Progression Of Acute Lymphoblastic Leukemia Research Articles

T-cell acute lymphoblastic leukemia progression is supported by inflammatory molecules including hepatocyte growth factor

T-cell acute lymphoblastic leukemia (T-ALL) is a malignant hematological disorder characterized by an increased proliferation of immature T lymphocytes precursors. T-ALL treatment includes chemotherapy with strong side effects, and patients that undergo relapse display poor prognosis. Although cell-intrinsic oncogenic pathways are well-studied, the tumor microenvironment, like inflammatory cellular and molecular components is less explored in T-ALL. We sought to determine the composition of the inflammatory microenvironment induced by T-ALL, and its role in T-ALL progression. We show in two mouse T-ALL cell models that T-ALLs enhance blood neutrophils and resident monocytes, accompanied with a plasmatic acute secretion of inflammatory molecules. Depleting neutrophils using anti-Ly6G treatment or resident monocytes by clodronate liposomes treatment does not modulate plasmatic inflammatory molecule secretion and mice survival. However, inhibiting the secretion of inflammatory molecules by microenvironment with NECA, an agonist of adenosine receptors, diminishes T-ALL progression enhancing mouse survival. We uncovered Hepatocyte Growth Factor (HGF), T-ALL-driven and the most decreased molecule with NECA, as a potential therapeutic target in T-ALL. Altogether, we identified a signature of inflammatory molecules that can potentially be involved in T-ALL evolution and uncovered HGF/cMET pathway as important to target for limiting T-ALL progression.

Mutations of epigenetic modifier genes predict poor outcome in adult acute lymphoblastic leukemia.

Epigenetic modifier (EM) genes play important roles in the occurrence and progression of acute lymphoblastic leukemia (ALL). However, the prognostic significance of EM mutations in ALL has not yet been thoroughly investigated. This retrospective study included 205 adult patients with ALL engaged in a pediatric-type regimen. Based on targeted next-generation sequencing, they were divided into EM mutation group (EM-mut, n = 75) and EM wild-type group (EM-wt, n = 130). The EM-mut group showed a higher positive rate of minimal residual disease (MRD) on treatment day24 and before consolidation therapy (P = 0.026, 0.020). Multivariate Cox regression analysis showed that EM-mut was an independent adverse factor for overall survival (OS) and event-free survival (EFS) (HR = 2.123, 1.742; P = 0.009, 0.007). Survival analysis revealed that the OS and EFS rates were significantly lower in the EM-mut group than in the EM-wt group (3-year OS rate, 45.8% vs. 65.0%, P = 0.0041; 3-year EFS rate, 36.7% vs. 53.2%, P = 0.011). In conclusion, EM was frequently mutated in adult ALL and was characterized by poor response to induction therapy and inferior clinical outcomes.

Polo-like kinase 1 Decrease During Induction Therapy Could Indicate Good Treatment Response, Favorable Risk Stratification, and Prolonged Survival in Pediatric Acute Lymphoblastic Leukemia.

Polo-like kinase 1 (PLK1) modulates leukemia cell apoptosis, proliferation, and cell cycle arrest in the progression of acute lymphoblastic leukemia (ALL). This study intended to investigate the dysregulation of PLK1 and its association with induction therapy response and prognosis in pediatric ALL patients. Bone marrow mononuclear cell samples were collected from 90 pediatric ALL patients at baseline and on the 15th day of induction therapy (D15), as well as from 20 controls after enrollment, for the detection of PLK1 by reverse transcription-quantitative polymerase chain reaction. PLK1 was increased in pediatric ALL patients compared with controls ( P <0.001). In pediatric ALL patients, PLK1 decreased from baseline to D15 ( P <0.001). Lower PLK1 at baseline was associated with a good prednisone response ( P =0.002), while decreased PLK1 at D15 was related to good prednisone response ( P =0.001), better bone marrow response ( P =0.025), and favorable risk stratification ( P =0.014). In addition, reduced PLK1 at baseline was linked with better event-free survival (EFS) ( P =0.046), and decreased PLK1 at D15 was related to prolonged EFS ( P =0.027) and overall survival (OS) ( P =0.047). Moreover, PLK1 decline ≥25% was linked to favorable EFS ( P =0.015) and OS ( P =0.008). Further multivariate Cox proportional regression analysis revealed that PLK1 decline ≥25% was independently linked with prolonged EFS (hazard ratio (HR)=0.324, P =0.024) and OS (HR=0.211, P =0.019). The reduction of PLK1 after induction therapy reflects a good treatment response and correlates with a favorable survival profile in pediatric ALL patients.

LncRNA15691 promotes T-ALL infiltration by upregulating CCR9 via increased MATR3 stability.

Our previous studies demonstrated that CCR9 plays an important role in several aspects of T-cell acute lymphoblastic leukemia progression and that CCR9 is a potential therapeutic target. However, the underlying mechanism that regulates CCR9 expression remains incompletely understood. In this study, bioinformatics analysis and validation in clinical samples revealed the lncRNA15691 to be positively correlated with CCR9 mRNA expression and significantly upregulated in T-cell acute lymphoblastic leukemia samples and CCR9high T-cell acute lymphoblastic leukemia cell lines. LncRNA15691, a previously uncharacterized lncRNA, was found to be located in both the cytoplasm and the nucleus via fluorescence in situ hybridization assay. In addition, lncRNA15691 upregulated the expression of CCR9 and was involved in T-cell acute lymphoblastic leukemia cell invasion. In vivo experiments showed that lncRNA15691 promoted leukemia cell homing/infiltration into the bone marrow, blood, and spleen, whereas the CCR9 ligand, CCL25, augmented the extramedullary infiltration of CCR9low leukemia cells overexpressing lncRNA15691 into blood, spleen, and liver. Subsequently, RNA protein pull-down assays, coupled with liquid chromatography-tandem mass spectrometry, were used to uncover potential lncRNA15691-interacting proteins, which were then validated by RNA immunoprecipitation. These mechanistic studies revealed that lncRNA15691 upregulated CCR9 expression via directly binding to and stabilizing MATR3 by inhibiting its nuclear degradation mediated by PKA. Collectively, our study revealed a novel mechanism of regulating CCR9 expression and implicated lncRNA15691 as a potential novel biomarker for T-cell acute lymphoblastic leukemia infiltration.

Abstract IA005: From hematopoiesis to immunity: Delineating the impact of aging on B-cell acute lymphoblastic leukemia progression

Abstract The world’s aging population, those 65 and older, is projected to increase from 703 million people to 1.5 billion people by 2050. This great accomplishment comes with the added obligation of providing adequate healthcare for this vulnerable population given the number of diseases that manifest with age, including cancer. Chronic inflammation is a well-established hallmark of aging, and we have demonstrated that this state compromises hematopoiesis, notably the function of B-progenitor cells. Furthermore, we have shown that aging-associated functional declines in B-progenitor cells can be rescued with the anti-inflammatory cytokine interleukin-37, which also reduces the expression of checkpoint proteins on aged innate immune cells and augments the function of aged lymphocytes. Importantly, interleukin-37-mediated improvements in hematopoiesis and immunity suppress B-cell acute lymphoblastic leukemia (B-ALL) progression and enhance the protective capacity of aged chimeric antigen receptor (CAR) T-cells in murine models of B-ALL. Our results highlight the therapeutic potential of anti-inflammatory agents in treating hematological malignancies and suggest that combining anti-inflammatory cytokine treatment with immunotherapy strategies may represent a novel approach for treating aging-associated blood cancers. Citation Format: Curtis J. Henry. From hematopoiesis to immunity: Delineating the impact of aging on B-cell acute lymphoblastic leukemia progression [abstract]. In: Proceedings of the AACR Special Conference: Aging and Cancer; 2022 Nov 17-20; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_1):Abstract nr IA005.

Semisynthetic aurones A14 protects against T-cell acute lymphoblastic leukemia via suppressing proliferation and inducing cell cycle arrest with apoptosis

BackgroundAcute lymphoblastic leukemia is an aggressive neoplasm and seriously threatens human health. A14 is one kind of semisynthetic aurone that exhibits the capability to inhibit prostate cancer, but little is known about the role of A14 on T-cell acute lymphoblastic leukemia.MethodsFirstly, the effects of A14 on the ability of leukemia cells to proliferate were measured by Vi-cell counter. Then, we detected the cell cycle and apoptosis by flow cytometry and characterized the related protein expression using immunoblotting. In addition, we constructed stable luciferase expressing cell lines for use in a cell derived xenograft mouse model to measure the effect of A14 on T-cell acute lymphoblastic leukemia.ResultsResults exhibited that A14 markedly suppressed cell proliferation and induced G2/M phase arrest along with cell cycles regulating proteins changes. A14 led to apoptosis in leukemia cells, at least partly, through the cytochrome c signaling pathway. Experiments in cell derived xenograft mouse model also showed that A14 markedly ameliorated the survival rate.ConclusionsThe present study revealed that semisynthetic aurones A14 can effectively protect against T-cell acute lymphoblastic leukemia progression both in vitro and in vivo, indicating the capability of A14 as a promising drug for the treatment of T-cell acute lymphoblastic leukemia.

Deferoxamine Inhibits Acute Lymphoblastic Leukemia Progression through Repression of ROS/HIF-1α, Wnt/β-Catenin, and p38MAPK/ERK Pathways.

Acute lymphoblastic leukemia (ALL) is the most common type of childhood cancer, with a feature of easy to induce multidrug resistance and relapse. Abundant studies have proved that iron overload strengthens the growth and metastasis of tumor cells. Herein, we found that deferoxamine (DFO) effectively decreased the concentration of intracellular iron in ALL cells. DFO inhibited proliferation, induced apoptosis, and obstructed cell cycle of ALL cells, whereas DFO and dextriferron (Dex) used in combination significantly decreased the sensitivity of ALL cells to DFO. Reactive oxygen species (ROS) level was reduced in ALL cells treated with DFO, and the combination of DFO and Dex reversed the effects of DFO. In vivo, DFO inhibited mouse tumor growth. Besides, cyclinD1, β-catenin, c-Myc, hypoxia inducible factor 1 (HIF-1), p-p38MAPK, and p-ERK1/2 protein levels were significantly downregulated, and the levels of prolyl hydroxylase-2 (PHD-2) were upregulated after treated with DFO, whereas Dex treatment reversed those in vivo and in vitro. In conclusion, DFO inhibited the proliferation and ALL xenograft tumor growth, obstructed the cell cycle, and induced apoptosis of ALL cells, probably via inactivating the ROS/HIF-1α, Wnt/β-catenin, and p38MAPK/ERK signaling.

Identification of lncRNAs associated with the progression of acute lymphoblastic leukemia using a competing endogenous RNAs network.

Acute lymphoblastic leukemia (ALL) is a malignancy of bone marrow lymphoid precursors. Despite effective treatments, the causes of its progression or recurrence are still unknown. Finding prognostic biomarkers is needed for early diagnosis and more effective treatment. This study was performed to identify long non-coding RNAs (lncRNAs) involved in ALL progression by constructing a competitive endogenous RNA (ceRNA) network. These lncRNAs may serve as potential new biomarkers in the development of ALL. The GSE67684 dataset identified changes in lncRNAs and mRNAs involved in ALL progression. Data from this study were re-analyzed, and probes related to lncRNAs were retrieved. Targetscan, miRTarBase, and miRcode databases were used to identify microRNAs (miRNAs) related to the discovered genes and lncRNAs. The ceRNA network was constructed, and the candidate lncRNAs were selected. Finally, the results were validated with reverse transcription quantitative real-time PCR (RT-qPCR). The ceRNA network outcomes demonstrated that the top lncRNAs associated with altered mRNAs in ALL are IRF1-AS1, MCM3AP-AS1, TRAF3IP2-AS1, HOTAIRM1, CRNDE, and TUG1. Investigations of the subnets linked to MCM3AP-AS1, TRAF3IP2-AS1, and IRF1-AS1 indicated that these lncRNAs were considerably related to pathways associated with inflammation, metastasis, and proliferation. Higher expression levels of IRF1-AS1, MCM3AP-AS1, TRAF3IP2-AS1, CRNDE, and TUG1 were found in ALL samples compared to controls. The expression of MCM3AP-AS1, TRAF3IP2-AS1, and IRF1-AS1 is significantly elevated during the progression of ALL, playing an oncogenic role. Due to their role in the main cancer pathways, lncRNAs could be suitable therapeutic and diagnostic targets in ALL.

Quantitative Determination of Serum Level of TLR4, TLR7 and TLR9 in Pediatric Acute Lymphoblastic Leukemia (ALL) Patients in Basrah, Iraq

Acute Lymphoblastic Leukemia (ALL) is one of most frequent malignancy detected in children, accounting for three quarters of all leukemia occurrences in children. Toll-Like Receptors (TLRs) have been shown to be expressed or up regulated in tumors (solid) and tumor cell lines, but their expression level or role in the etiology and progression of acute lymphoblastic leukemia in children is not studied widely. This study intended to explore the association of serum level of TLR4, TLR7, and TLR9 in children with acute lymphoblastic leukemia. A case control study was conducted on patients (pediatric) with ALL who have been admitted to Basrah Children Specialty Hospital, Basrah, Iraq. Three ml of serum samples were collected for the measurement of TLRs concentration by using Sandwich Enzyme-Linked Immuno Sorbent Assay (ELISA). The mean level of TLR4, TLR7 and TLR9 in patients were higher than the control group. However, the difference was statistically significant for TLR4 and TLR7 (P-value less than 0.005) but not for TLR9. The mean value of TLRs are higher in the newly diagnosed group than the relapse. The higher serum concentration of TLR4, TLR7 and TLR9 in patients, whether new or in relapse, compared to control group might be part of the immune-evasion mechanism developed by the malignant cells that plays a serious role in leukomogenicity and disease advancement.

Circ_0000745 promotes acute lymphoblastic leukemia progression through mediating miR-494-3p/NET1 axis

ABSTRACT Background Circular RNAs (circRNAs) have shown important regulatory roles in tumorigenesis. However, the role and working mechanism of circ_0000745 in acute lymphoblastic leukemia (ALL) development remain largely unclear. Methods The expression of circ_0000745, sperm antigen with calponin homology and coiled-coil domains 1 (SPECC1), microRNA-494-3p (miR-494-3p), and neuroepithelial cell transforming 1 (NET1) messenger RNA (mRNA) and protein was analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot assay. Flow cytometry was performed to assess cell apoptosis and cell cycle progression. Extracellular acidification rate (ECAR) was assessed to analyze cell glycolysis. Cell viability was analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay. Ferroptosis was assessed through measuring the intracellular levels of iron and lipid reactive oxygen species (ROS). Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were conducted to validate the interaction between miR-494-3p and circ_0000745 or NET1. Results Circ_0000745 expression was elevated in ALL patients and cell lines. Circ_0000745 knockdown restrained cell cycle progression and glycolysis and triggered cell apoptosis and ferroptosis. Circ_0000745 acted as a molecular sponge for miR-494-3p in ALL cells. miR-494-3p silencing partly diminished circ_0000745 knockdown-induced anti-tumor effects in ALL cells. NET1 was a target of miR-494-3p, and miR-494-3p overexpression-induced anti-tumor influences were partly counteracted by the accumulation of NET1 in ALL cells. Circ_0000745 can positively regulate NET1 expression by sponging miR-494-3p in ALL cells. Conclusion Circ_0000745 contributed to ALL development partly by binding to miR-494-3p to induce NET1 expression.0020.

LINC00265/miR-4500 Axis Accelerates Acute Lymphoblastic Leukemia Progression by Enhancing STAT3 Signals.

BackgroundLong noncoding RNA LINC00265 or miR-4500 is involved in the pathogenesis of many cancers. However, their functions in acute lymphoblastic leukemia (ALL) remain unknown. In this study, we investigated how LINC00265 and miR-4500 regulate the malignant characteristics of ALL.MethodsReal-time PCR was used in examining the expression of LINC00265 in ALL cell lines and blood of patients with ALL. Cell proliferation, cell migration, and xenograft tumor assays were performed to verify the function of LINC00265 subjected to overexpressing and silencing experiments. The ceRNA mechanism with LINC00265/miR-4500/STAT3 was investigated through luciferase and RNA pull-down assays. Finally, the function of the LINC00265/miR-4500/STAT3 axis subjected to overexpressing and silencing assays was determined through cell proliferation, cell migration, and xenograft tumor assays.ResultsLINC00265 was highly expressed in ALL cell lines and blood of patients with ALL and facilitated the proliferation, migration, invasion, and growth of xenograft tumors of ALL cells. The silencing of LINC00265 expression with LINC00265 siRNA significantly inhibited the malignancy of the ALL cells. RNA pull-down and luciferase assays demonstrated that LINC00265 competitively targeted miR-4500 and enhanced STAT3 expression. Furthermore, miR-4500 inhibitors or overexpressed LINC00265 up-regulated STAT3 expression, and miR-4500 mimics or STAT3 shRNAs eliminated the LINC00265-induced malignancy of the ALL cells.ConclusionMechanistically, LncRNA LINC00265 can competitively interact with miR-4500 and thereby up-regulates STAT3 signaling and enhances the malignancy of tumors.

PHF6 and JAK3 mutations cooperate to drive T-cell acute lymphoblastic leukemia progression

T-cell acute lymphoblastic leukemia (T-ALL) is a malignant hematologic disease caused by gene mutations in T-cell progenitors. As an important epigenetic regulator, PHF6 mutations frequently coexist with JAK3 mutations in T-ALL patients. However, the role(s) of PHF6 mutations in JAK3-driven leukemia remain unclear. Here, the cooperation between JAK3 activation and PHF6 inactivation is examined in leukemia patients and in mice models. We found that the average survival time is shorter in patients with JAK/STAT and PHF6 comutation than that in other patients, suggesting a potential role of PHF6 in leukemia progression. We subsequently found that Phf6 deficiency promotes JAK3M511I-induced T-ALL progression in mice by inhibiting the Bai1-Mdm2-P53 signaling pathway, which is independent of the JAK3/STAT5 signaling pathway. Furthermore, combination therapy with a JAK3 inhibitor (tofacitinib) and a MDM2 inhibitor (idasanutlin) reduces the Phf6 KO and JAK3M511I leukemia burden in vivo. Taken together, our study suggests that combined treatment with JAK3 and MDM2 inhibitors may potentially increase the drug benefit for T-ALL patients with PHF6 and JAK3 comutation.

The age of the bone marrow microenvironment influences B-cell acute lymphoblastic leukemia progression via CXCR5-CXCL13

AbstractB-cell acute lymphoblastic leukemia (B-ALL) occurs most commonly in children, whereas chronic myeloid leukemia is more frequent in adults. The myeloid bias of hematopoiesis in elderly individuals has been considered causative, but the age of the bone marrow microenvironment (BMM) may be contributory. Using various murine models of B-ALL in young vs old mice, we recapitulated B-ALL preponderance in children vs adults. We showed differential effects of young vs old BM macrophages on B-ALL cell function. Molecular profiling using RNA- and ATAC-sequencing revealed pronounced differences in young vs old BMM-derived macrophages and enrichment for gene sets associated with inflammation. In concordance with the role of C-X-C motif chemokine (CXCL) 13 for disease-associated B-cell chemoattraction, we found CXCL13 to be highly expressed in young macrophages on a translational compared with a transcriptional level. Inhibition of CXCL13 in BM macrophages impaired leukemia cell migration and decreased the proliferation of cocultured B-ALL cells, whereas recombinant CXCL13 increased pAKT and B-ALL cell expansion. Pretreatment of B-ALL–initiating cells with CXCL13 accelerated B-ALL progression. Deficiency of Cxcr5, the receptor for CXCL13, on B-ALL–initiating cells prolonged murine survival, whereas high expression of CXCR5 in pediatric B-ALL may predict central nervous system relapse. CXCL13 staining was increased in bone sections from pediatric compared with adult patients with B-ALL. Taken together, our study shows that the age of the BMM and, in particular, BM macrophages influence the leukemia phenotype. The CXCR5-CXCL13 axis may act as prognostic marker and an attractive novel target for the treatment of B-ALL.

SIRT1 regulates the phosphorylation and degradation of P27 by deacetylating CDK2 to promote T-cell acute lymphoblastic leukemia progression

BackgroundDespite marked advances in the clinical therapies, clinical outcome of most T-cell acute lymphoblastic leukemia (T-ALL) patients remains poor, due to the high risk of relapse, even after complete remission. Previous studies suggest that the NAD-dependent deacetylase sirtuin 1 (SIRT1) has a dual role in hematologic malignancies, acting as a tumor suppressor or tumor promoter depending on the tumor type. However, little is known about the expression and functions of SIRT1 in T-ALL leukemogenesis.MethodsPublic RNA-seq data, a Notch1 driven T-ALL mouse model and γ-secretase inhibitor were used to identify SIRT1 expression in T-ALL. We knocked down SIRT1 expression with ShRNAs and assessed the impacts of SIRT1 deficiency on cell proliferation, colony formation, the cell cycle and apoptosis. Transgenic SIRT1 knockout mice were used to determine the function of SIRT1 in vivo. RT-PCR, western blot, co-immunoprecipitation and ubiquitination analyses were used to detect SIRT1, p27 and CDK2 expression and their interactions.ResultsSIRT1 protein expression was positively correlated with the activation of Notch1. Downregulation of SIRT1 expression suppressed the proliferation and colony formation of T-ALL cell lines, which was reversed by SIRT1 overexpression. SIRT1 silencing prolonged the lifespan of T-ALL model mice. We demonstrated that p27 was involved in the downstream mechanism of cell cycle arrest induced by silencing SIRT1. SIRT1 increased the phosphorylation of p27 on Thr187 by deacetylating CDK2 and enhanced the interaction between p27 and SKP2 leading to the degradation of p27.ConclusionOur findings suggest that SIRT1 is a promising target in T-ALL and offer a mechanistic link between the upregulation of SIRT1 and downregulation of p27.

Therapeutic delivery of siRNA with polymeric carriers to down-regulate STAT5A expression in high-risk B-cell acute lymphoblastic leukemia (B-ALL).

Overexpression and persistent activation of STAT5 play an important role in the development and progression of acute lymphoblastic leukemia (ALL), the most common pediatric cancer. Small interfering RNA (siRNA)-mediated downregulation of STAT5 represents a promising therapeutic approach for ALL to overcome the limitations of current treatment modalities such as high relapse rates and poor prognosis. However, to effectively transport siRNA molecules to target cells, development of potent carriers is of utmost importance to surpass hurdles of delivery. In this study, we investigated the use of lipopolymers as non-viral delivery systems derived from low molecular weight polyethylenimines (PEI) substituted with lauric acid (Lau), linoleic acid (LA) and stearic acid (StA) to deliver siRNA molecules to ALL cell lines and primary samples. Among the lipid-substituted polymers explored, Lau- and LA-substituted PEI displayed excellent siRNA delivery to SUP-B15 and RS4;11 cells. STAT5A gene expression was downregulated (36–92%) in SUP-B15 and (32%) in RS4;11 cells using the polymeric delivery systems, which consequently reduced cell growth and inhibited the formation of colonies in ALL cells. With regard to ALL primary cells, siRNA-mediated STAT5A gene silencing was observed in four of eight patient cells using our leading polymeric delivery system, 1.2PEI-Lau8, accompanied by the significant reduction in colony formation in three of eight patients. In both BCR-ABL positive and negative groups, three of five patients demonstrated marked cell growth inhibition in both MTT and trypan blue exclusion assays using 1.2PEI-Lau8/siRNA complexes in comparison with their control siRNA groups. Three patient samples did not show any positive results with our delivery systems. Differential therapeutic responses to siRNA therapy observed in different patients could result from variable genetic profiles and patient-to-patient variability in delivery. This study supports the potential of siRNA therapy and the designed lipopolymers as a delivery system in ALL therapy.

Circular RNA circRNA_0000094 sponges microRNA-223-3p and up-regulate F-box and WD repeat domain containing 7 to restrain T cell acute lymphoblastic leukemia progression.

Circular RNAs (circRNAs) exert crucial regulatory effects in the pathogenesis of multiple tumors. This work aimed to probe into the role of circ_0000094 in T cell acute lymphoblastic leukemia (T-ALL). In this work, quantitative real-time polymerase chain reaction (qRT-PCR) was applied to quantify circ_0000094, miR-223-3p, and F-box and WD repeat domain containing 7 (FBW7) mRNA expressions in lymph node samples from T-ALL patients; Western blot was adopted to examine FBW7 protein expression in T-ALL cells; cell proliferation was detected by cell counting kit-8 (CCK-8) experiment; apoptosis was examined by flow cytometry; Transwell experiments were applied to assess T-ALL cell migration and invasion; the interactions among circ_0000094 and miR-223-3p, and miR-223-3p and FBW7 were validated by bioinformatics prediction, dual-luciferase reporter gene assay, and RNA immunoprecipitation experiment. We reported that, circ_0000094 expression was markedly reduced in T-ALL and circ_0000094 was predominantly located in the cytoplasm; gain-of-function and loss-of-function assays verified that circ_0000094 overexpression remarkably suppressed T-ALL cell proliferation, migration, and invasion, and enhanced apoptosis while knocking down circ_0000094 enhanced the malignant phenotypes of T-ALL cells; "rescue experiments" implied that miR-223-3p mimics partly reversed the inhibitory effects on the malignant phenotype of T-ALL cells due to the circ_0000094 up-regulation; circ_0000094 was proved to be a molecular sponge for miR-223-3p, and it could up-regulate the expression of FBW7 via repressing miR-223-3p expression. Taken together, it was concluded that circ_0000094 impedes T-ALL progression by modulating the miR-223-3p/FBW7 axis.

MicroRNA-591 inhibits malignant progression of acute lymphoblastic leukemia of childhood by down-regulating ZEB1.

MicroRNA-591 inhibits malignant progression of acute lymphoblastic leukemia of childhood by down-regulating ZEB1.

Abstract B21: The gastrointestinal microbiota controls cancer cell intrinsic mechanisms to promote the progression of acute lymphoblastic leukemia

Abstract Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer and the second most common acute leukemia in adults. Despite best existing therapy, older children and elderly ALL patients have poor prognoses. Thus, there is a need to identify alternative therapeutics for these patients. There has been controversy about the function of the gut microbiota in cancer, with some reports showing that it supports tumor growth and others showing tumor growth inhibition. Recently, Dr. Melvyn Greaves proposed that ALL development may have a microbial trigger; however, gut microbiota studies in ALL are scarce. Little is known about the role of the gut microbiota in ALL progression and in reshaping cancer cell-intrinsic pathways that are as important as immune responses in the outcome of ALL. Recently, we found that gut microbiota depletion in immunocompromised mice reduces ALL growth by inducing apoptosis and inhibiting proliferation. We show that in immunocompromised microbiome-depleted mice, the rate of ALL tumor growth is reduced compared to microbiome-competent mice. Molecularly, we found that microbiome ablation results in changes in cancer cell-intrinsic pathways of apoptosis and proliferation in these tumors. To further understand how the gut microbiota affects these cancer cell-intrinsic pathways, we have performed RNA sequencing on tumors from microbiome-competent and microbiome-depleted mice accompanied by 16s rRNA sequencing from stool samples and mass spectrometry of blood serum to identify metabolites secreted by the gut microbiota that reach the tumor site, affecting cancer cell growth. Our goal is to define bacterial species and metabolites involved in ALL progression and to mechanistically determine how these bacterial species and metabolites regulate ALL growth via regulation of cancer cell-intrinsic pathways. These data suggest that the gut microbiota may regulate ALL progression in an immune-independent manner via transcriptional changes of cancer cell-autonomous pathways. We envision that the gut microbiota can be reshaped in ALL patients who are elderly, chemo-refractive, and/or immunocompromised to alter cancer cell-intrinsic pathways to treat ALL. The clinical impact of these findings is significant given that ALL patients who are immunocompromised could still benefit from therapeutics aiming at modulating the gut microbiota. Citation Format: Wadie Mahauad-Fernandez, Soumaya Zlitni, Ami Bhatt, Dean Felsher. The gastrointestinal microbiota controls cancer cell intrinsic mechanisms to promote the progression of acute lymphoblastic leukemia [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr B21.

Transcriptional Regulation of Genes by Ikaros Tumor Suppressor in Acute Lymphoblastic Leukemia.

Regulation of oncogenic gene expression by transcription factors that function as tumor suppressors is one of the major mechanisms that regulate leukemogenesis. Understanding this complex process is essential for explaining the pathogenesis of leukemia as well as developing targeted therapies. Here, we provide an overview of the role of Ikaros tumor suppressor and its role in regulation of gene transcription in acute leukemia. Ikaros (IKZF1) is a DNA-binding protein that functions as a master regulator of hematopoiesis and the immune system, as well as a tumor suppressor in acute lymphoblastic leukemia (ALL). Genetic alteration or functional inactivation of Ikaros results in the development of high-risk leukemia. Ikaros binds to the specific consensus binding motif at upstream regulatory elements of its target genes, recruits chromatin-remodeling complexes and activates or represses transcription via chromatin remodeling. Over the last twenty years, a large number of Ikaros target genes have been identified, and the role of Ikaros in the regulation of their expression provided insight into the mechanisms of Ikaros tumor suppressor function in leukemia. Here we summarize the role of Ikaros in the regulation of the expression of the genes whose function is critical for cellular proliferation, development, and progression of acute lymphoblastic leukemia.

Heme Oxygenase-1 in Leukemia Cells Promotes Cancer Associated Fibroblasts Mediating Progression of Acute Lymphoblastic Leukemia

Backgroud and objective: Recurrence and resistance is still the biggest challenges for Acute lymphoblastic leukemia (ALL). In recent years, a new concept has been proposed that the interaction between bone marrow microenvironment and leukemia cells could reduce the sensitivity of leukemia cells to chemotherapy. As an important matric element of the bone marrow microenvironment, Cancerassociated fibroblasts (CAFs) can mediate changes in bone marrow microenvironment to promote tumor proliferation and infiltration, but its role in ALL has not been described. Heme Oxygenase-1 (HO-1) is a rate-limiting enzyme in the process of heme catabolism, which is highly expressed in leukemia cells and can promote chemo-resistance by regulating the preservation of hematopoietic stem progenitor cells in the bone marrow microenvironment according to the recent research. In this article, we explored that HO-1 may be a key factor for promoting cancer associated fibroblasts to mediated chemo-resistance of ALL in the bone marrow microenvironment. M ethods : For clinical sample analysis, Bone marrow nucleated cells of 16 ALL patients with complete remission (ALL-CR), 12 ALL with relapse/refractory (ALL-R/R) and 10 normal controls were btained from bone marrow puncture. The expression of HO-1 and CAFs markers which includes α-SMA, FAP and FSP-1 was examined by quantitative reverse transcription-PCR (RT-PCR) and Western blot. In vitro cell experiments, CAFs was obtained from transfusion of bone marrow-derived mesenchymal stem cells (BM-MSCs) with recombinant human TGF-β1 (rhTGF-β1) stimulating. We used ALL primary cells and ALL cell lines (Nalm-6/Super-B15) to culture alone or co-culture with CAFs to detect proliferation, apoptosis and cell cycle of leukemia cells. In addition, we transfected ALL cell lines by constructing siHO-1 lentiviral vector, and co-cultured with CAFs or cultured separately to detect the above index changes in leukemia cells. R esults : The expressions of α-SMA, FAP, FSP-1 and HO-1 were significantly higher in ALL-R/R patients than in ALL-CR group and normal control group (P&lt;0.05), which suggested that CAFs and HO-1 are closely related to recurrence and resistance of ALL. In vitro tests, after rhTGF-β1 stimulated BM-MSCs for 48h, the mRNA and protein expression levels of α-SMA, FAP and FSP-1 were significantly higher than those in BM-MSCs alone (P&lt;0.05), This step was used to obtain CAFs. Then proceed to CAFs and Nalm-6/Super-B15 cell lines or ALL primary cells co-cultured tests. Results showed that CAFs can enhanced the leukemia cells proliferation and decreased apoptosis, and leukemia cells arrested in the G0/G1 phase was increased. Interestingly, this effect could be decreased by silencing HO-1 expression in Nalm-6/Super-B15 cell lines, which suggested that HO-1 may be a key factor mediating the interaction between leukemia cells and CAFs in bone marrow microenvironment. Conclusion:As an important component of the bone marrow microenvironment, CAFs are closely related to the recurrence and resistance of ALL. HO-1 may be a key component mediating the interaction between CAFs and leukemia cells of ALL. This results may provide a new entry point for deepening the mechanism of ALL progression and finding more effective targeted therapies. But further in vitro and in vivo experiments are still needed for verification. Disclosures No relevant conflicts of interest to declare.