Low expression of miR-182 caused by DNA hypermethylation accelerates acute lymphocyte leukemia development by targeting PBX3 and BCL2: miR-182 promoter methylation is a predictive marker for hypomethylation agents + BCL2 inhibitor venetoclax.

BACKGROUND: miR-182 promoter hypermethylation frequently occurs in various tumors, including acute myeloid leukemia, and leads to low expression of miR-182. However, whether adult acute lymphocyte leukemia (ALL) cells have high miR-182 promoter methylation has not been determined. METHODS: To assess the methylation status of the miR-182 promoter, methylation and unmethylation-specific PCR analysis, bisulfite-sequencing analysis, and MethylTarget™ assays were performed to measure the frequency of methylation at the miR-182 promoter. Bone marrow cells were isolated from miR-182 knockout (182KO) and 182 wild type (182WT) mice to construct BCR-ABL (P190) and Notch-induced murine B-ALL and T-ALL models, respectively. Primary ALL samples were performed to investigate synergistic effects of the hypomethylation agents (HMAs) and the BCL2 inhibitor venetoclax (Ven) in vitro. RESULTS: miR-182 (miR-182-5P) expression was substantially lower in ALL blasts than in normal controls (NCs) because of DNA hypermethylation at the miR-182 promoter in ALL blasts but not in normal controls (NCs). Knockout of miR-182 (182KO) markedly accelerated ALL development, facilitated the infiltration, and shortened the OS in a BCR-ABL (P190)-induced murine B-ALL model. Furthermore, the 182KO ALL cell population was enriched with more leukemia-initiating cells (CD43+B220+ cells, LICs) and presented higher leukemogenic activity than the 182WT ALL population. Furthermore, depletion of miR-182 reduced the OS in a Notch-induced murine T-ALL model, suggesting that miR-182 knockout accelerates ALL development. Mechanistically, overexpression of miR-182 inhibited proliferation and induced apoptosis by directly targeting PBX3 and BCL2, two well-known oncogenes, that are key targets of miR-182. Most importantly, DAC in combination with Ven had synergistic effects on ALL cells with miR-182 promoter hypermethylation, but not on ALL cells with miR-182 promoter hypomethylation. CONCLUSIONS: Collectively, we identified miR-182 as a tumor suppressor gene in ALL cells and low expression of miR-182 because of hypermethylation facilitates the malignant phenotype of ALL cells. DAC + Ven cotreatment might has been applied in the clinical try for ALL patients with miR-182 promoter hypermethylation. Furthermore, the methylation frequency at the miR-182 promoter should be a potential biomarker for DAC + Ven treatment in ALL patients.

Low-dose hypomethylating agents cooperate with ferroptosis inducers to enhance ferroptosis by regulating the DNA methylation-mediated MAGEA6-AMPK-SLC7A11-GPX4 signaling pathway in acute myeloid leukemia.

BACKGROUND: Ferroptosis is a new form of nonapoptotic and iron-dependent type of cell death. Glutathione peroxidase-4 (GPX4) plays an essential role in anti-ferroptosis by reducing lipid peroxidation. Although acute myeloid leukemia (AML) cells, especially relapsed and refractory (R/R)-AML, present high GPX4 levels and enzyme activities, pharmacological inhibition of GPX4 alone has limited application in AML. Thus, whether inhibition of GPX4 combined with other therapeutic reagents has effective application in AML is largely unknown. METHODS: Lipid reactive oxygen species (ROS), malondialdehyde (MDA), and glutathione (GSH) assays were used to assess ferroptosis in AML cells treated with the hypomethylating agent (HMA) decitabine (DAC), ferroptosis-inducer (FIN) RAS-selective lethal 3 (RSL3), or their combination. Combination index (CI) analysis was used to assess the synergistic activity of DAC + RSL3 against AML cells. Finally, we evaluated the synergistic activity of DAC + RSL3 in murine AML and a human R/R-AML-xenografted NSG model in vivo. RESULTS: We first assessed GPX4 expression and found that GPX4 levels were higher in AML cells, especially those with MLL rearrangements, than in NCs. Knockdown of GPX4 by shRNA and indirect inhibition of GPX4 enzyme activity by RSL3 robustly induced ferroptosis in AML cells. To reduce the dose of RSL3 and avoid side effects, low doses of DAC (0.5 µM) and RSL3 (0.05 µM) synergistically facilitate ferroptosis by inhibiting the AMP-activated protein kinase (AMPK)-SLC7A11-GPX4 axis. Knockdown of AMPK by shRNA enhanced ferroptosis, and overexpression of SLC7A11 and GPX4 rescued DAC + RSL3-induced anti-leukemogenesis. Mechanistically, DAC increased the expression of MAGEA6 by reducing MAGEA6 promoter hypermethylation. Overexpression of MAGEA6 induced the degradation of AMPK, suggesting that DAC inhibits the AMPK-SLC7A11-GPX4 axis by increasing MAGEA6 expression. In addition, DAC + RSL3 synergistically reduced leukemic burden and extended overall survival compared with either DAC or RSL3 treatment in the MLL-AF9-transformed murine model. Finally, DAC + RSL3 synergistically reduced viability in untreated and R/R-AML cells and extended overall survival in two R/R-AML-xenografted NSG mouse models. CONCLUSIONS: Our study first identify vulnerability to ferroptosis by regulating MAGEA6-AMPK-SLC7A11-GPX4 signaling pathway. Combined treatment with HMAs and FINs provides a potential therapeutic choice for AML patients, especially for R/R-AML.

DNA hypermethylation-induced miR-182 silence targets BCL2 and HOXA9 to facilitate the self-renewal of leukemia stem cell, accelerate acute myeloid leukemia progression, and determine the sensitivity of BCL2 inhibitor venetoclax.

Rationale: microRNAs (miRNAs) are frequently deregulated and play important roles in the pathogenesis and progression of acute myeloid leukemia (AML). miR-182 functions as an onco-miRNA or tumor suppressor miRNA in the context of different cancers. However, whether miR-182 affects the self-renewal of leukemia stem cells (LSCs) and normal hematopoietic stem progenitor cells (HSPCs) is unknown. Methods: Bisulfite sequencing was used to analyze the methylation status at pri-miR-182 promoter. Lineage-negative HSPCs were isolated from miR-182 knockout (182KO) and wild-type (182WT) mice to construct MLL-AF9-transformed AML model. The effects of miR-182 depletion on the overall survival and function of LSC were analyzed in this mouse model in vivo. Results: miR-182-5p (miR-182) expression was lower in AML blasts than normal controls (NCs) with hypermethylation observed at putative pri-miR-182 promoter in AML blasts but unmethylation in NCs. Overexpression of miR-182 inhibited proliferation, reduced colony formation, and induced apoptosis in leukemic cells. In addition, depletion of miR-182 accelerated the development and shortened the overall survival (OS) in MLL-AF9-transformed murine AML through increasing LSC frequency and self-renewal ability. Consistently, overexpression of miR-182 attenuated AML development and extended the OS in the murine AML model. Most importantly, miR-182 was likely dispensable for normal hematopoiesis. Mechanistically, we identified BCL2 and HOXA9 as two key targets of miR-182 in this context. Most importantly, AML patients with miR-182 unmethylation had high expression of miR-182 followed by low protein expression of BCL2 and resistance to BCL2 inhibitor venetoclax (Ven) in vitro. Conclusions: Our results suggest that miR-182 is a potential therapeutic target for AML patients through attenuating the self-renewal of LSC but not HSPC. miR-182 promoter methylation could determine the sensitivity of Ven treatment and provide a potential biomarker for it.

Lipase-triggered drug release from BCL2 inhibitor ABT-199-loaded nanoparticles to elevate anti-leukemic activity through enhanced drug targeting on the mitochondrial membrane.

Selective BCL2 inhibitor ABT-199 has been approved to treat hematological malignancies including acute myeloid leukemia (AML). However, acquired drug resistance and severe side effects occur after extended treatment limiting the clinical usage of ABT-199. Here, we successfully encapsulated pure ABT-199 in amphiphilic mPEG-b-PTMC169 block copolymer, forming mPEG-b-PTMC169@ABT-199 nanoparticles (abbreviated as PEG-ABT-199), which presented better aqueous dispersion and higher efficiency of loading and encapsulation than pure ABT-199. We then compared the anti-leukemic ability of pure ABT-199 and PEG-ABT-199 in vitro and in vivo. PEG-ABT-199 had a lower IC50 value compared with pure ABT-199 in MV4-11 and MOLM-13 cell lines. In addition, PEG-ABT-199 significantly induced apoptosis and decreased colony number than pure ABT-199. Most importantly, PEG-ABT-199 markedly reduced leukemic burden, inhibited the infiltration of leukemic blasts in the spleen, and extended the overall survival (OS) in MLL-AF9-transduced murine AML compared with free ABT-199. Meanwhile, the blank PEG169 NP was non-toxic to normal hematopoiesis in vitro and in vivo, suggesting that PEG169 NP is a safe carrier. Mechanistically, PEG-ABT-199 enhanced mitochondria-targeted delivery of ABT-199 to trigger the collapse of mitochondrial membrane potential (MMP), the release of cytochrome c (cyt-c), and mitochondria-based apoptosis. In conclusion, our results suggest that PEG-ABT-199 has more vital anti-leukemic ability than pure ABT-199. PEG-ABT-199 has potential application in clinical trials to alleviate side effects and improve anti-leukemia ability. STATEMENT OF SIGNIFICANCE: ATB-199, an orally selective inhibitor for BCL2 protein, presents marked activity in relapsed or refractory AML, T-ALL, and CLL patients. However, ABT-199 resistance severely limits the further clinical usage because of off-target effects, non-specific toxicities, and low delivery of drugs. To reduce the side-effects and improve the solubility and bioavailability, ABT-199 was encapsulated into the amphiphilic mPEG-b-PTMC block copolymer by co-assembly method to obtain mPEG-b-PTMC@ABT-199 nanoparticles (PEG-ABT-199). PEG-ABT-199 has several advantages compared with pure ABT-199. 1.PEG-ABT-199 presents better aqueous dispersion and higher efficiencies of loading and encapsulation than pure ABT-199. 2. PEG-ABT-199 substantially enhances the anti-leukemic ability in vitro and in vivo compared with pure ABT-199. 3. PEG-ABT-199 has little effects on normal cells. 4. PEG-ABT-199 can reduce treatment cost.

Bortezomib suppresses self-renewal and leukemogenesis of leukemia stem cell by NF-ĸB-dependent inhibition of CDK6 in MLL-rearranged myeloid leukemia.

Acute myeloid leukaemia (AML) with chromosomal rearrangements involving the H3K4 methyltransferase mixed-lineage leukaemia (MLL) is an aggressive subtype with low overall survival. Bortezomib (Bort) is first applied in multiple myeloma. However, whether bort possesses anti-self-renewal and leukemogenesis of leukaemia stem cell (LSC) in AML with MLL rearrangements is still unclear. Here, we found that bort suppressed cell proliferation and decreased colony formation in human and murine leukaemic blasts. Besides, bort reduced the frequency and function of LSC, inhibited the progression, and extended the overall survival in MLL-AF9 (MF9) -transformed leukaemic mice. Furthermore, bort decreased the percentage of human LSC (CD34+ CD38- ) cells and extended the overall survival in AML blasts-xenografted NOD/SCID-IL2Rγ (NSG) mice. Mechanistically, cyclin dependent kinase 6 (CDK6) was identified as a bort target by RNA sequencing. Bort reduced the expressions of CDK6 by inhibiting NF ĸB recruitment to the promoter of CDK6, leading to the abolishment of NF ĸB DNA-binding activity for CDK6 promoter. Overexpression of CDK6 partially rescued bort-induced anti-leukemogenesis. Most importantly, bort had little side-effect against the normal haematological stem and progenitor cell (HSPC) and did not affect CDK6 expression in normal HSPC. In conclusion, our results suggest that bort selectively targets LSC in MLL rearrangements. Bort might be a prospective drug for AML patients bearing MLL rearrangements.

Higher Red Blood Cell Distribution Width is a Poor Prognostic Factor for Patients with Chronic Myeloid Leukemia.

PURPOSE: Red blood cell distribution width (RDW) has been considered as a potential indicator of the effects of treatment or as a prognostic indicator for various malignancies. Most chronic myeloid leukemia (CML) patients are in the chronic phase, but some have transformed to accelerated phase or blast phase (blast crisis). However, the clinical significance of RDW in CML remains limited. PATIENTS AND METHODS: In the present study, detailed clinical information and the RDW of 168 healthy people and 153 CML patients (106 patients for the training cohort and 47 patients for the validation cohort) were retrospectively assessed. RESULTS: Multivariate analysis demonstrated that patient age (OR, 1.081; 95CI% 1.039~1.125; p < 0.001), platelet counts (OR, 0.997; 95CI% 0.994~0.999; p = 0.001) and RDW at admission (OR,1.469; 95CI% 1.121~1.925; p = 0.005) were significantly associated with the patients with advanced phase. Among CML patients in the chronic phase, higher RDW was significantly associated with overall survival (OS; p = 0.0008) and the event-free survival (EFS; p = 0.0221) among CML patients with chronic phase, but not with Transformation-free survival (TFS; p = 0.0821). Furthermore, higher RDW was associated with higher mortality compared to patients with low RDW (CML-associated deaths; p < 0.0001). In addition, a decline in RDW is associated with the treatment of CML patients with tyrosine kinase inhibitors, especially at 6 and 12 months after the start of treatment. CONCLUSION: Higher RDW is a potential prognostic biomarker for chronic CML patients.

Targeting USP47 overcomes tyrosine kinase inhibitor resistance and eradicates leukemia stem/progenitor cells in chronic myelogenous leukemia.

Identifying novel drug targets to overcome resistance to tyrosine kinase inhibitors (TKIs) and eradicating leukemia stem/progenitor cells are required for the treatment of chronic myelogenous leukemia (CML). Here, we show that ubiquitin-specific peptidase 47 (USP47) is a potential target to overcome TKI resistance. Functional analysis shows that USP47 knockdown represses proliferation of CML cells sensitive or resistant to imatinib in vitro and in vivo. The knockout of Usp47 significantly inhibits BCR-ABL and BCR-ABLT315I-induced CML in mice with the reduction of Lin-Sca1+c-Kit+ CML stem/progenitor cells. Mechanistic studies show that stabilizing Y-box binding protein 1 contributes to USP47-mediated DNA damage repair in CML cells. Inhibiting USP47 by P22077 exerts cytotoxicity to CML cells with or without TKI resistance in vitro and in vivo. Moreover, P22077 eliminates leukemia stem/progenitor cells in CML mice. Together, targeting USP47 is a promising strategy to overcome TKI resistance and eradicate leukemia stem/progenitor cells in CML.

CD9 knockdown suppresses cell proliferation, adhesion, migration and invasion, while promoting apoptosis and the efficacy of chemotherapeutic drugs and imatinib in Ph+ ALL SUP­B15 cells.

Philadelphia chromosome­positive acute lymphoblastic leukemia (Ph+ ALL) is regarded as a prognostically unfavorable subgroup, as this ALL subgroup has an increased risk of relapse/refractory disease. CD9, which belongs to the tetraspanin membrane proteins, is implicated in several pathological processes, including tumor progression. However, the role of CD9 in the pathogenesis of Ph+ ALL and the potential benefit of applying CD9­targeted RNA interference strategies for treatment of Ph+ ALL require further investigation. The aim of the present study was to determine the effects of CD9 on leukemic cell progression and the efficacy of therapeutic agents in Ph+ ALL cells, in addition to assessing the in vitro anti­leukemia activity of CD9­targeted RNA interference in Ph+ ALL cells. In the present study, a lentiviral short hairpin RNA (shRNA) expression vector targeting CD9 gene in Ph+ ALL SUP­B15 cells was constructed. The present results demonstrated that treatment of SUP­B15 cells with lentiviral­mediated shRNA against CD9 decreased CD9 mRNA and protein expression compared with the shControl cells transduced with a blank vector. In addition, CD9 knockdown could suppress cell proliferation, adhesion, migration and invasion, and promote apoptosis and the efficacy of chemotherapeutic drugs (such as vincristine, daunorubicin, cyclophosphamide and dexamethasone) and the tyrosine kinase inhibitor imatinib in SUP­B15 cells. Furthermore, CD9 knockdown suppressed cell proliferation and promoted apoptosis in SUP­B15 cells via a p53­dependent pathway. These findings suggested that gene silencing of CD9 using a shRNA­expressing lentivirus vector may provide a promising treatment for Ph+ ALL.

WT1 facilitates the self-renewal of leukemia-initiating cells through the upregulation of BCL2L2: WT1-BCL2L2 axis as a new acute myeloid leukemia therapy target.

BACKGROUND: Overexpression of Wilms' tumor-1 (WT1) transcription factor facilitates proliferation in acute myeloid leukemia (AML). However, whether WT1 is enriched in the leukemia-initiating cells (LICs) and leukemia stem cells (LSCs) and facilitates the self-renewal of LSCs remains poorly understood. METHODS: MLL-AF9-induced murine leukemia model was used to evaluate the effect of knockdown of wt1 on the self-renewal ability of LSC. RNA sequencing was performed on WT1-overexpressing cells to select WT1 targets. Apoptosis and colony formation assays were used to assess the anti-leukemic potential of a deubiquitinase inhibitor WP1130. Furthermore, NOD/SCID-IL2Rγ (NSG) AML xenotransplantation and MLL-AF9-induced murine leukemia models were used to evaluate the anti-leukemogenic potential of WP1130 in vivo. RESULTS: We found that wt1 is highly expressed in LICs and LSCs and facilitates the maintenance of leukemia in a murine MLL-AF9-induced model of AML. WT1 enhanced the self-renewal of LSC by increasing the expression of BCL2L2, a member of B cell lymphoma 2 (BCL2) family, by direct binding to its promoter region. Loss of WT1 impaired self-renewal ability in LSC and delayed the progression of leukemia. WP1130 was found to modify the WT1-BCL2L2 axis, and WP1130-induced anti-leukemic activity was mediated by ubiquitin proteasome-mediated destruction of WT1 protein. WP1130 induced apoptosis and decreased colony formation abilities of leukemia cells and prolonged the overall survival in the THP1-based xenograft NSG mouse model. WP1130 also decreased the frequency of LSC and prolonged the overall survival in MLL-AF9-induced murine leukemia model. Mechanistically, WP1130 induced the degradation of WT1 by positively affecting the ubiquitination of WT1 protein. CONCLUSIONS: Our results indicate that WT1 is required for the development of AML. WP1130 exhibits anti-leukemic activity by inhibiting the WT1-BCL2L2 axis, which may represent a new acute myeloid leukemia therapy target.

Deubiquitinase inhibitor degrasyn suppresses metastasis by targeting USP5-WT1-E-cadherin signalling pathway in pancreatic ductal adenocarcinoma.

Wilm's tumour-1 (WT1) is overexpressed in pancreatic ductal adenocarcinoma (PDAC) and enhances metastasis. Deubiquitination stabilizes target proteins, and inhibiting deubiquitination facilitates the degradation of target proteins. However, whether inhibiting deubiquitination of WT1 facilitates its degradation and presents anti-cancer ability in PDAC is unknown. Here, we found that deubiquitinase inhibitor degrasyn rapidly induced the degradation of endogenous and exogenous WT1 through enhancing ubiquitination of WT1 followed by the up-regulation of E-cadherin. Knockdown of WT1 by short hairpin RNAs (shRNAs) inhibited metastasis and overexpression of WT1 partially prevented degrasyn-induced anti-metastasis activity, suggesting that degrasyn presents anti-metastasis activity partially through degrading WT1 protein. We further identified that USP5 deubiquitinated WT1 and stabilized its expression. The higher expressions of USP5 and WT1 are associated with tumour metastasis. More importantly, degrasyn inhibited the activity of USP5 and overexpression of USP5 partially prevented degrasyn-induced degradation of WT1 protein, suggesting that degrasyn degraded WT1 protein through inhibiting the activity of USP5. Finally, degrasyn reduced the tumorigenicity in a xenograft mouse model and reduced the metastasis in vivo. Our results indicate that degrasyn presents strong anti-cancer activity through USP5-WT1-E-cadherin signalling in PDAC. Therefore, degrasyn holds promise as cancer therapeutic agent in PDAC with high expressions of USP5 and WT1.

Targeting miR-193a-AML1-ETO-ß-catenin axis by melatonin suppresses the self-renewal of leukaemia stem cells in leukaemia with t (8;21) translocation.

AML1-ETO, the most common fusion oncoprotein by t (8;21) in acute myeloid leukaemia (AML), enhances hematopoietic self-renewal and leukemogenesis. However, currently no specific therapies have been reported for t (8;21) AML patients as AML1-ETO is still intractable as a pharmacological target. For this purpose, leukaemia cells and AML1-ETO-induced murine leukaemia model were used to investigate the degradation of AML1-ETO by melatonin (MLT), synthesized and secreted by the pineal gland. MLT remarkedly decreased AML1-ETO protein in leukemic cells. Meanwhile, MLT induced apoptosis, decreased proliferation and reduced colony formation. Furthermore, MLT reduced the expansion of human leukemic cells and extended the overall survival in U937T-AML1-ETO-xenografted NSG mice. Most importantly, MLT reduced the infiltration of leukaemia blasts, decreased the frequency of leukaemia stem cells (LSCs) and prolonged the overall survival in AML1-ETO-induced murine leukaemia. Mechanistically, MLT increased the expression of miR-193a, which inhibited AML1-ETO expression via targeting its putative binding sites. Furthermore, MLT decreased the expression of ß-catenin, which is required for the self-renewal of LSC and is the downstream of AML1-ETO. Thus, MLT presents anti-self-renewal of LSC through miR-193a-AML1-ETO-ß-catenin axis. In conclusion, MLT might be a potential treatment for t (8;21) leukaemia by targeting AML1-ETO oncoprotein.

Idarubicin-loaded methoxy poly(ethylene glycol)-b-poly(l-lactide-co-glycolide) nanoparticles for enhancing cellular uptake and promoting antileukemia activity.

PURPOSE: Nanoparticle (NP)-based drug delivery approaches have tremendous potential for enhancing treatment efficacy and decreasing doses of chemotherapeutics. Idarubicin (IDA) is one of the most common chemotherapeutic drugs used in the treatment of acute myeloid leukemia (AML). However, severe side effects and drug resistance markedly limit the application of IDA. METHODS: In this study, we encapsulated IDA in polymeric NPs and validated their antileukemia activity in vitro and in vivo. RESULTS: NPs with an average diameter of 84 nm was assembled from a methoxy poly(ethylene glycol)-b-poly(l-lactide-co-glycolide) (mPEG-PLGA). After loading of IDA, IDA-loaded mPEG-PLGA NPs (IDA/mPEG-PLGA NPs) were formed. The in vitro release data showed that the IDA/mPEG-PLGA NPs have excellent sustained release property. IDA/mPEG-PLGA NPs had exhibited the lower IC50 than pure IDA. Moreover, IDA/mPEG-PLGA NPs in the same concentration substantially induced apoptosis than did pure IDA. Most importantly, IDA/MPEG-PLGA NPs significantly decreased the infiltration of leukemia blasts and improved the overall survival of MLL-AF9-induced murine leukemia compared with free IDA. However, the blank NPs were nontoxic to normal cultured cells in vitro, suggesting that NPs were the safe carrier. CONCLUSION: Our data suggest that IDA/mPEG-PLGA NPs might be a suitable carrier to encapsulate IDA. Low dose of IDA/mPEG-PLGA NPs can be used as a conventional dosage for antileukemia therapy to reduce side effect and improve survival.

Overexpression of novel lncRNA NLIPMT inhibits metastasis by reducing phosphorylated glycogen synthase kinase 3ß in breast cancer.

Long noncoding RNAs (lncRNAs) are considered as regulators of gene expression in cancers. However, cancer profiling has little focused on noncoding genes. Here, we reported that RP11-115N4.1 (here renamed novel lncRNA inhibiting proliferation and metastasis [NLIPMT]) was downregulated in breast cancer tissues. Ectopic expression of NLIPMT inhibited mammary cell proliferation, motility in vitro. Moreover, lnc-NLIPMT reduced the growth of implanted MDA-MB-231 cells in vivo. Mechanistically, glycogen synthase kinase 3ß (GSK3ß) was identified as an effector protein regulated by lnc-NLIPMT. Inhibition of GSK3ß activity restored NLIPMT-induced inhibition of proliferation and motility in breast cancer cells. These data reveal that lnc-NLIPMT functions as a driver of breast cancer progression and might serve as a potential target for antimetastatic therapies.

Long noncoding RNA HOTAIR promotes the self-renewal of leukemia stem cells through epigenetic silencing of p15.

Acute myeloid leukemia (AML) is a heterogeneous hematopoietic disorder initiated from a small subset of leukemia stem cell (LSC), which presents unrestricted self-renewal and proliferation. Long non-coding RNA HOTAIR is abundantly expressed and plays oncogenic roles in solid cancer and AML. However, whether HOTAIR regulates the self-renewal of LSC is largely unknown. Here, we reported that the expression of HOTAIR was increased in LSC than in normal hematological stem and progenitor cells (HSPCs). HOTAIR inhibition by short hairpin RNAs (shRNAs) decreased colony formation in leukemia cell lines and primary AML blasts. We then investigated the role of HOTAIR in leukemia in vivo. HOTAIR knockdown extends the survival time in U937-transplanted NSG mice. Furthermore, HOTAIR knockdown reduced infiltration of leukemic blasts, decreased frequency of LSC, and prolonged overall survival in MLL-AF9-induced murine leukemia, suggesting that HOTAIR is required for the maintenance of AML. Mechanistically, HOTAIR inhibited p15 expression through zeste homolog 2 (EZH2)-enrolled tri-methylation of Lys 27 of histone H3 (H3K27me3) in p15 promoter. In addition, p15 partially reversed the decrease of colony and proliferation induced by HOTAIR knockdown, suggesting that p15 plays an important role in the leukemogenesis by HOTAIR. In conclusion, our study suggests that HOTAIR facilitates leukemogenesis by enhancing self-renewal of LSC. HOTAIR might be a potential target for anti-LSC therapy.

Mebendazole exhibits potent anti-leukemia activity on acute myeloid leukemia.

Acute myeloid leukemia (AML) is one of the most common types of acute leukemia in adults with the lowest survival rate of all leukemia. Resistance to cytarabine and anthracycline-based chemotherapy is a major cause of treatment failure. Thus, finding new drugs with anti-leukemia activities and minimal side effect is urgently needed. Here through screening more than 1000 drugs approved by the Food and Drug Administration (FDA) of United States, the anthelmintic drug mebendazole (MBZ) was found to inhibit the growth of AML cell lines (THP-1, U937, NB4 and K562) and bone marrow mononuclear cells (BM-MNCs) from AML patients at pharmacologically achievable concentrations. In contrast, similar concentration of MBZ had little inhibitory effect on the growth of normal peripheral blood mononuclear cells (PBMC) or human umbilical vein endothelial cells (HUVEC). In addition, MBZ induced mitotic arrest and mitotic catastrophe in AML cells based on nuclear morphology, cell cycle distribution, mitotic marker analyses and the number of multinucleated cells and apoptotic cells. Furthermore, MBZ treatment inhibited activation of Akt and Erk in AML leukemic cells. Finally, MBZ repressed the progression of leukemic cells in vivo and prolonged survival in AML xenograft mouse model. Taken together, our results suggest that MBZ could be a potential new therapeutic agent for the treatment of AML patients.

Congenital hypodysfibrinogenemia associated with a novel deletion of three residues (γAla289_Asp291del) in fibrinogen.

Hypodysfibrinogenemia is the least frequently reported congenital fibrinogen disorder, characterized by both quantity and quality defects of fibrinogen. In this study, we investigated the molecular basis of hypodysfibrinogenemia in a Chinese family. Functional fibrinogen was measured by Clauss method, and the antigenic fibrinogen was measured by immunoturbidimetry assay. All the exons and exon-intron boundaries of fibrinogen genes (FGA, FGB and FGG) were analysed by direct DNA sequencing. To further evaluate its molecular and functional characterizations, fibrinogen was purified from the plasma of propositus, then SDS-PAGE, fibrin polymerization, clot lysis, and electron microscopy scanning were all performed. The propositus showed a slight decrease of immunologic fibrinogen (1.52 g/L) but dramatically reduced functional fibrinogen (0.3 g/L). DNA sequencing revealed a novel heterozygous CCTTTGATG deletion in the exon 8 of FGG, leading to the deletion of Ala289, Phe290, and Asp291 in fibrinogen γ-chain. The polymerization of the fibrinogen from the propositus was markedly impaired, with prolonged lag period and decreased final turbidity. The fibrinogen clottability showed a reduced fraction of participating clot formation. While the clot lysis showed normal. Scanning electron microscopy revealed that the fibers of the propositus were thicker than normal, with larger pores and curlier meshworks. We conclude that γAla289_Asp291del is responsible for the hypodysfibrinogenemia in this case.

A novel miR-375-HOXB3-CDCA3/DNMT3B regulatory circuitry contributes to leukemogenesis in acute myeloid leukemia.

BACKGROUND: Acute myeloid leukemia (AML) is a heterogeneous group of hematopoietic malignancies due to sophisticated genetic mutations and epigenetic dysregulation. MicroRNAs (miRNAs), a class of small non-coding RNAs, are important regulators of gene expression in all biological processes, including leukemogenesis. Recently, miR-375 has been reported to be a suppressive miRNA in multiple types of cancers, but its underlying anti-leukemia activity in AML is largely unknown. METHODS: Quantitative reverse transcriptase PCR (qRT-PCR) was used to measure the expression of miR-375 and HOXB3 in leukemic cells and normal controls. Targets of miR-375 were confirmed by western blot and luciferase assay. Phenotypic effects of miR-375 overexpression and HOXB3 knockdown were assessed using viability (trypan blue exclusion assay), colony formation/replating, as well as tumor xenograft assays in vivo. RESULTS: The expression of miR-375 was substantially decreased in leukemic cell lines and primary AML blasts compared with normal controls, because DNA hypermethylation of precursor-miR-375 (pre-miR-375) promoter was discovered in leukemic cells but not in normal controls. Lower expression of miR-375 predicted poor outcome in AML patients. Furthermore, forced expression of miR-375 not only decreased proliferation and colony formation in leukemic cells but also reduced xenograft tumor size and prolonged the survival time in a leukemia xenograft mouse model. Mechanistically, overexpression of miR-375 reduced HOXB3 expression and repressed the activity of a luciferase reporter through binding 3'-untranslated regions (3'-UTR) of HOXB3 mRNA. Overexpression of HOXB3 partially blocked miR-375-induced arrest of proliferation and reduction of colony number, suggesting that HOXB3 plays an important role in miR-375-induced anti-leukemia activity. Knockdown of HOXB3 by short hairpin RNAs reduced the expression of cell division cycle associated 3 (CDCA3), which decreased cell proliferation. Furthermore, HOXB3 induced DNA methyltransferase 3B (DNMT3B) expression to bind in the pre-miR-375 promoter and enhanced DNA hypermethylation of pre-miR-375, leading to the lower expression of miR-375. CONCLUSIONS: Collectively, we have identified a miR-375-HOXB3-CDCA3/DNMT3B regulatory circuitry which contributes to leukemogenesis and suggests a therapeutic strategy of restoring miR-375 expression in AML.

A regulatory circuitry between miR-193a/miR-600 and WT1 enhances leukemogenesis in acute myeloid leukemia.

The aberrant overexpression of Wilms tumor-1 (WT1) in acute myeloid leukemia (AML) plays an important role in blast cell survival by enhancing proliferation and inhibiting apoptosis. However, the mechanism underlying the overexpression of WT1 remains unclear. Here, we identified miR-193a (miR-193a-5p) and miR-600 targeting and degrading WT1. MiR-193a and miR-600 synergistically reduced WT1 expression and suppressed the activity of a luciferase reporter by binding coding sequence and the 3'-untranslated region of WT1 mRNA, respectively. Furthermore, the expression of miR-193a and miR-600 was decreased in AML patients compared with normal controls. DNA hypermethylation in pre-miR-193a promoter, but not pre-miR-600 promoter, caused the downregulation of miR-193a. Most intriguingly, ectopic expression of WT1 inhibited miR-600 expression, in turn, by binding the putative pre-miR-600 promoter, leading to the downregulation of miR-600 in AML blasts. Ectopic expression of miR-193a and miR-600 synergistically inhibited cell proliferation, induced apoptosis, and decreased colony formation in leukemia cells. Finally, overexpression of miR-193a and miR-600 decreased the growth of K562-inoculated tumor xenografts and extended survival time in THP1-transplanted leukemia mice. In conclusion, these data reveal an important role of miRNAs-WT1 circuitry in leukemia cells and the therapeutic promise of restoring miR-193a and miR-600 expression in AML patients.

WT1 protein is cleaved by caspase-3 in apoptotic leukemic cells.

The aberrant overexpression of Wilms' tumor-1 gene (WT1) plays an important role in blast cell survival and resistance to chemotherapy in acute myeloid leukemia (AML). Here, we found in chemotherapeutic drug etoposide-induced apoptosis, WT1 protein was cleaved into smaller fragment by caspase-3 in leukemic cells. The cleavage was blocked by pan-caspase inhibitor and special caspase-3 inhibitor, suggesting that caspase-3 might cleave WT1 protein. Furthermore, recombinant active caspase-3 cleaved the Flag-WT1 and GST-WT1 proteins in vitro. However, site-directed mutagenesis analyses failed to identify caspase-3-targeted sites in WT1 protein, indicating that caspase-3 cleaved uncommon sites but not classical motifs (DXXD) and non-classical motifs (XXXD). Finally, Eto decreased c-Myc and Bcl-2 expression via reducing the binding of WT1 to the promoter and Eto-induced apoptosis was partially prevented by overexpression of WT1. Collectively, we identify a new substrate for caspase-3 and shed new light on understanding the complicated biology of WT1 in leukemia.

MicroRNA-193a inhibits breast cancer proliferation and metastasis by downregulating WT1.

In many cancers, microRNA-193a (miR-193a) is a suppressor miRNA, but its underlying anti-oncogenic activity in breast cancer is not known. In this study, we found decreased miR-193a (specifically, miR-193a-5p) expression not only in breast cancer cell lines but also in breast cancer tissues as compared with the adjacent non-tumor tissues. Ectopic miR-193a overexpression inhibited the proliferation, colony formation, migration, and invasion of MDA-MB-231 and BT549 cells. miR-193a reduced Wilms' tumor 1 (WT1) expression and repressed luciferase reporter activity by binding WT1 coding region sequences; mutation of the predicted miR-193a binding site abolished this effect. miR-193a and WT1 expression were significantly inversely correlated in breast cancer tissues. Importantly, the anti-cancer activity induced by miR-193a was partially reversed by WT1 overexpression, indicating an important role for WT1 in such activity related to miR-193a. Our results reveal that miR-193a-WT1 interaction plays an important role in breast cancer metastasis, and suggest that restoring miR-193a expression is a therapeutic strategy in breast cancer.