Multiorgan Failure in Hemophagocytic Lymphohistiocytosis Secondary to Acute Monocytic Leukemia and Myocarditis in a Pediatric Patient

Acute monocytic leukemia (AML), a subtype of acute myeloid leukemia, is a rare leukemia found in children. It occurs more frequently in adults over the age of 60. Myocarditis represents inflammation of the muscular layer of the heart, the myocardium causing weakening of the muscles that can lead to hemodynamic instability from a reduced ejection fraction. Myocarditis in the pediatric population is most commonly secondary to a viral or infectious etiology. Hemophagocytic lymphohistiocytosis (HLH) is a rare condition of immune dysregulation characterized by severe organ damage induced by an increased inflammatory response and uncontrolled T-cell and macrophage activation. In this case report, we examine a rare presentation of leukemic myocarditis in the presence of HLH, which displays an uncommon cause of an inflammatory state with several complicated concomitant diagnoses. Our patient developed severe multiorgan dysfunction involving liver and kidney failure that required prolonged critical care support, and the patient expired due to his multiorgan failure. We highlight the unusual clinical presentation of myocarditis in the setting of HLH and AML in this complicated pediatric patient and aim to improve outcomes of patients presenting similarly in the future.

Eltrombopag and its iron chelating properties in pediatric acute myeloid leukemia

Pediatric acute myeloid leukemia (AML) represents 20% of total childhood leukemia diagnoses and is characterized by poor prognosis with a long-term survival rate around the 50%, when patients are properly treated. The standard treatment for pediatric AML currently consists in a combination of cytarabine (Ara-C) and antracycline. Iron plays an important role in cancer development and progression. Targeting iron and its metabolism mediators could be a novel therapeutic strategy in cancer.Deferasirox (DFX) inhibits cancer cell proliferation and its use as an antiblastic drug could be suggested. Eltrombopag (ELT), a thrombopoietin receptor agonist used in immunethrombocytopenia, shows anticancer properties related to its emerging iron chelating properties. We compare the anticancer effect of classically used cytarabine with DFX and ELT effects in a pediatric AML cell line, THP-1, in order to identify innovative and more effective therapeutic strategies. ELT and DFX reduce intracellular iron concentration by inhibiting its uptake and by promoting its release. In particular, even though further investigations are needed to better understand the extact underlying action mechanisms, we demonstrated that ELT improves cytarabine antineoplastic activity in pediatric AML cell line.

Solasonine Suppresses the Proliferation of Acute Monocytic Leukemia Through the Activation of the AMPK/FOXO3A Axis

Solasonine, the main active ingredient of Solanum nigrum L., has been reported to exert extensive antitumor activity. However, the antitumor effects in acute monocytic leukemia and the exact mechanisms involved are unknown. In this study, we investigated the role of solasonine on inhibiting the progression of acute monocytic leukemia. Our findings showed that solasonine inhibited the proliferation of acute monocytic leukemic cell lines (THP-1 and MV4-11) in vitro. Solasonine promoted apoptosis and induced cell cycle arrest in the G2/M phase. Analysis of RNA-seq data suggested that solasonine correlated with increased expression of genes in the AMPK/FOXO3A pathway. Inhibition of AMPK with compound C followed by treatment with solasonine showed that solasonine reduced apoptosis, caused less cell cycle arrest, and inactivated the AMPK/FOXO3A axis in THP-1 and MV4-11 cells. Solasonine also inhibited tumor growth by the activation of the AMPK/FOXO3A axis. In conclusion, solasonine inhibited the progress of acute monocytic leukemia in vitro and in vivo and triggered the apoptosis and cell cycle arrest in the G2/M phase by upregulating the AMPK/FOXO3A pathway.

Integrated analysis of microRNA and transcription factors in the bone marrow of patients with acute monocytic leukemia

Acutemonocytic leukemia (AMoL) is a distinct subtype of acute myeloid leukemia (AML) with poor prognosis. However, the molecular mechanisms and key regulators involved in the global regulation of gene expression levels in AMoL are poorly understood. In order to elucidate the role of microRNAs (miRNAs/miRs) and transcription factors (TFs) in AMoL pathogenesis at the network level, miRNA and TF expression level profiles were systematically analyzed by miRNA sequencing and TF array, respectively; this identified 285 differentially expressed miRNAs and 139 differentially expressed TFs in AMoL samples compared with controls. By combining expression level profile data and bioinformatics tools available for predicting TF and miRNA targets, a comprehensive AMoL-specific miRNA-TF-mediated regulatory network was constructed. A total of 26 miRNAs and 23 TFs were identified as hub nodes in the network. Among these hubs, miR-29b-3p, MYC, TP53 and NFKB1 were determined to be potential AMoL regulators, and were subsequently extracted to construct sub-networks. A hypothetical pathway model was also proposed for miR-29b-3p to reveal the potential co-regulatory mechanisms of miR-29b-3p, MYC, TP53 and NFKB1 in AMoL. The present study provided an effective approach to discover critical regulators via a comprehensive regulatory network in AMoL, in addition to enhancing understanding of the pathogenesis of this disease at the molecular level.

Acute monocytic leukemia presenting as generalized lymphadenopathy and skin rash in a toddler: highlighting the clinicopathologic mimics

Acute myeloid leukemia (AML) is the fifth most common malignancy in children. Extramedullary involvement in acute myeloid leukemia is rare and can be seen in soft tissues, central nervous system, skin and lymphoreticular organs. The clinical presentations can often be non-specific and hence, the diagnosis can be very challenging, especially in cases without a prior hematologic diagnosis. We report a case of pediatric acute monocytic leukemia presenting with generalized lymphadenopathy and cutaneous rash. Fine-needle aspiration was performed from the lymph nodes and a cytologic diagnosis of infiltration by a lymphoreticular malignancy was suggested. Peripheral blood, bone marrow and cerebrospinal fluid involvement were noted subsequently. Flow cytometry on the bone marrow aspirate confirmed a diagnosis of acute monocytic leukemia. The index case besides highlighting an uncommon presentation of acute monocytic leukemia in a toddler, also emphasizes the need to consider acute monocytic leukemia as a cytomorphologic differential in such presentations.

MLAA-34 knockdown shows enhanced antitumor activity via JAK2/STAT3 signaling pathway in acute monocytic leukemia

MLAA-34 is a novel leukemia-associated gene closely related to the carcinogenesis of acute monocytic leukemia (AML). MLAA-34 over expression has been observed to inhibit apoptosis in vitro. JAK2/STAT3 pathway plays an important role in cell proliferation, differentiation and inhibition of apoptosis in number of cancers. However, the relationship and interaction between MLAA-34 and JAK2/STAT3 has never been investigated in AML.

This study investigates and reports a novel relationship between MLAA-34 and JAK2/STAT3 pathway in AML both in vitro and in vivo. We constructed MLAA-34 knockdown vector and transfected U937 cells to observe its apoptotic activities in relation to JAK2/STAT3 signaling pathway in vitro and then in vivo in mouse model. Levels of expression of MLAA-34 and JAK2/STAT3 and its downstream targets were also measured in AML patients and a few volunteers.

We found that MLAA-34 knockdown increased U937 apoptosis in vitro and inhibited tumor growth in vivo. Components of the canonical JAK2/STAT3 pathway or its downstream targets, including c-myc, bcl-2, Bax, and caspase-3, were shown to be involved in the carcinogenesis of AML. We also found that the JAK2/STAT3 pathway positively regulated MLAA-34 expression. We additionally identified a STAT3 binding site in the MLAA-34 promoter where STAT3 binds directly and activates MLAA-34 expression. In addition, MLAA-34 was found to form a complex with JAK2 and was enhanced by JAK2 activation. Correlation of MLAA-34 and JAK2/STAT3 was further confirmed in AML patients.

In conclusion, MLAA-34 is a novel regulator for JAK2/STAT3 signaling, and in turn, is regulated by this interaction in a positive feedback loop. Thus we report a novel model of interaction mechanism between MLAA-34 and JAK2/STAT3 which can be utilized as a potential target for a novel therapeutic approach in AML.

Leukocyte immunoglobulin-like receptor B1 and B4 (LILRB1 and LILRB4): Highly sensitive and specific markers of acute myeloid leukemia with monocytic differentiation

BACKGROUND

Acute myeloid leukemia (AML) with monocytic differentiation (M-AML) remains a diagnostic challenge largely due to lack of sensitive and specific markers for immature monocytes. The immunoglobulin-like inhibitory receptors, LILRB1 and LILRB4, are expressed on monocytes but have not yet been systematically evaluated in the clinical setting.

METHODS

We evaluated the diagnostic performance of LILRB1 and LILRB4 as monocytic markers for both immature and mature monocytes in comparison to other myelomonocytic markers including CD14, CD15, CD33, CD36, and CD64 in eight cases of control bone marrow (BM, 5) and peripheral blood (PB, 3), 64 cases of (M-AML), and 57 cases of AML without monocytic differentiation (NM-AML) by flow cytometric immunophenotyping.

RESULTS

In control BM, LILRB1 and LILRB4 were consistently expressed on monocytes at all stages of maturation, from CD34⁺ /CD14^- monocytic precursors to CD14^-/dim+ maturing and CD14⁺ mature monocytes. In M-AML, LILRB1 and LILRB4 were consistently expressed on monocytes, regardless of the degree of maturity, from CD14^-/dim+ monoblasts/promonocytes to CD14⁺ mature monocytes but were not expressed on myeloblasts. The diagnostic performances as a monocytic marker assessed by sensitivity/specificity were 100%/100% for LILRB1/LILRB4, 100%/82% for CD11b, 80%/100% for CD14, 100%/81% for CD64, 100%/58% for CD15/CD33, and 89%/97% for CD36/CD64.

CONCLUSION

The co-expression of LILRB1/LILRB4 outperformed other myelomonocytic markers as a highly sensitive and specific marker for monocytes at all stages of maturation and could reliably distinguish M-AML from NM-AML. LILRB4 additionally represents a novel therapeutic target for treating M-AML.

Rare Case of Diffuse Large B-Cell Lymphoma Mimicking Acute Monocytic Leukemia, Associated with Complex Karyotype

OBJECTIVE

Diffuse Large B-Cell Lymphoma (DLBCL), NOS, constitutes 25-35% of adult non-Hodgkin lymphomas in developed countries, and a higher percentage in developing countries; older people are prone to the disease. Three frequent morphological variants have been recognized, including centroblastic, immunoblastic, and anaplastic variants. However, there are still other rare morphological variants of DLBCL, presenting challenge in diagnosis and treatment.

CASE PRESENTATION

A 62-year-old woman sought medical attention with a previous 6-month history of intermittent fever and leukocytosis. Bone marrow (BM) aspiration presented AML with acute monocytic leukemia-like morphologic features. The results of the immunophenotypic analysis suggested mature B cell lymphoma without obvious subtype characteristics. Lymph node biopsy indicated DLBCL of non-germinal centre B-cell subtype (n-GCB). Cytogenetic analysis of the BM cells revealed a 46,XX, trp(1)(q21q32),del(7)(q32q36),t(9;14)(p13;q32) [4]/46,XX [16] karyotype. The patient was diagnosed with EBV-positive DLBCL, NOS based on the combination of lymph node biopsy, clinical, cytological, immunophenotypic, and cytogenetic analyses.

CONCLUSION

To date, no case reports of a patient diagnosed with DLBCL mimicking acute monocytic leukemia with complex karyotype have been reported. We present the case given its rarity, easy misdiagnosis, and poor prognosis. The case highlights the importance of awareness about the rare morphological variant to laboratory staff and hematologists.

Prognostic stratification of molecularly and clinically distinct subgroup in children with acute monocytic leukemia

Background

The prognosis of children with acute monocytic leukemia (AML‐M5) remains unsatisfactory and the risk profile is still controversial. We aim to investigate the prognostic value of clinical and cytogenetic features and propose a new risk stratification in AML‐M5 children.

Methods

We included 132 children with AML‐M5. Overall survival (OS) and progression‐free survival (PFS) were documented. Cox regression was performed to evaluate the potential risk factors of prognosis.

Results

The 5‐year‐OS was 46.0% (95% confidence intervals, 41.6%‐50.4%) in all patients. There was significantly lower OS in the age ≤ 3 years old (P = .009) and hyperleukocytosis (P < .001). The FMS‐like tyrosine kinase 3 (FLT3)‐internal tandem duplication (ITD) and MLL‐rearrangement carriers were associated with fewer survivors in all patients (37.1% and 36.7%) and chemotherapy‐only group (19.0% and 35.0%). Notably, the number of survivor with MLL‐rearrangement did not increase in hematopoietic stem cell transplant (HSCT) group. According to the Cox regression analysis, HSCT was a significantly favorable factor (P = .001), while hyperleukocytosis, age ≤ 3 years old, and BM blast ≥ 70% adversely affected the OS in all patients (all P < .05). Additionally, FLT3‐ITD was a risk factor for OS in the chemotherapy‐only group (P = .023), while hyperleukocytosis and age ≤ 3 years independently contributed to poor PFS (both P < .05). In comparison to the standard‐risk group, significant poorer outcome was found in the high‐risk group (both P < .005).

Conclusions

We propose that AML‐M5 children with any of MLL‐rearrangement, FLT3‐ITD, hyperleukocytosis, BM blast ≥ 70%, or age ≤ 3 years old are classified into the high‐risk group, and HSCT is beneficial especially in patients with FLT3‐ITD mutation, hyperleukocytosis, and age ≤ 3 years old. Importantly, the choice of HSCT should be made more carefully in children with MLL‐rearrangement for its suboptimal performance.

Development of myelofibrosis and acute monocytic leukemia in a patient with hereditary spherocytosis: A case report

INTRODUCTION

Common symptoms of hereditary spherocytosis (HS) include intermittent jaundice and splenomegaly. Here, we present an unusual clinical course wherein a patient with HS treated with splenectomy developed secondary myelofibrosis and acute monocytic leukemia (M5).

PATIENT CONCERNS

After presenting with paleness, fatigue and jaundice, the patient was diagnosed with HS. After splenectomy, follow-up testing, including bone marrow biopsy, revealed myelofibrosis. Subsequently, the patient exhibited blood cell abnormalities consistent with M5.

DIAGNOSIS

M5 comorbid with myelofibrosis and a history of HS.

INTERVENTIONS

HS was treated with splenectomy. Myelofibrosis was treated with hydroxyurea. The patient refused chemotherapy for M5 and was discharged. He was maintained on hydroxyurea and received periodic blood product transfusions with regular routine blood test monitoring.

OUTCOMES

Because of intracranial hemorrhage, the patient died on May 17, 2018, a little >10 months after being diagnosed with leukemia.

CONCLUSION

The present patient developed M5 while undergoing treatment for myelofibrosis and after undergoing splenectomy for HS, raising the question of whether these conditions might be associated. Examination of this question will require the analysis of additional cases.

Establishment and characterization of a DOT1L inhibitor-sensitive human acute monocytic leukemia cell line YBT-5 with a novel KMT2A-MLLT3 fusion

Immortalized cell lines are useful for deciphering the pathogenesis of acute leukemia and developing novel therapeutic agents against this malignancy. In this study, a new human myeloid leukemia cell line YBT-5 was established. After more than 1-year cultivation from the bone marrow of a patient with acute monocytic leukemia, YBT cell line was established. Then a subclone, YBT-5, was isolated from YBT using single cell sorting. Morphological and cytogenetical characterizations of the YBT-5 cell line were determined by cytochemical staining, flow cytometry analysis, and karyotype analysis. Molecular features were identified by transcriptomic analysis and reverse transcription-polymerase chain reaction. To establish a tumor model, 5 × 10⁶ YBT-5 cells were injected subcutaneously in nonobese diabetic/severe combined immune-deficiency (NOD/SCID) mice. DOT1L has been proposed as a potential therapeutic target for KMT2A-related leukemia; therefore, to explore the potential application of this new cell line, its sensitivity to a specific DOT1L inhibitor, EPZ004777 was measured ex vivo. The growth of YBT-5 does not depend on granulocyte-macrophage colony-stimulating factor. Cytochemical staining showed that α-naphthyl acetate esterase staining was positive and partially inhibited by sodium fluoride, while peroxidase staining was negative. Flow cytometry analysis of YBT-5 cells showed positive myeloid and monocytic markers. Karyotype analysis of YBT-5 showed 48,XY,+8,+8. The breakpoints between KMT2A exon 10 and exon 11 (KMT2A exon 10/11) and MLLT3 exon 5 and exon 6 (MLLT3 exon 5/6) were identified, which was different from all known breakpoint locations, and a novel fusion transcript KMT2A exon 10/MLLT3 exon 6 was formed. A tumor model was established successfully in NOD/SCID mice. EPZ004777 could inhibit the proliferation and induce the differentiation of YBT-5 cells. Therefore, a new acute monocytic leukemia cell line with clear biological and molecular features was established and may be used in the research and development of new agents targeting KMT2A-associated leukemia.

Tanshinone IIA induces apoptosis and autophagy in acute monocytic leukemia via downregulation of PI3K/Akt pathway

Acute myeloid leukemia (AML) is characterized by unrestrained proliferation of myeloid cells. In has been shown that tanshinone IIA (Tan IIA), exhibited anti-tumor activities on different types of cancers. However, the underlying mechanisms by which Tan IIA regulates apoptosis and autophagy in AML remain unclear. Thus, this study aimed to investigate the effects of Tan IIA on AML in vitro and in vivo. CCK-8 assay, EdU staining, flow cytometry, MDC staining, immunofluorescence, transwell migration and invasion assay were used to detect cell proliferation, apoptosis, autophagy, migration and invasion, respectively. In addition, western blotting was used to examine the protein levels of Bax, Bcl-2, active caspase-3, Beclin-1, Atg-5, p-mTOR and p-Akt in cells. Moreover, animal studies were performed to evaluate anti-tumor effect of Tan IIA on AML in vivo. The results revealed that Tan IIA significantly suppressed the growth of U937 cells in vitro and in vivo. Meanwhile, Tan IIA induced apoptosis in U937 cells via up-regulating the levels of active caspase-3 and Bax, and down-regulating Bcl-2 in vitro and in vivo. In addition, Tan IIA inhibited the capacity of migration and invasion in U937 cells. Moreover, Tan IIA induced autophagy in U937 cells via upregulation of the expression of LC3 II, Atg5 and Beclin 1, which was further confirmed by MDC staining and immunofluorescence assays. For the first time, we have shown that autophagy inhibitor 3MA significantly enhanced Tan IIA-induced apoptosis in U937 cells. Furthermore, Tan IIA induced apoptosis and autophagy via downregulation of PI3K/Akt pathway in vitro and in vivo. Therefore, the accumulating evidences suggested that Tan IIA could be a potential agent for improving the symptoms of AML in the future.

[Small interfering RNA-mediated LPXN silencing suppresses proliferation and enhances drug sensitivity of human acute monocytic leukemia SHI-1 cells in vitro]

OBJECTIVE

To investigate the effect of silencing LPXN expression by RNA interference on the proliferation and drug sensitivity of human acute monocytic leukemia SHI-1 cells in vitro.

METHODS

Small interfering RNA (siRNA) sequences targeting LPXN were designed and transiently transfected in SHI-1 cells via Lipofectamine 2000, and the most efficient siRNA sequence for LPXN silencing was identified using Western blotting. The protein expression levels of LPXN, p-JNK, p-P38 MAPK and p-ERK were in the cells transfected with the selected siRNA were detected using Western blotting, and the cell proliferation changes were assessed using CCK-8 reagent.

RESULTS

LPXN silencing by siRNA transfection resulted in significant proliferation suppression in SHI-1 cells with an inhibition rate of(27.04±2.05) % (P < 0.05). Western blotting showed that treatment of the siRNA-transfected SHI-1 cells with 0-25 μmol/L curcumin or with 0-2.0 μmol/L Ara-C further increased the cell inhibition rate and obviously enhanced the expressions of p-P38 MAPK and p-JNK without significantly affecting p-ERK expression.

CONCLUSIONS

Down-regulation of LPXN expression by siRNA transfection can suppress the proliferation and increase the drug sensitivity of SHI-1 cells probably by activating JNK and P38 MAPK.

Anti-Leukemic Properties of Histamine in Monocytic Leukemia: The Role of NOX2

In patients with acute myeloid leukemia (AML), treatment with histamine dihydrochloride (HDC) and low-dose IL-2 (HDC/IL-2) in the post-chemotherapy phase has been shown to reduce the incidence of leukemic relapse. The clinical benefit of HDC/IL-2 is pronounced in monocytic forms of AML, where the leukemic cells express histamine type 2 receptors (H2R) and the NAPDH oxidase-2 (NOX2). HDC ligates to H2Rs to inhibit NOX2-derived formation of reactive oxygen species, but details regarding the anti-leukemic actions of HDC remain to be elucidated. Here, we report that human NOX2+ myelomonocytic/monocytic AML cell lines showed increased expression of maturation markers along with reduced leukemic cell proliferation after exposure to HDC in vitro. These effects of HDC were absent in corresponding leukemic cells genetically depleted of NOX2 (NOX2-/-). We also observed that exposure to HDC altered the expression of genes involved in differentiation and cell cycle progression in AML cells and that these effects required the presence of NOX2. HDC promoted the differentiation also of primary monocytic, but not non-monocytic, AML cells in vitro. In a xenograft model, immunodeficient NOG mice were inoculated with wild-type or NOX2-/- human monocytic AML cells and treated with HDC in vivo. The administration of HDC reduced the in vivo expansion of NOX2+/+, but not of NOX2-/- human monocytic AML cells. We propose that NOX2 may be a conceivable target in the treatment of monocytic AML.

Enhanced Response of Acute Monocytic Leukemia Cells to Low-dose Cytarabine by 1,25-dihydroxyvitamin D3

Low-dose cytarabine combined with differentiating or DNA hypomethylating agents, such as vitamin D compounds, is a potential regimen to treat acute myeloid leukemia (AML) patients who are unfit for high-intensity chemotherapy. The present study aimed to determine which subset of AML would be most responsive to low-dose cytarabine with the differentiating agent 1,25-dihydroxyvitamin D3 (1,25-D3). Here, firstly, cBioPortal database was used and we found out that vitamin D receptor (VDR) was highly expressed in acute monocytic leukemia (M5) and high VDR expression was associated with a poor survival of AML patients. Then, we confirmed that 1,25-D3 at clinical available concentration could induce more significant differentiation in acute monocytic leukemia cell lines (U937, MOLM-13, THP-1) and blasts from M5 patients than in non-monocytic cell lines (KGla and K562) and blasts from M2 patient. Finally, it was shown that the combination of 1,25-D3 and low-dose cytarabine further increased the differentiating rate, growth inhibition and G0/G1 arrest, while mild changes were found in the apoptosis in acute monocytic leukemia cell lines. Our study demonstrates that the enhanced response of acute monocytic leukemia cells to low-dose cytarabine by 1,25-D3 might indicate a novel therapeutic direction for patients with acute monocytic leukemia, especially for elderly and frail ones.

Virosecurinine induces apoptosis in human leukemia THP-1 cells and other underlying molecular mechanisms

Virosecurinine, a primary alkaloid from Securinega suffruticosa plant is known as a potent differentiation-inducing agent in acute leukemia cells. The present study aimed to investigate the effects and underlying mechanisms of virosecurinine on human leukemia THP-1 cells in vitro. The effects of virosecurinine on cell proliferation were assessed by CCK-8. The effects on apoptosis and cell cycle were assessed by staining with annexin V-fluorescein isothiocyanate and propidium iodide, respectively followed by flow cytometric analysis. The apoptotic cell bodies were observed using a transmission electron microscope, while the mRNA expression of phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), mechanistic target of rapamycin (mTOR) and phosphatase and tensin homolog (PTEN) in THP-1 was evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Treatment with virosecurinine was able to decrease the viability of THP-1 cells in a dose- and time-dependent manner. The IC₅₀ values of virosecurinine at 24, 48, and 72 h post-treatment were 68.128, 23.615, and 13.423 µmol/l, respectively. Cell cycle was arrested at the G1/S phase in virosecurinine-treated cells; however, not in untreated control cells. Numerous apoptotic bodies were observed in the THP-1 cells, which were treated with 12.5 µmol/l virosecurinine for 48 h. RT-qPCR indicated that treatment with virosecurinine resulted in upregulated PTEN expression and downregulated expression of PI3K, AKT and mTOR in THP-1 cells. The present study demonstrated that treatment with virosecurinine was able to inhibit proliferation and induce apoptosis in THP-1cells by exerting an inhibitory effect on the activation of PI3K/AKT/mTOR signaling pathways. Therefore, our data suggested that virosecurinine is a promising anti-tumor agent for the treatment of acute monocytic leukemia.

Hypoxia inducible factor-1α regulates a pro-invasive phenotype in acute monocytic leukemia

Hypoxia inducible transcription factors (HIFs) are the main regulators of adaptive responses to hypoxia and are often activated in solid tumors, but their role in leukemia is less clear. In acute myeloid leukemia (AML), in particular, controversial new findings indicate that HIF-1α can act either as an oncogene or a tumor suppressor gene, and this may depend on the stage of leukemia development and/or the AML sub-type.

In this study, we find that HIF-1α promotes leukemia progression in the acute monocytic leukemia sub-type of AML through activation of an invasive phenotype. By applying a list of validated HIF-1α-target genes to different AML sub-types, we identified a HIF-1α signature that typifies acute monocytic leukemia when compared with all other AML sub-types. We validated expression of this signature in cell lines and primary cells from AML patients. Interestingly, this signature is enriched for genes that control cell motility at different levels. As a consequence, inhibiting HIF-1α impaired leukemia cell migration, chemotaxis, invasion and transendothelial migration in vitro, and this resulted in impaired bone marrow homing and leukemia progression in vivo. Our data suggest that in acute monocytic leukemia an active HIF-1α-dependent pro-invasive pathway mediates the ability of leukemic cells to migrate and invade extramedullary sites and may be targeted to reduce leukemia dissemination.

Dihydroartemisinin-induced apoptosis in human acute monocytic leukemia cells

Dihydroartemisinin (DHA) is a derivative of artemisinin. The present study aimed to investigate whether DHA induces apoptosis in the THP-1 human acute monocytic leukemia cell line (AMoL), and to identify the relative molecular mechanisms. The results of the present study demonstrated that the viability of THP-1 cells were inhibited by DHA in a dose- and time-dependent manner, which was accompanied by morphological characteristics associated with apoptosis. After 24 h of 200 µM DHA treatment, the proportion of apoptotic cells was significantly increased compared with the untreated controls (P<0.01). In addition, DHA downregulated the levels of B-cell lymphoma (Bcl)-2, protein kinase B (Akt)1, Akt2 and Akt3 gene expression, and increased the expression of the Bcl-2-associated X protein apoptosis regulator. The protein expression of phospho-Akt and phospho-extracellular signal-regulated kinase (ERK) was also decreased, and the protein expression level of cleaved caspase-3 was increased following treatment with DHA. Therefore, DHA may induce apoptosis in the AMoL THP-1 cell line via currently unknown underlying molecular mechanisms, including the downregulation of ERK and Akt, and the activation of caspase-3.

Prokaryotic expression of MLAA-34 and generation of a novel human ScFv against MLAA-34 by phage display technology

MLAA-34 is a newly identified monocytic leukemia-associated antigen that is overexpressed in acute monocytic leukemia specifically, thus providing a novel target for the therapy of acute monocytic leukemia. In this study, we first expressed MLAA-34 protein in Escherichia coli (E.coli) BL21 (DE3) cells and purified it by nickel ion affinity chromatography with high purity (>90%). Then, MLAA-34 was used as antigen for biopanning anti-MLAA-34 single chain antibody fragment (ScFv) from a fully human ScFv library, and a high affinity ScFv named MA1 was selected by phage-ELISA. Finally, after expression of MA1, we found that MA1 can specifically bind with U937 MLAA-34 positive cells, and the binding affinity of MA1 was at the nanomolar level. Furthermore, inhibition of U937 cell proliferation indicated that the novel antibody MA1 has the potential to be used as a therapeutic agent for acute monocytic leukemia.

Cutaneous presentation preceding acute monocytic leukemia: A CARE-compliant article

RATIONALE

Cutaneous presentation preceding acute myeloid leukemia (AML) is rare, and the prognosis is poor.

PATIENT CONCERNS

We report 4 cases of AML cutis, where skin infiltration precedes any blood or bone marrow evidence of leukemia. We also reviewed 13 cases reported in English and Chinese literature. The 4 cases all presented typical cutaneous lesions without any systemic evidence of leukemia. Histopathological examination found that dense monomorphous cell infiltration involved the dermis. Some cells surrounded blood vessels and skin appendages in a concentric manner or showed single-row arrangement in the collagen fiber bundles. Uninvolved papillary dermis was found to separate normal epidermis from dermal infiltration. Minor cells had a large kidney-shaped or oval nucleus with nucleoli and slightly eosinophilic cytoplasm. Immunohistochemical analysis was positive for CD4, CD56, while CD123 was negative in all cases.

DIAGNOSES

AML-M5.

INTERVENTIONS

2 patients received chemotherapy ,but others rejected treatment.

OUTCOMES

Most patients died within 1 year after the onset of skin lesions.

LESSONS

These findings suggest that skin infiltration of AML may precede any systemic evidence, and typical cutaneous lesions in elderly individuals may be indicative for AML.

Caspase-1 promotes monocyte-macrophage differentiation by repressing PPARγ

Monocyte-to-macrophage differentiation is tightly controlled in vivo, as disruption of the normal differentiation program can lead to diverse disorders. Caspase-1, the first identified member of the caspase family, regulates differentiation in various cell types such as Th17 cells and adipocytes. However, the contribution of caspase-1 in monocyte-macrophage differentiation remains elusive. Here we report that caspase-1 is significantly downregulated in leukemia cells from patients with acute monocytic leukemia. By using the phorbol 12-myristate 13-acetate-induced cell differentiation model, we found that caspase-1 activation was required for the differentiation of human monocytes to macrophages. Further analysis of peroxisome proliferator-activated receptor γ (PPARγ) protein levels revealed that the monocyte-macrophage differentiation program could be divided into two stages. Caspase-1-mediated downregulation of PPARγ was important in the late stage of monocyte-macrophage differentiation; however, PPARγ protein levels had little effect on the early stage differentiation. Accumulation of PPARγ protein by troglitazone treatment potently suppressed the late stage of macrophage differentiation, which might be linked to inhibition of nuclear factor-κB activity. The data provide a plausible mechanistic basis by which caspase-1 promotes the differentiation of macrophages from monocytes.

An unusual initial manifestation of acute myeloid leukemia

Leukemia cutis is seen in around 20% of acute monocytic leukemia. They usually present as papules or nodules or infiltrated plaques but ulceration is uncommon. A 28-year-old female presented with multiple painless indurated genital ulcers of three weeks' duration with low-grade fever, gum hyperplasia, and generalized lymphadenopathy. Tissue smear from the edge of the ulcer showed atypical monocytes suggestive of leukemic infiltrate which was further confirmed by peripheral smear and bone marrow aspirate. Herein, we report a case of acute monocytic leukemia (AML) with leukemia cutis presenting initially with genital ulcers simulating chancre.

B7-H3 silencing by RNAi inhibits tumor progression and enhances chemosensitivity in U937 cells

BACKGROUND

The role of B7-H3 in acute monocytic leukemia U937 cells has not been thoroughly investigated.

MATERIALS AND METHODS

B7-H3 knockdown in the U937 cell line was performed using small hairpin (sh)RNA lentivirus transduction. The effects on cell proliferation, cycle, migration, and invasion were investigated by Cell Counting Kit-8 assay, methyl cellulose colony-forming assay, propidium iodide staining, and Transwell assays in vitro. Changes in cell growth inhibition and apoptosis, when combined with chemotherapy drugs, were determined using the Cell Counting Kit-8 and Annexin V-FITC/PI assays. U937 xenograft models were used to assess the effects of B7-H3 on tumorigenicity and the therapeutic effect of B7-H3 knockdown in combination with chemotherapy drugs in vivo.

RESULTS

Downregulation of B7-H3 significantly decreased U937 cell growth and colony-forming ability. The mean inhibition rate of tumor growth with B7-H3 knockdown was 59.4%, and the expression of both Ki-67 and PCNA in xenografts was significantly reduced. After B7-H3 silencing, the U937 cell cycle was arrested at the G0/G1 phase. The cell migration rate of B7-H3 knockdown cells was reduced more than fivefold, and invasion capacity decreased by 86.7%. B7-H3 RNAi profoundly increased the antitumor effect of chemotherapy in vitro and in vivo. On day 19, inhibition rates of tumor growth in B7-H3 shRNA combined with idarubicin, cytarabine, and idarubicin plus cytarabine were 70.5%, 80.0%, and 90.0%, respectively (P=0.006, P=0.004, and P=0.016, respectively).

CONCLUSION

B7-H3 may promote U937 cell progression, and shRNA targeting B7-H3 significantly enhances sensitivity to chemotherapeutic drugs. These results may provide new insight into the function of B7-H3 and a promising therapeutic approach targeting B7-H3 in acute monocytic leukemia.

Concurrent chronic neutrophilic leukemia blast crisis and multiple myeloma: A case report and literature review

The current study presents the case of a 78-year-old male with concurrent chronic neutrophilic leukemia (CNL) and multiple myeloma (MM) who developed acute myeloid leukemia after two years of treatment with hydroxyurea, cyclophosphamide, prednisone and thalidomide. The patient presented with mature neutrophilic leukocytosis, hepatosplenomegaly, a high neutrophil alkaline phosphatase score and an absence of the Philadelphia chromosome or the BCR-ABL fusion gene. A bone marrow aspirate smear and biopsy indicated that the CNL coexisted with a plasma cell neoplasm. In addition, monoclonal λ-paraproteinemia was detected by serum protein immunofixation electrophoresis, and bone lesions were identified in multiple vertebrae. The patient achieved complete remission following one cycle of induction chemotherapy with the decitabine regimen in combination with the low-dose cytarabine, aclarubicin and granulocyte-colony stimulating factor (CAG) priming regimen. The occurrence of CNL and MM concurrently is extremely rare and thus, it has only been reported in a small number of cases. The occurrence of CNL and MM in the same patient as two distinct hematological malignancies indicates the neoplastic transformation of a pluripotent stem cell. Decitabine combined with the CAG priming regimen may present a good therapeutic strategy for elderly patients with secondary acute myeloid leukemia.

Quantitative assessment of MLAA-34 expression in diagnosis and prognosis of acute monocytic leukemia

MLAA-34 is a newly identified monocytic leukemia-associated antigen. Previous data indicated that MLAA-34 might be a novel anti-apoptosis factor related closely to carcinogenesis or progression of acute monocytic leukemia. The over-expression of MLAA-34 is intuitively expected to be associated with unfavorable clinical features in acute myeloid leukemia. However, there have been no clinical studies about the prognostic relevance of MLAA-34 expression in human malignancies. This study was done to investigate the clinical relevance of the expression of MLAA-34 in de novo acute myeloid leukemia. In 126 patients with de novo acute myeloid leukemia, the level of MLAA-34 expression and protein expression ratio were determined by using quantitative reverse transcriptase-PCR and western blot, respectively. The results were analyzed with respect to the patients' clinical features and treatment outcomes. Both MLAA-34 expression rates and expression levels were found to be higher in patients with the French-American-British classification subtype M5, and the expression levels were also higher in patients with a leukocyte number of ≥ 20 × 10(9)/L and patients with extramedullary disease. In addition, MLAA-34 over-expression (≥ median expression) was associated with an unfavorable day 7 response to induction chemotherapy and also associated with a poor survival rate. In multivariate analysis, high MLAA-34 levels was independently associated with a poorer relapse-free survival and overall survival in AML patients. In conclusion, our data indicate that MLAA-34 may be used as a prognostic marker for treatment decision-making in acute monocytic leukemia through validation by further studies.