Hematopoietic stem cell development requires transient Wnt/β-catenin activity

Understanding how hematopoietic stem cells (HSCs) are generated and the signals that control this process is a crucial issue for regenerative medicine applications that require in vitro production of HSC. HSCs emerge during embryonic life from an endothelial-like cell population that resides in the aorta-gonad-mesonephros (AGM) region. We show here that β-catenin is nuclear and active in few endothelial nonhematopoietic cells closely associated with the emerging hematopoietic clusters of the embryonic aorta during mouse development. Importantly, Wnt/β-catenin activity is transiently required in the AGM to generate long-term HSCs and to produce hematopoietic cells in vitro from AGM endothelial precursors. Genetic deletion of β-catenin from the embryonic endothelium stage (using VE-cadherin-Cre recombinase), but not from embryonic hematopoietic cells (using Vav1-Cre), precludes progression of mutant cells toward the hematopoietic lineage; however, these mutant cells still contribute to the adult endothelium. Together, those findings indicate that Wnt/β-catenin activity is needed for the emergence but not the maintenance of HSCs in mouse embryos.     

Inactivation of Wnt/β-catenin signaling in human adipose-derived stem cells is necessary for chondrogenic differentiation and maintenance

The Wnt/β-catenin signaling pathway plays critical roles in self-renewal and differentiation of mesenchymal stem cells. However, very little is known about its role in the chondrogenesis of human adipose-derived stem cells (hADSCs). In this study, we analyzed protein expression of several key components of the Wnt/β-catenin signaling pathway using a 21-day in vitro model of hADSC chondrogenesis. Wnt1, β-catenin, and GSK3β levels increased sharply at day 12, peaked at day 18, and then declined. Expression of TCF1, a target gene of Wnt/β-catenin signaling, closely followed that of Wnt1. These results were consistent with changes in endonuclear β-catenin levels. Gene expression of the chondrocyte-specific markers, collagen type II (COL II), SOX9, and aggrecan, increased during hADSC chondrogenesis, peaked at day 12, and then declined. Adding a Wnt inhibitor (days 0–21) resulted in consistently elevated levels of COL II, SOX9, and aggrecan mRNA. In contrast, adding Wnt1 (days 0–21) to cultures led to sustained Wnt/β-catenin signaling over the 21 days and suppressed expression of chondrocyte-specific markers. Moreover, adding Wnt1 at late stages of differentiation (day 18) further diminished chondrocyte-specific marker expression. Together, these results showed that inactivation of Wnt/β-catenin signaling is needed for the progression of chondrogenesis and the maturation and phenotype maintenance of chondroid cells.     

Wnt/β-catenin信号转导途径与白血病

Wntβ-catenin途径是Wnt中一条重要的信号转导途径,它与许多恶性肿瘤的发生、发展密切相关。已明确c-myc、cyclinD1等是此途径下游的靶基因,最近发现造血系统肿瘤中也存在Wntβ-catenin途径异常,β-catenin蛋白质在造血系统肿瘤中高表达并且还可能上调cox2基因。本文就Wntβ-catenin信号转导途径及其在白血病中的作用作一综述,希望能为白血病的治疗提供新的方向。     

Blockade of the Wnt/β-catenin pathway attenuates bleomycin-induced pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease and characterized by abnormal growth of fibroblasts and lung scarring. While the pathogenesis of IPF is not clearly understood, activation of transforming growth factor-β (TGF-β) and disruption of alveolar basement membrane seem to play important roles in leading to excess disruption of the matrix, which is associated with activated matrix metalloproteinase (MMP) and aberrant proliferation of myofibroblasts. The Wnt/β-catenin pathway is an important regulator of cellular proliferation and differentiation and abnormal activation of Wnt/β-catenin signal was observed in IPF. We examined whether inhibition of the Wnt/β-catenin pathway could attenuate pulmonary fibrosis in a bleomycin-induced murine model of pulmonary fibrosis. Pulmonary fibrosis was induced in C57BL/6N mice by intratracheal instillation of bleomycin. To inhibit the Wnt/β-catenin pathway, small interfering RNA (siRNA) for β-catenin was administered into trachea 2 h before bleomycin instillation and every 48 h afterward until sacrifice on day 14. The level of β-catenin expression was increased in the epithelial cells of bleomycin-administered mice. Intratracheal treatment with β-catenin siRNA significantly reduced β-catenin expression, pulmonary fibrosis and collagen synthesis in bleomycin-administered mice compared with controls, with no significant effect on the inflammatory response. The β-catenin-targeted siRNA also significantly decreased the levels of MMP-2 (P<0.01) and TGF-β (P<0.01) expression in the lung tissue. Blockade of the Wnt/β-catenin pathway by β-catenin siRNA decreased bleomycin-induced pulmonary fibrosis in the murine model. These findings suggest that targeting Wnt/β-catenin signaling may be an effective therapeutic approach in the treatment of IPF.     

Knockdown of TRIM47 inhibits glioma cell proliferation,migration and invasion through the inactivation of Wnt/β-catenin pathway

Tripartite motif 47 (TRIM47), a member of the TRIM protein family, plays a crucial role in tumor development and progression. However, the role of TRIM47 in glioma has not been investigated. In the present study, we investigated the expression of TRIM47 in glioma and explored the role of TRIM47 in glioma proliferation and migration both in vitro and in vivo. Our results showed that TRIM47 expression was significantly increased in glioma tissues compared to the normal brain tissues. Knockdown of TRIM47 in U87 and U251 cells inhibited cell proliferation, as well as cell migration and invasion. TRIM47 knockdown caused significant increase in E-cadherin expression and remarkable decrease in N-cadherin and vimentin expressions in both U87 and U251 cells. In vivo assay proved that knockdown of TRIM47 prevented tumor growth of glioma. Furthermore, TRIM47 silencing significantly inhibited the activation of Wnt/β-catenin pathway. Additionally, treatment with LiCl reversed the inhibitory effects of TRIM47 knockdown on cell proliferation and migration in U87 cells. In conclusion, these findings indicated that knockdown of TRIM47 suppressed cell proliferation and metastasis of glioma both in vitro and in vivo. TRIM47 exerted an oncogenic role in glioma and might be a therapeutic target for the treatment of glioma.     

Roles of Wnt/β-catenin signaling pathway related microRNAs in esophageal cancer

MicroRNAs (miRNAs) are endogenous, noncoding, single-stranded small RNAs that regulate expression of tumor suppressor genes and oncogenes and are involved in almost all tumor-related processes. MiRNA dysregulation plays an important role in the occurrence and development of esophageal cancer through specific signal pathways, including the Wnt/β-catenin signaling pathway, and is closely related to the malignant characteristics of esophageal cancer. The interaction between miRNAs and the Wnt/β-catenin signaling pathway, which is specifically expressed in esophageal cancer tissues, shows potential as a new biomarker and therapeutic target. This article reviews the role of miRNAs related to the Wnt pathway in the carcinogenesis of esophageal carcinoma and its role in Wnt signal transduction. The content of this review can be used as the basis for formulating or improving the treatment strategy of esophageal cancer.     

Wnt/β-catenin途径在血液肿瘤中的研究

Wnt/β-catenin信号传导途径与多种肿瘤的发生发展有关,同时在髓系和淋巴系造血和细胞发育中也发挥重要作用.近年该途径在血液系统肿瘤中的作用逐渐成为人们关注的焦点.研究证明,该途径在急性白血病、慢性白血病、多发性骨髓瘤和部分淋巴瘤等血液肿瘤中存在活化和高表达,对于恶性细胞的生长生存发挥着重要作用.进一步的机制研究显示该途径的异常参与某些血液肿瘤的发生和进展.针对该途径的治疗研究是值得探讨.     

Extracorporeal regulation effect of cytokines combination on stem cell or progenitor of umbilical blood

AIM：To study the regulation effect of different cytokines combinations on stem cell or progemitor of umbilical blood when no blood serum and matrix exist.METHODS:Collect and analyze the 23 sample of umbilical blood.RESULTS:(1) The combination of SCF+Flk2/Flt3 ligand and (FL)&;#177;TPO can amplify CD34^+,CD34+Thy-1^+,CD34+CD33+and LTC-IC in umbilical blood effectively and rapidly.(2) After add solubility type (sIL-6R) of IL-6 and IL-6 receptor into this combination,the stem cell or progenitor pmliferated prominently,When add IL-6 alone(without sIL 6R),the content of CD34^+ cells and LTC IC didn‘‘‘‘‘‘‘‘t increased obviously in early stage,but the amplification of CFU-Mix and BFU-E was not prominent as CFU-GM.(3) Detect apoptosis rate of cells by FITC-Annexin-V labeled by membranous change in early stage of cellular apoptosis,After add Flt3L and /or IL-6+ sIL-6R,the Annexin-V positive cells decreased from 15.2%-19.1% to 2.8%-3.5%,CONCLUSION:In suspending system composed with SCF+TPO+Flt3L+IL-6+sIL-6R without matrix and blood serum,the umbilical blood can not only produce large amount of committed progenitor but also Keep certain quantitive hematopoietic cells of early stage.     

Pivotal role for glycogen synthase kinase–3 in hematopoietic stem cell homeostasis in mice

Hematopoietic stem cell (HSC) homeostasis depends on the balance between self renewal and lineage commitment, but what regulates this decision is not well understood. Using loss-of-function approaches in mice, we found that glycogen synthase kinase–3 (Gsk3) plays a pivotal role in controlling the decision between self renewal and differentiation of HSCs. Disruption of Gsk3 in BM transiently expanded phenotypic HSCs in a β-catenin–dependent manner, consistent with a role for Wnt signaling in HSC homeostasis. However, in assays of long-term HSC function, disruption of Gsk3 progressively depleted HSCs through activation of mammalian target of rapamycin (mTOR). This long-term HSC depletion was prevented by mTOR inhibition and exacerbated by β-catenin knockout. Thus, GSK-3 regulated both Wnt and mTOR signaling in mouse HSCs, with these pathways promoting HSC self renewal and lineage commitment, respectively, such that inhibition of Gsk3 in the presence of rapamycin expanded the HSC pool in vivo. These findings identify unexpected functions for GSK-3 in mouse HSC homeostasis, suggest a therapeutic approach to expand HSCs in vivo using currently available medications that target GSK-3 and mTOR, and provide a compelling explanation for the clinically prevalent hematopoietic effects observed in individuals prescribed the GSK-3 inhibitor lithium.     

Protein tyrosine phosphatase–σ regulates hematopoietic stem cell–repopulating capacity

Hematopoietic stem cell (HSC) function is regulated by activation of receptor tyrosine kinases (RTKs). Receptor protein tyrosine phosphatases (PTPs) counterbalance RTK signaling; however, the functions of receptor PTPs in HSCs remain incompletely understood. We found that a receptor PTP, PTPσ, was substantially overexpressed in mouse and human HSCs compared with more mature hematopoietic cells. Competitive transplantation of bone marrow cells from PTPσ-deficient mice revealed that the loss of PTPσ substantially increased long-term HSC-repopulating capacity compared with BM cells from control mice. While HSCs from PTPσ-deficient mice had no apparent alterations in cell-cycle status, apoptosis, or homing capacity, these HSCs exhibited increased levels of activated RAC1, a RhoGTPase that regulates HSC engraftment capacity. shRNA-mediated silencing of PTPσ also increased activated RAC1 levels in wild-type HSCs. Functionally, PTPσ-deficient BM cells displayed increased cobblestone area–forming cell (CAFC) capacity and augmented transendothelial migration capacity, which was abrogated by RAC inhibition. Specific selection of human cord blood CD34⁺CD38^–CD45RA^–lin^– PTPσ^– cells substantially increased the repopulating capacity of human HSCs compared with CD34⁺CD38^–CD45RA^–lin^– cells and CD34⁺CD38^–CD45RA^–lin^–PTPσ⁺ cells. Our results demonstrate that PTPσ regulates HSC functional capacity via RAC1 inhibition and suggest that selecting for PTPσ-negative human HSCs may be an effective strategy for enriching human HSCs for transplantation.     

Down-regulated PLAC8 promotes hepatocellular carcinoma cell proliferation by enhancing PI3K/Akt/GSK3β/Wnt/β-catenin signaling

Hepatocellular carcinoma (HCC) is a common, prevalent malignancy. Its poor prognosis is mainly related to high rate of diagnosis in non-curable stages, in which patients are suitable for palliative treatment. Placenta-specific 8 (PLAC8), also known as Onzin, is a small, highly conserved, cysteine-rich protein. In current study, we found that PLAC8 is prominently decreased in HCC tissues compared with adjacent tissues and patients with low level of PLAC8 suffered a poor prognosis. In addition, cellular function assays demonstrate that down-regulated PLAC8 promotes cell viability, proliferation and tumor formation both in vitro and in vivo. Furthermore, we validate that down-regulated PLAC8 enhances the activity of PI3K/Akt/GSK3β and Wnt/β-catenin signaling to promote cell proliferation. Moreover, we proved that highly expressed miR-185-5p targets PLAC8 in HCC tissues. In conclusion, our findings enlarged our knowledge about the roles of PLAC8 in HCC progression and miR-185-5p/PLAC8/β-catenin axis might be a novel pathway for HCC treatment.     

骨关节病软骨细胞Wnt/β-catenin信号通路的研究进展

骨关节病是一种发病率极高且严重影响功能的退化性疾病且发病机制研究尚不透彻.Wnt/β-catenin信号通路在其关节软骨的发育和关节形成中起到重要作用.Wnt分子通过β-catenin 信号激活相关的基因,影响关节软骨细胞分泌细胞因子,参与细胞外基质的合成与代谢,导致软骨组织丧失、骨赘增生等退行性病变发生,因此Wntt/β-catenin信号通路在骨关节病发病机制的研究中开辟了新的途径.     

BMP4 Wnt/β-catenin信号通路与结直肠癌

结直肠癌是消化道最常见的恶性肿瘤之一。近年来,随着人民生活水平的不断提高,饮食习惯和饮食结构的改变以及人口老龄化,我国结直肠癌的发病率和病死率均保持上升趋势。根据我国卫生部2002年的统计报告,结直肠癌的发病率占恶性肿瘤的第三位,病死率占恶性肿瘤的第五位。和其它恶性肿瘤一样,结直肠癌的发生是一个多因素、多阶段、多基因变异累积的复杂过程,其机制仍未完全明了。     

Wnt／β-catenin信号转导途径与白血病

Wnt／β-catenin途径是Wnt中一条重要的信号转导途径，它与许多恶性肿瘤的发生、发展密切相关。已明确c-myc、cyclinD1等是此途径下游的靶基因，最近发现造血系统肿瘤中也存在Wnt／β-catenin途径异常，β-catenin蛋白质在造血系统肿瘤中高表达并且还可能上调cox2基因。本文就Wnt／β-catenin信号转导途径及其在白血病中的作用作一综述，希望能为白血病的治疗提供新的方向。     

Autologous hematopoietic stem cells for refractory Crohn’s disease

Introduction: Autologous hematopoietic stem cells are gaining ground as an effective and safe treatment for treating severe refractory Crohn’s disease (CD). Autologous hematopoietic stem cell therapy (AHSCT) induces resetting of the immune system by de novo regeneration of T-cell repertoire and repopulation of epithelial cells by bone-marrow derived cells to help patients achieve clinical and endoscopic remission.

Areas covered: Herein, the authors discuss the use of AHSCT in treating patients with CD. Improvements in disease activity have been seen in patients with severe autoimmune disease and patients with severe CD who underwent AHSCT for a concomitant malignant hematological disease. Clinical and endoscopic remission has been achieved in patients treated with AHSCT for CD. The only randomized trial published to date, the ASTIC Trial, did not support further use of AHSCT to treat CD. Yet, critics of this trial have deemed AHSCT as a promising treatment for severe refractory CD.

Expert opinion: Even with the promising evidence presented for HSCT for refractory CD, protocols need to be refined through the collaboration of GI and hemato-oncology professionals. The goal is to incorporate safe AHSCT and restore tolerance by delivering an effective immune ‘cease fire’ as a treatment option for severe refractory CD.     

What is the role of biosimilar G-CSF agents in hematopoietic stem cell mobilization at present?

Mobilization of hematopoietic stem cells, which has largely replaced bone marrow harvesting as a source of hematopoietic stem cells, using recombinant agents such as filgrastim or lenograstim has become a standard procedure in both patients and healthy donors prior to peripheral blood stem cell collection for autologous and allogeneic stem cell transplantation. Published literature data suggest that mobilization with recombinant granulocyte-colony stimulating factor (G-CSF) is safe and mobilization outcomes are satisfactory. In recent years, besides G-CSF originators, biosimilar G-CSF agents have been approved by the regulatory agencies for the same indications. Current data showed that by using the biosimilar G-CSF, similar results regarding safety and efficacy of hematopoietic stem cell mobilization may be achieved compared to the originator G-CSF. Although the issues such as the similarity to a licenced biological medicine, differences in manufacturing processes, the potential to cause immunogenicity, extrapolation and interchangeability of these biosimilar products are still being discussed by the scientific area, however, more experience with these agents now exists in approved endications and there seems to be no reason to expect significant differences between biosimilar G-CSF and originator G-CSF regarding their efficacy and safety in both patients and healthy donors. Also, the significant cost savings of biosimilars in real life setting may enhance the use of these agents in the future. Nonetheless, the collection of long-term follow-up data is mandatory for both patients and healthy donors, and multicentre randomized clinical trials that directly compare biosimilar G-CSF with the originator G-CSF are needed in order to allow the transplant community to make informed decisions regarding the choice of G-CSF.     

Wnt/β-catenin信号通路在肝癌耐药中的作用研究

目的 建立肝癌顺铂耐药细胞系,探讨Wnt/β-catenin信号通路在肝癌顺铂耐药中的作用.方法 使用顺铂逐步增加剂量法诱导人肝癌HepG-2细胞,以建立其多药耐药细胞株HepG-2/DDP;MTT细胞毒实验检测顺铂对HepG-2和HepG-2/DDP细胞的生长抑制作用;荧光定量-PCR检测β-catenin 基因的表达;基因转染双链SiRNA干扰β-catenin基因的表达;Western blot实验检测目的蛋白的表达改变.结果 成功建立了人肝癌HepG-2顺铂耐药细胞株;MTT细胞毒实验结果显示顺铂对HepG-2和HepG-2/DDP细胞的IC50值分别为(2.29±0.14) μmol/L和(20.51±0.84)μmol/L(t=95.68,P＜0.01),与HepG-2细胞比较,HepG-2/DDP细胞对顺铂耐药8.96倍.荧光定量PCR结果显示:HepG-2和HepG-2/DDP细胞中β-catenin基因表达的2-△Ct值分别为0.323±0.065和0.674±0.097(P＜0.01),Western blot检测也显示β-catenin蛋白的表达在HepG-2/DDP细胞也显著高于HepG-2细胞.化学合成的靶向SiRNA可以显著下调β-catenin的表达,顺铂对照组、SiRNA靶向干扰组、SiRNA阴性干扰组HepG-2/DDP细胞的IC50值分别为(21.02±1.64)、(6.23±0.68)、(20.44±1.26) μmol/L,对照组和SiRNA靶向干扰组之间差异有统计学意义(P＜0.01).结论 顺铂耐药细胞HepG-2/DDP出现了Wnt/β-catenin信号通路的激活,SiRNA干扰β-catenin基因表达可显著提高顺铂耐药细胞HepG-2/DDP对顺铂的敏感性,为克服肝癌顺铂新靶点的寻找提供了理论依据.     

Wnt/β-catenin信号通路在骨重建中的作用研究进展

<正>骨重建包括骨吸收及其耦联的骨形成两方面,在正常情况下,成骨细胞介导的骨形成和破骨细胞介导的骨吸收维持动态平衡。Wnt/β-catenin信号通路在骨重建过程中起到重要的作用,与成骨细胞分化、增殖和骨形成密切相关,并通过不同途径影响破骨细胞及骨细胞的功能,现就Wnt/β-catenin信号通路在骨重建过程中的作用作一综述。Wnt/β-catenin信号通路,进化保守,在胚胎发育、器官形