Stimulation of haemopoietic stem cell proliferation: Characteristics of the stimulator-producing cells

Media conditioned by regenerating murine bone marrow cells contain a stimulator of haemopoietic stem cell proliferation. Fractionated cell populations have been examined for production of this stimulatory activity in order to characterize its cellular source. The stimulator is produced by adherent, phagocytic radioresistant, Thy 1.2^?, Fc⁺ cells in a population concentrated in a density range of 1.064 – 1.072 g/ml. The results indicate that the producer cells reside in the heterogenous mononuclear phagocytic population of the bone marrow.     

Production of stem cell proliferation regulators by fractionated haemopoietic cell suspensions.

Fractionated cell populations from haemopoietic tissues have been examined for their yield of stem cell proliferation inhibitory or stimulatory activities. These activities show marked concentration differences depending on the proliferative state of the stem cells in the haemopoietic tissues investigated. However, irrespective of whether haemopoietic tissue contains stem cells which are actively or minimally proliferating, inhibitory activity is produced by cells with a density of 1.052-1.060 gm/cm³, whilst cells with density 1.064-1.072 gm/cm³ elaborate stimulatory material. From inhibitor/stimulator dose response studies, it is concluded that the control of stem cell proliferation is mediated by an appropriate balance of stimulatory and inhibitory factors which, however, are unlikely to be produced by the stem cells themselves.     

Spatial organisation of CFU-S proliferation regulators in the mouse femur

CFU-S proliferation can be regulated by an inhibitor and a stimulator which are produced locally in the bone marrow. The spatial distribution of cells elaborating these factors has been studied by separating marrow, zonally, into axial, marginal and bone-associated fractions and further separating the inhibitor and stimulator producing cells from these fractions by means of density cuts in bovine serum albumin. The inhibitor- and stimulator-producing cells are found respectively in bands of density < 1.064 g/cm³ and 1.064–1.072 g/cm³. Factors synthesised by these individual fractions were assayed for their ability to inhibit or stimulate CFU-S proliferation by thymidine suicide measurements. Axial cells contain a high concentration of inhibitor-producing cells but the marginal and bone fractions contain relatively few. Stimulator-producing cells have a very sharp gradient in the opposite direction with an extremely high concentration in the vicinity of the bone surface. These distributions fit with those of CFU-S proliferation and of fibroblastoid-CFC suggesting that the inhibitor-producing cell is an integral part of the micro-environment which maintains the stem cell's capacities while the stimulator-producing cell may be more closely associated with the differentiation processes which take place closer to the bone surface.     

Regulation of murine granulocyte-macrophage progenitor cell and haemopoietic stem cell proliferation by factors produced in human fetal liver

At early stages (11–14 weeks) of gestation in human fetal liver few granulocyte-macrophage colony-forming cells (GM-CFC) are in DNA synthesis, whereas later in gestation (> 14 weeks) a large proportion of GM-CFC are in S-phase [Moore M.A.S. & Williams N. (1973) Cell Tissue Kinet.6, 461].Incubation of normal murine bone marrow GM-CFC (approx. 40% in DNA synthesis) with a supernatant from an early human fetal liver (11–14 weeks), reduced the proportion synthesizing DNA to <5%. In contrast, the proportion of murine GM-CFC synthesizing DNA was not affected by incubation with a supernatant from a late fetal liver (> 14 weeks).GM-CFC that had been switched out of cycle by incubation with a supernatant from an early gestation human fetal liver were switched back into cycle following incubation with a late human fetal liver supernatant.It is likely that changes in the relative levels of a proliferation inhibitor and stimulator throughout gestation might control the proportion of GM-CFC in cycle. In normal murine bone marrow (NMBM) approx. 10% of the haematopoietic stem cells (CFU-S) are synthesizing DNA. The proportion of CFU-S synthesizing DNA was increased to approx. 40% by incubation with a human fetal liver supernatant from all gestational ages tested (11–18 weeks).The specificity of these CFU-S and GM-CFC proliferation regulators is well demonstrated by an early gestation human fetal liver supernatant which will stimulate CFU-S proliferation but inhibit GM-CFC proliferation.The inhibitor and stimulator of GM-CFC proliferation are both produced by non-adherent human fetal liver cells. The GM-CFC proliferation inhibitor has a mol. wt of > 100,000 and the stimulator a mol. wt of 30,000–50,000. In contradistinction, the CFU-S proliferation stimulator is produced by adherent human fetal liver cells and has a mol. wt of 30,000–50,000.     

Brain tumor stem cells: The cancer stem cell hypothesis writ large

Brain tumors, which are typically very heterogeneous at the cellular level, appear to have a stem cell foundation. Recently, investigations from multiple groups have found that human as well as experimental mouse brain tumors contain subpopulations of cells that functionally behave as tumor stem cells, driving tumor growth and generating tumor cell progeny that form the tumor bulk, but which then lose tumorigenic ability. In human glioblastomas, these tumor stem cells express neural precursor markers and are capable of differentiating into tumor cells that express more mature neural lineage markers. In addition, modeling brain tumors in mice suggests that neural precursor cells more readily give rise to full blown tumors, narrowing potential cells of origin to those rarer brain cells that have a proliferative potential. Applying stem cell concepts and methodologies is giving fresh insight into brain tumor biology, cell of origin and mechanisms of growth, and is offering new opportunities for development of more effective treatments. The field of brain tumor stem cells remains very young and there is much to be learned before these new insights are translated into new patient treatments.     

Stem cells: an autonomous cell producing system

Stem cells have been traditionally considered to be a reserve population, in which the primary control is the rate of differentiation. Alterations in proliferation rate are then considered to be the results of changes in the number of stem cells. This article suggests that perhaps the reverse is true, namely that the rate of stem cell production is primarily controlled, and not the number of stem cells.     

组蛋白去乙酰化酶抑制剂联合紫杉醇抑制宫颈癌细胞增殖的体外实验

目的：研究组蛋白去乙酰化酶抑制剂SAHA联合紫杉醇对宫颈癌HeLa细胞增殖的抑制效果及其机制。方法：设置空白对照组、紫杉醇（10 nmol/L）、SAHA（10 μmol/L）、紫杉醇（10 nmol/L）+SAHA（10 μmol/L）联合组,采用四甲基噻唑蓝（MTT）法检测各组HeLa细胞的生长抑制率,计算紫杉醇对HeLa细胞的IC₅₀。RT-PCR法检测各组HeLa细胞中抑癌基因p27 mRNA的相对表达,Western blot检测HeLa细胞乙酰化组蛋白H4（Ac-H4）的表达。结果：紫杉醇、SAHA、紫杉醇+SAHA联合组处理HeLa细胞24 h的相对抑制率分别为25.93%±5.32%、46.38%±3.66%、54.27%±4.02%,联合组抑制率与紫杉醇组相比明显升高,差异具有统计学意义（P < 0.01）;48 h的抑制率分别为29.12%±3.09%、65.26%±3.03%、77.02%±3.86%,联合组抑制率最强,显著高于SAHA组和紫杉醇组（P < 0.01）。经SAHA预处理后紫杉醇对HeLa细胞的IC₅₀较单独紫杉醇组均显著下降（P < 0.05或P < 0.01）。紫杉醇组、SAHA组、紫杉醇+SAHA联合组细胞中p27 mRNA的相对表达量分别为5.845±0.548、0.978±0.117和10.601±0.673,乙酰化组蛋白H4（Ac-H4）的相对表达分别为0.878±0.068、1.148±0.018、1.282±0.033,联合组中表达量均显著高于SAHA组和紫杉醇组（P均 < 0.01）。结论：SAHA联合紫杉醇在体外能显著抑制宫颈癌细胞HeLa的增殖,增强组蛋白乙酰化水平,诱导抑癌基因的表达。     

Thermal enhancement of oxaliplatin-induced inhibition of cell proliferation and cell cycle progression in human carcinoma cell lines

Hyperthermia is used to treat intraperitoneal colorectal carcinomatosis. In this setting, the molecular effects of oxaliplatin and hyperthermia, in combination and alone, were deciphered in ovarian and colon cancer cells. The combined antiproliferative effects of hyperthermia and oxaliplatin (Eloxatine?;) on human IGROV-1 ovarian carcinoma, Caco-2 and HT-29 colon carcinoma cell lines were investigated by cell viability test, cell cycle analysis and modulation of expression of cell cycle-related proteins. Oxaliplatin inhibited growth of all cell lines in a dose-dependent manner. The efficacy of the drug was markedly enhanced by concurrent exposure to mild heat shock (1?h, 42°C). In IGROV-1 cells, a low concentration (15?µg/ml) of oxaliplatin in combination with hyperthermia induced a transient G2/M arrest. In both colon carcinoma cell lines, a G1/S arrest with a reduction of the G0/G1 population occurred. In IGROV-1 and Caco-2 cells, growth arrest was accompanied by apoptosis as suggested by the appearance of sub-G1 population. Time-course changes of cell cycle regulatory proteins levels revealed accumulation of cyclins A and B as well as of cdc2 and cdk2 upon exposure of IGROV-1 cells to hyperthermia and oxaliplatin. In this cell line, p53 appeared to be implicated in both G2/M arrest and apoptosis. G1/S arrest of HT-29 cells was linked to up-regulation of cyclin E and p27^Kip1 and accumulation of the hypophosphorylated form of pRB, whereas in Caco-2 cells only the hyperphosphorylated form was detected as well as a down-regulation of the proto-oncogene c-myc. Taken together, the results of these in vitro studies suggest that hyperthermia and oxaliplatin might elicit antiproliferative effects by modulating the expression of cell cycle regulatory proteins through different signalling pathways.     

Role of MAP kinase in the enhanced cell proliferation of long term estrogen deprived human breast cancer cells

Women with estrogen receptor (ER) positive breast cancers frequently respond initially to inhibition of estrogen action but later relapse with re-growth of tumor. Previously, we have utilized MCF-7 human breast cancer cells deprived of estradiol long term (LTED cells) as the model system to study the regrowth phenomenon and have demonstrated that these cells exhibited increased cell proliferation rate and increased ER functionality during the adaptive processes. In this report, we examined the hypothesis that the mitogen-activated protein kinase (MAP kinase) signal was involved. We found that activated MAP kinase was elevated in LTED cells and that the MAP kinase specific inhibitor PD98059 was able to inhibit the elevated MAP kinase and [³H]thymidine uptake in LTED cells, suggesting mediation of DNA synthesis and proliferation by the MAP kinase pathway. Other MAP kinase upstream inhibitors, including genestein, RG13022, and mevastatin were also able to inhibit the [³H]thymidine uptake in LTED cells. Interestingly, the antiestrogen, ICI 182,780 was able to block the activated MAP kinase in LTED cells. Treatment with PD98059 did not block elevated basal ERE-CAT activity while at the same time inhibiting [³H]thymidine uptake in LTED cells. Furthermore, treatment with PD98059 partially blocked the E₂-stimulated ERE-CAT activity and [³H]thymidine uptake in both LTED and in wild type cells, indicating that both MAP kinase-dependent and MAP kinase-independent pathways are involved in the transactivation function of ER. Taken together, our data suggest that the MAP kinase pathway is, in part, involved in the adaptive process which results in enhanced DNA synthesis and cell proliferation in the absence of exogenous estrogen in LTED 3ptcells.     

Regulators of stem cell proliferation in the haemopoietic tissues of W/Wv and SI/SId mice

The presence of CFU-S proliferation stimulatory and inhibitory activities in the bone marrow and spleens of normal mice (+/+) and mice with mutations affecting the proliferative behaviour of stem cells (S1/S1^d and W/W^v) has been investigated.S1/S1^d and +/+ bone marrow and spleen contain virtually no detectable stimulator but the corresponding tissues from W/W^v mice are both strongly stimulatory. SI/SI^d marrow in particular, but also +/+ marrow are strongly inhibitory whilst +/+ spleen, S1/SI^d spleen, W/W^v marrow and W/W^v spleen all contain inhibitory activity but at a lower specific activity.The data are compatible with studies of cell and tissue grafts that have indicated an intrinsic haemopoietic stem cell defect in W/W^v mice and an extrinsic, microenvironmental defect in SI/SI^d mice. It is suggested that they are also compatible with defective regulatory interactions between stem cells and regulator-producing cells and that the W and S1 loci may code for products involved in the production of, or response to, CFU-S proliferation regulators.     

An inhibitor of murine stem cell proliferation produced by normal human bone marrow

Media conditioned by normal human bone marrow cells contain a specific inhibitor of haemopoietic stem cell proliferation. Molecular ultrafiltration and dose response studies indicate that it is similar to a previously described factor obtained from freshly isolated or long-term cultured murine bone marrow cells. It is suggested that the mechanisms involved in the control of murine and human stem cell proliferation may be essentially identical.     

Bruceantin inhibits multiple myeloma cancer stem cell proliferation

Multiple myeloma (MM) continues to claim the lives of a majority of patients. MM cancer stem cells (CSCs) have been demonstrated to sustain tumor growth. Due to their ability to self-renew and to express detoxifying enzymes and efflux transporters, MM-CSCs are rendered highly resistant to conventional therapies. Therefore, managing MM-CSCs characteristics could have profound clinical implications. Bruceantin (BCT) is a natural product previously demonstrated to inhibit the growth of MM in RPMI 8226 cells-inoculated mouse xenograft models, and to cause regression in already established tumors. The objectives of the present study were to test the inhibitory effects of BCT on MM-CSCs growth derived from a human primary tumor, and to explore a mechanism of action underlying these effects. BCT exhibited potent antiproliferative activity in MM-CSCs starting at 25 nM. BCT induced cell cycle arrest, cell death and apoptosis in MM-CSCs as well as inhibited cell migration and angiogenesis in vitro. Using a qPCR screen, it was found that the gene expression of a number of Notch pathway members was altered. Pretreatment of MM-CSCs with the γ-secretase inhibitor RO4929097, a Notch pathway inhibitor, reversed BCT-induced effects on MM-CSCs proliferation. In this study, BCT was shown to be an effective agent in controlling the proliferation, viability and migration of MM-CSCs as well as angiogenesis in vitro. The effect on MM-CSCs proliferation may be mediated by the Notch pathway. These results warrant further investigation of BCT in a broader set of human-derived MM-CSCs and with in vivo models representative of MM.     

新型CRM1抑制剂S109通过阻断核输出抑制非小细胞肺癌细胞增殖

目的：研究新型染色体区域稳定蛋白1（chromosome region maintenance 1, CRM1)抑制剂S109对非小细胞肺癌细胞增殖的影响及其机制。方法： S109作用于非小细胞肺癌细胞株H1975和H1650,以CCK-8法检测其对细胞生长的影响,以EdU法检测细胞中对细胞增殖的影响,以集落形成实验检测对细胞克隆形成能力的影响,以流式细胞术检测其对细胞周期的影响,以免疫荧光法检测对核输出标志蛋白RanBP1细胞内定位的影响,以Western blotting检测对细胞中CRM1和Cyclin D1蛋白表达的影响。结果： S109（0.04、0.2、1、5、25和50 μmol/L）可以剂量依赖方式显著抑制非小细胞肺癌H1975和H1650细胞生长（IC50值分别为1.4和1.2 μmol/L）;2和4 μmol/L的S109均可以显著抑制非小细胞肺癌增殖\[（51.3±28）%、（23.2±21）% vs（100±1.2）%, P<0.01\]和克隆形成\[（43.6±3.2）%、（26.8±2.8）% vs（100±1.4）%, P<001\],并使细胞阻滞在G1期（G1期细胞数量由50.5%增加至74.9%）。S109可以特异性抑制核质转运标志蛋白RanBP1的核输出,并诱导CRM1蛋白降解。结论： S109通过特异性抑制CRM1功能阻断核输出,从而抑制非小细胞肺癌细胞增殖并阻滞细胞周期。     

Regeneration of irradiated salivary glands with stem cell marker expressing cells

Background

Stem cell therapy could be a potential way for reducing radiation-induced hyposalivation and improving the patient’s quality of life. However, the identification and purification of salivary gland stem cells have not been accomplished. This study aims to better characterize the stem/progenitor cell population with regenerative potential residing in the mouse salivary gland.

Methods

Mouse submandibular gland tissue, isolated cells and cultured 3 day old salispheres were tested for their expression of stem cell markers c-Kit, CD133, CD49f, and CD24 using immunohistochemistry for tissue and flow cytometry for cells. Mice were locally irradiated with a single dose of 15 Gy and transplanted with cells expressing defined markers.

Results

Cells expressing known stem cell markers are localized in the larger ducts of the mouse salivary gland. Isolated cells and cells from day 3 salispheres also express these markers: c-Kit (0.058% vs. 0.65%), CD133 (6% vs. 5%), CD49f (78% vs. 51%), and CD24 (60% vs. 60%, respectively). Intraglandular transplantation of these cells into irradiated salivary glands of mice resulted in stem cell marker-specific recovery of salivary gland function.

Conclusions

Different stem cell-associated markers are expressed in mouse salivary gland cells, which upon transplantation are able to regenerate the irradiation damaged salivary gland.     

Suppression of cell proliferation, induction of apoptosis and cell cycle arrest: chemopreventive activity of vanadium in vivo and in vitro

In the present study, the authors evaluated the anticancer mechanism of vanadium, a dietary micronutrient and an important pharmacological agent, on a defined model of chemically induced rat mammary carcinogenesis in vivo and on human breast cancer cell line MCF7 in vitro. Female Sprague-Dawley rats were treated with 7,12-dimethylbenz(alpha)anthracene (0.5 mg/100 g body weight) by a single tail vein injection in an oil emulsion to induce mammary preneoplasia. Vanadium (ammonium monovanadate) at a concentration of 0.5 ppm (4.27 micromol/l) was supplemented in drinking water and given ad libitum to the experimental groups for 24 weeks. Histological finding showed substantial repair of hyperplastic lesions. There was a significant reduction in incidence, multiplicity (34%, p < 0.01), size of palpable mammary tumors and delay in mean latency period of tumor appearance. Immunohistochemical analysis in vivo indicated a decrease in cell proliferation (24.68% p < 0.05) and an increase among the TUNEL-positive apoptotic cells along with strong expressions of p53 and Bax, and downregulation of Bcl2 proteins in the mammary tissue of vanadium-treated animals. Further, MCF7 cells were cultured in minimal essential medium and were treated with 100, 175 and 250 microM of vanadium (ammonium monovanadate) for 36 hr. Exposure of MCF7 cells to vanadium led to induction of apoptosis in a dose-dependent manner. It was found further that vanadium treatment brought about a prominent cell cycle arrest and chromosomal condensation, leading to apoptosis (42.62%, p < 0.05). Results of both the in vivo and in vitro study demonstrate that vanadium has the potential to be developed into an anti-breast cancer drug in the near future.     

Identification of brain tumour initiating cells using the stem cell marker aldehyde dehydrogenase

Aldehyde dehydrogenase (ALDH) has been identified in stem cells from both normal and cancerous tissues. This study aimed to evaluate the potential of ALDH as a universal brain tumour initiating cell (BTIC) marker applicable to primary brain tumours and their biological role in maintaining stem cell status.Cells from various primary brain tumours (24 paediatric and 6 adult brain tumours) were stained with Aldefluor and sorted by flow cytometry. We investigated the impact of ALDH expression on BTIC characteristics in vitro and on tumourigenic potential in vivo.Primary brain tumours showed universal expression of ALDH, with 0.3–28.9% of the cells in various tumours identified as ALDH⁺. The proportion of CD133⁺ cells within ALDH⁺ is higher than ALDH cells. ALDH⁺ cells generate neurospheres with high proliferative potential, express neural stem cell markers and differentiate into multiple nervous system lineages. ALDH⁺ cells tend to show high expression of induced pluripotent stem cell-related genes. Notably, targeted knockdown of ALDH1 by shRNA interference in BTICs potently disturbed their self-renewing ability. After 3 months, ALDH⁺ cells gave rise to tumours in 93% of mice whereas ALDH cells did not. The characteristic pathology of mice brain tumours from ALDH⁺ cells was similar to that of human brain tumours, and these cells are highly proliferative in vivo.Our data suggest that primary brain tumours contain distinct subpopulations of cells that have high expression levels of ALDH and BTIC characteristics. ALDH might be a potential therapeutic target applicable to primary brain tumours.     

Profiling and targeting of cellular bioenergetics: inhibition of pancreatic cancer cell proliferation

Background:

Targeting both mitochondrial bioenergetics and glycolysis pathway is an effective way to inhibit proliferation of tumour cells, including those that are resistant to conventional chemotherapeutics.

Methods:

In this study, using the Seahorse 96-well Extracellular Flux Analyzer, we mapped the two intrinsic cellular bioenergetic parameters, oxygen consumption rate and proton production rate in six different pancreatic cancer cell lines and determined their differential sensitivity to mitochondrial and glycolytic inhibitors.

Results:

There exists a very close relationship among intracellular bioenergetic parameters, depletion of ATP and anti-proliferative effects (inhibition of colony-forming ability) in pancreatic cancer cells derived from different genetic backgrounds treated with the glycolytic inhibitor, 2-deoxyglucose (2-DG). The most glycolytic pancreatic cancer cell line was exquisitely sensitive to 2-DG, whereas the least glycolytic pancreatic cancer cell was resistant to 2-DG. However, when combined with metformin, inhibitor of mitochondrial respiration and activator of AMP-activated protein kinase, 2-DG synergistically enhanced ATP depletion and inhibited cell proliferation even in poorly glycolytic, 2-DG-resistant pancreatic cancer cell line. Furthermore, treatment with conventional chemotherapeutic drugs (e.g., gemcitabine and doxorubicin) or COX-2 inhibitor, celecoxib, sensitised the cells to 2-DG treatment.

Conclusions:

Detailed profiling of cellular bioenergetics can provide new insight into the design of therapeutic strategies for inhibiting pancreatic cancer cell metabolism and proliferation.     

Cytomegalovirus diseases after hematopoietic stem cell transplantation: A mini-review

Cytomegalovirus (CMV) infection remains a significant complication after hematopoietic stem cell transplantation (HSCT) and may have a deleterious impact on the overall outcome after transplantation. In addition to the direct effects of CMV infection, tissue-invasive CMV diseases may be associated with increased risk of graft versus host disease, myelosuppression, and invasive bacterial and fungal infections. Because of these direct and indirect adverse effects, prevention of CMV infection, mostly through pre-emptive therapy, is one of the essential strategies that may improve outcomes of HSCT recipients. Management of CMV infection relies mainly on intravenous (IV) antiviral therapy with ganciclovir and foscarnet, with or without IV polyclonal immunoglobulins. Although viral resistance remains rare, better tolerated antiviral agents with less serious side effects are needed, and a few will be evaluated in phase III clinical trials in the near future.     

Selective inhibition of cyclooxygenase (COX)-2 inhibits endothelial cell proliferation by induction of cell cycle arrest

High-level expression of cyclooxygenase (COX)-2 is reported in 80-90% of colorectal adenocarcinomas. Selective inhibition of COX-2 was shown to reduce colorectal tumorigenesis in different models of carcinogenesis and to prevent metastasis in xenograft tumor models, as well as to suppress in vitro induced angiogenesis. Recently, COX-2 was reported to be expressed not only in malignant epithelial cells, but also in the neovasculature that feeds the tumor in a variety of solid human cancers. Thus, one of the possible mechanisms by which selective COX-2 inhibitor reduces tumor growth and metastasis is through inhibition of tumor angiogenesis. Although a report suggested a possible role of endothelial COX-1 in the process of angiogenesis, in a recent study, the selective inhibition of COX-2 was shown to strongly inhibit angiogenesis by inducing endothelial cell (EC) apoptosis. In the present study, using human umbilical vein endothelial cells (HUVECs) as a model of angiogenesis, we investigated the potential antiangiogenic effect of the selective COX-2 inhibitor and its mechanism of action, and clearly demonstrated that selective inhibition of COX-2 caused a dose-dependent decrease in the proliferative activity of ECs, as well as an inhibition of capillary-like tube formation. The inhibitory effect on EC proliferation was dependent on the cell cycle arrest to the G1 phase and not on cell apoptosis.