INDUCTION OF APOPTOSIS OF HUMAN LEUKEMIA CELLS BY α-ANORDRIN

The apoptosis-inducing effect of a-anordrin (ANO)was investigated in this study. ANO 10-50 AM inhibited the growth of both human leukemia HL-60 and K562cells by 19-52%. Electron microscopy showed that ANO-treated cells exhibited the drastic changes including cell shrinkage, chromatin condensation, nuclear fragmentation, typical of apoptosis. Gel electrophoresis of DNA extracted farm botlt HL-60 and K562 cells treated with ANO revealed characteristic 'ladder' pattern.ANO 50 μM for 48 h caused approximately 50-70%apoptosis. Cycloheximide (CHX) and actinomycin D (Act D) did not prevent ANO-induced apoptosis in K562cells, however, apoptosis of HL-60 cells in the presence of ANO was partially blocked by these two agents.Moreover, it was found that tamoxifen synergically potcntiated and cstradiol partially antagonized ANOinduccd apoptosis in HL-60 cells. Results demonstrated that ANO could induce tumor cell apoptosis, which might contribute to its anticancer action.

IN VIVO COMPARATIVE OBSERVATION ON THE INVASIVENESS OF VARIOUS ORGANS BY DIFFERENT LEUKEMIA CELLS

Using patho-morphological method and transplantation bio-assay, the in vivo invasiveness of leukemia cells is three transplantable mouse T cell leukemia models was comparatively studied. The results showed that the invasion to the liver was consistent, but that to other organs was obviously different. L615 and L7212 leukemia cells preferred to the bone marrow and spleen than to the peritoneum while L7811 leukemia cells were just the opposite. Transplantation bio-assay demonstrated that leukemia cells were present in the bone marrow of L615 mice as early as 6 hours after leukemic cell inoculation, but no leukemia cells was detected in bone marrow of L7811 mice 2 days after inoculation. In the terminal phase, L615 mice bone marrow became filled with leukemia cells, but L7811 mice bone marrow contained only a few leukemia cells. The difference of invasiveness of leukemia cells among organs is probably related to "homing" receptor. The same type of leukemia cells may possess multiple "homing" receptor.

NUCLEAR MATRIX PROTEIN IN LEUKEMIA CELLS

Objective: To compare the composition of nuclear matrix proteins (NMP) between leukemia cells and normal bone marrow cells. Methods: NMP was isolated by high-salt extraction and identified in acute and chronic myelogenous leukemia cells as well as in the blast phase of chronic leukemia. On SDS-PAGE, NMPs with molecular myelogenous ferment from what were seen in normal bone marrow cells were present in both acute and chronic myelogenous leukemia. Conclusion: Marked changes of NMP, not only in contents but also in compositions, exist in leukemic cells compared with normal bone marrow cells. NMP may serve as a target of chemotherapeutic drug against leukemia.

Gossypol acetic acid regulates leukemia stem cells by degrading LRPPRC via inhibiting IL-6/JAK1/STAT3 signaling or resulting mitochondrial dysfunction

BACKGROUND Leukemia stem cells(LSCs)are found to be one of the main factors contributing to poor therapeutic effects in acute myeloid leukemia(AML),as they are protected by the bone marrow microenvironment(BMM)against conventional therapies.Gossypol acetic acid(GAA),which is extracted from the seeds of cotton plants,exerts anti-tumor roles in several types of cancer and has been reported to induce apoptosis of LSCs by inhibiting Bcl2.AIM To investigate the exact roles of GAA in regulating LSCs under different microenvironments and the exact mechanism.METHODS In this study,LSCs were magnetically sorted from AML cell lines and the CD34+CD38-population was obtained.The expression of leucine-rich pentatricopeptide repeat-containing protein(LRPPRC)and forkhead box M1(FOXM1)was evaluated in LSCs,and the effects of GAA on malignancies and mitochondrial RESULTS LRPPRC was found to be upregulated,and GAA inhibited cell proliferation by degrading LRPPRC.GAA induced LRPPRC degradation and inhibited the activation of interleukin 6(IL-6)/janus kinase(JAK)1/signal transducer and activator of transcription(STAT)3 signaling,enhancing chemosensitivity in LSCs against conventional chemotherapies,including L-Asparaginase,Dexamethasone,and cytarabine.GAA was also found to downregulate FOXM1 indirectly by regulating LRPPRC.Furthermore,GAA induced reactive oxygen species accumulation,disturbed mitochondrial homeostasis,and caused mitochondrial dysfunction.By inhibiting IL-6/JAK1/STAT3 signaling via degrading LRPPRC,GAA resulted in the elimination of LSCs.Meanwhile,GAA induced oxidative stress and subsequent cell damage by causing mitochondrial damage.CONCLUSION Taken together,the results indicate that GAA might overcome the BMM protective effect and be considered as a novel and effective combination therapy for AML.

Non-canonical BRAF variants and rearrangements in hairy cell leukemia

Hairy cell leukemia(HCL)is an uncommon mature B-cell malignancy characterized by a typical morphology,immunophenotype,and clinical profile.The vast majority of HCL patients harbor the canonical BRAF V600E mutation which has become a rationalized target of the subsequently deregulated RAS-RAF-MEK-MAPK signaling pathway in HCL patients who have relapsed or who are refractory to front-line therapy.However,several HCL patients with a classical phenotype display non-canonical BRAF mutations or rearrangements.These include sequence variants within alternative exons and an oncogenic fusion with the IGH gene.Care must be taken in the molecular diagnostic work-up of patients with typical HCL but without the BRAF V600E to include investigation of these uncommon mechanisms.Identification,functional characterization,and reporting of further such patients is likely to provide insights into the pathogenesis of HCL and enable rational selection of targeted inhibitors in such patients if required.

Treatment refractory mast cell leukemia with dominant gastrointestinal manifestation and concomitant skin symptoms:A case report

BACKGROUND Mast cell leukemia(MCL),a subtype of systemic mastocytosis(SM),is an extremely rare clinical entity characterized by a very poor prognosis.Chemotherapy,tyrosine kinase inhibitors,and allogeneic hematopoietic cell transplantation are the only treatment options,but they cannot provide the desired outcomes in most cases of MCL.However,other types of SM can be successfully treated.The disease has no specific manifestation,but gastroenterological symptoms are present in most cases.CASE SUMMARY The authors,hereby,report a case of a 46-year-old female patient diagnosed with MCL-the rarest subtype of SM.The patient presented to the gastroenterology clinic with multiple,various,and unspecific gastroenterological symptoms.Concomitance of skin lesions significantly contributed to a relatively prompt diagnosis.The serum tryptase level was extremely high and bone the marrow aspirate showed an infiltration of atypical mast cells.The disease was rapidly progressive and primary refractory to chemotherapy and the patient succumbed to the illness about a month after the initiation of treatment.CONCLUSION Despite its“hematological nature”,MCL,in most cases presents dominantly with unspecific gastroenterological symptoms.Thus,a high disease awareness among physicians other than hematologists is necessary to improve treatment outcomes.Serum tryptase level,due to its non-invasive nature and easy access,may serve as an initial step to estimate the probability of mastocytosis.

Pure total flavonoids from Citrus paradisi Macfadyen act synergistically with arsenic trioxide in inducing apoptosis of Kasumi-1 leukemia cells in vitro

To investigate the potential effects of pure total flavonoid compounds（PTFCs） from Citrus paradisi Macfadyen separately or combined with arsenic trioxide on the proliferation of human myeloid leukemia cells and the mechanisms underlying the action of PTFCs. The effects of PTFCs separately or combined with arsenic trioxide on the proliferation and apoptosis of leukemia cells were determined by 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide（MTT）, fluorescence microscopy, and flow cytometry. Their effects on the expression levels of apoptosisrelated regulators were determined by Western blot assay. PTFCs combined with arsenic trioxide significantly inhibited the growth of Kasumi-1 cells, and apoptosis was confirmed by flow cytometry analysis. Hoechst 33258 staining showed more significant morphological changes and more apoptosis following the combined treatment. Western blots showed changes in the expression of genes for poly ADP-ribose polymerase（PARP）, caspase 3/9, and P65. The results indicated that PTFCs separately or combined with arsenic trioxide inhibited proliferation of leukemia cells in vitro and induced their apoptosis by modulating the expression of apoptosis-related regulator genes.

Resveratrol Inhibits the Secretion of Vascular Endothelial Growth Factor and Subsequent Proliferation in Human Leukemia U937 Cells

This study examined the effect of resveratrol on the secretion of vascular endothelial growth factor （VEGF） and subsequent proliferation of human leukemia U937 cells, and explored the mechanisms involved. Human leukemia U937 cells were treated with resveratrol of different concentrations （12.5-200 μmol/L） for different time lengths （12-48 h）. The proliferation of the U937 leukemic cells was determined by MTT assay. Apoptosis was observed by Annexin- V-FIFC/PI double staining and flow cytometry （FCM）. Cells cycle was analyzed by PI staining and FCM. The content of VEGF was determined by ELISA. Human umbibical vein endothelial cells were examined for vasoformation in vitro after exposures to resveratrol of various concetrations. The results showed that resveratrol inhibited the proliferation of U937 leukemia cells in a dose- and time-dependent manner. Resveratrol induced apoptosis and S-phase cell cycle arrest in human leukemic U937 cells. Resveratrol inhibited the secretion of VEGF in U937 cells. Resveratrol inhibited the vasoformation of human vein endothelial cells in a dose-dependent manner. It was concluded that resveratrol could down-regulate the secretion of VEGE induce apoptosis and suppress the proliferation of U937 cells.

Menin expression is regulated by transforming growth factor beta signaling in leukemia cells

Background Menin is a ubiquitously expressed protein encoded by the multiple endocrine neoplasia type 1 （MEN1）gene. Besides its importance in endocrine organs, menin has been shown to interact with the mixed lineage leukemia （MLL） protein, a histone H3 lysine 4 methyltransferase, and plays a critical role in hematopoiesis and leukemogenesis.Previous studies have shown that menin promotes transforming growth factor beta （TGF-β） signaling in endocrine cells.However, little is known regarding the impact of TGF-β pathway on menin in hematopoietic system. Here, with leukemia cell lines generated from conditional MEN1 or TGF-p receptor （TβRII） knockout mouse models, we investigated the possible cross-talk of these two pathways in leukemia cells.Methods MEN1 or TβRII conditional knockout mice were bred and the bone marrow cells were transduced with retroviruses expressing oncogeneic MLL-AF9 （a mixed lineage leukemia fusion protein） to generate two leukemia cell lines. Cell proliferation assays were performed to investigate the effect of TGF-β treatment on MLL-AF9 transformed leukemia cells with/without MEN1 or TβRII excision. Menin protein was detected with Western blotting and mRNA levels of cell proliferation-related genes Cyclin A2 and Cyclin E2 were examined with real-time RT-PCR for each treated sample.In vivo effect of TGF-p signal on menin expression was also investigated in mouse liver tissue after TβRII excision.Results TGF-β not only inhibited the proliferation of wild type MLL-AF9 transformed mouse bone marrow cells, but also up-regulated menin expression in these cells. Moreover, TGF-P failed to further inhibit the proliferation of Men1-null cells as compared to Men1-expressing control cells. Furthermore, excision of TβRII, a vital component in TGF-β signaling pathway, down-regulated menin expression in MLL-AF9 transformed mouse bone marrow cells. In vivo data also confirmed that menin expression was decreased in liver samples of conditional TβRII knockout mice after TβRII excision.Conclusion These results provided the first piece of evidence of cross-talk between menin and TGF-β signaling pathways in regulating proliferation of leukemia cells, suggesting that manipulating the cross-talk of the two pathways may lead to a novel therapy for leukemia.

PATHOLOGICAL STUDIES ON THE ANTI－INVASIVE CHARACTER BY RECOMBINANT HUMAN INTERLEUKIN－6 GENE－TRANSFECTED MOUSE LEUKEMIA CELLS

Mouse FBL-3 erythroleukemia cells were transfected with recombinant human interleukin-6 (rhIL-6) gene and a clone secreting IL-6 was selected (i.e., FBL-3-IL-6+). The cell clone secreting IL-6 was inoculated into C57BL/6 mouse. The growth of tumors was observed and histologic analyses of the tumors in situ, liver, spleen and bone marrow were performed after inoculation. The mice inoculated with wild-type FBL-3 erythroleukemia cells were used as the control. The results showed that the later the tumor occurrence, the slower the tumor development,the lower the pathological changes degree and the longer the survival time in experimental group compared to that of the control. The results demonstrated that the inoculation of the FBL-3 cell clone secreting IL-6 can inhibit the invasion of leukemia cells, suggesting that the FBL-3-IL-6+ cells can he used as a vaccine to treat leukemia.

Augmented Effect of Composite Salvia Miltiorrhiza Injectionon Radiosensitivity of Leukemia Cells

Objective: To explore the effect of Composite Salviae miltiorrhizae Injection (CSMI) on radiosensitivity of leukemia cells. Methods:Semisolid agar culture and flow cytometry assay were performed for studying the change in radiosensitivity of HL60 cell line and fresh human leukemia cells after exposing to CSMI.Results: The D0 (the inverse of the slope of the survival curve) and SF2 (survival fraction at 2 Gy) of HL60 cell line were decreased from 1. 53, 0. 34 to 0. 93, 0. 12, respectively and apopotosis rates after radiation were raised significantly by CSMI. Furthermore, the concentration of CSMI and the time of mixed culture with CSMI before irradiation had positive relation to the effects mentioned above. Compared with control group, CSMI could increase the radiation-induced apoptosis of fresh leukemia cells (5. 89 ± 2. 91 vs 12. 05 ± 3. 06). Conclusion: CSMI could obviously enhance the radiosensitivity of leukemia cells.Original article on CJIM(Chin) 1998; 18(5): 279

Bone marrow niche-mediated survival of leukemia stem cells in acute myeloid leukemia: Yin and Yang

Acute myeloid leukemia （AML） is characterized by the accumulation of circulating immature blasts that exhibit uncontrolled growth, lack the ability to undergo normal differentiation, and have decreased sensitivity to apoptosis. Accumulating evidence shows the bone marrow （BM） niche is critical to the maintenance and retention of hematopoietic stem cells （HSC）, including leukemia stem cells （LSC）, and an increasing number of studies have demonstrated that crosstalk between LSC and the stromal cells associated with this niche greatly influences leukemia initiation, progression, and response to therapy. Undeniably, stromal cells in the BM niche provide a sanctuary in which LSC can acquire a drug-resistant phenotype and thereby evade chemotherapy- induced death. Yin and Yang, the ancient Chinese philosophical concept, vividly portrays the intricate and dynamic interactions between LSC and the BM niche. In fact, LSC-induced microenvironmental reprogramming contributes significantly to leukemogenesis. Thus, identifying the critical signaling pathways involved in these interactions will contribute to target optimization and combinatorial drug treatment strategies to overcome acquired drug resistance and prevent relapse following therapy. In this review, we describe some of the critical signaling pathways mediating BM niche-LSC interaction, including SDFI/CXCL12, Wnt/β-catenin, VCAM/VLA-4/NF-κB, CD44, and hypoxia as a newly-recognized physical determinant of resistance, and outline therapeutic strategies for overcoming these resistance factors.

Resveratrol-downregulated Phosphorylated Liver Kinase B1 Is Involved in Senescence of Acute Myeloid Leukemia Stem Cells

Summary： Senescence is an important obstacle to cancer development. Engaging a senescent response may be an effective way to cure acute myeloid leukemia （AML）. The aim of this study was to examine the effect of resveratrol-downregulated phosphorylated liver kinase B1 （pLKB1） on the senescence of acute myeloid leukemia （AML） stem cells. The protein expressions of pLKB 1 and Sirtuin 1 （SIRT1）, a regulator ofpLKB1, were measured in CD34＋CD38-KGla cells treated with resveratrol （40 μmol/L） or not by Western blotting. Senescence-related factors were examined, including p21 mRNA tested by real-time PCR, cell morphology by senescence-associated β-galactosidase （SA-β-gal） staining, cell pro- liferation by MTT assay and cell cycle by flow cytometry. Besides, apoptosis was flow cytometrically determined. The results showed that pLKB1 was highly expressed in CD34＋CD38- KGla cells, and resveratrol, which could downregulate pLKB1 through activation of SIRT1, induced senescence and apoptosis of CD34＋CD38- KGla cells. It was concluded that resveratrol-downregulated pLKB1 is in- volved in the senescence of AML stem cells.

Update on acute myeloid leukemia stem cells:New discoveries and therapeutic opportunities

The existence of cancer stem cells has been wellestablished in acute myeloid leukemia. Initial proof of the existence of leukemia stem cells(LSCs) was accomplished by functional studies in xenograft models making use of the key features shared with normal hematopoietic stem cells(HSCs) such as the capacity of self-renewal and the ability to initiate and sustain growth of progenitors in vivo. Significant progress has also been made in identifying the phenotype and signaling pathways specific for LSCs. Therapeutically, a multitude of drugs targeting LSCs are in different phases of preclinical and clinical development. This review focuses on recent discoveries which have advanced our understanding of LSC biology and provided rational targets for development of novel therapeutic agents. One of the major challenges is how to target the selfrenewal pathways of LSCs without affecting normal HSCs significantly therefore providing an acceptable therapeutic window. Important issues pertinent to the successful design and conduct of clinical trials evaluating drugs targeting LSCs will be discussed as well.

Higher PD-1 expression concurrent with exhausted CD8+ T cells in patients with de novo acute myeloid leukemia

Objective： To investigate the association between the T cell inhibitory receptor programmed death 1（PD-1）and T cell exhaustion status in T cells from patients with de novo acute myeloid leukemia（AML） and AML in complete remission（CR）.Methods：Surface expression of PD-1 and the exhaustion and immunosenescence markers CD244 and CD57 on CD3＋,CD4＋ and CD8＋ T cells from peripheral blood samples from 20 newly diagnosed,untreated AML patients and 10 cases with AML in CR was analyzed by flow cytometry.Twenty-three healthy individuals served as control.Results：A significantly higher percentage of PD-1＋ cells were found for CD3＋ T cells in the de novo AML group compared with healthy controls.In addition,an increased level of PD-1＋ CD8＋ T cells,but not PD-1＋ CD4＋,was found for CD3＋ T cells in the de novo AML and AML-CR samples.A higher percentage of CD244＋ CD4＋,CD244＋ CD8＋,CD57＋ CD4＋ and CD57＋ CD8＋ T cells was found in CD3＋ T cells in samples from those with de novo AML compared with those from healthy controls.Strong increased PD-1＋ CD244＋ and PD-1＋ CD57＋ coexpression was found for CD4＋ and CD8＋ T cells in the de novo AML group compared with healthy controls.Conclusions：We characterized the major T cell defects,including co-expression of PD-1 and CD244,CD57-exhausted T cells in patients with de novo AML,and found a particular influence on CD8＋ T cells,suggesting a poor anti-leukemia immune response in these patients.

Induction of T-cell immunity against leukemia by dendritic cells pulsed with total RNA isolated from leukemia cells

Objectives To assess the feasibility and efficacy of eliciting leukemia-specific T-cell responses in syngeneic mice in vitro and in vivo using dendritic cells (DCs) pulsed with total RNA from leukemia cells.Methods DCs generated from bone marrow culture in vitro in the presence of combined cytokines were pulsed with cellular total RNA isolated from cultured L615 cells by cationic lipid 1,2-dioleoyloxy-3-(trimethylammonium) propane (DOTAP). T-cell responses were evaluated by in vitro proliferation, and cytotoxicity assay. And in vivo immune protection and proghosis of mice with leukemia were studied.Results DCs pulsed with total RNA isolated from cultured L615 cells (DCs/RNA) were remarkably effective in stimulating L615-specific T-cell response in vitro, but did not cross-react with other leukemia cells from syngeneic mice. Vaccination of naive mice with viable DCs/RNA vaccine was able to partly protect from challenge with a lethal dose of live L615 cells, leading to low leukemia incidence and overall survival prolongation. Statistically significant survival was also observed in a low lethal dose of L615-bearing mice that received treatment using viable DCs / RNA vaccine alone, suggesting that systemic administration of IL-2 could enhance the anti-tumor efficacy of leukemia RNA/DCs vaccine.Conclusions These data support the use of DCs/RNA vaccine as a feasible and effective route to elicit leukemia immunity against unidentified leukemia-associated antigens for treatment of leukemia-bearing animals.

Spectroscopic and electrochemical studies on molecular recognition of tetrathiafulvalene derivative with P-glycoprotein and drug-resistant leukemia cells

Cancer is still one of the important diseases that threatens the health of people. Multidrug resistance(MDR) is the main factor that leads to the failure of cancer chemotherapy. Thus, MDR diagnosis could facilitate the monitoring of the therapy process and realization of efficient treatment of tumors. In this study, we have tried to use a new tetrathiafulvalene(TTF) derivative(TTF-(COONBu4)2) to sensitively recognize the MDR through the multi-signal responsive strategy. The relevant electrochemical and spectroscopic studies demonstrate the specific binding behavior of TTF-(COONBu4)2 with P-glycoprotein(P-gp) as well as drug-resistant leukemia cells. Especially due to the over-expression of specific components of P-gp on the plasma membranes of drug resistant cells, the electrochemical and hydrophilic/hydrophobic features of drug resistant-leukemia cells are apparently different from those of other kinds of leukemia cells. Meanwhile, Fourier transform infrared spectroscopic study illustrates that the most intense vibration band of TTF moieties in the 1400–1600 cm-1 range is almost smeared out upon binding to P-gp, and the binding of TTF-(COONBu4)2 to P-gp may also lead to changes in protein secondary structure and backbone. This observation may advance the development of the new TTF agent for the promising clinical diagnosis and monitoring of MDR of tumors with the aim of successful chemotherapy for human cancer.

Electrochemical study of the effect of functionalized nickel nanoparticles on cellular uptake of leukemia cancer cells in vitro

In this study, we have fabricated the functionalized nickel nanoparticles and investigated their effects on cellular uptake of quercetin in leukemia K562 cancer cells by using electrochemical assay. The results indicate that nickel nanoparticles could efficiently enhance the quercetin uptake and increase the intracellular accumulation in cancer cells, implying the great potential of functionalized nickel nanoparticles in target cancer therapy.

Study of Heat Shock Protein HSP90α，HSP70，HSP27 mRNA Expression in Human Acute Leukemia Cells

The expression of three heat shock proteins (HSPs)-HSP90, HSP70,HSP27 in cells obtained from 22 patients with leukemia, K562 erythroleukemia cell line, and normal blood cells was observed by means of RNA dot blot analysis.The results showed that the expression of the HSP27 gene was enhanced in 4 cases of acute lymphoid leukemia (ALL), 7 cases of acute nonlymphoid leukemia (ANLL) and 2 cases of myelodysplastic syndrome (MDS) as compared with that of the normal blood cells, yet there was no significant difference in the HSP27 expression between the ALL and ANLL cells. The expression of HSP70 in all the 5 ALL and ANLL patients was much lower than that of the normal subjects, except 1 case of ALL and 1 case of MDS, in which the expression was obviously enhanced. All the cases including 11 ANLL, 5 ALL and 1 MDS had higher HSP90α expression than the normal subjects. The enhanced expression of HSP90α in leukemia cells may be associated with the active and indefinite proliferation of leukemia cells. Our results also suggest that the high expression of the HSP27gene may not be confined to a specific type of acute leukemia.