Stromal cell CD9 and the differentiation of hematopoietic stem/progenitor cells

CD9 belongs to the tetraspan family of proteins that facilitates the regulation of cell proliferation, motility, and adhesion. In mouse hematopoietic organs, CD9 is expressed by myeloid and stromal cells. Although the precise mechanisms are not clear, antibody ligation of CD9 on stromal cells regulates the adhesion between stromal cells and hematopoietic stem cells, the production of myeloid cells in long term bone marrow cultures and the differentiation of hematopoietic stem cells. A 100 kD protein co-precipitated with CD9 is distinct from several previously reported CD9-associated molecules with respect to size and distribution. Identification and analysis of this interesting protein may clarify the molecular mechanisms through which CD9 bearing stromal cells control the differentiation of hematopoietic stem cells and/or allow them to maintain their vital self-renewal capacity.     

BCR-ABL alters the proliferation and differentiation response of multipotent hematopoietic cells to stem cell factor

Chronic myeloid leukaemia (CML), a hematopoietic stem cell disorder is characterized by the expression of BCR-ABL. To investigate the effects of BCR-ABL on multipotent hematopoietic cells, a temperature sensitive BCR-ABL tyrosine kinase was expressed in the cell line, FDCP-Mix. BCR-ABL mediated an increase in c-kit expression that correlated with an enhanced mitogenic response to SCF. This was not observed in the absence of Bcr-Abl kinase activity or presence of the BCR-ABL inhibitor STI571, which also inhibits c-kit. When cultured in a combination of SCF plus G-CSF the FDCP-Mix cells undergo neutrophilic differentiation over a 7-10 day period. When BCR-ABL was active there was a marked inhibition of cell maturation compared to control cells in which BCR-ABL was either inactive or not present. However, BCR-ABL did not block differentiation as the cells eventually undergo terminal maturation. These data argue that BCR-ABL is directly responsible for the enhanced response to SCF reported in CML progenitor cells. Furthermore, although the primary effect of STI571 is via direct inhibition of BCR-ABL, STI571 additionally reduces the enhanced response to SCF. Thus there are two sites of STI571 action of potential importance in Bcr-Abl expressing cells.     

Flt3 ligand promotes myeloid dendritic cell differentiation of human hematopoietic progenitor cells: possible application for cancer immunotherapy

Current in vitro culture systems allow the generation of human dendritic progenitor cells (CFU-DCs). The aim of this study was to assess the effect of Flt3 ligand (FL) on the proliferation of human peripheral blood-derived myeloid CFU-DCs and their differentiation into more committed precursor cells (pDCs) using in vitro culture systems. Immunomagnetically separated CD34+ cells were cultured in serum-free, as well as in serum-containing, liquid suspension cultures to investigate the expansion and/or proliferation/differentiation of CFU-DCs, pDCs, and more mature dendritic cells (DCs). FACS-sorted CD34+Flt3+/- cells were cultured in methylcellulose to assay hematopoietic progenitors, including CFU-DCs. In the clonal cell culture supplemented with granulocyte/macrophage (GM) colony-stimulating factor (CSF), interleukin-4, and tumor necrosis factor alpha, the frequency of CFU-DCs was significantly higher in the CD34+Flt3+ fraction than in the CD34+Flt3- population, thus suggesting functional Flt3 expression on CFU-DCs. Serum-free suspension culture of CD34+ cells revealed the potent effect of FL on the expansion of CFU-DCs in synergy with GM-CSF and thrombopoietin (TPO). In addition, FL strongly induced the maturation of CFU-DCs into functional CD1a+ pDCs in serum-containing liquid suspension culture. Moreover, these FL-generated pDCs showed remarkable potential to differentiate into mature DCs with surface CD83/CD86 expression, which induced a distinct allogeneic T-cell response. These results clearly demonstrate that FL supports not only the proliferation of early hematopoietic progenitor cells, but also the maturation process of committed precursor cells along with the DC-lineage differentiation. Therefore, it is possible to develop a more efficient DC-based cancer immunotherapy using this specific cytokine combination, GM-CSF+TPO+FL in vitro in the near future.     

Endothelial differentiation of hematopoietic stem and progenitor cells from patients with multiple myeloma.

PURPOSE: Vasculogenesis is a physiologic process typical of fetal development in which new blood vessels develop from undifferentiated precursors (or angioblasts). In tumors, near angiogenesis, vasculogenesis contributes to the formation of the microvascular plexus that is important for diffusion. Here, we show that hematopoietic stem and progenitor cells (HSPC) of multiple myeloma (MM) patients are able to differentiate into cells with endothelial phenotype on exposure to angiogenic cytokines. EXPERIMENTAL DESIGN: Circulating HSPCs were purified with an anti-CD133 antibody from patients with newly diagnosed MM before autologous transplantation and exposed to vascular endothelial growth factor (VEGF), fibroblast growth factor-2 and insulin-like growth factor in a 3-week culture. RESULTS: HSPCs gradually lost CD133 expression and acquired VEGF receptor-2, factor VIII-related antigen, and vascular endothelial-cadherin expression. The expression pattern overlapped with paired MM endothelial cells (MMEC). During culture, cells adhered to fibronectin, spread, and acquired an endothelial cell shape. Differentiated HSPCs also became capillarogenic in the Matrigel assay with maximal activity at the third week of culture. Bone marrow biopsies revealed HSPCs inside the neovessel wall in patients with MM but not in those with monoclonal gammopathy of undetermined significance. CONCLUSIONS: In patients with MM, but not in those with monoclonal gammopathy of undetermined significance, HSPCs contribute to the neovessel wall building together with MMECs. Therefore, besides angiogenesis, HSPC-linked vasculogenesis contributes to neovascularization in MM patients. Tentatively, we hypothesize that in HSPC cultures a multipotent cell population expressing low VEGF receptor-2 levels corresponds to the endothelial progenitor cell precursor and seems to be the MMEC precursor.     

Bestrophin 3高表达促进人肝癌细胞株HepG2的凋亡

目的：研究Bestrophin 3高表达对人肝癌细胞株HepG2凋亡能力的影响,并初步探讨其作用机制。 方法： 将Bestrophin 3腺病毒以感染复数(multiplicity of infection, MOI)10、20、40、80转染HepG2细胞株,Western blotting检测转染细胞内Bestrophin 3的表达,确定最佳MOI值。设对照组（未转染病毒）、LacZ组（转染携带LacZ的对照腺病毒载体）、Ad-Best3组（以最佳MOI值转染Bestrophin 3腺病毒）,CCK-8法和流式细胞术分别检测Bestrophin 3过表达对HepG2细胞增殖、凋亡的影响,Western blotting检测Bestrophin 3过表达对HepG2细胞内Bcl-2、Bax以及细胞色素C表达的影响,JC-1染色观察Bestrophin 3过表达对HepG2细胞线粒体膜电位的影响。 结果： Bestrophin 3腺病毒转染HepG2细胞的最佳MOI为40,转染后细胞过表达Bestrophin 3。Ad-Best3组的细胞存活率显著低于对照组和LacZ组\[(79.37±1.76)% vs (98.67±3.02)%、(99.67±325)%,均P<0.05\],而其细胞凋亡率显著升高\[（29.47±2.37）% vs （5.47±0.37）%,（4.95±0.44）%,均P<0.05\]。 Ad-Best3组HepG2细胞内Bcl-2的蛋白表达显著减少,Bax的蛋白表达显著增加,导致Bcl-2/Bax比值显著降低（0.32±0047 vs 1.00±000, P<0.05）;Ad-Best3组HepG2细胞的线粒体膜电位显著降低 \[(0.64±0.09)% vs （1.00±0.00)%, P<0.05\],同时线粒体中细胞色素C明显减少（P<0.05）,而细胞质中细胞色素C水平显著升高（P<0.05）。结论：过表达Bestrophin 3可能通过促使线粒体释放细胞色素C从而促进肝癌细胞株HepG2的凋亡。     

HOXB7 promotes invasion and predicts survival in pancreatic adenocarcinoma

BACKGROUND:

The homeobox gene HOXB7 is overexpressed across a range of cancers and promotes tumorigenesis through varying effects on proliferation, survival, invasion, and angiogenesis. Although published microarray data suggest HOXB7 is overexpressed in pancreatic ductal adenocarcinoma (PDAC), its function in pancreatic cancer has not been studied.

METHODS:

HOXB7 message and protein levels were examined in PDAC cell lines and patient samples, as well as in normal pancreas. HOXB7 protein expression in patient tumors was determined by immunohistochemistry and correlated with clinicopathologic factors and survival. The impact of HOXB7 on cell proliferation, growth, and invasion was assessed by knockdown and overexpression in PDAC cell lines. Candidate genes whose expression levels were altered following HOXB7 knockdown were determined by microarray analysis.

RESULTS:

HOXB7 message and protein levels were significantly elevated in PDAC cell lines and patient tumor samples relative to normal pancreas. Evaluation of a tissue microarray of 145 resected PDACs found high HOXB7 protein expression was correlated with lymph node metastasis (P = .034) and an independent predictor of worse overall survival in multivariate analysis (hazard ratio = 1.56, 95% confidence interval = 1.02‐2.39). HOXB7 knockdown or overexpression in PDAC cell lines resulted in decreased or increased invasion, respectively, without influencing proliferation or cell viability.

CONCLUSIONS:

HOXB7 is frequently overexpressed in PDAC, specifically promotes invasive phenotype, and is associated with lymph node metastasis and worse survival outcome. HOXB7 and its downstream targets may represent novel clinical biomarkers or targets of therapy for inhibiting the invasive and metastatic capacity of PDAC. Cancer 2013. © 2012 American Cancer Society.     

The regulation of hematopoietic stem cell and progenitor mobilization by chemokine SDF-1

The chemokine, stromal derived factor-1 (SDF1) has been shown to modulate the homing of stem cells to its site by mediating chemotaxis. We demontrated overexpression of SDF-1 induced mobilization of cells with stem cell potential (CFU-S, long-term reconstituting cells). Moreover, SDF-1 activated matrix metalloproteinase-9 induced in bone marrow (BM) cells, causing the release soluble Kit-ligand and permitting the transfer of hematopoietic stem cells (HSCs) from a quiescent to a proliferative niche. The role of SDF-1 in the process of HSC migration and the mechanism underlying this HSCs migration will be reviewed. These studies lay the foundation for using SDF-1 to induce mobilization of progenitor cells in a BM transplantation setting.     

Control of hematopoietic stem/progenitor cell fate by transforming growth factor-beta

A major obstacle to the use of adult somatic stem cells for cell therapy is our current inability to fully exploit stem cell self-renewal properties. The challenge is to obtain defined culture systems where cycling of primitive stem/progenitor cells is stimulated, while their differentiation and senescence are prevented. The cytokine transforming growth factor-beta1 (TGF-beta1) appears as a potential regulator of hematopoietic stem/ progenitor cell self-renewal, as it participates in the control of cell proliferation, survival/apoptosis, and cell immaturity/differentiation. TGF-beta1 acts via a complex regulatory network involving intracellular signaling molecules and cell surface receptors. According to the High Proliferative Potential-Quiescent (HPP-Q) cell working model that we introduced previously, TGF-beta1 maintains primitive hematopoietic stem/progenitor cells in a quiescent or slow cycling state, in part by downmodulating the cell surface expression of mitogenic cytokine receptors, thus preventing cells from responding rapidly to a mitogenic signal. We have established that this modulation concerns the tyrosine kinase receptors KIT and FLT3, and the IL-6 receptor (IL-6R), three important cytokine receptors controlling early human hematopoietic stem/progenitor cell development. In this article. we show a similar modulation by TGF-beta1 of a fourth receptor: the TPO receptor (MPL). As a consequence, TGF-beta1 decreased the cell cycle entry of stem/progenitor cells stimulated by the respective ligands of these receptors, the cytokines SF, FL, IL-6, and TPO, whereas neutralization of TGF-beta1 increased the cell responsiveness to these mitogenic cytokines. Other aspects of the function of TGF-beta1 in the regulation of early hematopoiesis (i.e., the control of stem/progenitor cell survival and immaturity) are reviewed in the discussion.     

CD105 (endoglin) expression on hematopoietic stem/progenitor cells

Endoglin (CD105) is a component of the transforming growth factor-beta (TGF-beta) receptor (TGF-betaR) complex. Together with betaglycan, CD105 is considered as a TGF-betaR accessory molecule (also called TGF-betaRIII), but its functions in the receptor-ligand interactions are still poorly understood. A small subset of human CD34+ hematopoietic stem/progenitor cells that has phenotypic and functional features suggestive of very primitive hematopoietic cells expresses the CD105 antigen. CD34+/CD105+ cells recirculate in the peripheral blood of mobilized subjects and can be purified by immunomagnetic isolation strategies. The hematopoietic potential of these CD34+/CD105+ cells appears to be sustained by a combination of hematopoietic and non-hematopoietic cytokines, which comprises Flt3 ligand, erythropoietin, interleukin-15 and vascular endothelial growth factor. Endogenous TGF-beta1 is a crucial factor for the maintenance of CD34+/CD105+ immaturity acting through positive modulation of both CD105 and CD34 molecules in the absence of relevant effects on the cell cycle profile. CD105 is absent on very primitive CD34-/lineage-/CD45+ (CD34-Lin-) human hematopoietic cells isolated from cord blood. However, in vitro exposure of CD34-Lin- cells to exogenous TGF-beta1 causes the appearance of a discrete population of CD34+/CD105+ cells. Collectively, available data on CD105 expression and function in primitive hematopoiesis indicate that this molecule could cooperate with the dissociation of TGF-beta1 cell cycle effects from its other effects on cell survival and differentiation.     

FGF9 promotes cell proliferation and tumorigenesis in TM3 mouse Leydig progenitor cells

Fibroblast growth factor 9 (FGF9) modulates cell proliferation, differentiation and motility for development and tissue repair in normal cells. Growing evidence shows that abnormal activation of FGF9 signaling is associated with tumor malignancy. We have previously reported that FGF9 increases MA-10 mouse Leydig tumor cell proliferation, in vitro, and tumor growth, in vivo. Also, FGF9 promotes the tumor growth and liver metastasis of mouse Lewis lung cancer cells, in vivo. However, the effects of FGF9 in the early stage of tumorigenesis remains elusive. In this study, TM3 mouse Leydig progenitor cells, that are not tumorigenic in immunocompromised mice, were used as a model cell line to investigate the role of FGF9 in tumorigenesis. The results demonstrated that FGF9 significantly induced cell proliferation and activated the MAPK, PI3K and PLCγ signaling pathways in TM3 cells. The percentage of the cell number in G1 phase was reduced and that in S and G2/M phases was increased after FGF9 stimulation in TM3 cells. Cyclin D1, cyclin A1, CDK2, CDK1, and p21 expressions and the phosphorylation level of Rb were all induced in FGF9-treated TM3 cells. In addition, FGF9 increased the expression of FGF receptor 1-4 in TM3 cells, suggesting the positive feedback loop between FGF9 and FGFRs. Furthermore, in the allograft mouse model, FGF9 promoted the tumorigenesis of TM3 cells characterized by higher expression of tumor markers, such as tumor necrosis factor alpha (TNFα) and α-fetoprotein (AFP), in the subcutaneously inoculated TM3 cell tissue. Conclusively, FGF9 induced cell cycle to increase cell proliferation of TM3 cells through FAK, MAPK, PI3K/Akt and PLCγ signaling pathways, in vitro, and promoted the tumorigenesis of TM3 cell allograft tissue, in vivo, which is a potential marker for tumor as well as a target for cancer therapeutic strategies.     

Enforced expression of RASAL1 suppresses cell proliferation and the transformation ability of gastric cancer cells

RAS protein activator like 1 (RASAL1) is a member of the RAS GTPase-activating protein (GAP) family, and it is an important molecule in the regulation of RAS activation. In the present study, we investigated the role of RASAL1 in gastric carcinogenesis. Decreased expression pattern of RASAL1 in gastric cancer tissues and cell lines was found in protein and RNA levels, although there was no statistically significant relationship between RASAL1 and clinicopathological features. Restored expression of RASAL1 induced by DNA methylation inhibitor 5-aza-2'-deoxycytidine (5'-AZA) and HDAC inhibitor trichostatin A (TSA) implied that RASAL1 expression is regulated by epigenetic mechanisms. The biological role of RASAL1 in gastric carcinogenesis was determined by in?vitro tumorigenicity assays. Overexpression of RASAL1 showed suppression of cell proliferation due to cell apoptosis. Subsequently, enforced expression of RASAL1 repressed significantly the gastric cancer cell transformation ability. These findings demonstrated that decreased RASAL1 expression is a characteristic of gastric cancer and regulated by epigenetic mechanisms. RASAL1 may be a functional tumor suppressor involved in gastric cancer. This study provides novel insights into the biological role of RASAL1 in gastric carcinogenesis.     

Generation and characterization of a novel hematopoietic progenitor cell line with DC differentiation potential.

Studies of hematopoietic stem cell (HSC)-derived dendritic cells (DCs) are often limited by the rarity of HSC. To facilitate the study of DCs, we have generated a novel cell line (CR1) by retroviral Notch(IC) gene transfer into Sca1(+)ckit(+)lin- HSC. CR1 cells proliferated in vitro in the presence of recombinant interleukin-3. They maintained an immature progenitor cell phenotype and an intact karyotype. In the presence of granulocyte-macrophage colony-stimulating factor or Flt3L, CR1 cells differentiated into myeloid and plasmacytoid DCs, respectively. Functionally, CR1 cells were comparable to primary bone-marrow-derived DCs with respect to Toll-like-receptor-mediated maturation, cytokine release and capacity to induce effective antitumor immunity. CR1 cells thus provide an elegant new cellular tool to study DC development, function and preclinical DC-based immunotherapies.     

The Zn-finger domain of RIZ protein promotes MCF-7 cell proliferation

In order to understand the oncogenic properties of retinoblastoma-interacting zinc-finger (RIZ) gene products, we produced an MCF-7-derived cell line expressing a fusion protein containing the zinc-finger (aa 359-497) domain of RIZ protein (MCF-7/znf). The Zn-finger domain contains three of the eight putative Zn-finger motifs and is located in proximity of the E1A-like domain containing the Rb protein-binding motif. The MCF-7/znf cells showed a higher growth rate than the parental or the control cell lines, both in hormone-deprived conditions or upon estrogen stimulation. Furthermore, they were less sensitive to the growth inhibitory effect of anti-estrogens and showed a higher level of expression of cyclin D1 and A. The expressed Zn-finger domain recombinant product was localized in the nucleus and in the nucleoli and its expression modified the pattern of actin staining in the cytoplasm. In conclusion the presented results indicated that the Zn-finger domain could be endowed with the putative oncogenic activity of RIZ2 gene product.     

CD34~ 细胞的体外定向诱导分化

目的 :研究CD34 细胞的体外定向诱导分化。方法 :利用吸附单克隆抗体 磁珠分离系统 (MACS)从外周血中分离CD34 细胞 ,加入白细胞介素 3(IL 3)、粒细胞 单核巨噬细胞集落刺激因子 (GM CSF)及G CSF培养 3天及 7天后取出用于细胞总数 ,CD34 细胞比例及粒系祖细胞检测。结果 :CD34 细胞在IL 3、G CSF、GM CSF刺激下 3天细胞总数扩增 5 1倍 ,7天细胞总数扩增 110倍。IL 3、G CSF、GM CSF可使CD34 细胞比例降低 ,且与时间呈正比 ,提示CD34 细胞向成熟细胞分化。粒系培养的集落数表明 ,IL 3、G CSF、GM CSF可使粒 单核巨噬系祖细胞 (CFU GM)在 3天和 7天时分别比对照组增加 8.44倍和 35 .0 8倍。结论 :含有IL 3、G CSF、GM CSF的细胞因子组合 ,可诱导CD34 细胞定向生成大量的粒系祖细胞和成熟粒细胞 ,输注后将可使患者白细胞得以迅速恢复 ,减少感染的发生率     

Mammary stem and progenitor cell regulation

Although mammary stem cells were first identified almost two decades ago, recent progress in the characterization of mouse and human mammary stem and progenitor cells has provided new insight into the regulation of their developmental hierarchy. In this review, we discuss the parameters that distinguish stem and progenitor cells from differentiated cells, as well as the signal transduction pathways that drive multilineage expansion. Lastly, we present the utility of modulating stem cell self-renewal through the use of inhibitors of the Notch and Wnt pathways.     

XB130 promotes bronchioalveolar stem cell and Club cell proliferation in airway epithelial repair and regeneration

Proliferation of bronchioalveolar stem cells (BASCs) is essential for epithelial repair. XB130 is a novel adaptor protein involved in the regulation of epithelial cell survival, proliferation and migration through the PI3K/Akt pathway. To determine the role of XB130 in airway epithelial injury repair and regeneration, a naphthalene-induced airway epithelial injury model was used with XB130 knockout (KO) mice and their wild type (WT) littermates. In XB130 KO mice, at days 7 and 14, small airway epithelium repair was significantly delayed with fewer number of Club cells (previously called Clara cells). CCSP (Club cell secreted protein) mRNA expression was also significantly lower in KO mice at day 7. At day 5, there were significantly fewer proliferative epithelial cells in the KO group, and the number of BASCs significantly increased in WT mice but not in KO mice. At day 7, phosphorylation of Akt, GSK-3β, and the p85α subunit of PI3K was observed in airway epithelial cells in WT mice, but to a much lesser extent in KO mice. Microarray data also suggest that PI3K/Akt-related signals were regulated differently in KO and WT mice. An inhibitory mechanism for cell proliferation and cell cycle progression was suggested in KO mice. XB130 is involved in bronchioalveolar stem cell and Club cell proliferation, likely through the PI3K/Akt/GSK-3β pathway.     

Increased Cul1 expression promotes melanoma cell proliferation through regulating p27 expression

Cullin1 (Cul1) serves as a rigid scaffold in SCF (Skp1/Cullin/Rbx1/F-box protein) complex, the largest family of ubiquitin-protein E3 ligases, and aberrant expression of Cul1 is involved in dysfunction of SCF E3 ligases. Previously, we found that Cul1 expression is increased in early stages of melanoma. In the present study, we further investigated the role of Cul1 in melanoma development. Our results showed that knockdown of Cul1 inhibits melanoma cell growth while overexpression of Cul1 enhances cell proliferation through the control of cell cycle progression. We also found that Cul1 regulates melanoma cell growth and cell cycle progression through degradation of p27 by functional SCFSkp2 complex. This study elucidates the role of Cul1 in melanoma cell proliferation and improves our understanding of increased expression of Cul1 in early stages of melanoma.