion and lung metastasis.