Human Acute Lymphoblastic Leukemia Research Articles

Loss of IP3R-dependent Ca2+ signalling in thymocytes leads to aberrant development and acute lymphoblastic leukemia.

Calcium ions (Ca(2+)) function as universal second messengers in eukaryotic cells, including immune cells. Ca(2+) is crucial for peripheral T-lymphocyte activation and effector functions, and influences thymocyte selection and motility in the developing thymus. However, the role of Ca(2+) signalling in early T-lymphocyte development is not well understood. Here we show that the inositol triphosphate receptors (IP3Rs) Ca(2+) ion channels are required for proliferation, survival and developmental progression of T-lymphocyte precursors. Our studies indicate that signalling via IP3Rs represses Sox13, an antagonist of the developmentally important transcription factor Tcf-1. In the absence of IP3R-mediated Ca(2+) signalling, repression of key Notch transcriptional targets--including Hes1--fail to occur in post β-selection thymocytes, and mice develop aggressive T-cell malignancies that resemble human T-cell acute lymphoblastic leukemia (T-ALL). These data indicate that IP3R-mediated Ca(2+) signalling reinforces Tcf-1 activity to both ensure normal development and prevent thymocyte neoplasia.

MIP-1α enhances Jurkat cell transendothelial migration by up-regulating endothelial adhesion molecules VCAM-1 and ICAM-1

The aim of this study is to evaluate the expression of macrophage inflammatory protein-1α (MIP-1α) in Jurkat cells and its effect on transendothelial migration. In the present study, human acute lymphoblastic leukemia Jurkat cells (Jurkat cells) were used as a model of T cells in human T-cell acute lymphoblastic leukemia (T-ALL), which demonstrated significantly higher MIP-1α expression compared with that in normal T-cell controls. The ability of Jurkat cells to cross a human brain microvascular endothelial cell (HBMEC) monolayer was almost completely abrogated by MIP-1α siRNA. In addition, the overexpression of MIP-1α resulted in the up-regulated expression of endothelial adhesion molecules, which enhanced the migration of Jurkat cells through a monolayer of HBMEC. MIP-1α levels in Jurkat cells appeared to be an important factor for its transendothelial migration, which may provide the theoretical basis to understand the mechanisms of brain metastases of T-ALL at cellular and molecular levels.

Antiproliferative potential of a novel parthenin analog P16 as evident by apoptosis accompanied by down-regulation of PI3K/AKT and ERK pathways in human acute lymphoblastic leukemia MOLT-4 cells

Leukemia is one of the deadliest types of cancer. Lack of effective treatment strategies has resulted in an extensive quest for new therapeutic molecules against it. This study explores the molecular mechanism of anticancer activity of P16, a semisynthetic analog of parthenin, against the human acute lymphoblastic leukemia MOLT-4 cells. P16 displayed antiproliferative activity in different cancer cell lines; however, MOLT-4 cells showed highest sensitivity for P16 with IC50 value of 0.6μM. Further studies revealed that P16 induced cell death by apoptosis. It caused mitochondrial stress, which was mediated by the translocation of Bax from cytosol to mitochondria and release of cytochrome c into the cytosol and consequent activation of caspase-9.However, P16 was also able to activate caspase-8, thus involving both extrinsic and intrinsic pathways of apoptosis. Further, activation of caspase-3 led to cleavage of its target proteins PARP-1 and ICAD, which resulted in apoptotic DNA damage. P16 induced apoptosis was accompanied by the down-regulation of important leukemic cell survival proteins like pAKT (S473), pAKT (T308), pP70S6K, pCRAF, and pERK1/2. However, inhibition of caspases by Z-VAD-FMK reversed the down-regulatory effect of P16 on pAKT (S473) and pP70S6K, as evident by the cell viability assay and flow cytometric analysis but this inhibition did not completely reverse the antiproliferative effect of P16, thereby indicating the role of additional factors apart from caspases in P16 induced apoptosis in MOLT-4 cells. Owing to its antiproliferative potential against leukemia cells, P16 can further be explored as an effective therapeutics against leukemia.

Cytotoxic compounds isolated from Murraya tetramera Huang.

A new compound and seven known compounds were isolated from Murraya tetramera Huang for the first time, and they were identified with NMR and MS spectral analysis. It was confirmed that the new compound was 10-methoxy-7-methyl-2H-benzo[g]chromen-2-one (3) and the others were β-eudesmol (1), trans-3β-(1-hydroxy-1-methylethyl)-8aβ-methyl-5-methylenedecalin-2-one (2), 5,7-dimethoxy-8-[(Z)-3'-methyl-butan-1',3'-dienyl]coumarin (4), 7-geranyloxy-6-methoxycoumarin (5), 5,7-dimethoxy-8-(3-methyl-2-oxo-butyl)coumarin (6), murrangatin acetate (7) and toddalenone (8). Furthermore, the cytotoxic activity against human lung adenocarcinoma (A549), human hepatocellular carcinoma cells (SMMC-7721), human bladder tumor cells (EJ), human cervical carcinoma cells (HeLa), and human B-lineage acute lymphoblastic leukemia 1 cells (BALL-1) was evaluated for all compounds. It was found that five of them displayed various degrees of cytotoxicity against different testing targets. Compound 1 showed significant cytotoxic activity against the five cell lines (A549, SMMC-7721, EJ, Hela and BALL-1). Compounds 2 and 5 showed significant cytotoxicity against three cell lines (A549, SMMC-7721 and BALL-1). Compound 4 showed significant cytotoxicity against three cell lines (A549, EJ and BALL-1). However, compound 3 only showed fair cytotoxicity against the BALL-1 cell line. The structure-active relationships were investigated as well. These active compounds might be potential lead compounds for the treatment of cancer.

Cellular proteolytic modification of tumor-suppressor CYLD is critical for the initiation of human T-cell acute lymphoblastic leukemia.

There exists a general recognition of the fact that post translational modification of CYLD protein through proteolytic cleavage by MALT-1 results in sustained cellular NF-kB activity which is conspicuously found to be associated with cancer in general and hematological malignancies in particular. The present study was directed to understand the contribution of MALT-1 and deubiquitinase CYLD to the initiation of T-cell acute lymphoblastic leukemia (T-ALL). Such a study revealed for the first time that the 35kDa CYLD cleaved factor generated by MALT-1 mediated proteolytic cleavage was conspicuously present in human T- ALL subjects of pediatric age group. Further, over-expression of this 35kDa CYLD factor within normal human peripheral blood mononuclear cells had the inherent capacity to program the genome of these cells resulting in T-cell lineage ALL. Based upon these results, we propose that MALT1 inhibitors may be of crucial importance in the treatment of T-ALL subjects of pediatric age group.

The Sox4/Tcf7l1 axis promotes progression of BCR-ABL-positive acute lymphoblastic leukemia.

The transcription factor Sox4 plays an indispensable role in the development of early progenitor B cells from hematopoietic stem cells. However, its role in B-cell acute lymphoblastic leukemia, a malignant counterpart of normal progenitor B cells, is not fully understood. Here we show that SOX4 is highly expressed in human acute lymphoblastic leukemia cells. To systematically study the function of Sox4 in acute lymphoblastic leukemia, we established a genetically defined mouse leukemia model by transforming progenitor B cells carrying a floxed Sox4 allele and inducing deletion of the allele by the self-excising Cre recombinase. This model allowed us to work with two groups of leukemic cells that had either one copy or both copies of Sox4 deleted. We found that depletion of Sox4 in transformed cells in vitro reduced cell growth in vitro and the progression of leukemia in vivo. Moreover, depletion of Sox4 in leukemic cells in vivo prolonged the survival of the mice, suggesting that it could be a potential target in acute lymphoblastic leukemia therapy. Our microarray and bioChIP studies revealed that Tcf7l1 was the key gene directly regulated by Sox4. Knockdown of Tcf7l1 reduced cell proliferation, just as did knockout of Sox4, and ectopic expression of Tcf7l1 could reverse the effect of Sox4 knockout on cell proliferation. These data suggest that Sox4 and Tcf7l1 form a functional axis that promotes the progression of BCR-ABL-positive acute lymphoblastic leukemia.

Mouse xenograft modeling of human adult acute lymphoblastic leukemia provides mechanistic insights into adult LIC biology

AbstractThe distinct nature of acute lymphoblastic leukemia (ALL) in adults, evidenced by inferior treatment outcome and different genetic landscape, mandates specific studies of disease-initiating mechanisms. In this study, we used NOD/LtSz-scid IL2Rγ nullc (NSG) mouse xenotransplantation approaches to elucidate leukemia-initiating cell (LIC) biology in primary adult precursor B (pre-B) ALL to optimize disease modeling. In contrast with xenografting studies of pediatric ALL, we found that modification of the NSG host environment using preconditioning total body irradiation (TBI) was indispensable for efficient engraftment of adult non-t(4;11) pre-B ALL, whereas t(4;11) pre-B ALL was successfully reconstituted without this adaptation. Furthermore, TBI-based xenotransplantation of non-t(4;11) pre-B ALL enabled detection of a high frequency of LICs (<1:6900) and permitted frank leukemic engraftment from a remission sample containing drug-resistant minimal residual disease. Investigation of TBI-sensitive stromal-derived factor-1/chemokine receptor type 4 signaling revealed greater functional dependence of non-t(4;11) pre-B ALL on this niche-based interaction, providing a possible basis for the differential engraftment behavior. Thus, our studies establish the optimal conditions for experimental modeling of human adult pre-B ALL and demonstrate the critical protumorogenic role of microenvironment-derived SDF-1 in regulating adult pre-B LIC activity that may present a therapeutic opportunity.

Genome-wide Mapping and Characterization of Notch-Regulated Long Noncoding RNAs in Acute Leukemia

Notch signaling is a key developmental pathway that is subject to frequent genetic and epigenetic perturbations in many different human tumors. Here we investigate whether long noncoding RNA (lncRNA) genes, in addition to mRNAs, are key downstream targets of oncogenic Notch1 in human Tcell acute lymphoblastic leukemia (T-ALL). By integrating transcriptome profiles with chromatin state maps, we have uncovered many previously unreported T-ALL-specific lncRNA genes, a fraction of which are directly controlled by the Notch1/Rpbjκ activator complex. Finally we have shown that one specific Notch-regulated lncRNA, LUNAR1, is required for efficient T-ALL growth invitro and invivo due to its ability to enhance IGF1R mRNA expression and sustain IGF1 signaling. These results confirm that lncRNAs are important downstream targets of the Notch signaling pathway, and additionally they are key regulators of the oncogenic state in T-ALL.

Targeting transcription regulation in cancer with a covalent CDK7 inhibitor.

Tumor oncogenes include transcription factors that co-opt the general transcriptional machinery to sustain the oncogenic state1, but direct pharmacological inhibition of transcription factors has thus far proven difficult2. However, the transcriptional machinery contains various enzymatic co-factors that can be targeted for development of new therapeutic candidates3, including cyclin-dependent kinases (CDKs)4. Here we present the discovery and characterization of the first covalent CDK7 inhibitor, THZ1, which has the unprecedented ability to target a remote cysteine residue located outside of the canonical kinase domain, providing an unanticipated means of achieving selectivity for CDK7. Cancer cell line profiling indicates that a subset of cancer cell lines, including T-ALL, exhibit exceptional sensitivity to THZ1. Genome-wide analysis in Jurkat T-ALL shows that THZ1 disproportionally affects transcription of RUNX1 and suggests that sensitivity to THZ1 may be due to vulnerability conferred by the RUNX1 super-enhancer and this transcription factor’s key role in the core transcriptional regulatory circuitry of these tumor cells. Pharmacological modulation of CDK7 kinase activity may thus provide an approach to identify and treat tumor types exhibiting extreme dependencies on transcription for maintenance of the oncogenic state.

Caspase-dependent Mcl-1 cleavage and effect of Mcl-1 phosphorylation in ABT-737-induced apoptosis in human acute lymphoblastic leukemia cell lines.

ABT-737 is a BH3-mimetic that has a wide spectrum of single-agent activity against acute lymphoblastic leukemia (ALL) cell lines and xenografts. Previously, we reported that in response to ABT-737, ABT-737-resistant ALL cell lines showed an apparent increase in Mcl-1 (an anti-apoptotic Bcl-2 family protein that is not effectively inhibited by ABT-737) while ABT-737-sensitive ALL cell lines showed decreased Mcl-1 levels. Here we explored the mechanism of Mcl-1 cleavage by ABT-737 and the effect of adjacent phosphorylation sites on Mcl-1 cleavage and apoptosis induced by ABT-737 in a human B-lineage ALL cell line. Caspase cleavage sites in Mcl-1 and the effect of mutation in Mcl-1 phosphorylation sites were determined by transducing Mcl-1 variants tagged with the V5 epitope into human ALL cells. Cytotoxicity was by fluorescence-based DIMSCAN, and changes in protein by immunoblotting. ABT-737 induced a caspase-dependent cleavage of Mcl-1. Of the two Mcl-1 caspase cleavage sites (D127 and D157), D157 was the site of ABT-737-induced cleavage in ALL cells. Cells with exogenously expressed Mcl-1 Δ157 fragment showed greater caspase-3 and caspase-9 activation when they were treated with ABT-737 compared with cells expressing wild-type or D157A mutant Mcl-1. Cells with mutated phosphorylation sites on Mcl-1 (S159A and T163A) were less susceptible to Mcl-1 cleavage and apoptosis induced by ABT-737. Our data showed that Mcl-1 is post-translationally regulated in response to ABT-737 treatment, primarily via a caspase-dependent cleavage that generates a pro-apoptotic Mcl-1 fragment.

CD7 promotes extramedullary involvement of the B-cell acute lymphoblastic leukemia line Tanoue by enhancing integrin β2-dependent cell adhesiveness.

Extramedullary involvement (EMI) is a factor that defines prognosis of acute lymphoblastic leukemia; however, the molecular mechanism(s) remain elusive. Here, we show that CD7 promotes EMI of the human B-cell acute lymphoblastic leukemia cell line Tanoue. The Tanoue cell line expressing firefly luciferase, Luc-Tanoue, was transplanted into non-obese diabetic/severe combined immunodeficient mice, and cells infiltrated into the brain were cultured ex vivo. This process was repeated 4 times to obtain the highly invasive line Luc-Tanoue-F4. Comparison of the global gene expression signatures of Luc-Tanoue-F4 and Luc-Tanoue indicated that the CD7 gene showed the largest increase in expression among EMI-related genes in Luc-Tanoue-F4 cells. Overexpression of CD7 in Tanoue enhanced cell invasiveness. Among cell migration, proliferation, adhesion and protease activity, only cell adhesiveness showed enhancement in Luc-Tanoue-F4. Expression of the intracellular domain, but not the extracellular domain, of CD7 enhanced cell adhesiveness. Luc-Tanoue-F4 showed a higher level of integrin β2 expression; overexpression of CD7 induced the expression of integrin β2 in Luc-Tanoue. These results show that CD7 induces integrin β2 and enhances cell adhesiveness and invasiveness in Tanoue cells. This study highlights the role of the CD7/integrin β2 axis as a critical pathway in the process of EMI of human B-cell acute lymphoblastic leukemia.

Cladieunicellin J, a New Hydroperoxyeunicellin from Cladiella sp

A new 6-hydroperoxyeunicellin diterpenoid, designated as cladieunicellin J (1), was isolated from an octocoral Cladiella sp., and its structure elucidated by spectroscopic methods. Compound 1 was found to exhibit cytotoxicity toward CCRF-CEM human T-cell acute lymphoblastic leukemia.

Sensitive Electrochemical Aptamer Biosensor for Dynamic Cell Surface N-Glycan Evaluation Featuring Multivalent Recognition and Signal Amplification on a Dendrimer–Graphene Electrode Interface

We demonstrate a multivalent recognition and highly selective aptamer signal amplification strategy for electrochemical cytosensing and dynamic cell surface N-glycan expression evaluation by the combination of concanavalin A (Con A), a mannose binding protein, as a model, conjugated poly(amidoamine) dendrimer on a chemically reduced graphene oxide (rGO-DEN) interface, and aptamer- and horseradish peroxidase-modified gold nanoparticles (HRP-aptamer-AuNPs) as nanoprobes. In this strategy, the rGO-DEN can not only enhance the electron transfer ability but also provide a multivalent recognition interface for the conjugation of Con A that avoids the weak carbohydrate-protein interaction and dramatically improves the cell capture efficiency and the sensitivity of the biosensor for cell surface glycan. The high-affinity aptamer- and HRP-modified gold nanoparticles provide an ultrasensitive electrochemical probe with excellent specificity. As proof-of-concept, the detection of CCRF-CEM cell (human acute lymphoblastic leukemia) and its surface N-glycan was developed. It has demonstrated that the as-designed biosensor can be used for highly sensitive and selective cell detection and dynamic evaluation of cell surface N-glycan expression. A detection limit as low as 10 cells mL(-1) was obtained with excellent selectivity. Moreover, this strategy was also successfully applied for N-glycan expression inhibitor screening. These results imply that this biosensor has potential in clinical diagnostic and drug screening applications and endows a feasibility tool for insight into the N-glycan function in biological processes and related diseases.

Antileukemic activity and mechanism of drug resistance to the marine Salinispora tropica proteasome inhibitor salinosporamide A (Marizomib).

Salinosporamide A (NPI-0052, marizomib) is a naturally occurring proteasome inhibitor derived from the marine actinobacterium Salinispora tropica, and represents a promising clinical agent in the treatment of hematologic malignancies. Recently, these actinobacteria were shown to harbor self-resistance properties to salinosporamide A by expressing redundant catalytically active mutants of the 20S proteasome β-subunit, reminiscent of PSMB5 mutations identified in cancer cells with acquired resistance to the founding proteasome inhibitor bortezomib (BTZ). Here, we assessed the growth inhibitory potential of salinosporamide A in human acute lymphocytic leukemia CCRF-CEM cells, and its 10-fold (CEM/BTZ7) and 123-fold (CEM/BTZ200) bortezomib-resistant sublines harboring PSMB5 mutations. Parental cells displayed sensitivity to salinosporamide A (IC50 = 5.1 nM), whereas their bortezomib-resistant sublines were 9- and 17-fold cross-resistant to salinosporamide A, respectively. Notably, combination experiments of salinosporamide A and bortezomib showed synergistic activity in CEM/BTZ200 cells. CEM cells gradually exposed to 20 nM salinosporamide A (CEM/S20) displayed stable 5-fold acquired resistance to salinosporamide A and were 3-fold cross-resistant to bortezomib. Consistent with the acquisition of a PSMB5 point mutation (M45V) in CEM/S20 cells, salinosporamide A displayed a markedly impaired capacity to inhibit β5-associated catalytic activity. Last, compared with parental CEM cells, CEM/S20 cells exhibited up to 2.5-fold upregulation of constitutive proteasome subunits, while retaining unaltered immunoproteasome subunit expression. In conclusion, salinosporamide A displayed potent antileukemic activity against bortezomib-resistant leukemia cells. β-Subunit point mutations as a common feature of acquired resistance to salinosporamide A and bortezomib in hematologic cells and S. tropica suggest an evolutionarily conserved mechanism of resistance to proteasome inhibitors.

Loss of function tp53 mutations do not accelerate the onset of myc‐induced T‐cell acute lymphoblastic leukaemia in the zebrafish

The TP53 tumour suppressor is activated in response to distinct stimuli, including an ARF-dependent response to oncogene stress and an ATM/ATR-dependent response to DNA damage. In human T-cell acute lymphoblastic leukaemia (T-ALL), TP53-dependent tumour suppression is typically disabled via biallelic ARF deletions. In murine models, loss of Arf (Cdkn2a) or Tp53 markedly accelerates the onset of Myc-induced lymphoblastic malignancies. In zebrafish, no ARF ortholog has been identified, but the sequence of ARF is very poorly conserved evolutionarily, making it difficult to exclude the presence of a zebrafish ARF ortholog without functional studies. Here we show that tp53 mutations have no significant influence on the onset of myc-induced T-ALL in zebrafish, consistent with the lack of additional effects of Tp53 loss on lymphomagenesis in Arf-deficient mice. By contrast, irradiation leads to complete T-ALL regression in tp53 wild-type but not homozygous mutant zebrafish, indicating that the tp53-dependent DNA damage response is intact. We conclude that tp53 inactivation has no impact on the onset of myc-induced T-ALL in the zebrafish, consistent with the lack of a functional ARF ortholog linking myc-induced oncogene stress to tp53-dependent tumour suppression. Thus, the zebrafish model is well suited to the study of ARF-independent pathways in T-ALL pathobiology.

Genetic characteristics of human acute lymphoblastic leukemia cell line Molt-4

This study was aimed to investigate the genetic characteristics of human acute lymphoblastic leukemia cell line Molt-4, and evaluate its application in measuring telomere length by Flow-FISH. Molt-4 cell line was cultured in suspension and subcultured regularly. Eight different passages of Molt-4 cells in exponential stage were selected.The growth curves were drawn by cell counting method, meanwhile calculating the population doubling times of cells,DNA ploidies were determined by flow cytometry,karyotypes were analyzed by G-banding and telomere lengths were measured by Southern blot. The results showed that the population doubling time of Molt-4 cell line was (1.315 ± 0.062) d, DNA ploidy index was (2.085 ± 0.0093) , and the telomere length was (32.05 ± 5.27) kb. There were no significant difference among different passages (P = 0.931,0.888 and 0.935 separately). The karyotypes showed that the chromosome numbers of Molt-4 cell line were from 91 to 99 in different metaphases, and the majority of them were hypertetraploid, and stable and recurrent structural abnormalities of chromosomes could be kept. It is concluded that the stable genetic characteristics and the longer telomere length of Molt-4 cell line makes it be a feasible control cells in measurement of telomere length by Flow-FISH.

Nucleostemin knocking-down causes cell cycle arrest and apoptosis in human T-cell acute lymphoblastic leukemia MOLT-4 cells via p53 and p21Waf1/Cip1 up-regulation

ObjectivesNucleostemin (NS), a recently discovered nucleolar protein, is essential for maintaining self-renewal and proliferation of embryonic and adult stem cells as well as cancerous cells. The aim of this study was to determine biological function of NS in MOLT-4 cells as a human T-cell acute lymphocytic leukemia (T-ALL) model.MethodsEfficacy of a specific small interference RNA on NS depletion was studied by quantitative polymerase chain reaction and western blotting. The growth rate and viability were analyzed by trypan blue exclusion test. Fluorescent microscopy was used for detecting apoptosis. Cell cycle and apoptosis were mechanistically studied by flow cytometry and western blotting.ResultsKnockdown of NS inhibited proliferation, arrested the cell cycle, and induced apoptosis through p53 and p21Waf1/Cip1 pathways in MOLT-4 cells.DiscussionThese findings demonstrate critical roles of NS in MOLT-4 cells and may implicate on its therapeutic potential in this human T-ALL model.

Alternative Messenger RNA Splicing of Autophagic Gene Beclin 1 in Human B-cell Acute Lymphoblastic Leukemia Cells

Beclin 1 is a key factor for initiation and regulation of autophagy, which is a cellular catabolic process involved in tumorigenesis. To investigate the role of alternative splicing of Beclin1 in the regulation of autophagy in leukemia cells, Beclin1 mRNA from 6 different types of cell lines and peripheral blood mononuclear cells from 2 healthy volunteers was reversely transcribed, subcloned, and screened for alternative splicing. New transcript variants were analyzed by DNA sequencing. A transcript variant of Beclin 1 gene carrying a deletion of exon 11, which encoded a C-terminal truncation of Beclin 1 isoform, was found. The alternative isoform was assessed by bioinformatics, immunoblotting and subcellular localization. The results showed that this variable transcript is generated by alternative 3' splicing, and its translational product displayed a reduced activity in induction of autophagy by starvation, indicating that the spliced isoform might function as a dominant negative modulator of autophagy. Our findings suggest that the alternative splicing of Beclin 1 might play important roles in leukemogenesis regulated by autophagy.

Establishment of mouse model with humanized Philadelphia chromosome-positive acute lymphoblastic leukemia

The purpose of this study was to establish a novel xenotransplant mouse model with human Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+)ALL). The bone marrow mononuclear cells (BMMNC) were separated from newly diagnosed Ph(+)ALL patients, and injected into 2.1 Gy of (60)Co irradiated and anti-CD122-conditioned NOD/SCID mice through intra femoral injection. Human hematopoietic chimerism in bone marrow and spleen of the recipients was detected by flow cytometry. Morphological analysis of murine marrow cells were performed using May-Giemsa staining. BCR/ABL1 level was detected by RQ-PCR and FISH assays. Furthermore, leukemia infiltration in the organs was evaluated by hematoxylin-eosin staining, immunohistochemical staining with anti-human CD19 and anti-human CD34 antibodies. The results indicated that the unsorted BMMNC from Ph(+)ALL patients were able to repopulate human Ph(+)ALL in vivo. The percentages of human CD45(+)CD19(+) cells in bone marrow, and spleen of the recipient mice were 87.2% ± 10.1% and 79.9% ± 9.2%, respectively. Furthermore, the engrafted cells possessed same morphology, phenotypic and cytogenetic characteristics as cells from the original Ph(+)ALL patients. Compatible with the clinical features, transplanted Ph(+)ALL cells infiltrated into the brain, liver, and kidney of the recipients. It is concluded that the human-mouse xenotransplant established model using intra femoral injection of an anti-CD122-conditioned NOD/SCID repopulation may provide a promising system to study the biology of human Ph(+)ALL in vivo.

Cytotoxic Clerodane Diterpenes from Zuelania guidonia

The leaves of Zuelania guidonia yielded eight new clerodane diterpenes, namely, zuelaguidins A-H (1-8), and the known clerodane diterpene esculentin A (9). Some of these structures contained a 3,6-dihydro-1,2-dioxin moiety. The new compounds were isolated and identified using 1D- and 2D-NMR experiments. All compounds were evaluated for cytotoxicity against the CCRF-CEM (human acute lymphocytic leukemia), CEM-ADR5000 (human acute lymphocytic leukemia resistant to doxorubicin), and MIA-PaCa-2 (human pancreatic carcinoma) cell lines as well as for their selectivity against peripheral blood mononuclear cells from healthy human subjects. Zuelaguidins B, C, and E were the most potent compounds against the CCRF-CEM cell line, with IC50 values ranging from 1.6 to 2.5 μM.