Cancer stem cells and human malignant melanoma

Cancer stem cells (CSC) have been identified in hematological malignancies and several solid cancers. Similar to physiological stem cells, CSC are capable of self-renewal and differentiation and have the potential for indefinite proliferation, a function through which they may cause tumor growth. Although conventional anti-cancer treatments might eradicate most malignant cells in a tumor, they are potentially ineffective against chemoresistant CSC, which may ultimately be responsible for recurrence and progression. Human malignant melanoma is a highly aggressive and drug-resistant cancer. Detection of tumor heterogeneity, undifferentiated molecular signatures, and increased tumorigenicity of melanoma subsets with embryonic-like differentiation plasticity strongly suggest the presence and involvement of malignant melanoma stem cells (MMSC) in the initiation and propagation of this malignancy. Here, we review these findings in the context of functional properties ascribed to melanocyte stem cells and CSC in other cancers. We discuss the association of deregulated signaling pathways, genomic instability, and vasculogenic mimicry phenomena observed in melanoma subpopulations in light of the CSC concept. We propose that a subset of MMSC may be responsible for melanoma therapy-resistance, tumor invasiveness, and neoplastic progression and that targeted abrogation of a MMSC compartment could therefore ultimately lead to stable remissions and perhaps cures of metastatic melanoma.     

免疫信号轴揭示水稻与病原菌斗争的秘密

近年,我国学者在水稻(Oryza sativa)广谱抗病机制、抗性与产量协调机制等方向的研究取得了一系列突破性进展。最近,何祖华和杨卫兵团队在水稻抗病性研究中再次取得突破,发现1个以钙感应蛋白ROD1和过氧化氢酶CatB为核心的信号轴,通过负调控水稻免疫反应,保证正常生长条件下维持低水平的免疫反应,促进水稻正常生长发育...     

Combination stem cell therapy using dental pulp stem cells and human umbilical vein endothelial cells for critical hindlimb ischemia

Narrowing of arteries supplying blood to the limbs provokes critical hindlimb ischemia (CLI). Although CLI results in irreversible sequelae, such as amputation, few therapeutic options induce the formation of new functional blood vessels. Based on the proangiogenic potentials of stem cells, in this study, it was examined whether a combination of dental pulp stem cells (DPSCs) and human umbilical vein endothelial cells (HUVECs) could result in enhanced therapeutic effects of stem cells for CLI compared with those of DPSCs or HUVECs alone. The DPSCs+ HUVECs combination therapy resulted in significantly higher blood flow and lower ischemia damage than DPSCs or HUVECs alone. The improved therapeutic effects in the DPSCs+ HUVECs group were accompanied by a significantly higher number of microvessels in the ischemic tissue than in the other groups. In vitro proliferation and tube formation assay showed that VEGF in the conditioned media of DPSCs induced proliferation and vessel-like tube formation of HUVECs. Altogether, our results demonstrated that the combination of DPSCs and HUVECs had significantly better therapeutic effects on CLI via VEGF-mediated crosstalk. This combinational strategy could be used to develop novel clinical protocols for CLI proangiogenic regenerative treatments.     

Water loss and viability in Zizania (Poaceae) seeds during short-term desiccation

How Texas wild rice, Zizania texana, became isolated in the San Marcos River of Central Texas, hundreds of kilometres from other wild rice populations is not known. Zizania seeds are intolerant of short-term desiccation. Seeds desiccated at 14% relative humidity (RH) and 75% RH do not survive after only 5-6 d and 2-3 wk of drying. Water loss is rapid and reaches a maximum at the time of seed death due to drying. And although all Zizania seeds germinate well following a long, cold dormancy period, Z. texana seeds readily germinate in the isothermic water (22°C) of the San Marcos River and Springs without an obligate, cold dormant period. Within 30-60 d of collection, Z. texana seeds germinate in substantial numbers, unlike seeds of Z. palustris, which require a long, cold dormant period. The Texas population of Z. texana may represent a relict population of a once more widely dispersed wild rice population, since the San Marcos springs probably have never gone dry.     

The plant glycosyltransferase clone collection for functional genomics

The glycosyltransferases (GTs) are an important and functionally diverse family of enzymes involved in glycan and glycoside biosynthesis. Plants have evolved large families of GTs which undertake the array of glycosylation reactions that occur during plant development and growth. Based on the Carbohydrate‐Active enZymes (CAZy) database, the genome of the reference plant Arabidopsis thaliana codes for over 450 GTs, while the rice genome (Oryza sativa) contains over 600 members. Collectively, GTs from these reference plants can be classified into over 40 distinct GT families. Although these enzymes are involved in many important plant specific processes such as cell‐wall and secondary metabolite biosynthesis, few have been functionally characterized. We have sought to develop a plant GTs clone resource that will enable functional genomic approaches to be undertaken by the plant research community. In total, 403 (88%) of CAZy defined Arabidopsis GTs have been cloned, while 96 (15%) of the GTs coded by rice have been cloned. The collection resulted in the update of a number of Arabidopsis GT gene models. The clones represent full‐length coding sequences without termination codons and are Gateway^® compatible. To demonstrate the utility of this JBEI GT Collection, a set of efficient particle bombardment plasmids (pBullet) was also constructed with markers for the endomembrane. The utility of the pBullet collection was demonstrated by localizing all members of the Arabidopsis GT14 family to the Golgi apparatus or the endoplasmic reticulum (ER). Updates to these resources are available at the JBEI GT Collection website http://www.addgene.org/ .     

Survival of priceless cells: active and passive protection of embryonic stem cells against immune destruction

This review focuses on our current knowledge of the mechanisms employed by embryonic stem (ES) cells to avoid destruction by cell-mediated immune responses. Recently, ES cells have been found to shield themselves against cytotoxic effector cells by expressing CD95L and serine protease inhibitor SPI-6 mediating apoptosis of the cytotoxic cells and inactivation of granzyme B, respectively. These findings are discussed in view of their implications for using ES cell-derived transplants in regenerative medicine as well as for our understanding of early embryonic stages during invasion and implantation.     

Purification of pluripotent embryonic stem cells using dielectrophoresis and a flow control system

Pluripotent stem cells (PSCs) such as embryonic stem cells and induced PSCs can differentiate into all somatic cell types such as cardiomyocytes, nerve cells, and chondrocytes. However, PSCs can easily lose their pluripotency if the culture process is disturbed. Therefore, cell sorting methods for purifying PSCs with pluripotency are important for the establishment and expansion of PSCs. In this study, we focused on dielectrophoresis (DEP) to separate cells without fluorescent dyes or magnetic antibodies. The goal of this study was to establish a cell sorting method for the purification of PSCs based on their pluripotency using DEP and a flow control system. The dielectrophoretic properties of mouse embryonic stem cells (mESCs) with and without pluripotency were evaluated in detail, and mESCs exhibited varying frequency dependencies in the DEP response. Based on the variance in DEP properties, mixed cell suspensions of mESCs can be separated according to their pluripotency with an efficacy of approximately 90%.     

Wnt通路中蓬松蛋白DNA甲基化对骨质疏松患者骨髓间充质干细胞成骨分化影响

摘要 目的：探讨蓬松蛋白（DVL）DNA甲基化对骨质疏松（OP）患者骨髓间充质干细胞（BMSCs）成骨分化及Wnt通路的影响。方法：分离、培养OP患者的BMSCs,成骨诱导培养BMSCs 0、7、14、21天,观察BMSCs细胞形态变化,检测碱性磷酸酶（ALP）染色及活性,检测茜素红染色及钙结节形成,荧光定量聚合酶链式反应（RT-PCR）及免疫印迹检测远端缺失同源盒5（Dlx5）、核心结合蛋白因子2（Runx2）、成骨细胞特异性转录因子（OSX）、Ⅰ型胶原蛋白（Colla Ⅰ）表达。检测DVL1、Wnt、糖原合成酶激酶3（GSK3）、β连环蛋白（β-catenin）表达及DVL DNA甲基化水平。在成骨诱导培养基中加入甲基转移酶抑制剂5-Aza,将BMSCs分为对照组（Control组）、甲基转移酶抑制剂组（5-Aza组）、甲基转移酶抑制剂+si-NC组（5-Aza+si-NC组）、甲基转移酶抑制剂+si-Wnt组（5-Aza+si-Wnt组）,依次进行ALP活性测定,茜素红染色及钙结节形成测定。RT-PCR检测Dlx5、Runx2、OSX、Colla 1水平,免疫印迹检测Dlx5、Runx2、OSX、Colla Ⅰ、DVL1、Wnt、GSK3、β-catenin的蛋白表达量,并检测DVL DNA甲基化水平。结果：成骨诱导后BMSCs具有强的ALP活性和矿化结节生成能力,且随着培养时间的增长,BMSCs细胞ALP活性和矿化结节生成能力增强,Dlx5、Runx2、OSX、Colla Ⅰ mRNA水平和Wnt、GSK3、β-catenin、DVL1表达升高,DVL DNA甲基化水平降低（P＜0.05）。5-Aza组较Control组ALP染色加深,活性增强,钙结节形成增多（P＜0.05）,Dlx5、Runx2、OSX、Colla Ⅰ mRNA及蛋白表达、Wnt、GSK3、β-catenin、DVL1表达升高,DVL DNA甲基化水平降低（P＜0.05）。5-Aza+si-Wnt组较5-Aza+si-NC组ALP染色变浅,活性降低,钙结节形成减少（P＜0.05）,Dlx5、Runx2、OSX、Colla Ⅰ mRNA及蛋白表达、Wnt、GSK3、β-catenin、DVL1表达降低,DVL DNA甲基化水平升高（P＜0.05）。结论：DVL DNA甲基化可以通过抑制Wnt/β-catenin信号通路抑制OP患者BMSCs成骨分化。