Accumulation Of Immature Cells Research Articles

Differentiation of Acute Leukemia Cells Including Cells with MLL-AF4 Rearrangements Induced by Jiyuan Oridonin A.

Chromosomal rearrangements involving the Mixed lineage leukemia (MLL) gene are observed in acute leukemia (AL) patients, which have poor prognosis, especially in infants. Hence, there is still a challenge to develop other effective agents to treat AL with MLL rearrangements (MLLr). MLL has been shown to rearrange with partner genes, of which the most frequently observed are AF4 and AF9. Moreover, AL is characterized by a differentiation blockage resulting in the accumulation of immature cells. An ent-kaurene diterpenoid compound, Jiyuan Oridonin A (JOA), has been shown to reduce the viability of AML cells by differentiation. We aimed to evaluate the effect of JOA on the growth and differentiation of AL cells (SEM, JURKAT and MV4-11) including cells with MLLr-AF4 by cell proliferation assay, colony formation assay, cell cycle analysis, cell apoptosis analysis, measurement of cell surface antigens, cell morphology, mRNA-sequencing analysis, quantitative Real-time PCR and Western blotting analysis. Our findings demonstrated that the proliferation of AL cells including cells with MLLr-AF4 was significantly suppressed by JOA, which induced cell differentiation followed by G0/G1 cell cycle withdrawal. Moreover, JOA-mediated cell differentiation was likely due to activation of G-CSFR in MV4-11 cells. Our results suggest that JOA may be considered a promising anti-leukemia compound to develop to surmount the differentiation block in AL patients.

Systematic identification of regulatory elements in Leukemia.

Background: Leukemia is a type of cancer that originates from the bone marrow's blood-forming stem cells. Cancer cells don't follow the usual cellular differentiation and function pathway, so they supersede the healthy cells. Depending on the population and maturity level of abnormal cells, leukemia can be classified as Acute or Chronic. Methodology: We mapped defined leukemia mutations from the COSMIC- The Catalogue of Somatic Mutations to perspective regulatory elements. GeneCards - Human Genes Database and Factorbook were utilized in this work to extract data to analyze gene-centric data related to AML and CML. The chromosomal location, Ensembl version, GRCh37 coordinates, and detailed examination of exons, introns, promoter binding regions, and enhancers were used to investigate co-expressed and differentially expressed genes. Downloaded from Factorbook, the expression levels of healthy and sick genes were compared to known transcription factor binding patterns. Results: When translational control genes become mutated, they begin performing their function excessively, leading to uncontrolled cell proliferation and an accumulation of immature cells in the blood that are unable to perform any function on the one hand and interfering with healthy cells' ability to function optimally due to overpopulation and growth on the other. There is a group of genes whose expression level declines as they are affected by the gene, suggesting that these genes should function as insulators or silencers under normal circumstances. The data for Myc and Max genes were extracted from the Human Genome database and sorted using different techniques to find the common regulatory regions (CRRs). These CRRs were then divided into distinct categories based on the degree to which they co-expressed or their level of expression. Conclusion: Regulatory elements have been identified depending on the values of their expression level and how they are changing concerning the control group. This work will help in understanding the guidelines of blood malignancy at the cellular level by recognizing administrative destinations and are, in this manner, possible focuses for the treatment plans and precession accuracy medication.

Evaluation The Role of CD33+ CD11b+ myeloid-derived Suppressor Cells in Patients With AML

Acute myeloid leukemia is a genetically heterogeneous clonal disease defined by the accumulation of immature cells in bone marrow and blood. The aim of this study is to evaluate the CD33, CD11b, and HLA-DR expression in Iraqi AML patients and its role in evasion of malignant cells from the immune system. This study was conducted on 60 patients with AML and 20 healthy individuals as a control group to evaluate the expression of CD33 and CD11b using flow-cytometry in peripheral blood, and evaluate Interferons-γ (IFN-γ) and Transforming Growth Factor-β1 (TGF-β1) levels. A statistically non-significant difference (P < 0.005) between the AML patients and control group with regard to the expression of CD33, CD11b, and HLA-DR was observed. Analysis of CD33 expression in myeloid-derived suppressor cells (MDSCs) showed a significant decrease in the proportion of CD33 positive MDSC cells in isolated peripheral blood samples (88.078 ± 1.284). Also, the expression of CD11b in MDSC cells was high (98.841±1.935) in MDSC cells. The mean level of IFN-γ (pg/ml) increased in AML in compared to control group (9.202 ± 0.244), (7.906±1.22), respectively. While TGF- β1 (pg/ml) concentration was found to be elevated in AML patients (69.04 ± 9.92) compared to control group (33.884 ± 2.888). In conclusion, circulating MDSCs were significantly elevated in peripheral blood of patients with AML and characterized by the CD33+CD11b + phenotype; TGF-β1 and IFN-γ can be released in the presence of native human AML cells and affect AML cell proliferation and evasion from immune system.

Prognostics and Clinical Outcomes in Patients Diagnosed With Acute Lymphoblastic Leukemia in King Abdulaziz University Hospital, Jeddah, Saudi Arabia.

BackgroundAcute lymphoblastic leukemia (ALL) is a hematological cancer that causes an accumulation of immature cells in the bone marrow. The count of white blood cells (WBCs) is an independent predictor of survival. Integrating first-line treatment, such as intensive chemotherapy, with prognostic factors aids in developing critical therapeutic decisions and improving long-term outcomes. This study evaluated several prognostics such as age, WBCs, ALL cell subtypes, and absolute WBC counts.MethodsThis study involved a retrospective record review and was conducted by scanning the medical records of all individuals who developed ALL and were on chemotherapy at a teaching Hospital in Jeddah between 2012 and 2018. The data entry was done using Microsoft Excel, while the analysis was done using SPSS Version 21. To test any associations, frequency and measure of central tendencies, t-test, and chi-square test were used.ResultsA total of 98 of ALL patients were on chemotherapy, and 18 were excluded. Thus, 80 patients were analyzed. The mean age for all patients was 13.6 years (range: 0.6-26.6 years), and the most frequent ages were less than 18 years (90%). More than half of them (62.5%) were males. The majority of the patients were Bangladeshi, Pakistani, Indian, Afghan, Indonesian, and Myanmar (37.7%), and the least were Saudi (3.8%). B subtype (75.9%) was more common than T subtype (24.1%). The first remission after treatment was in 66 patients, with a mean of 6.86 years. There was a significant adverse relationship between the ability of patients to reach the first remission and WBC count (p = 0.032). There was strong significant negative correlation between absolute lymphocyte count (ALC) and survival duration after treatment (r = -0.669; p = 0.012).ConclusionsThe impact regarding age and WBC is almost like most previous studies. ALC shows a strong poor prognosis, while ALL cell subtypes demonstrate a contradictory prognosis effect.

The effects of cannabidiol via TRPV2 channel in chronic myeloid leukemia cells and its combination with imatinib.

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by accumulation of immature cells in bone marrow and peripheral blood. Although successful results were obtained with tyrosine kinase inhibitors, several patients showed resistance. For this reason, the identification of new strategies and therapeutic biomarkers represents an attractive goal. The role of transient receptor potential (TRP) ion channels as possible drug targets has been elucidated in different types of cancer. Among natural compounds known to activate TRPs, cannabidiol (CBD) displays anticancer properties. By using FACS analysis, confocal microscopy, gene silencing, and cell growth assay, we demonstrated that CBD, through TRPV2, inhibits cell proliferation and cell cycle in CML cells. It promoted mitochondria dysfunction and mitophagy as shown by mitochondrial mass reduction and up‐regulation of several mitophagy markers. These effects were associated with changes in the expression of octamer‐binding transcription factor 4 and PU.1 markers regulated during cellular differentiation. Interestingly, a synergistic effect by combining CBD with the standard drug imatinib was found and imatinib‐resistant cells remain susceptible to CBD effects. Therefore, the targeting of TRPV2 by using CBD, through the activation of mitophagy and the reduction in stemness, could be a promising strategy to enhance conventional therapy and improve the prognosis of CML patients.

Stress hematopoiesis induces a proliferative advantage in TET2 deficiency.

TET2 loss-of-function mutations are recurrent events in a wide range of hematological malignancies and a physiologic occurrence in blood cells of healthy older adults. It is currently unknown what determines if a person harboring a somatic TET2 mutation will progress to myelodysplastic syndrome or acute myeloid leukemia. Here we develop a zebrafish tet2 mutant through which we show that tet2 loss leads to restricted hematopoietic differentiation combined with a modest upregulation of p53, which is also characteristic of many inherited bone marrow failure syndromes. Uniquely in the context of emergency hematopoiesis by external stimuli, such as infection or cytokine stimulation, lack of tet2 leads hematopoietic stem cells to undergo excessive proliferation, resulting in an accumulation of immature cells, which are poised to become leukemogenic following additional genetic/epigenetic perturbations. This same phenomenon observed in zebrafish extends to human hematopoietic stem cells, identifying TET2 as a critical relay switch in the context of stress hematopoiesis.

LKB1/STK11 Is a Tumor Suppressor in the Progression of Myeloproliferative Neoplasms.

The myeloproliferative neoplasms (MPN) frequently progress to blast phase disease, an aggressive form of acute myeloid leukemia. To identify genes that suppress disease progression, we performed a focused CRISPR/Cas9 screen and discovered that depletion of LKB1/Stk11 led to enhanced in vitro self-renewal of murine MPN cells. Deletion of Stk11 in a mouse MPN model caused rapid lethality with enhanced fibrosis, osteosclerosis, and an accumulation of immature cells in the bone marrow, as well as enhanced engraftment of primary human MPN cells in vivo. LKB1 loss was associated with increased mitochondrial reactive oxygen species and stabilization of HIF1α, and downregulation of LKB1 and increased levels of HIF1α were observed in human blast phase MPN specimens. Of note, we observed strong concordance of pathways that were enriched in murine MPN cells with LKB1 loss with those enriched in blast phase MPN patient specimens, supporting the conclusion that STK11 is a tumor suppressor in the MPNs. SIGNIFICANCE: Progression of the myeloproliferative neoplasms to acute myeloid leukemia occurs in a substantial number of cases, but the genetic basis has been unclear. We discovered that loss of LKB1/STK11 leads to stabilization of HIF1a and promotes disease progression. This observation provides a potential therapeutic avenue for targeting progression.This article is highlighted in the In This Issue feature, p. 1307.

β-Catenin–TCF/LEF signaling promotes steady-state and emergency granulopoiesis via G-CSF receptor upregulation

AbstractThe canonical Wnt signaling pathway is mediated by interaction of β-catenin with the T-cell factor/lymphoid enhancer-binding factor (TCF/LEF) transcription factors and subsequent transcription activation of Wnt-target genes. In the hematopoietic system, the function of the pathway has been mainly investigated by rather unspecific genetic manipulations of β-catenin that yielded contradictory results. Here, we used a mouse expressing a truncated dominant negative form of the human TCF4 transcription factor (dnTCF4) that specifically abrogates β-catenin-TCF/LEF interaction. Disruption of the β-catenin-TCF/LEF interaction resulted in the accumulation of immature cells and reduced granulocytic differentiation. Mechanistically, dnTCF4 progenitors exhibited downregulation of the Csf3r gene, reduced granulocyte colony-stimulating factor (G-CSF) receptor levels, attenuation of downstream Stat3 phosphorylation after G-CSF treatment, and impaired G-CSF-mediated differentiation. Chromatin immunoprecipitation assays confirmed direct binding of TCF/LEF factors to the promoter and putative enhancer regions of CSF3R. Inhibition of β-catenin signaling compromised activation of the emergency granulopoiesis program, which requires maintenance and expansion of myeloid progenitors. Consequently, dnTCF4 mice were more susceptible to Candida albicans infection and more sensitive to 5-fluorouracil-induced granulocytic regeneration. Importantly, genetic and chemical inhibition of β-catenin-TCF/LEF signaling in human CD34+ cells reduced granulocytic differentiation, whereas its activation enhanced myelopoiesis. Altogether, our data indicate that the β-catenin-TCF/LEF complex directly regulates G-CSF receptor levels, and consequently controls proper differentiation of myeloid progenitors into granulocytes in steady-state and emergency granulopoiesis. Our results uncover a role for the β-catenin signaling pathway in fine tuning the granulocytic production, opening venues for clinical intervention that require enhanced or reduced production of neutrophils.

Nanocarriers as Magic Bullets in the Treatment of Leukemia.

Leukemia is a type of hematopoietic stem/progenitor cell malignancy characterized by the accumulation of immature cells in the blood and bone marrow. Treatment strategies mainly rely on the administration of chemotherapeutic agents, which, unfortunately, are known for their high toxicity and side effects. The concept of targeted therapy as magic bullet was introduced by Paul Erlich about 100 years ago, to inspire new therapies able to tackle the disadvantages of chemotherapeutic agents. Currently, nanoparticles are considered viable options in the treatment of different types of cancer, including leukemia. The main advantages associated with the use of these nanocarriers summarized as follows: i) they may be designed to target leukemic cells selectively; ii) they invariably enhance bioavailability and blood circulation half-life; iii) their mode of action is expected to reduce side effects. FDA approval of many nanocarriers for treatment of relapsed or refractory leukemia and the desired results extend their application in clinics. In the present review, different types of nanocarriers, their capability in targeting leukemic cells, and the latest preclinical and clinical data are discussed.

Β-Catenin-Tcf/Lef Signaling Promotes Steady State and Emergency Granulopoiesis through G-CSF Receptor Upregulation

The canonical Wnt signaling pathway is mediated by interaction of β-catenin with the Tcf/Lef transcription factors and subsequent transcriptional activation of Wnt-target genes. This pathway acts as an essential regulator of differentiation and cell fate decisions in various tissues. In the hematopoietic system, the function of the pathway has been investigated mainly by genetic manipulation of β-catenin. However, this approach does not allow to discriminate between Tcf/Lef dependent or independent β-catenin activity. In order to specifically identify the function of β-catenin-Tcf/Lef signaling in hematopoietic cells, we employed a transgenic mouse model expressing a dominant negative form of the human TCF4 transcription factor (dnTCF4). dnTCF4, a truncated protein lacking the β-catenin binding domain, abrogates activation of Wnt target genes, even when β-catenin is stabilized and translocated into the nucleus. In our model, expression of dnTCF4 is activated from the Rosa26 locus only in cells producing Cre recombinase (driven by Vav-iCre). Importantly, all components of Wnt signaling, including endogenous Tcf/Lef proteins and β-catenin, are intact in Cre-expressing cells. We observed that dnTCF4 transgenic mice have reduced numbers of granulocytes together with accumulation of short-term hematopoietic stem cells (ST-HSC) and common myeloid progenitors (CMPs) in bone marrow. Accordingly, dnTCF4-expressing bone marrow consistently showed a block of granulocytic differentiation and retention of an immature phenotype in colony forming assays. This differentiation arrest and accumulation of immature cells was also observed when wild type cells were cultured in semi-solid medium in the presence of a cell-penetrating peptide that disrupts β-catenin-Tcf/Lef interaction. Together, these results indicate that disruption of the β-catenin/Tcf-Lef interaction, either by genetic manipulation or a drug based approach, alters steady-state hematopoiesis. To identify a mechanism through which β-catenin-Tcf/Lef signaling affects granulopoiesis, wild type and dnTCF4 expressing ST-HSCs were subjected to RNA sequencing. Several genes related to myeloid development were differentially expressed in dnTCF4 expressing cells, including downregulation of Csf3r, the gene encoding for the G-CSF receptor. Publicly available datasets from ChIP-seq experiments on human cell lines confirmed TCF4 enrichment in the distal promoter of the CSF3R gene, suggesting that CSF3R is directly regulated by canonical Wnt signaling. Using flow cytometry we verified reduced levels of G-CSF receptor on the cell surface of dnTCF4 progenitor cells, and attenuation of downstream Stat3 phosphorylation after G-CSF treatment. Finally, when grown in the presence of G-CSF, dnTCF4-expressing bone marrow cells showed impaired differentiation abilities and reduced granulocytic counts compared to wild type bone marrow cells. These results encouraged us to investigate the role of the β-catenin-Tcf/Lef signaling pathway during emergency granulopoiesis by challenging mice with lipopolysaccharide (LPS). Remarkably, dnTCF4 mice showed defects upon LPS stimulation, and completely failed to maintain and expand myeloid progenitor populations, a critical step during emergency granulopoiesis. Altogether, we showed that β-catenin-Tcf/Lef signaling axis is crucial for proper differentiation of myeloid progenitors into granulocytes in steady-state and emergency granulopoiesis. Mechanistically, we demonstrated that the β-catenin-Tcf/Lef interaction controls expression of genes involved in myeloid differentiation, and directly enhances expression of the G-CSF receptor, a crucial molecule for proper development of granulocytes. Disclosures No relevant conflicts of interest to declare.

A human mode of intestinal type gastric carcinoma

Gastric cancer is a malignant tumor originating from the gastric mucosa epithelium. Intestinal type gastric cancer is frequently taken on elderly men, and there are many high incidence areas around the world. Intestinal type gastric cancer often is accompanied by gastric mucosal atrophy, intestinal metaplasia. The clinical manifestation involves hypergastrinemia, low stomach acid, PG I/II progressive decreasing, anemia, and protein energy malnutrition.The neck cells of gastric glands act as tissue stem cells to regenerate the gastric glands. In addition to secreting gastric acid and intrinsic factor, the parietal cells also have the function of inducing differentiation of themselves and gastric epithelial cells. When the function of parietal cells is normal, the neck cells differentiate into mature cells, and the glands regenerate intact. When the function of parietal cells is defective, the neck cells maybe differentiate into mature intestinal cells, and the gastric glands will regenerate in form of the intestinal metaplasia. When the function of parietal cells is lost, the neck cells can not differentiate into mature cells successfully, and the accumulation of immature cells in gastric mucosal tissue forms atypical hyperplasia of different degrees and cancers of various differentiation grades.Any factors that can reduce the function of parietal cell could result in intestinal type gastric carcinogenesis.Adrenal cortical hypofunction can make the parietal cell hypofunction, hypohematopoiesis, protein synthesis rates reducing and protein degradation rates increasing. The patients develop gastric cancer, and come with lack of gastric acid and intrinsic factor, anemia, protein energy malnutrition.Autoimmune gastritis can produce parietal cell antibodies to damage parietal cells. Patients with autoimmune gastritis gastric exhibit hypergastrinemia, lack of gastric acid and internal factor, higher incidence of gastric cancer.H. pylori can damage gastric parietal cells directly and indirectly. When declining in quantity of parietal cells, the patients exhibit hypergastrinemia, low gastric acid, mucosa atrophy, intestinal metaplasia and gastric cancer.Medicine that inhibits the function of parietal cells also could increase the risk of gastric cancer development.The distribution of mucosa atrophy, intestinal metaplasia and intestinal type gastric cancer is opposite with the distribution of parietal cells in stomach. With age the quantity of parietal cells decreases, the atrophy area of gastric mucosa extends upward from antrum to body and downward from cardia to body along lesser curvature, and the location of distal gastric cancer moves upward and the gastric cardiac cancer increase.

A new signaling cascade linking BMP4, BMPR1A, \u0394Np73 and NANOG impacts on stem-like human cell properties and patient outcome

In a significant number of cases cancer therapy is followed by a resurgence of more aggressive tumors derived from immature cells. One example is acute myeloid leukemia (AML), where an accumulation of immature cells is responsible for relapse following treatment. We previously demonstrated in chronic myeloid leukemia that the bone morphogenetic proteins (BMP) pathway is involved in stem cell fate and contributes to transformation, expansion, and persistence of leukemic stem cells. Here, we have identified intrinsic and extrinsic dysregulations of the BMP pathway in AML patients at diagnosis. BMP2 and BMP4 protein concentrations are elevated within patients’ bone marrow with a BMP4-dominant availability. This overproduction likely depends on the bone marrow microenvironment, since MNCs do not overexpress BMP4 transcripts. Intrinsically, the receptor BMPR1A transcript is increased in leukemic samples with more cells presenting this receptor at the membrane. This high expression of BMPR1A is further increased upon BMP4 exposure, specifically in AML cells. Downstream analysis demonstrated that BMP4 controls the expression of the survival factor ΔNp73 through its binding to BMPR1A. At the functional level, this results in the direct induction of NANOG expression and an increase of stem-like features in leukemic cells, as shown by ALDH and functional assays. In addition, we identified for the first time a strong correlation between ΔNp73, BMPR1A and NANOG expression with patient outcome. These results highlight a new signaling cascade initiated by tumor environment alterations leading to stem-cell features and poor patients’ outcome.

Development of high cytotoxic NK cell model for leukemia treatment (TUM10P.1041)

Abstract Natural killer (NK) cells play an important role in innate immune system to against virus-infected cells, transformed cells and tumor cells without further stimulation. The killing functions of NK cells regulated by the signals from a large set of activating receptors and inhibitor receptors. Moreover, either the directly interaction with other immune cells, including dendritic cells, macrophages and T cells, or the cytokines secreted from other cells also enhance the NK cell killing activity. The NK cell produces cytokines, such as IFN-γ and TNF-α, recruit immune cells to enhance the inflammatory response as well. Acute myeloid leukemia is characterized by the accumulation of immature cells in bone marrow and affects the hematopoiesis. By standard chemo- and radio-therapy, leukemia could be controlled on the remission status. However, the leukemia stem cells which are resistant to conventional treatments, cause the relapse leading to the death of AML patients. So far it is believed that hematopoietic stem cell transplantation is a curable treatment for AML, but it is limited by the patient age and the availability of HLA-matched donor. According to previous study, NK cells seem to have the potential to kill LSCs and lower the disease relapse. In this study, we try to develop a NK cell model with the ability to eliminate both leukemia cells and LSCs. If success, the highly cytotoxic NK model may apply to clinical AML treatment to prevent the relapse of AML.

Distribution of the cytoskeletal protein, Nestin, in acute leukemia

Nestin is a neuroepithelial stem cell marker that is expressed in some types of tumor cells. Recent reports suggest that Nestin may be closely related to malignant cell proliferation and migration. Acute leukemia (AL) is characterized by a lack of differentiation, which results in uncontrolled proliferation in the bone marrow and accumulation of immature cells. The expression and function of Nestin in AL is unclear. We investigated Nestin immunohistochemical patterns of 87 patients that included 47 cases of acute myeloid leukemia (AML) and 40 cases of acute lymphoblastic leukemia (ALL), and 20 patients in complete remission (CR) from AML or ALL. We also investigated the clinico-pathological features of 87 cases of AL and their CR and overall survival (OS). Nestin was expressed in leukemic blasts and mature granulocytic cells in most cases (39/47) of AML. Conversely, Nestin was expressed in mature granulocytic cells in fewer cases (6/40) of ALL, but not in blasts. Nestin expression appeared in leukemic blasts of AML, but not ALL. Nestin expression in AML blast cells was not associated with CR or OS. We provide evidence that Nestin is expressed in AL and might be a useful immunohistochemical marker for identifying AML and ALL.

Relative receptor tyrosine kinases and anti-apoptotic transcripts hold potential for predicting inferior outcome in adult acute myeloid leukemia: a prospective pilot study.

Acute myeloid leukemia is characterized by accumulation of immature cells because of imbalance between proliferation and apoptosis. In AML, simultaneous expression of proliferative (FLT-3, c-KIT) and antiapoptotic genes (BCL-2), are unknown. We prospectively assessed proliferative and antiapoptotic gene transcripts using Taqman probe chemistry in 48 adult AML patients. A stepwise Cox regression model was applied for independent prognostic factors. Thirty-two of 48 (75%) patients achieved complete remission. At follow-up ranging from 0.5 to 57.3 months, event-free survival (EFS) was 26.9 ± 6.3% (range, 15.5%-39.6%) and OS 34.5 ± 7.46% (range, 20.5%-48.9%). High white blood cell count correlated with an inferior complete remission rate (P = .021). Cytogenetics and FLT-3 internal tandem duplication did not predict EFS or OS. The transcripts of FLT-3, c-KIT, and BCL-2 showed a significant linear association with each other in Pearson correlation (FLT-3 vs. c-KIT: R = 0.8234; P < .001; c-KIT vs. BCL-2: R = 0.3377; P = .01; FLT-3 vs. BCL-2: R = 0.3815; P = .007). In a validation cohort (Microarray Data Set GSE1159) of adult AML patients, the global gene expression profile depicted a similar interrelationship. Patients with a greater platelet count were associated with increased transcript levels of BCL-2 (P = .034). In univariate analysis, a high transcript level of FLT-3 and high transcript ratio of FLT-3/BCL-2 and FLT-3 and c-KIT/BCL-2 significantly predicted OS (P = .043, .028, and .028, respectively). In a stepwise Cox regression model, high FLT-3 and c-KIT/BCL-2 ratio predicted OS (HR, 2.29). To our knowledge, this is the first study that evaluated proliferative and antiapoptotic transcripts simultaneously, and results have shown that it is the relative levels of these transcripts that determine outcome in AML patients rather than their expression in isolation.

High expression of FCHSD2 is associated with chemoresistance in adult acute myeloid leukemia

Acute myeloid leukemia (AML) is a clonal disease, characterized by the growth and accumulation of immature cells in the bone marrow, which in turn affects production of normal blood cells. Increasing need for biomarkers that can predict the outcome of treatment are becoming of potential value because of the heterogenous response to induction chemotherapy. FCHSD2 was identified as a potential chemoprotector. In the present study, we used qRT-PCR to assess FCHSD2 expression levels in peripheral blood or bone marrow blasts of 50 de novo AML patients before remission induction chemotherapy. There was higher expression levels of mRNA in AML patients than control group median (1.36, 0.70), respectively. Patients were subgrouped into responders(R) and nonresponders (NR) after remission induction therapy. The mean expression level of FCHSD2 mRNA in responders (32/50) was 1.7 ± 2.8, while it was 7.9 ± 6.6 in NR (18/50). Our results demonstrated that the patients with lower FCHSD2 expression prior to the treatment had an increased chance of attaining remission compared to patients with high-level FCHSD2. In conclusion, our data suggests that FCHSD2 can serve as a new biomarker for the prediction of treatment outcome in AML patients. The quantitation of FCHSD2 expression at the time of diagnosis could help to identify the responses to chemotherapy.

Retinoid Differentiation Therapy for Common Types of Acute Myeloid Leukemia

Many cancers arise in a tissue stem cell, and cell differentiation is impaired resulting in an accumulation of immature cells. The introduction of all-trans retinoic acid (ATRA) in 1987 to treat acute promyelocytic leukemia (APL), a rare subtype of acute myeloid leukemia (AML), pioneered a new approach to obtain remission in malignancies by restoring the terminal maturation of leukemia cells resulting in these cells having a limited lifespan. Differentiation therapy also offers the prospect of a less aggressive treatment by virtue of attenuated growth of leukemia cells coupled to limited damage to normal cells. The success of ATRA in differentiation therapy of APL is well known. However, ATRA does not work in non-APL AML. Here we examine some of the molecular pathways towards new retinoid-based differentiation therapy of non-APL AML. Prospects include modulation of the epigenetic status of ATRA-insensitive AML cells, agents that influence intracellular signalling events that are provoked by ATRA, and the use of novel synthetic retinoids.

Influence of Thyroid Hormone and Thyroid Hormone Receptors in the Generation of Cerebellar γ-Aminobutyric Acid-Ergic Interneurons from Precursor Cells

Thyroid hormones have important actions in the developing central nervous system. We describe here a novel action of thyroid hormone and its nuclear receptors on maturation of cerebellar gamma-aminobutyric acid (GABA)-ergic interneurons from their precursor cells. In rats, the density of GABAergic terminals in the cerebellum was decreased by hypothyroidism, as shown by immunohistochemistry for the GABA transporter GAT-1. This was due, at least partially, to a decreased number of GABAergic cells, because the number of Golgi II cells in the internal granular layer was decreased. GABAergic interneurons in the cerebellum differentiate from precursors expressing the Pax-2 transcription factor, generated in the subventricular zone of the embryonic fourth ventricle from where they migrate to the cerebellum. Hypothyroidism caused both decreased proliferation and delayed differentiation of precursors, with the net effect being an accumulation of immature cells during the neonatal period. The contribution of thyroid hormone receptors was studied by treating hypothyroid rats with T(3) or with the thyroid hormone receptor (TR) beta-selective agonist GC-1. Whereas treatment with T(3) reduced the number of precursors to control levels, GC-1 had only a partial effect, indicating that both TRalpha1 and TRbeta mediate the actions of T(3). Deletion of TRalpha1 in mice decreased cerebellar GAT-1 expression and Pax-2 precursor cell proliferation. It is concluded that thyroid hormone, acting through the nuclear receptors, has a major role in the proliferation and further differentiation of the Pax-2 precursors of cerebellar GABAergic cells.

350. Ectopic Retroviral Expression of LMO2, but Not IL2Rγ, Blocks Human T-Cell Development from CD34+ Progenitor Cells: Implications for Gene Therapy

The occurrence of leukemia in 3 out of 11 patients in a gene therapy trial for SCID-X1 emphasized insertional mutagenesis as an adverse effect. In two out of three patients retroviral integration occurred near the T-cell acute lymphoblastic leukemia (T-ALL) oncogene LIM-only protein 2 (LMO2). It has remained unclear why LMO2 was preferentially targeted. We show here that of classical T-ALL oncogenes, mainly LMO2 is transcribed in CD34+ progenitor cells derived from umbilical cord blood (UCB). Upon stimulation with growth factors typically used in gene therapy protocols, transcription of LMO2, LYL1 and TAL1 increased 2|[ndash]|3 fold in CD34+ UCB cells, whereas the other T-ALL oncogenes remained unaffected. Similarly, when mobilized peripheral blood CD34+ cells were stimulated according to transduction protocols used for clinical SCID-X1 gene therapy trials, the same pattern of T-ALL oncogene transcription was observed, suggesting that cytokine stimulation leads to upregulation of proto-oncogenes irrespective of the source of CD34+ progenitor cells used. Transcription of LMO2, LYL1 and TAL1 is particularly high and their loci could therefore be preferentially accessible for viral integration. Retroviral overexpression of LMO2 in CD34+ cells led to severe abnormalities in human T-cell development, but B-cell, NK cell and myeloid development remained unaffected. The interleukin-2 receptor gamma chain (IL2R|[gamma]|), causing SCID-X1 when mutated, has been proposed to act as an oncogene cooperative to LMO2. However, we found that overexpression of IL2R|[gamma]| had no effect on T-cell development. Moreover, IL2R|[gamma]| normally is expressed at high levels in CD34+ progenitor cells and at even higher levels in the thymus. Thus, transduction of IL2R|[gamma]| in CD34+ progenitor cells does not cause ectopic expression of this gene. In conclusion, our data provide an explanation why LMO2 was preferentially targeted over other known T-ALL oncogenes. Furthermore, IL2R|[gamma]| does not appear to act as an oncogene. Rather, the normal IL2R|[gamma]| chain restores IL7 receptor signalling in the progeny of transduced SCID-X1 cells developing in the thymus, allowing T-cell development to progress to stages where ectopic LMO2 expression hampers T-cell development in the thymus, creating a probable pre-leukemic condition by accumulation of immature cells under intense proliferative pressure.

Cotylenin A--A Plant Growth Regulator as a Differentiation-inducing Agent Against Myeloid Leukemia

Acute myeloid leukemia (AML) is characterized by the arrest of differentiation leading to the accumulation of immature cells. This maturation arrest can be reversed by certain agents. Although differentiation therapy for patients with acute promyelocytic leukemia (APL) using all- trans retinoic acid (ATRA) has been established, the clinical response of AML patients other than those with APL to ATRA is limited. We must consider novel therapeutic drugs against other forms of AML for the development of a differentiation therapy for leukemia. Regulators that play an important role in the differentiation and development of plants or invertebrates may also affect the differentiation of human leukemia cells through a common signal transduction system, and might be clinically useful for treating AML. Cotylenin A, a plant growth regulator, is a potent and novel inducer of the monocytic differentiation of human myeloid leukemia cell lines and leukemia cells freshly isolated from AML patients.