Multilevel targeting of hematopoietic stem cell self-renewal, differentiation and apoptosis for leukemia therapy

Searching for Essential Genes and Targeted Drugs Common to Breast Cancer and Osteoarthritis

BACKGROUND

It is documented that osteoarthritis can promote the progression of breast cancer (BC).

OBJECTIVE

This study aims to search for the essential genes associated with breast cancer (BC) and osteoarthritis (OA), explore the relationship between epithelial-mesenchymal transition (EMT)- related genes and the two diseases, and identify the candidate drugs.

METHODS

The genes related to both BC and OA were determined by text mining. Protein-protein Interaction (PPI) analysis was carried out, and as a result, the exported genes were found to be related to EMT. PPI and the correlation of mRNA of these genes were also analyzed. Different kinds of enrichment analyses were performed on these genes. A prognostic analysis was performed on these genes for examining their expression levels at different pathological stages, in different tissues, and in different immune cells. Drug-gene interaction database was employed for potential drug discovery.

RESULTS

A total number of 1422 genes were identified as common to BC and OA and 58 genes were found to be related to EMT. We found that HDAC2 and TGFBR1 were significantly poor in overall survival. High expression of HDAC2 plays a vital role in the increase of pathological stages. Four immune cells might play a role in this process. Fifty-seven drugs were identified that could potentially have therapeutic effects.

CONCLUSION

EMT may be one of the mechanisms by which OA affects BC. Using the drugs can have potential therapeutic effects, which may benefit patients with both diseases and broaden the indications for drug use.

Chromosomal Analysis in Lineage-Specific Mouse Hematopoietic Stem Cells and Progenitors

Hematopoiesis is maintained throughout life from the hematopoietic stem cell niche in which hematopoietic stem cells and lineage-specific hematopoietic progenitors (HSPCs) reside and regulate hematopoiesis. Meanwhile, HSPCs behavior is modulated by both cell intrinsic (e.g., transcriptional factors) and cell extrinsic (e.g., cytokines) factors. Dysregulation of these factors can alter HSPCs function, leading to disrupted hematopoiesis, cellular changes, and subsequent hematological diseases and malignancies. Moreover, it has been reported that chromosomal aberration (CA) in HSPCs following exposure to carcinogenic or genotoxic agents can initiate leukemia stem cells (LSCs) formation which lays a fundamental mechanism in leukemogenesis. Despite reported studies concerning the chromosomal integrity in HSPCs, CA analysis in lineage-specific HSPCs remains scarce. This indicates a need for a laboratory technique that allows the study of CA in specific HSPCs subpopulations comprising differential hematopoietic lineages. Thus, this chapter focuses on the structural (clastogenicity) and numerical (aneugenicity) form of CA analysis in lineage-specific HSPCs comprised of myeloid, erythroid and lymphoid lineages.In this protocol, we describe how to perform CA analysis in lineage-specific HSPCs derived from freshly isolated mouse bone marrow cells (MBMCs) using the combined techniques of colony-forming unit (CFU) and karyotyping. Prior to CA analysis, lineage-specific HSPCs for myeloid, erythroid, and lymphoid were enriched through colony-forming unit (CFU) assay. CFU assay assesses the proliferative ability and differentiation potential of an individual HSPC within a sample. About 6 to 14 days of cultures are required depending on the type of HSPCs lineage. The optimal duration is crucial to achieve sufficient colony growth that is needed for accurate CFU analysis via morphological identification and colony counting. Then, the CA focusing on clastogenicity and aneugenicity anomalies in respective HSPCs lineage for myeloid, erythroid and Pre-B lymphoid were investigated. The resulted karyotypes were classified according to the types of CA known as Robertsonian (Rb) translocation, hyperploidy or complex. We believe our protocol offers a significant contribution to be utilized as a reference method for chromosomal analysis in lineage-specific HSPCs subpopulations.

Circulating Biomarkers Associated with the Diagnosis and Prognosis of B-Cell Progenitor Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is a hematological disease characterized by the dysfunction of the hematopoietic system that leads to arrest at a specific stage of stem cells development, suppressing the average production of cellular hematologic components. BCP-ALL is a neoplasm of the B-cell lineage progenitor. BCP-ALL is caused and perpetuated by several mechanisms that provide the disease with its tumor potential and genetic and cytological characteristics. These pathological features are used for diagnosis and the prognostication of BCP-ALL. However, most of these paraclinical tools can only be obtained by bone marrow aspiration, which, as it is an invasive study, can delay the diagnosis and follow-up of the disease, in addition to the anesthetic risk it entails for pediatric patients. For this reason, it is crucial to find noninvasive and accessible ways to supply information concerning diagnosis, prognosis, and the monitoring of the disease, such as circulating biomarkers. In oncology, a biomarker is any measurable indicator that demonstrates the presence of malignancy, tumoral behavior, prognosis, or responses to treatments. This review summarizes circulating molecules associated with BCP-ALL with potential diagnostic value, classificatory capacity during monitoring specific clinic features of the disease, and/or capacity to identify each BCP-ALL stage regarding its evolution and outcome of the patients with BCP-ALL. In the same way, we provide and classify biomarkers that may be used in further studies focused on clinical approaches or therapeutic target identification for BCP-ALL.

Clastogenicity and Aneugenicity of 1,4-Benzoquinone in Different Lineages of Mouse Hematopoietic Stem/Progenitor Cells

Previous reports on hematotoxicity and leukemogenicity related to benzene exposure highlighted its adverse effects on hematopoiesis. Despite the reported findings, studies concerning the mechanism of benzene affecting chromosomal integrity in lineage-committed hematopoietic stem/progenitor cells (HSPCs) remain unclear. Here, we studied the clastogenicity and aneugenicity of benzene in lineage-committed HSPCs via karyotyping. Isolated mouse bone marrow cells (MBMCs) were exposed to the benzene metabolite 1,4-benzoquinone (1,4-BQ) at 1.25, 2.5, 5, 7, and 12 μM for 24 h, followed by karyotyping. Then, the chromosomal aberration (CA) in 1,4-BQ-exposed hematopoietic progenitor cells (HPCs) comprising myeloid, Pre-B lymphoid, and erythroid lineages were evaluated following colony-forming cell (CFC) assay. Percentage of CA, predominantly via Robertsonian translocation (Rb), was increased significantly (p < 0.05) in MBMCs and all progenitors at all concentrations. As a comparison, Pre-B lymphoid progenitor demonstrated a significantly higher percentage of CA (p < 0.05) than erythroid progenitor at 1.25, 2.5, and 7 μM as well as a significantly higher percentage (p < 0.05) than myeloid progenitor at 7 μM of 1,4-BQ. In conclusion, 1,4-BQ induced CA, particularly via Rb in both MBMCs and HPCs, notably via a lineage-dependent response. The role of lineage specificity in governing the clastogenicity and aneugenicity of 1,4-BQ deserves further investigation.

Isobavachalcone inhibits acute myeloid leukemia: Potential role for ROS-dependent mitochondrial apoptosis and differentiation

Isobavachalcone (IBC) has been shown to induce apoptosis and differentiation of acute myeloid leukemia (AML) cells. However, the underlying molecular mechanisms are not fully understood. Herein, IBC exhibited significant inhibition on the cell viability, proliferation, and the colony formation ability of AML cells. Moreover, IBC induced mitochondrial apoptosis evidenced by reduced mitochondrial membrane potential, increased Bax level, decreased Bcl-2, Bcl-xL, and Mcl-1 levels, elevated cytochrome c level in the cytosol and increased cleavage of caspase-9, caspase-3, and PARP. Furthermore, IBC obviously promoted the differentiation of AML cells, accompanied by the increase of the phosphorylation of MEK and ERK and the C/EBPα expression as well as the C/EBPβ LAP/LIP isoform ratio, which was significantly reversed by U0126, a specific inhibitor of MEK. Notably, IBC enhanced the intracellular ROS level. More importantly, IBC-induced apoptosis and differentiation of HL-60 cells were significantly mitigated by NAC. In addition, IBC also exhibited an obvious anti-AML effect in NOD/SCID mice with the engraftment of HL-60 cells. Together, our study suggests that the ROS-medicated signaling pathway is highly involved in IBC-induced apoptosis and differentiation of AML cells.

Genetic, epigenetic, and lineage-directed mechanisms in benzene-induced malignancies and hematotoxicity targeting hematopoietic stem cells niche

Benzene is a known hematotoxic and leukemogenic agent with hematopoietic stem cells (HSCs) niche being the potential target. Occupational and environmental exposure to benzene has been linked to the incidences of hematological disorders and malignancies. Previous studies have shown that benzene may act via multiple modes of action targeting HSCs niche, which include induction of chromosomal and micro RNA aberrations, leading to genetic and epigenetic modification of stem cells and probable carcinogenesis. However, understanding the mechanism linking benzene to the HSCs niche dysregulation is challenging due to complexity of its microenvironment. The niche is known to comprise of cell populations accounted for HSCs and their committed progenitors of lymphoid, erythroid, and myeloid lineages. Thus, it is fundamental to address novel approaches via lineage-directed strategy to elucidate precise mechanism involved in benzene-induced toxicity targeting HSCs and progenitors of different lineages. Here, we review the key genetic and epigenetic factors that mediate hematotoxicological effects by benzene and its metabolites in targeting HSCs niche. Overall, the use of combined genetic, epigenetic, and lineage-directed strategies targeting the HSCs niche is fundamental to uncover the key mechanisms in benzene-induced hematological disorders and malignancies.

Leukemia stem cells promote chemoresistance by inducing downregulation of lumican in mesenchymal stem cells

Leukemia stem cells (LSCs) are responsible for therapeutic failure and relapse of acute lymphoblastic leukemia. As a result of the interplay between LSCs and bone marrow mesenchymal stem cells (BM-MSCs), cancer cells may escape from chemotherapy and immune surveillance, thereby promoting leukemia progress and relapse. The present study identified that the crosstalk between LSCs and BM-MSCs may contribute to changes of immune phenotypes and expression of hematopoietic factors in BM-MSCs. Furthermore, Illumina Genome Analyzer/Hiseq 2000 identified 7 differentially expressed genes between BM-MSCs^LSC and BM-MSCs. The Illumina sequencing results were further validated by reverse transcription-quantitative polymerase chain reaction. Following LSC simulation, 2 genes were significantly upregulated, whereas the remaining 2 genes were significantly downregulated in MSCs. The most remarkable changes were identified in the expression levels of lumican (LUM) gene. These results were confirmed by western blot analysis. In addition, decreased LUM expression led to decreased apoptosis, and promoted chemoresistance to VP-16 in Nalm-6 cells. These results suggest that downregulation of LUM expression in BM-MSCs contribute to the anti-apoptotic properties and resistance to chemotherapy in LSCs.

The Wave2 scaffold Hem-1 is required for transition of fetal liver hematopoiesis to bone marrow

The transition of hematopoiesis from the fetal liver (FL) to the bone marrow (BM) is incompletely characterized. We demonstrate that the Wiskott–Aldrich syndrome verprolin-homologous protein (WAVE) complex 2 is required for this transition, as complex degradation via deletion of its scaffold Hem-1 causes the premature exhaustion of neonatal BM hematopoietic stem cells (HSCs). This exhaustion of BM HSC is due to the failure of BM engraftment of Hem-1^−/− FL HSCs, causing early death. The Hem-1^−/− FL HSC engraftment defect is not due to the lack of the canonical function of the WAVE2 complex, the regulation of actin polymerization, because FL HSCs from Hem-1^−/− mice exhibit no defects in chemotaxis, BM homing, or adhesion. Rather, the failure of Hem-1^−/− FL HSC engraftment in the marrow is due to the loss of c-Abl survival signaling from degradation of the WAVE2 complex. However, c-Abl activity is dispensable for the engraftment of adult BM HSCs into the BM. These findings reveal a novel function of the WAVE2 complex and define a mechanism for FL HSC fitness in the embryonic BM niche.

Hematopoietic stem cells (HSCs) migrate from the fetal liver to the bone marrow (BM) during embryogenesis. Here the authors show that the WAVE2 complex scaffold Hem1 is required for engraftment of HSCs in BM, not through its canonical role regulating actin polymerization, but through c-Abl survival signaling.

Hematopoietic stem cells from induced pluripotent stem cells - considering the role of microRNA as a cell differentiation regulator

Although hematopoietic stem cell (HSC) therapy for hematological diseases can lead to a good outcome from the clinical point of view, the limited number of ideal donors, the comorbidity of patients and the increasing number of elderly patients may limit the application of this therapy. HSCs can be generated from induced pluripotent stem cells (iPSCs), which requires the understanding of the bone marrow and liver niches components and function in vivo iPSCs have been extensively applied in several studies involving disease models, drug screening and cellular replacement therapies. However, the somatic reprogramming by transcription factors is a low-efficiency process. Moreover, the reprogramming process is also regulated by microRNAs (miRNAs), which modulate the expression of the transcription factors OCT-4 (also known as POU5F1), SOX-2, KLF-4 and MYC, leading somatic cells to a pluripotent state. In this Review, we present an overview of the challenges of cell reprogramming protocols with regard to HSC generation from iPSCs, and highlight the potential role of miRNAs in cell reprogramming and in the differentiation of induced pluripotent stem cells.

The NF-κB p65/miR-23a-27a-24 cluster is a target for leukemia treatment

p65 is a transcription factor that is involved in many physiological and pathologic processes. Here we report that p65 strongly binds to the miR-23a-27a-24 cluster promoter to up-regulate its expression. As bone marrow-derived cells differentiate into red blood cells in vitro, p65/miR-23a-27a-24 cluster expression increases sharply and then declines before the appearance of red blood cells, suggesting that this cluster is negatively related to erythroid terminal differentiation. Bioinformatic and molecular biology experiments confirmed that the miR-23a-27a-24 cluster inhibited the expression of the erythroid proteome and contributed to erythroleukemia progression. In addition, high level of the p65/miR-23a-27a-24 cluster was found in APL and AML cell lines and in nucleated peripheral blood cells from leukemia patients. Furthermore, anti-leukemia drugs significantly inhibited the expression of the p65/miR-23a-27a-24 cluster in leukemia cells. Administration of the p65 inhibitor parthenolide significantly improved hematology and myelogram indices while prolonging the life span of erythroleukemia mice. Meanwhile, stable overexpression of these three miRNAs in mouse erythroleukemia cells enhanced cell malignancy. Our findings thus connect a novel regulation pathway of the p65/miR-23a-27a-24 cluster with the erythroid proteome and provide an applicable approach for treating leukemia.

Potential Diagnostic, Prognostic and Therapeutic Targets of MicroRNAs in Human Gastric Cancer

Human gastric cancer (GC) is characterized by a high incidence and mortality rate, largely because it is normally not identified until a relatively advanced stage owing to a lack of early diagnostic biomarkers. Gastroscopy with biopsy is the routine method for screening, and gastrectomy is the major therapeutic strategy for GC. However, in more than 30% of GC surgical patients, cancer has progressed too far for effective medical resection. Thus, useful biomarkers for early screening or detection of GC are essential for improving patients' survival rate. MicroRNAs (miRNAs) play an important role in tumorigenesis. They contribute to gastric carcinogenesis by altering the expression of oncogenes and tumor suppressors. Because of their stability in tissues, serum/plasma and other body fluids, miRNAs have been suggested as novel tumor biomarkers with suitable clinical potential. Recently, aberrantly expressed miRNAs have been identified and tested for clinical application in the management of GC. Aberrant miRNA expression profiles determined with miRNA microarrays, quantitative reverse transcription-polymerase chain reaction and next-generation sequencing approaches could be used to establish sample specificity and to identify tumor type. Here, we provide an up-to-date summary of tissue-based GC-associated miRNAs, describing their involvement and that of their downstream targets in tumorigenic and biological processes. We examine correlations among significant clinical parameters and prognostic indicators, and discuss recurrence monitoring and therapeutic options in GC. We also review plasma/serum-based, GC-associated, circulating miRNAs and their clinical applications, focusing especially on early diagnosis. By providing insights into the mechanisms of miRNA-related tumor progression, this review will hopefully aid in the identification of novel potential therapeutic targets.

Hematopoietic stem cell transplantation for multiple sclerosis: is it a clinical reality?

Hematopoietic stem cell transplantation (HSCT) is a treatment paradigm that has long been utilized for cancers of the blood and bone marrow but has gained some traction as a treatment paradigm for multiple sclerosis (MS). Success in the treatment of patients with this approach has been reported primarily when strict inclusion criteria are imposed that have eventuated a more precise understanding of MS pathophysiology, thereby governing trial design. Moreover, enhancing the yield and purity of hematopoietic stem cells during isolation along with the utility of appropriate conditioning agents has provided a clearer foundation for clinical translation studies. To support this approach, preclinical data derived from animal models of MS, experimental autoimmune encephalomyelitis, have provided clear identification of multipotent stem cells that can reconstitute the immune system to override the autoimmune attack of the central nervous system. In this review, we will discuss the rationale of HSCT to treat MS by providing the benefits and complications of the clinically relevant protocols, the varying graft types, and conditioning regimens. However, we emphasize that future trials based on HSCT should be focused on specific therapeutic strategies to target and limit ongoing neurodegeneration and demyelination in progressive MS, in the hope that such treatment may serve a greater catchment of patient cohorts with potentially enhanced efficiency and lower toxicity. Despite these future ambitions, a proposed international multicenter, randomized clinical trial of HSCT should be governed by the best standard care of treatment, whereby MS patients are selected upon strict clinical course criteria and long-term follow-up studies of patients from international registries are imposed to advocate HSCT as a therapeutic option in the management of MS.

Arsenic Primes Human Bone Marrow CD34+ Cells for Erythroid Differentiation

Arsenic trioxide exhibits therapeutic effects on certain blood malignancies, at least partly by modulating cell differentiation. Previous in vitro studies in human hematopoietic progenitor cells have suggested that arsenic may inhibit erythroid differentiation. However, these effects were all observed in the presence of arsenic compounds, while the concomitant cytostatic and cytotoxic actions of arsenic might mask a prodifferentiating activity. To eliminate the potential impacts of the cytostatic and cytotoxic actions of arsenic, we adopted a novel protocol by pretreating human bone marrow CD34+ cells with a low, noncytotoxic concentration of arsenic trioxide, followed by assaying the colony forming activities in the absence of the arsenic compound. Bone marrow specimens were obtained from chronic myeloid leukemia patients who achieved complete cytogenetic remission. CD34+ cells were isolated by magnetic-activated cell sorting. We discovered that arsenic trioxide enhanced the erythroid colony forming activity, which was accompanied by a decrease in the granulomonocytic differentiation function. Moreover, in erythroleukemic K562 cells, we showed that arsenic trioxide inhibited erythrocyte maturation, suggesting that arsenic might have biphasic effects on erythropoiesis. In conclusion, our data provided the first evidence showing that arsenic trioxide could prime human hematopoietic progenitor cells for enhanced erythroid differentiation.

Genetic manipulation of RPS5 gene expression modulates the initiation of commitment of MEL cells to erythroid maturation: Implications in understanding ribosomopathies

Impairment of ribosome biogenesis contributes to the molecular pathophysiology of ribosomopathies by deregulating cell-lineage specific proliferation, differentiation and apoptosis decisions of haematopoietic progenitor cells. Here, using pro-erythroblast-like murine erythroleukemia (MEL) cells, a model system of erythroid maturation, we aimed to investigate whether genetic manipulation of RPS5 expression affects the capacity of cells to grow and differentiate in culture. Parental MEL cells stably transfected with full length RPS5 cDNA in sense (MEL-C14 culture) or antisense (MEL-antisenseRPS5 culture) orientation, as well as MEL cells transiently transfected with siRNAs specific for RPS5 gene silencing (MEL-RPS5siRNA culture) were assessed for their ability to fully execute their erythroid maturation program in culture. The data obtained thus far indicate that: a) MEL-antisenseRPS5 exhibit a pronounced delay in the initiation of differentiation, as well as an impairment of commitment, since the continuous presence of the inducer in culture is required for the cells to fully execute their erythroid maturation program. b) RNAi-mediating silencing of RPS5 gene expression resulted in the inability of MEL cells to differentiate; however, when these cells were allowed to recapitulate normal RPS5 gene expression levels they regained their differentiation capacity by accumulating high proportion of erythroid mature cells. c) Interestingly the latter, is accompanied by morphological changes of cells and an impairment of their proliferation and apoptosis potential. Such data for the first time correlate the RPS5 gene expression levels with the differentiation capacity of MEL cells in vitro, a fact that might also have implications in understanding ribosomopathies.

New insights into 4-amino-2-tri-fluoromethyl-phenyl ester inhibition of cell growth and migration in the A549 lung adenocarcinoma cell line

OBJECTIVE

The present study was designed to investigate the probable mechanisms of synthetic retinoid 4-amino-2-tri-fluoromethyl-phenyl ester (ATPR) inhibition of the proliferation and migration of A549 human lung carcinoma cells.

MATERIALS AND METHODS

After the A549 cells were treated with different concentrations of ATPR or all-trans retinoic acid (ATRA) for 72 h, scratch-wound assays were performed to assess migration. Immunofluorescence was used to determine the distribution of CAV1 and RXRα, while expression of CAV1, MLCK, MLC, P38, and phosphorylation of MLC and P38 were detected by Western blotting.

RESULTS

ATPR could block the migration of A549 cells. The relative migration rate of ML-7 group had significantly decreased compared with control group. In addition, ATPR decreased the expression of a migration related proteins, MLCK, and phosphorylation of MLC and P38. ATPR could also influence the expression of RARs or RXRs. At the same time, CAV1 accumulated at cell membranes, and RXRα relocated to the nucleus after ATPR treatment.

CONCLUSIONS

Caveolae may be implicate in the transport of ATPR to the nucleus. Change in the expression and distribution of RXRα may be implicated in ATPR inhibition of A549 cell proliferation. The mechanisms of ATPR reduction in A549 cell migration may be associated with expression of MLCK and phosphorylation of MLC and P38.

Vorinostat induces apoptosis and differentiation in myeloid malignancies: genetic and molecular mechanisms

Background

Aberrant epigenetic patterns are central in the pathogenesis of haematopoietic diseases such as myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML). Vorinostat is a HDACi which has produced responses in these disorders. The purpose of this study was to address the functional effects of vorinostat in leukemic cell lines and primary AML and MDS myeloid cells and to dissect the genetic and molecular mechanisms by which it exerts its action.

Methodology/Principal Findings

Functional assays showed vorinostat promoted cell cycle arrest, inhibited growth, and induced apoptosis and differentiation of K562, HL60 and THP-1 and of CD33⁺ cells from AML and MDS patients. To explore the genetic mechanism for these effects, we quantified gene expression modulation by vorinostat in these cells. Vorinostat increased expression of genes down-regulated in MDS and/or AML (cFOS, COX2, IER3, p15, RAI3) and suppressed expression of genes over-expressed in these malignancies (AXL, c-MYC, Cyclin D1) and modulated cell cycle and apoptosis genes in a manner which would favor cell cycle arrest, differentiation, and apoptosis of neoplastic cells, consistent with the functional assays. Reporter assays showed transcriptional effect of vorinostat on some of these genes was mediated by proximal promoter elements in GC-rich regions. Vorinostat-modulated expression of some genes was potentiated by mithramycin A, a compound that interferes with SP1 binding to GC-rich DNA sequences, and siRNA-mediated SP1 reduction. ChIP assays revealed vorinostat inhibited DNA binding of SP1 to the proximal promoter regions of these genes. These results suggest vorinostat transcriptional action in some genes is regulated by proximal promoter GC-rich DNA sequences and by SP1.

Conclusion

This study sheds light on the effects of vorinostat in AML and MDS and supports the implementation of clinical trials to explore the use of vorinostat in the treatment of these diseases.

MYC oncogene in myeloid neoplasias

MYC is a transcription factor that regulates many critical genes for cell proliferation, differentiation, and biomass accumulation. MYC is one of the most prevalent oncogenes found to be altered in human cancer, being deregulated in about 50 % of tumors. Although MYC deregulation has been more frequently associated to lymphoma and lymphoblastic leukemia than to myeloid malignancies, a body of evidence has been gathered showing that MYC plays a relevant role in malignancies derived from the myeloid compartment. The myeloid leukemogenic activity of MYC has been demonstrated in different murine models. Not surprisingly, MYC has been found to be amplified or/and deregulated in the three major types of myeloid neoplasms: acute myeloid leukemia, myelodysplastic syndromes, and myeloproliferative neoplasms, including chronic myeloid leukemia. Here, we review the recent literature describing the involvement of MYC in myeloid tumors.

Surface antigenic profiling of stem cells from human omentum fat in comparison with subcutaneous fat and bone marrow

Omentum fat derived stem cells have emerged as an alternative and accessible therapeutic tool in recent years in contrast to the existing persuasive sources of stem cells, bone marrow and subcutaneous adipose tissue. However, there has been a scanty citation on human omentum fat derived stem cells. Furthermore, identification of specific cell surface markers among aforesaid sources is still controversial. In lieu of this existing perplexity, the current research work aims at signifying omentum fat as a ground-breaking source of stem cells by surface antigenic profiling of stem cell population. In this study, we examined and compared the profiling of cell surface antigenic expressions of hematopoietic stem cells, mesenchymal stem cells, cell adhesion molecules and other unique markers such as ABCG2, ALDH and CD 117 in whole cell population of human omentum fat, subcutaneous fat and bone marrow. The phenotypic characterization through flowcytometry revealed the positive expressions of CD 34, CD 45, CD 133, HLADR, CD 90, CD 105, CD 73, CD 29, CD 13, CD 44, CD 54, CD 31, ALDH and CD 117 in all sources. The similarities between the phenotypic expressions of omentum fat derived stem cells to that of subcutaneous fat and bone marrow substantiates that identification of ultimate source for curative therapeutics is arduous to assess. Nevertheless, these results support the potential therapeutic application of omentum fat derived stem cells.

Effects of novel all-trans retinoic acid retinamide derivatives on the proliferation and apoptosis of human lung adenocarcinoma cell line A549 cells

The aim of the present study was to synthesize a series of retinamide derivatives using all-trans retinoic acid (ATRA) as raw material and observe their effects on the differentiation and apoptosis of human lung adenocarcinoma A549 cells. Four new synthesized ATRA retinamide derivatives were structurally confirmed by spectral analysis, including (1)H-NMR, (13)C-NMR, and MS. The results showed that the new ATRA retinamide derivatives significantly decreased the carcinoembryonic antigen secretion of A549 cells, significantly decreased the proliferation of A549 cells in a dose- and time-dependent manner, and promoted the apoptosis of A549 cells compared with ATRA. The Western blot assay indicated that the expression of Bcl-2 was decreased more in A549 cells treated with N-(3-trifluoromethylphenyl) retinamide than that in A549 cells treated with ATRA. The results also showed that the effects of N-(3-trifluoromethyl-phenyl) retinamide on differentiation and apoptosis were the strongest among the newly synthesized ATRA retinamide derivatives. Our results suggested that the effects of novel ATRA retinamide derivatives on increasing the differentiation, decreasing the proliferation, and promoting the apoptosis of A549 cells were greater than those of ATRA. The apoptosis of A549 cells induced by N-(3-trifluoromethylphenyl) retinamide may be related to downregulating the expression of Bcl-2.

Factors and networks that underpin early hematopoiesis

Multiple trajectories have recently been described through which hematopoietic progenitor cells travel prior to becoming lineage-committed effectors. A wide spectrum of transcription factors has recently been identified that modulate developmental progression along such trajectories. Here we describe how distinct families of transcription factors act and are linked together to orchestrate early hematopoiesis.

Stem cell-biomaterial interactions for regenerative medicine

The synergism of stem cell biology and biomaterial technology promises to have a profound impact on stem-cell-based clinical applications for tissue regeneration. Biomaterials development is rapidly advancing to display properties that, in a precise and physiological fashion, could drive stem-cell fate both in vitro and in vivo. Thus, the design of novel materials is trying to recapitulate the molecular events involved in the production, clearance and interaction of molecules within tissue in pathologic conditions and regeneration of tissue/organs. In this review we will report on the challenges behind translating stem cell biology and biomaterial innovations into novel clinical therapeutic applications for tissue and organ replacements (graphical abstract).

Acute myeloid leukemia stem cells: seek and destroy

Most adult patients with acute myeloid leukemia (AML) die from their disease. Relapses are frequent even after aggressive multiagent chemotherapy and allogeneic stem cell transplantation. AML is a biologically heterogeneous disease, characterized by frequent cytogenetic abnormalities and an increasing spectrum of genetic mutations and molecular aberrations. Laboratory data suggest that AML originates from a rare population of cells, termed leukemic stem cells (LSCs) or leukemia-initiating cells, which are capable of self-renewal, proliferation and differentiation. These cells may persist after treatment and are probably responsible for disease relapse. This review will describe bench and translational research in LSCs and discuss how the data should be used to change the direction of developmental therapeutics and clinical trials in AML.

Mechanisms controlling hematopoietic stem cell functions during normal hematopoiesis and hematological malignancies

Hematopoiesis, the process by which all mature blood cells are generated from multipotent hematopoietic stem cells (HSCs), is a finely tuned balancing act in which HSCs must constantly decide between different cell fates: to proliferate, to self-renew or differentiate, to stay quiescent in the bone marrow niche or migrate to the periphery, to live or die. These fates are regulated by a complex interplay between cell-extrinsic cues and cell-intrinsic regulatory pathways whose function is to maintain a homeostatic balance between HSC self-renewal and life-long replenishment of lost blood cells. Improper regulation of these competing cellular programs can transform HSCs and progenitor cells into disease-initiating leukemic stem cells (LSCs). Strikingly, many of the mechanisms required for maintenance of normal HSC fate decisions are equally critical for the aberrant functions of LSCs. Because of the inherent complexities of these molecular mechanisms, a systematic approach to understanding the regulatory networks underlying HSC self-renewal is critical for uncovering the similarities and differences between HSCs and LSCs. In this review, we focus on recent developments in elucidating the regulatory networks governing normal HSC self-renewal programs and their implications for leukemic transformation. We describe the current technical and methodological limitations in isolating and characterizing HSCs and LSCs, and the emerging approaches that may afford a better understanding of the regulation of normal and leukemic hematopoiesis. Finally, we discuss how such basic mechanistic information may be of use for the design of novel therapies that will selectively reprogram and/or eliminate LSCs.

Epigenetic regulation of caspase-3 gene expression in rat brain development

The expression levels of caspase-3, a major contributor to the execution of neuronal apoptosis, markedly decrease in the process of brain maturation. We have previously cloned the rat caspase-3 gene promoter and identified its essential regulatory elements. In the present study, we extended previous findings by examining transcriptional regulation of caspase-3 expression in the rat brain of two different ages, corresponding to the immature and mature brain. In particular, we determined that the rate of transcription initiation substantially declines during brain maturation. Furthermore, we established that mRNA levels of Ets1, Ets2, and Sp1 do not change in the brain with maturation, suggesting that these transcription factors do not contribute to age-dependent caspase-3 down-regulation. Hence, we examined a role of DNA methylation and histone modification in this process. Utilizing bisulfite DNA sequencing, we determined the presence of age-dependent differentially methylated fragments within the caspase-3 promoter region. Strikingly, differentially methylated CpG sites correspond to the predicted binding sites for a number of transcription factors that have been previously shown to be involved in neuronal development and differentiation. Moreover, using chromatin immunoprecipitation, we found that mature brains displayed significantly lower levels of histone 3 acetylated Lys14 and histone 4 acetylated Lys5, 8, 12, and 16. This observation is consistent with the decreased level of expression of caspase-3 in the mature brain. Together with our observation that histone deacetylase inhibitor, trichostatin A, increased the level of caspase-3 mRNA in cortical neurons in vitro, these results further indicate an important role of epigenetic factors in the regulation of caspase-3 gene expression.