SIRT2 regulates proliferation and chemotherapy response of MLL-ENL-driven acute myeloid leukemia.

Both MLL-AF9 and MLL-ENL leukemia fusion proteins drive oncogenic transformation of hematopoietic cells through their N-terminal DNA/histone binding mixed-lineage leukemia 1 domain and C-terminal fragment of AF9 or ENL containing an unstructured linker region and the ANC1 homology domain, which recruits transcription factors. Despite of their structural similarity, acute myeloid leukemia (AML) patients bearing MLL-ENL show more adverse outcomes compared to those with MLL-AF9. We recapitulated the clinical patterns of these two MLL-fusions driven AMLs using murine models and found that MLL-ENL AML cells showed slower cell cycle progression and more resistance to standard chemotherapy than MLL-AF9 cells. These phenotypes were primarily controlled by the linker regions of ENL and a highly conserved lysine residue K469 within. Substitution of K469 with an acetylated mimic glutamine abolished the ability of MLL-ENL to suppress proliferation and promote chemo-resistance. We showed that deacetylase Sirt2 might act as an upstream regulator of MLL-ENL. Deletion of Sirt2 promoted proliferation of AML cells with either MLL fusions. Importantly, loss of Sirt2 greatly enhanced the sensitivity of the MLL-ENL AML cells to chemo-treatment. Taken together, our study uncovered a unique regulatory role of Sirt2 in leukemogenesis and suggested targeting SIRT2 as a new way to sensitize MLL-ENL AML patience for chemotherapy.

Biomarker LEPRE1 induces pelitinib-specific drug responsiveness by regulating ABCG2 expression and tumor transition states in human leukemia and lung cancer.

Biomarkers for treatment sensitivity or drug resistance used in precision medicine include prognostic and predictive molecules, critical factors in selecting appropriate treatment protocols and improving survival rates. However, identification of accurate biomarkers remain challenging due to the high risk of false-positive findings and lack of functional validation results for each biomarker. Here, we discovered a mechanical correlation between leucine proline-enriched proteoglycan 1 (LEPRE1) and pelitinib drug sensitivity using in silico statistical methods and confirmed the correlation in acute myeloid leukemia (AML) and A549 lung cancer cells. We determined that high LEPRE1 levels induce protein kinase B activation, overexpression of ATP-binding cassette superfamily G member 2 (ABCG2) and E-cadherin, and cell colonization, resulting in a cancer stem cell-like phenotype. Sensitivity to pelitinib increases in LEPRE1-overexpressing cells due to the reversing effect of ABCG2 upregulation. LEPRE1 silencing induces pelitinib resistance and promotes epithelial-to-mesenchymal transition through actin rearrangement via a series of Src/ERK/cofilin cascades. The in silico results identified a mechanistic relationship between LEPRE1 and pelitinib drug sensitivity, confirmed in two cancer types. This study demonstrates the potential of LEPRE1 as a biomarker in cancer through in-silico prediction and in vitro experiments supporting the clinical development of personalized medicine strategies based on bioinformatics findings.

A novel aryl-guanidinium derivative, VP79s, targets the signal transducer and activator of transcription 3 signaling pathway, downregulates myeloid cell leukaemia-1 and exhibits preclinical activity against multiple myeloma.

AIMS: We have recently described a novel guanidinium-based compound, VP79s, which induces cytotoxicity in various cancer cell lines. Here, we aim to investigate the activity of VP79s and associated mechanisms of action in multiple myeloma (MM) cells in vitro and ex vivo. MAIN METHODS: The effects of VP79s on cell viability and induction of apoptosis was examined in a panel of drug-sensitive and drug-resistant MM cell lines, as well as ex vivo patient samples and normal donor lymphocytes and platelets. Cell signaling pathways associated with the biological effects of VP79s were analysed by immunoblotting and flow cytometry. Gene expression changes were assessed by quantitative real-time PCR analysis. KEY FINDINGS: VP79s was found to rapidly inhibit both constitutively active and IL-6-induced STAT3 signaling with concurrent downregulation of the IL-6 receptors, CD130 and CD126. VP79s induced a rapid and dose-dependent downregulation of anti-apoptotic Bcl-2 family member, myeloid cell leukaemia-1 (MCL-1). VP79s enhanced bortezomib induced cell death and was also found to overcome bone marrow stromal cell induced drug resistance. VP79s exhibited activity in ex vivo patient samples at concentrations which had no effect on peripheral blood mononuclear cells, lymphocytes and platelets isolated from healthy donors. SIGNIFICANCE: As VP79s resulted in rapid inhibition of the key IL-6/STAT3 signaling pathway and downregulation of MCL-1 expression with subsequent selective anti-myeloma activity, VP79s may be a potential therapeutic agent with a novel mechanism of action in MM cells.

GPX1-associated prognostic signature predicts poor survival in patients with acute myeloid leukemia and involves in immunosuppression.

OBJECTIVE: Treatment of acute myeloid leukemia (AML) remains a challenge. It is urgent to understand the microenvironment to improve therapy and prognosis. METHODS: Bioinformatics methods were used to analyze transcription expression profile of AML patient samples with complete clinical information from UCSC Xena TCGA-AML datasets and validate with GEO datasets. Western blot, qPCR, RNAi and CCK8 assay were used to assay the effect of GPX1 expression on AML cell viability and the expression of genes of interest. RESULTS: Our analyses revealed that highly expressed GPX1 in AML patients links to unfavorable prognosis. GPX1 expression was positively associated with not only fraction levels of myeloid-derived suppressor cells (MDSCs), monocytes and T cell exhaustion, the expression levels of MDSC markers, MDSC-promoting CCR2 and immune inhibitory checkpoints (TIM3/Gal-9, SIRPα and VISTA), but also negatively with low fraction levels of CD4+ and CD8+ T cells. Silencing GPX1 expression reduced AML cell viability and CCR2 expression. Moreover, GPX1-targetd kinases were PKC family, SRC family, SYK and PAK1, which promote AML progression and the resistance to therapy. Furthermore, Additionally, GPX1-associated prognostic signature (GPS) is an independent risk factor with high area under curve (AUC) values of receiver operating characteristic (ROC) curves. High risk group based on GPS enriched not only with endocytosis which transfers mitochondria to favor AML cell survival in response to chemotherapy, but also NOTCH, WNT and TLR signaling which promote therapy resistance. CONCLUSION: Our results revealed the significant involvement of GPX1 in AML immunosuppression via and provided a prognostic signature for AML patients.

Glycoproteome remodeling in MLL-rearranged B-cell precursor acute lymphoblastic leukemia.

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) with mixed-lineage leukemia gene rearrangement (MLL-r) is a poor-prognosis subtype for which additional therapeutic targets are urgently needed. Currently no multi-omics data set for primary MLL r patient cells exists that integrates transcriptomics, proteomics and glycomics to gain an inclusive picture of theranostic targets. Methods: We have integrated transcriptomics, proteomics and glycomics to i) obtain the first inclusive picture of primary patient BCP-ALL cells and identify molecular signatures that distinguish leukemic from normal precursor B-cells and ii) better understand the benefits and limitations of the applied technologies to deliver deep molecular sequence data across major cellular biopolymers. Results: MLL-r cells feature an extensive remodeling of their glycocalyx, with increased levels of Core 2-type O-glycans and complex N-glycans as well as significant changes in sialylation and fucosylation. Notably, glycosaminoglycan remodeling from chondroitin sulfate to heparan sulfate was observed. A survival screen, to determine if glycan remodeling enzymes are redundant, identified MGAT1 and NGLY1, essential components of the N-glycosylation/degradation pathway, as highly relevant within this in vitro screening. OGT and OGA, unique enzymes that regulate intracellular O-GlcNAcylation, were also indispensable. Transcriptomics and proteomics further identified Fes and GALNT7-mediated glycosylation as possible therapeutic targets. While there is overall good correlation between transcriptomics and proteomics data, we demonstrate that a systematic combined multi-omics approach delivers important diagnostic information that is missed when applying a single omics technology. Conclusions: Apart from confirming well-known MLL-r BCP-ALL glycoprotein markers, our integrated multi-omics workflow discovered previously unidentified diagnostic/therapeutic protein targets.

Telomerase (hTERT) Overexpression Reveals a Promising Prognostic Biomarker and Therapeutical Target in Different Clinical Subtypes of Pediatric Acute Lymphoblastic Leukaemia.

Acute Lymphoblastic Leukemia (ALL) is a neoplasm of the hematopoietic system defined as a clonal expansion of an abnormal lymphoid precursor cell. It mostly affects children under five years of age and is the most common tumor to afflict pediatric patients. The expression of the human telomerase gene (hTERT) in patients with ALL has been studied as a biomarker and could become a new therapeutic target. We evaluate the role of hTERT gene expression in ALL pediatric patients, through quantitative real-time PCR technique, and the possible correlation between hTERT expression and clinical variables: gender, age, white blood cells (WBC), gene fusions, and immunophenotyping. The analysis between healthy controls and ALL patients (N = 244) was statistically significant (p < 0.001), demonstrating hTERT overexpression in these patients. In comparison with the usual set of clinical variables, the data were not statistically significant (p > 0.05), indicating that hTERT is equally overexpressed among patients regardless of gender, age, gene fusions, and immunophenotyping. Moreover, patients who presented a higher hTERT expression level had a significant (p < 0.0001) lower overall survival rate. In summary, hTERT expression emerges as an important molecular pathway in leukemogenesis regardless patient's clinical variables, thus, the data here presented pointed it as a valuable biomarker in pediatric acute lymphoblastic leukemia and a promising target for new therapeutic and prognostic measures.

KIR3DL1 Allotype-Dependent Modulation of NK Cell Immunity against Chronic Myeloid Leukemia.

Tyrosine kinase inhibitor (TKI)-treated chronic myeloid leukemia (CML) patients with increased NK cell number have a better prognosis, and thus, NK cells may suppress CML. However, the efficacy of TKIs varies for reasons yet to be fully elucidated. As NK cell activity is modulated by interactions between their killer cell Ig-like receptors (KIRs) and HLAs of target cells, the combination of their polymorphisms may have functional significance. We previously showed that allelic polymorphisms of KIR3DL1 and HLAs were associated with the prognosis of TKI-treated CML patients. In this study, we focus on differential NK cell activity modulation through KIR3DL1 allotypes. KIR3DL1 expression levels varied according to their alleles. The combination of KIR3DL1 expression level and HLA-Bw4 motifs defined NK cell activity in response to the CML-derived K562 cell line, and Ab-mediated KIR3DL1 blocking reversed this activity. The TKI dasatinib enhanced NK cell activation and cytotoxicity in a KIR3DL1 allotype-dependent manner but did not significantly decrease effector regulatory T cells, suggesting that it directly activated NK cells. Dasatinib also enhanced NK cell cytotoxicity against K562 bearing the BCR-ABL1 T315I TKI resistance-conferring mutation, depending on KIR3DL1/HLA-Bw4 allotypes. Transduction of KIR3DL1*01502 into the NK cell line NK-92 resulted in KIR3DL1 expression and suppression of NK-92 activity by HLA-B ligation, which was reversed by anti-KIR3DL1 Ab. Finally, KIR3DL1 expression levels also defined activation patterns in CML patient-derived NK cells. Our findings raise the possibility of a novel strategy to enhance antitumor NK cell immunity against CML in a KIR3DL1 allotype-dependent manner.

Omics Technologies to Decipher Regulatory Networks in Granulocytic Cell Differentiation.

Induced granulocytic differentiation of human leukemic cells under all-trans-retinoid acid (ATRA) treatment underlies differentiation therapy of acute myeloid leukemia. Knowing the regulation of this process it is possible to identify potential targets for antileukemic drugs and develop novel approaches to differentiation therapy. In this study, we have performed transcriptomic and proteomic profiling to reveal up- and down-regulated transcripts and proteins during time-course experiments. Using data on differentially expressed transcripts and proteins we have applied upstream regulator search and obtained transcriptome- and proteome-based regulatory networks of induced granulocytic differentiation that cover both up-regulated (HIC1, NFKBIA, and CASP9) and down-regulated (PARP1, VDR, and RXRA) elements. To verify the designed network we measured HIC1 and PARP1 protein abundance during granulocytic differentiation by selected reaction monitoring (SRM) using stable isotopically labeled peptide standards. We also revealed that transcription factor CEBPB and LYN kinase were involved in differentiation onset, and evaluated their protein levels by SRM technique. Obtained results indicate that the omics data reflect involvement of the DNA repair system and the MAPK kinase cascade as well as show the balance between the processes of the cell survival and apoptosis in a p53-independent manner. The differentially expressed transcripts and proteins, predicted transcriptional factors, and key molecules such as HIC1, CEBPB, LYN, and PARP1 may be considered as potential targets for differentiation therapy of acute myeloid leukemia.

3D genome alterations associated with dysregulated HOXA13 expression in high-risk T-lineage acute lymphoblastic leukemia.

3D genome alternations can dysregulate gene expression by rewiring enhancer-promoter interactions and lead to diseases. We report integrated analyses of 3D genome alterations and differential gene expressions in 18 newly diagnosed T-lineage acute lymphoblastic leukemia (T-ALL) patients and 4 healthy controls. 3D genome organizations at the levels of compartment, topologically associated domains and loop could hierarchically classify different subtypes of T-ALL according to T cell differentiation trajectory, similar to gene expressions-based classification. Thirty-four previously unrecognized translocations and 44 translocation-mediated neo-loops are mapped by Hi-C analysis. We find that neo-loops formed in the non-coding region of the genome could potentially regulate ectopic expressions of TLX3, TAL2 and HOXA transcription factors via enhancer hijacking. Importantly, both translocation-mediated neo-loops and NUP98-related fusions are associated with HOXA13 ectopic expressions. Patients with HOXA11-A13 expressions, but not other genes in the HOXA cluster, have immature immunophenotype and poor outcomes. Here, we highlight the potentially important roles of 3D genome alterations in the etiology and prognosis of T-ALL.

A novel leukemic route of mutant NPM1 through nuclear import of the overexpressed long noncoding RNA LONA.

The most frequent genetic alteration in acute myeloid leukemia (AML) is the mutation of nucleophosmin 1 (NPM1). Yet, its downstream oncogenic routes are not fully understood. Here, we report the identification of one long noncoding RNA (lncRNA) overexpressed in NPM1-mutated AML patients (named LONA) whose intracellular localization inversely reflects that of NPM1. While NPM1 is nuclear and LONA cytoplasmic in wild-type NPM1 AML cells, LONA becomes nuclear as mutant NPM1 moves toward the cytoplasm. Gain or loss of function combined with a genome-wide RNA-seq search identified a set of LONA mRNA targets encoding proteins involved in myeloid cell differentiation (including THSB1, MAFB, and ASB2) and interaction with its microenvironment. Consistently, LONA overexpression in mutant NPM1 established cell lines and primary AML cells exerts an anti-myeloid differentiation effect, whilst it exerts an opposite pro-myeloid differentiation effect in a wild type NPM1 setting. In vivo, LONA overexpression acts as an oncogenic lncRNA reducing the survival of mice transplanted with AML cells and rendering AML tumors more resistant to AraC chemotherapy.These data indicate that mutation-dependent nuclear export of NPM1 leads to nuclear retention and consequent oncogenic functions of the overexpressed lncRNA LONA, thus uncovering a novel NPM1 mutation-dependent pathway in AML pathogenesis.

CircRNA_OTUD7A upregulates FOXP1 expression to facilitate the progression of diffuse large B-cell lymphoma via acting as a sponge of miR-431-5p.

BACKGROUND: A growing number of studies have shown that circular RNA (circRNA) is an important regulator molecule in cancer progression, but it has been poorly studied in diffuse large b-cell lymphoma (DLBCL). OBJECTIVE: This study aimed to explore the role of circ_OTUD7A in DLBCL. METHODS: Relative expression levels of circ_OTUD7A, microRNA (miR)-431-5p and forkhead box P1 (FOXP1) were determined by quantitative real-time PCR (qRT-PCR). The proliferation of cells was elevated by colony formation assay and MTT assay. Western blot (WB) analysis was employed to measure the protein levels of proliferation marker, epithelial-mesenchymal transition (EMT) markers, cyclin marker, apoptosis markers and FOXP1. Moreover, the apoptosis, cell cycle process, migration and invasion of cells were detected using flow cytometry and transwell assay, respectively. In addition, the interaction between miR-431-5p and circ_OTUD7A or FOXP1 was confirmed by dual-luciferase reporter assay. RESULTS: Circ_OTUD7A was highly expressed in DLBCL, and its knockdown could inhibit DLBCL cell proliferation and metastasis, while promote cell cycle arrest and apoptosis. Similarly, FOXP1 also was upregulated in DLBCL, and its silencing could restrain the progression of DLBCL cells. Further experiments revealed that circ_OTUD7A could sponge miR-431-5p and miR-431-5p could target FOXP1. MiR-431-5p inhibitor could reverse the suppressive effect of circ_OTUD7A silencing on DLBCL progression, and FOXP1 overexpression also could reverse the inhibitory effect of miR-431-5p mimic on DLBCL progression. CONCLUSION: Circ_OTUD7A promoted the progression of DLBCL by regulating the miR-431-5p/FOXP1 axis, which suggested that circ_OTUD7A might function as an oncogene in DLBCL.

Long non-coding RNA CRNDE suppressing cell proliferation is regulated by DNA methylation in chronic lymphocytic leukemia.

Long non-coding RNA CRNDE and DNA methylation play a vital role in the occurrence and development of chronic lymphocytic leukemia (CLL). This study attempted to investigate the biological role of CRNDE methylation in CLL. The expression and methylation levels of CRNDE in CLL cell lines (MEC-1 and HG3) before or after methylation inhibitor (5-Aza-2'-deoxycytidine, 5-Aza-CdR) treatment was detected by quantitative real-time PCR or methylation-Specific PCR. The relationship among CRNDE, miR-28 and NDRG2 was verified by luciferase reporter assay. The effect of CRNDE overexpression and 5-Aza-CdR treatment on cell proliferation and apoptosis of MEC-1 and HG3 cells were assessed by CCK8 and flow cytomery. Compared with normal B lymphocytes, CRNDE was down-regulated and the methylation level of CRNDE was increased in MEC-1 and HG3 cells. Then, 5-Aza-CdR treatment caused an increase of CRNDE expression in MEC-1 and HG3 cells by demethylation. The overexpression or demethylation of CRNDE inhibited cell proliferation and promoted apoptosis in MEC-1 and HG3 cells by up-regulating CRNDE expression. Moreover, CRNDE functioned as a competing endogenous RNA to repress miR-28, which controlled its down-stream target NDRG2. CRNDE overexpression inhibited cell proliferation and promoted apoptosis via miR-28/NDRG2 axis in CLL. In conclusion, our data elaborated that CRNDE expression was regulated by DNA methylation, and the protective effect of CRNDE on CLL was attributed to the inhibition of proliferation in CLL via miR-28/NDRG2 axis. Thus, this work highlights a novel competing endogenous RNA circuitry involving key regulators of CLL.

The JmjC-domain protein NO66/RIOX-1 affects the balance between proliferation and maturation in acute myeloid leukemia.

As epigenetic regulators are frequently dysregulated in acute myeloid leukemia (AML) we determined expression levels of the JmjC-protein NO66 in AML cell lines and sub fractions of healthy human hematopoietic cells. NO66 is absent in the AML cell lines KG1/KG1a which consist of cells with the immature CD34+/CD38- phenotype and is regarded as a "stem cell-like" model system. Similarly, NO66 is not detectable in CD34+/CD38- cells purified from healthy donors but is clearly expressed in the more committed CD34+/CD38+ cell population. Loss of NO66 expression in KG1/KG1a cells is due to hyper-methylation of its promoter and is released by DNA-methyltransferase inhibitors. In KG1a cells stably expressing exogenous wild type (KG1a66wt) or enzymatically inactive mutant (KG1a66mut) NO66, respectively, the wild type protein inhibited proliferation and rDNA transcription. Gene expression profiling revealed that the expression of NO66 induces a transcriptional program enriched for genes with roles in proliferation and maturation (e.g.EPDR1, FCER1A, CD247, MYCN, SNORD13). Genes important for the maintenance of stem cell properties are downregulated (e.g. SIRPA, Lin28B, JAML). Our results indicate that NO66 induces lineage commitment towards myeloid progenitor cell fate and suggest that NO66 contributes to loss of stem cell properties.

Integrative network analysis reveals USP7 haploinsufficiency inhibits E-protein activity in pediatric T-lineage acute lymphoblastic leukemia (T-ALL).

USP7, which encodes a deubiquitylating enzyme, is among the most frequently mutated genes in pediatric T-ALL, with somatic heterozygous loss-of-function mutations (haploinsufficiency) predominantly affecting the subgroup that has aberrant TAL1 oncogene activation. Network analysis of > 200 T-ALL transcriptomes linked USP7 haploinsufficiency with decreased activities of E-proteins. E-proteins are also negatively regulated by TAL1, leading to concerted down-regulation of E-protein target genes involved in T-cell development. In T-ALL cell lines, we showed the physical interaction of USP7 with E-proteins and TAL1 by mass spectrometry and ChIP-seq. Haploinsufficient but not complete CRISPR knock-out of USP7 showed accelerated cell growth and validated transcriptional down-regulation of E-protein targets. Our study unveiled the synergistic effect of USP7 haploinsufficiency with aberrant TAL1 activation on T-ALL, implicating USP7 as a haploinsufficient tumor suppressor in T-ALL. Our findings caution against a universal oncogene designation for USP7 while emphasizing the dosage-dependent consequences of USP7 inhibitors currently under development as potential cancer therapeutics.

Tissue factor pathway inhibitor upregulates CXCR7 expression and enhances CXCL12-mediated migration in chronic lymphocytic leukemia.

The infiltration of chronic lymphocytic leukemia (CLL) cells into lymphoid organs correlates with disease severity. CXCL12 is a key chemotactic factor for the trafficking of CLL. Tissue factor pathway inhibitor (TFPI) is a serine protease inhibitor and plays a role in CXCL12-mediated hematopoietic stem cell homing. We aim to explore the role of TFPI in CXCL12-mediated migration of CLL cells. In this study, plasma TFPI concentrations were measured by ELISA. CLL cells were isolated from patients and used for trans-endothelial migration (TEM) assays. Quantitative RT-PCR and Western blotting were used to detect the expression of CXCR7, CXCR4 and ß-catenin. Immunofluorescence and co-immunoprecipitation was used to detect the binding of TFPI and glypican-3 (GPC3). We found that plasma TFPI levels in CLL patients were higher than in healthy controls, particularly in the patients with advanced disease. TFPI enhanced CXCL12-mediated TEM of CLL cells by increasing the expression of the CXCL12 receptor CXCR7, but not of the CXCL12 receptor CXCR4. The effect of TFPI on TEM was abolished by the CXCR7 inhibitor, CCX771, while the CXCR4 inhibitor AMD3100 strongly increased TEM. TFPI co-localized with GPC3 on the cell surface. An antibody to GPC3, HS20, decreased CXCR7 expression and abolished the effect of TFPI on TEM. TFPI activated ß-catenin and the Wnt/ß-catenin inhibitor IWP4 repressed the effect of TFPI on CXCR7 expression and TEM. We conclude that TFPI may contribute to organ infiltration in CLL patients.

Identifying a novel 5-gene signature predicting clinical outcomes in acute myeloid leukemia

Background Acute myeloid leukemia (AML) is the most common type of acute leukemia and biologically heterogeneous diseases with poor prognosis. Thus, we aimed to identify prognostic markers to effectively predict the prognosis of AML patients and eventually guide treatment. Methods Prognosis-associated genes were determined by Kaplan–Meier and multivariate analyses using the expression and clinical data of 173 AML patients from The Cancer Genome Atlas database and validated in an independent Oregon Health and Science University dataset. A prognostic risk score was computed based on a linear combination of 5-gene expression levels using the regression coefficients derived from the multivariate logistic regression model. The classification of AML was established by unsupervised hierarchical clustering of CALCRL, DOCK1, PLA2G4A, FCHO2 and LRCH4 expression levels. Results High FCHO2 and LRCH4 expression was related to decreased mortality. While high CALCRL, DOCK1, PLA2G4A expression was associated with increased mortality. The risk score was predictive of increased mortality rate in AML patients. Hierarchical clustering analysis of the five genes discovered three clusters of AML patients. The cluster1 AML patients were associated with lower cytogenetics risk than cluster2 or 3 patients, and better prognosis than cluster3 patients (P values < 0.05 for all cases, fisher exact test or log-rank test). Conclusion The gene panel comprising CALCRL, DOCK1, PLA2G4A, FCHO2 and LRCH4 as well as the risk score may offer novel prognostic biomarkers and classification of AML patients to significantly improve outcome prediction (AU)

LncRNA-SNHG16 promotes proliferation and migration of acute myeloid leukemia cells via PTEN/PI3K/AKT axis through suppressing CELF2 protein.

The silence of lncRNA small nucleolar RNA host gene 16 (SNHG16) suppressed acute lymphoblastic leukemia (ALL) cell proliferation and migration, whereas its role in acute myeloid leukemia (AML) still lacks clarity. This study showed that SNHG16 was upregulated in AML patients and cells. And SNHG16 overexpression remarkably enhanced the proliferation and migration capacities of HL60 and AML-193 cells, while SNHG16 knockdown acted the opposite way. Subsequently, we revealed that SNHG16 directly bound to CELF2 (CUGBP Elav-like family member 2) protein, and caused CELF2 mRNA unstably and proteins reducing. CELF2 was decreased both in AML patients and cells. CELF2 overexpression or interference weakened the effect of overexpressing or silencing SNHG16 on proliferation and migration. Moreover, the transfection of pcDNA-CELF2 elevated PTEN (phosphatase and tensin homolog) activity and hindered the phosphoinositide 3-kinase (PI3K)/AKT signaling. And SNHG16 reduced PTEN activity and promoted the PI3K/AKT pathway activation by restraining CELF2. Furthermore, GDC-0941 (a specific inhibitor of the PI3K/AKT pathway) impeded the effect of SNHG16 increase, and bpV(pic) (a specific PTEN inhibitor) declined the effect of SNHG16 decrease on cell proliferation and migration. Taken together, the present study indicated that SNHG16 promoted proliferation and migration of AML cells via PTEN/PI3K/AKT axis through suppressing CELF2 protein.

Menin is necessary for long term maintenance of meningioma-1 driven leukemia.

Translocations of Meningioma-1 (MN1) occur in a subset of acute myeloid leukemias (AML) and result in high expression of MN1, either as a full-length protein, or as a fusion protein that includes most of the N-terminus of MN1. High levels of MN1 correlate with poor prognosis. When overexpressed in murine hematopoietic progenitors, MN1 causes an aggressive AML characterized by an aberrant myeloid precursor-like gene expression program that shares features of KMT2A-rearranged (KMT2A-r) leukemia, including high levels of Hoxa and Meis1 gene expression. Compounds that target a critical KMT2A-Menin interaction have proven effective in KMT2A-r leukemia. Here, we demonstrate that Menin (Men1) is also critical for the self-renewal of MN1-driven AML through the maintenance of a distinct gene expression program. Genetic inactivation of Men1 led to a decrease in the number of functional leukemia-initiating cells. Pharmacologic inhibition of the KMT2A-Menin interaction decreased colony-forming activity, induced differentiation programs in MN1-driven murine leukemia and decreased leukemic burden in a human AML xenograft carrying an MN1-ETV6 translocation. Collectively, these results nominate Menin inhibition as a promising therapeutic strategy in MN1-driven leukemia.

ZEB2 Knock-down Induces Apoptosis in Human Myeloid Leukemia HL-60 Cells.

INTRODUCTION: Acute myeloid leukemia (AML) is the most prevalent type of cancer in the adult hematopoietic system. Conventional therapies are associated with unfavorable side effects in individuals diagnosed with AML. These after-effects with partial remission reflect the urgent need for novel therapeutic approaches for inducing apoptosis, specifically in malignant cells, without affecting other cells. As a transcription factor (TF), ZEB2 (Zinc Finger E-Box Binding Homeobox 2) regulates the expression of specific genes in normal conditions. However, increased expression of ZEB2 is reported in various cancers, especially in AML, which is related to a higher degree of apoptosis inhibition of malignant cells. In this work, the role of ZEB2 in apoptosis inhibition is surveyed through ZEB2 specific knocking-down in human myeloid leukemia HL-60 cells. MATERIALS AND METHODS: Transfection of HL-60 cells was conducted using ZEB2-siRNA at concentrations of 20, 40, 60, and 80 pmol within 24, 48, and 72 h. After determining the optimum dose and time, flow cytometry was used to measure the apoptosis rate. The MTT assay was also utilized to evaluate the cytotoxic impact of transfection on the cells. The expression of candidate genes was measured before and after transfection using qRT-PCR. RESULTS: According to obtained results, suppression of ZEB2 expression through siRNA was associated with the induction of apoptosis, increased pro-apoptotic, and decreased anti-apoptotic gene expression. Transfection of ZEB2-siRNA was also associated with reduced cell proliferation and viability. CONCLUSION: Our study results suggest that ZEB2 suppression in myeloid leukemia cells through apoptosis induction could be a proper therapeutic method.

Loss of H3K27 methylation identifies poor outcomes in adult-onset acute leukemia.

BACKGROUND: Acute leukemia is an epigenetically heterogeneous disease. The intensity of treatment is currently guided by cytogenetic and molecular genetic risk classifications; however these incompletely predict outcomes, requiring additional information for more accurate outcome predictions. We aimed to identify potential prognostic implications of epigenetic modification of histone proteins, with a focus on H3K4 and H3K27 methylation marks in relation to mutations in chromatin, splicing and transcriptional regulators in adult-onset acute lymphoblastic and myeloid leukemia. RESULTS: Histone 3 lysine 4 di- and trimethylation (H3K4me2, H3K4me3) and lysine 27 trimethylation (H3K27me3) mark expression was evaluated in 241 acute myeloid leukemia (AML), 114 B-cell acute lymphoblastic leukemia (B-ALL) and 14T-cell ALL (T-ALL) patient samples at time of diagnosis using reverse phase protein array. Expression levels of the marks were significantly lower in AML than in B and T-ALL in both bone marrow and peripheral blood, as well as compared to normal CD34+ cells. In AML, greater loss of H3K27me3 was associated with increased proliferative potential and shorter overall survival in the whole patient population, as well as in subsets with DNA methylation mutations. To study the prognostic impact of H3K27me3 in the context of cytogenetic aberrations and mutations, multivariate analysis was performed and identified lower H3K27me3 level as an independent unfavorable prognostic factor in all, as well as in TP53 mutated patients. AML with decreased H3K27me3 demonstrated an upregulated anti-apoptotic phenotype. In ALL, the relative quantity of histone methylation expression correlated with response to tyrosine kinase inhibitor in patients who carried the Philadelphia cytogenetic aberration and prior smoking behavior. CONCLUSION: This study shows that proteomic profiling of epigenetic modifications has clinical implications in acute leukemia and supports the idea that epigenetic patterns contribute to a more accurate picture of the leukemic state that complements cytogenetic and molecular genetic subgrouping. A combination of these variables may offer more accurate outcome prediction and we suggest that histone methylation mark measurement at time of diagnosis might be a suitable method to improve patient outcome prediction and subsequent treatment intensity stratification in selected subgroups.