Intake of oligoelements with cytarabine or etoposide alters dopamine levels and oxidative damage in rat brain.

Research on the relationships between oligoelements (OE) and the development of cancer or its prevention is a field that is gaining increasing relevance. The aim was to evaluate OE and their interactions with oncology treatments (cytarabine or etoposide) to determine the effects of this combination on biogenic amines and oxidative stress biomarkers in the brain regions of young Wistar rats. Dopamine (DA), 5-Hydroxyindoleacetic acid (5-Hiaa), Glutathione (Gsh), Tiobarbituric acid reactive substances (TBARS) and Ca+2, Mg+2 ATPase enzyme activity were measured in brain regions tissues using spectrophometric and fluorometric methods previously validated. The combination of oligoelements and cytarabine increased dopamine in the striatum but decreased it in cerebellum/medulla-oblongata, whereas the combination of oligoelements and etoposide reduced lipid peroxidation. These results suggest that supplementation with oligoelements modifies the effects of cytarabine and etoposide by redox pathways, and may become promising therapeutic targets in patients with cancer.

Metformin as an Enhancer for the Treatment of Chemoresistant CD34+ Acute Myeloid Leukemia Cells.

Acute myeloid leukemia is the second most frequent type of leukemia in adults. Due to a high risk of development of chemoresistance to first-line chemotherapy, the survival rate of patients in a 5-year period is below 30%. One of the reasons is that the AML population is heterogeneous, with cell populations partly composed of very primitive CD34+CD38- hematopoietic stem/progenitor cells, which are often resistant to chemotherapy. First-line treatment with cytarabine and idarubicin fails to inhibit the proliferation of CD34+CD38- cells. In this study, we investigated Metformin's effect with or without first-line conventional chemotherapy, or with other drugs like venetoclax and S63845, on primitive and undifferentiated CD34+ AML cells in order to explore the potential of Metformin or S63845 to serve as adjuvant therapy for AML. We found that first-line conventional chemotherapy treatment inhibited the growth of cells and arrested the cells in the S phase of the cell cycle; however, metformin affected the accumulation of cells in the G2/M phase. We observed that CD34+ KG1a cells respond better to lower doses of cytarabine or idarubicin in combination with metformin. Also, we determined that treatment with cytarabine, venetoclax, and S63845 downregulated the strong tendency of CD34+ KG1a cells to form cell aggregates in culture due to the downregulation of leukemic stem cell markers like CD34 and CD44, as well as adhesion markers. Also, we found that idarubicin slightly upregulated myeloid differentiation markers, CD11b and CD14. Treatment with cytarabine, idarubicin, venetoclax, metformin, and S63845 upregulated some cell surface markers like HLA-DR expression, and metformin upregulated CD9, CD31, and CD105 cell surface marker expression. In conclusion, we believe that metformin has the potential to be used as an adjuvant in the treatment of resistant-to-first-line-chemotherapy AML cells. Also, we believe that the results of our study will stimulate further research and the potential use of changes in the expression of cell surface markers in the development of new therapeutic strategies.

SOX11 is a novel binding partner and endogenous inhibitor of SAMHD1 ara-CTPase activity in mantle cell lymphoma.

The sterile alpha motif and histidine-aspartate (HD) domain containing protein 1 (SAMHD1) is a deoxynucleoside triphosphate triphosphohydrolase with ara-CTPase activity that confers cytarabine (ara-C) resistance in several haematological malignancies. Targeting SAMHD1's ara-CTPase activity has recently been demonstrated to enhance ara-C efficacy in acute myeloid leukemia. Here, we identify the transcription factor SRY-related HMG-box containing protein 11 (SOX11) as a novel direct binding partner and first known endogenous inhibitor of SAMHD1. SOX11 is aberrantly expressed not only in mantle cell lymphoma (MCL), but also in some Burkitt lymphomas. Co-immunoprecipitation of SOX11 followed by mass spectrometry in MCL cell lines identified SAMHD1 as the top SOX11 interaction partner which was validated by proximity ligation assay. In vitro, SAMHD1 bound to the HMG box of SOX11 with low-micromolar affinity. In situ crosslinking studies further indicated that SOX11-SAMHD1 binding resulted in a reduced tetramerization of SAMHD1. Functionally, expression of SOX11 inhibited SAMHD1 ara-CTPase activity in a dose-dependent manner resulting in ara-C sensitization in cell lines and in a SOX11-inducible mouse model of MCL. In SOX11-negative MCL, SOX11-mediated ara-CTPase inhibition could be mimicked by adding the recently identified SAMHD1 inhibitor hydroxyurea. Taken together, our results identify SOX11 as a novel SAMHD1 interaction partner and its first known endogenous inhibitor with potentially important implications for clinical therapy stratification.

Targeting Metabolic Dependencies Fueling the TCA Cycle to Circumvent Therapy Resistance in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is one of the most prevalent blood cancers, characterized by a dismal survival rate. This poor outcome is largely attributed to AML cells that persist despite treatment and eventually result in relapse. Relapse-initiating cells exhibit diverse resistance mechanisms, encompassing genetic factors and, more recently discovered, nongenetic factors such as metabolic adaptations. Leukemic stem cells (LSC) rely on mitochondrial metabolism for their survival, whereas hematopoietic stem cells primarily depend on glycolysis. Furthermore, following treatments such as cytarabine, a standard in AML treatment for over four decades, drug-persisting leukemic cells exhibit an enhanced reliance on mitochondrial metabolism. In this issue of Cancer Research, two studies investigated dependencies of AML cells on two respiratory substrates, α-ketoglutarate and lactate-derived pyruvate, that support mitochondrial oxidative phosphorylation (OXPHOS) following treatment with the imipridone ONC-213 and the BET inhibitor INCB054329, respectively. Targeting lactate utilization by interfering with monocarboxylate transporter 1 (MCT1 or SLC16A1) or lactate dehydrogenase effectively sensitized cells to BET inhibition in vitro and in vivo. In addition, ONC-213 affected αKGDH, a pivotal NADH-producing enzyme of the TCA cycle, to induce a mitochondrial stress response through ATF4 activation that diminished the expression of the antiapoptotic protein MCL1, consequently promoting apoptosis of AML cells. In summary, targeting these mitochondrial dependencies might be a promising strategy to kill therapy-naïve and treatment-resistant OXPHOS-reliant LSCs and to delay or prevent relapse. See related articles by Monteith et al., p. 1101 and Su et al., p. 1084.

A Novel Approach for Glioblastoma Treatment by Combining Apoptosis Inducers (TMZ, MTX, and Cytarabine) with E.V.A. (Eltanexor, Venetoclax, and A1210477) Inhibiting XPO1, Bcl-2, and Mcl-1.

Adjuvant treatment for Glioblastoma Grade 4 with Temozolomide (TMZ) inevitably fails due to therapeutic resistance, necessitating new approaches. Apoptosis induction in GB cells is inefficient, due to an excess of anti-apoptotic XPO1/Bcl-2-family proteins. We assessed TMZ, Methotrexate (MTX), and Cytarabine (Ara-C) (apoptosis inducers) combined with XPO1/Bcl-2/Mcl-1-inhibitors (apoptosis rescue) in GB cell lines and primary GB stem-like cells (GSCs). Using CellTiter-Glo® and Caspase-3 activity assays, we generated dose-response curves and analyzed the gene and protein regulation of anti-apoptotic proteins via PCR and Western blots. Optimal drug combinations were examined for their impact on the cell cycle and apoptosis induction via FACS analysis, paralleled by the assessment of potential toxicity in healthy mouse brain slices. Ara-C and MTX proved to be 150- to 10,000-fold more potent in inducing apoptosis than TMZ. In response to inhibitors Eltanexor (XPO1; E), Venetoclax (Bcl-2; V), and A1210477 (Mcl-1; A), genes encoding for the corresponding proteins were upregulated in a compensatory manner. TMZ, MTX, and Ara-C combined with E, V, and A evidenced highly lethal effects when combined. As no significant cell death induction in mouse brain slices was observed, we conclude that this drug combination is effective in vitro and expected to have low side effects in vivo.

Homoharringtonine enhances cytarabine-induced apoptosis in acute myeloid leukaemia by regulating the p38 MAPK/H2AX/Mcl-1 axis.

Acute myeloid leukaemia (AML) is a fatal haematopoietic malignancy and is treated with the conventional combination of cytarabine (Ara-C) and daunorubicin (Dau). The survival rate of AML patients is lower due to the cardiotoxicity of daunorubicin. Clinically, homoharringtonine (HHT) plus Ara-C has been reported to be equally effective as Dau plus Ara-C in some types of AML patients with less toxic effects. We utilized the clinical use of homoharringtonine in combination with Ara-C to test its combination mechanism. We found that the insensitivity of AML cells to cytarabine-induced apoptosis is associated with increased Mcl-1 stability and p38 inactivation. HHT downregulates Mcl-1, phosphorylates H2AX and induces apoptosis by activating p38 MAPK. Inactivation of p38 through inhibitors and siRNA blocks apoptosis, H2AX phosphorylation and Mcl-1 reduction. HHT enhances Ara-C activation of the p38 MAPK signalling pathway, overcoming Ara-C tolerance to cell apoptosis by regulating the p38/H2AX/Mcl-1 axis. The optimal ratio of HHT to Ara-C for synergistic lethality in AML cells is 1:4 (M/M). HHT synergistically induces apoptosis in combination with Ara-C in vitro and prolongs the survival of xenografts. We provide a new mechanism for AML treatment by regulating the p38 MAPK/H2AX/Mcl-1 axis to improve cytarabine therapy.

Mathematical modelling of clonal reduction therapeutic strategies in acute myeloid leukemia.

Over the years, the overall survival of older patients diagnosed with acute myeloid leukemia (AML) has not significantly increased. Although standard cytotoxic therapies that rapidly eliminate dividing myeloblasts are used to induce remission, relapse can occur due to surviving therapy-resistant leukemic stem cells (LSCs). Hence, anti-LSC strategies have become a key target to cure AML. We have recently shown that previously approved cardiac glycosides and glucocorticoids target LSC-enriched CD34+ cells in the primary human AML 8227 model with more efficacy than normal hematopoietic stem cells (HSCs). To translate these in vitro findings into humans, we developed a mathematical model of stem cell dynamics that describes the stochastic evolution of LSCs in AML post-standard-of-care. To this, we integrated population pharmacokinetic-pharmacodynamic (PKPD) models to investigate the clonal reduction potential of several promising candidate drugs in comparison to cytarabine, which is commonly used in high doses for consolidation therapy in AML patients. Our results suggest that cardiac glycosides (proscillaridin A, digoxin and ouabain) and glucocorticoids (budesonide and mometasone) reduce the expansion of LSCs through a decrease in their viability. While our model predicts that effective doses of cardiac glycosides are potentially too toxic to use in patients, simulations show the possibility of mometasone to prevent relapse through the glucocorticoid's ability to drastically reduce LSC population size. This work therefore highlights the prospect of these treatments for anti-LSC strategies and underlines the use of quantitative approaches to preclinical drug translation in AML.

Rapamycin increases leukemia cell sensitivity to chemotherapy by regulating mTORC1 pathway-mediated apoptosis and autophagy.

This study investigated the effect of rapamycin alone and in combination with chemotherapy (doxorubicin and cytarabine) on AML. Human acute monocytic leukemia cell line SHI-1 and NPG AML model mice created by intravenous injection of SHI-1 cell were treated with rapamycin, chemotherapy, or rapamycin plus chemotherapy. Analysis by cell counting kit-8, western blot, flow cytometry, and immunohistochemistry was performed, and results suggested that both rapamycin and chemotherapy inhibited proliferation of SHI-1 cells both in vitro and in vivo, suppressed neoplasm growth in vivo, and promoted survival of NPG AML mice. The antitumor effect of rapamycin plus chemotherapy was better than that of rapamycin alone and chemotherapy alone. In addition, western blot results demonstrated that rapamycin inhibited the phosphorylation of mTOR downstream targets 4EBP1 and S6K1 in SHI-1 cells, and increased the pro-apoptosis-related protein Bax and autophagy-associated proteins Beclin-1, LC3B-II, and ATG5 while reducing the anti-apoptosis-related protein Bcl-2. In conclusion, the results of this study indicate that rapamycin acts synergistically with doxorubicin and cytarabine in AML treatment, and its underlying mechanism might be associated with mTORC1 pathway-mediated apoptosis and autophagy.

Polyamine Inhibitor SAM486A Augments Cytarabine Cytotoxicity in Methylthioadenosine Phosphorylase-deficient Leukemia Cells.

BACKGROUND/AIM: Methionine metabolism contributes to supplying sulfur-containing amino acids, controlling the methyl group transfer reaction, and producing polyamines in cancer cells. Polyamines play important roles in various cellular functions. Methylthioadenosine phosphorylase (MTAP), the key enzyme of the methionine salvage pathway, is reported to be deficient in 15-62% of cases of hematological malignancies. MTAP-deficient cancer cells accumulate polyamines, resulting in enhanced cell proliferation. The aim of this study was to investigate the combined effects of the polyamine synthesis inhibitor SAM486A and the anticancer antimetabolite cytarabine in MTAP-deficient leukemic cells in vitro. MATERIALS AND METHODS: The leukemia cell line U937 and the subline, U937/MTAP(-), in which MTAP was knocked down by shRNA, were used. The experiments were performed in media supplemented with 20% methionine (low methionine), which was the minimum concentration for maintaining cellular viability. RESULTS: The knockdown efficiency test confirmed a 70% suppression of the expression of the MTAP gene in U937/MTAP(-) cells. Even in the media with low methionine, the intracellular methionine concentration was not reduced in U937/MTAP(-) cells, suggesting that the minimum supply of methionine was sufficient to maintain intracellular levels of methionine. Both U937/MTAP(+) and U937/MTAP(-) cells were comparably sensitive to anticancer drugs (cytarabine, methotrexate, clofarabine and 6-thioguanine). The combination of SAM486A and cytarabine was demonstrated to have synergistic cytotoxicity in U937/MTAP(-) cells with regard to cell growth inhibition and apoptosis induction, but not in U937/MTAP(+) cells. Mechanistically, SAM486A altered the intracellular polyamine concentrations and reduced the antiapoptotic proteins. CONCLUSION: Methionine metabolism and polyamine synthesis can be attractive therapeutic targets in leukemia.

Identification of several African swine fever virus replication inhibitors by screening of a library of FDA-approved drugs.

African swine fever (ASF) caused by African swine fever virus (ASFV) is a highly infectious and lethal swine disease. Currently, there is only one novel approved vaccine and no antiviral drugs for ASFV. In the study, a high-throughput screening of an FDA-approved drug library was performed to identify several drugs against ASFV infection in primary porcine alveolar macrophages. Triapine and cytarabine hydrochloride were identified as ASFV infection inhibitors in a dose-dependent manner. The two drugs executed their antiviral activity during the replication stage of ASFV. Furthermore, molecular docking studies showed that triapine might interact with the active center Fe2+ in the small subunit of ASFV ribonucleotide reductase while cytarabine hydrochloride metabolite might interact with three residues (Arg589, Lys593, and Lys631) of ASFV DNA polymerase to block new DNA chain extension. Taken together, our results suggest that triapine and cytarabine hydrochloride displayed significant antiviral activity against ASFV in vitro.

AHR signaling pathway mediates mitochondrial oxidative phosphorylation which leads to cytarabine resistance.

The aryl hydrocarbon receptor (AHR) has been identified as a significant driver of tumorigenesis. However, its clinical significance in acute myeloid leukemia (AML) remains largely unclear. In this study, RNA-Seq data from AML patients (bone marrow samples from 173 newly diagnosed AML patients) obtained from the TCGA database, and normal human RNA-Seq data (bone marrow samples from 70 healthy individuals) obtained from the GTEX database are downloaded for external validation and complementarity. The data analysis reveals that the AHR signaling pathway is activated in AML patients. Furthermore, there is a correlation between the expressions of AHR and mitochondrial oxidative phosphorylation genes. In vitro experiments show that enhancing AHR expression in AML cells increases mitochondrial oxidative phosphorylation and induces resistance to cytarabine. Conversely, reducing AHR expression in AML cells decreases cytarabine resistance. These findings deepen our understanding of the AHR signaling pathway's involvement in AML.

ULK2 Is a Key Pro-Autophagy Protein That Contributes to the High Chemoresistance and Disease Relapse in FLT3-Mutated Acute Myeloid Leukemia.

We recently demonstrated that a small subset of cells in FLT3-mutated acute myeloid leukemia (AML) cell lines exhibit SORE6 reporter activity and cancer stem-like features including chemoresistance. To study why SORE6+ cells are more chemoresistant than SORE6- cells, we hypothesized that these cells carry higher autophagy, a mechanism linked to chemoresistance. We found that cytarabine (Ara-C) induced a substantially higher protein level of LC3B-II in SORE6+ compared to SORE6- cells. Similar observations were made using a fluorescence signal-based autophagy assay. Furthermore, chloroquine (an autophagy inhibitor) sensitized SORE6+ but not SORE6- cells to Ara-C. To decipher the molecular mechanisms underlying the high autophagic flux in SORE6+ cells, we employed an autophagy oligonucleotide array comparing gene expression between SORE6+ and SORE6- cells before and after Ara-C treatment. ULK2 was the most differentially expressed gene between the two cell subsets. To demonstrate the role of ULK2 in conferring higher chemoresistance in SORE6+ cells, we treated the two cell subsets with a ULK1/2 inhibitor, MRT68921. MRT68921 significantly sensitized SORE6+ but not SORE6- cells to Ara-C. Using our in vitro model for AML relapse, we found that regenerated AML cells contained higher ULK2 expression compared to pretreated cells. Importantly, inhibition of ULK2 using MRT68921 prevented in vitro AML relapse. Lastly, using pretreatment and relapsed AML patient bone marrow samples, we found that ULK2 expression was higher in relapsed AML. To conclude, our results supported the importance of autophagy in the relapse of FLT3-mutated AML and highlighted ULK2 in this context.

SOX11 is a novel binding partner and endogenous inhibitor of SAMHD1 ara-CTPase activity in mantle cell lymphoma.

ABSTRACT: Sterile alpha motif and histidine-aspartate (HD) domain-containing protein 1 (SAMHD1) is a deoxynucleoside triphosphate triphosphohydrolase with ara-CTPase activity that confers cytarabine (ara-C) resistance in several hematological malignancies. Targeting SAMHD1's ara-CTPase activity has recently been demonstrated to enhance ara-C efficacy in acute myeloid leukemia. Here, we identify the transcription factor SRY-related HMG-box containing protein 11 (SOX11) as a novel direct binding partner and first known endogenous inhibitor of SAMHD1. SOX11 is aberrantly expressed not only in mantle cell lymphoma (MCL), but also in some Burkitt lymphomas. Coimmunoprecipitation of SOX11 followed by mass spectrometry in MCL cell lines identified SAMHD1 as the top SOX11 interaction partner, which was validated by proximity ligation assay. In vitro, SAMHD1 bound to the HMG box of SOX11 with low-micromolar affinity. In situ crosslinking studies further indicated that SOX11-SAMHD1 binding resulted in a reduced tetramerization of SAMHD1. Functionally, expression of SOX11 inhibited SAMHD1 ara-CTPase activity in a dose-dependent manner resulting in ara-C sensitization in cell lines and in a SOX11-inducible mouse model of MCL. In SOX11-negative MCL, SOX11-mediated ara-CTPase inhibition could be mimicked by adding the recently identified SAMHD1 inhibitor hydroxyurea. Taken together, our results identify SOX11 as a novel SAMHD1 interaction partner and its first known endogenous inhibitor with potentially important implications for clinical therapy stratification.

Mitocurcumin utilizes oxidative stress to upregulate JNK/p38 signaling and overcomes Cytarabine resistance in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a type of blood cancer that is characterized by the rapid growth of abnormal myeloid cells. The goal of AML treatment is to eliminate the leukemic blasts, which is accomplished through intensive chemotherapy. Cytarabine is a key component of the standard induction chemotherapy regimen for AML. However, despite a high remission rate, 70-80% of AML patients relapse and develop resistance to Cytarabine, leading to poor clinical outcomes. Mitocurcumin (MitoC), a derivative of curcumin that enters mitochondria, leading to a drop in mitochondrial membrane potential and mitophagy induction. Further, it activates oxidative stress-mediated JNK/p38 signaling to induce apoptosis. MitoC demonstrated a preferential ability to kill leukemic cells from AML cell lines and patient-derived leukemic blasts. RNA sequencing data suggests perturbation of DNA damage response and cell proliferation pathways in MitoC-treated AML. Elevated reactive oxygen species (ROS) in MitoC-treated AML cells resulted in significant DNA damage and cell cycle arrest. Further, MitoC treatment resulted in ROS-mediated enhanced levels of p21, which leads to suppression of CHK1, RAD51, Cyclin-D and c-Myc oncoproteins, potentially contributing to Cytarabine resistance. Combinatorial treatment of MitoC and Cytarabine has shown synergism, increased apoptosis, and enhanced DNA damage. Using AML xenografts, a significant reduction of hCD45+ cells was observed in AML mice bone marrow treated with MitoC (mean 0.6%; range0.04%-3.56%) compared to control (mean 38.2%; range10.1%-78%), p = 0.03. The data suggest that MitoC exploits stress-induced leukemic oxidative environment to up-regulate JNK/p38 signaling to lead to apoptosis and can potentially overcome Cytarabine resistance via ROS/p21/CHK1 axis.

Exosome-shuttled FTO from BM-MSCs contributes to cancer malignancy and chemoresistance in acute myeloid leukemia by inducing m6A-demethylation: A nano-based investigation.

Although bone marrow mesenchymal stem cells (BM-MSCs)-derived exosomes have been reported to be closely associated with acute myeloid leukemia (AML) progression and chemo-resistance, but its detailed functions and molecular mechanisms have not been fully delineated. Besides, serum RNA m6A demethylase fat mass and obesity-associated protein (FTO)-containing exosomes are deemed as important indicators for cancer progression, and this study aimed to investigate the role of BM-MSCs-derived FTO-exosomes in regulating the malignant phenotypes of AML cells. Here, we verified that BM-MSCs-derived exosomes delivered FTO to promote cancer aggressiveness, stem cell properties and Cytosine arabinoside (Ara-C)-chemoresistance in AML cells, and the underlying mechanisms were also uncovered. Our data suggested that BM-MSCs-derived FTO-exo demethylated m6A modifications in the m6A-modified LncRNA GLCC1 to facilitate its combination with the RNA-binding protein Hu antigen R (HuR), which further increased the stability and expression levels of LncRNA GLCC1. In addition, LncRNA GLCC1 was verified as an oncogene to facilitate cell proliferation and enhanced Ara-C-chemoresistance in AML cells. Further experiments confirmed that demethylated LncRNA GLCC1 served as scaffold to facilitate the formation of the IGF2 mRNA binding protein 1 (IGF2BP1)-c-Myc complex, which led to the activation of the downstream tumor-promoting c-Myc-associated signal pathways. Moreover, our rescuing experiments validated that the promoting effects of BM-MSCs-derived FTO-exo on cancer aggressiveness and drug resistance in AML cells were abrogated by silencing LncRNA GLCC1 and c-Myc. Thus, the present firstly investigated the functions and underlying mechanisms by which BM-MSCs-derived FTO-exo enhanced cancer aggressiveness and chemo-resistance in AML by modulating the LncRNA GLCC1-IGF2BP1-c-Myc signal pathway, and our work provided novel biomarkers for the diagnosis, treatment and therapy of AML in clinic.

n-Tuples on Scaffold Diversity Inspired by Drug Hybridisation to Enhance Drugability: Application to Cytarabine.

A mathematical concept, n-tuples are originally applied to medicinal chemistry, especially with the creation of scaffold diversity inspired by the hybridisation of different commercial drugs with cytarabine, a synthetic arabinonucleoside derived from two marine natural products, spongouridine and spongothymidine. The new methodology explores the virtual chemical-factorial combination of different commercial drugs (immunosuppressant, antibiotic, antiemetic, anti-inflammatory, and anticancer) with the anticancer drug cytarabine. Real chemical combinations were designed and synthesised for 8-duples, obtaining a small representative library of interesting organic molecules to be biologically tested as proof of concept. The synthesised library contains classical molecular properties regarding the Lipinski rules and/or beyond rules of five (bRo5) and is represented by the covalent combination of the anticancer drug cytarabine with ibuprofen, flurbiprofen, folic acid, sulfasalazine, ciprofloxacin, bortezomib, and methotrexate. The insertion of specific nomenclature could be implemented into artificial intelligence algorithms in order to enhance the efficiency of drug-hunting programs. The novel methodology has proven useful for the straightforward synthesis of most of the theoretically proposed duples and, in principle, could be extended to any other central drug.

8-Hydroxydaidzein Induces Apoptosis and Inhibits AML-Associated Gene Expression in U-937 Cells: Potential Phytochemical for AML Treatment.

BACKGROUND: 8-hydroxydaidzein (8-OHD) is a compound derived from daidzein, known for its anti-inflammatory and anti-proliferative properties in K562 human chronic myeloid leukemia (CML) cells. However, its effects on acute myeloid leukemia (AML) cells have not been fully understood. METHOD: To investigate its potential anti-AML mechanism, we employed an integrated in vitro-in silico approach. RESULTS: Our findings demonstrate that 8-OHD suppresses the expression of CDK6 and CCND2 proteins and induces cell apoptosis in U-937 cells by activating Caspase-7 and cleaving PARP-1. Microarray analysis revealed that 8-OHD downregulates differentially expressed genes (DEGs) associated with rRNA processing and ribosome biogenesis pathways. Moreover, AML-target genes, including CCND2, MYC, NPM1, FLT3, and TERT, were downregulated by 8-OHD. Additionally, molecular docking software predicted that 8-OHD has the potential to interact with CDK6, FLT3, and TERT proteins, thereby reducing their activity and inhibiting cell proliferation. Notably, we discovered a synergic pharmacological interaction between 8-OHD and cytarabine (Ara-C). CONCLUSIONS: Overall, this study provides insights into the therapeutic applications of 8-OHD in treating AML and elucidates its underlying mechanisms of action.

Artesunate reverses cytarabine resistance in acute myeloid leukemia by blocking the JAK/STAT3 signaling.

OBJECTIVES: Although cytarabine (AraC) has greatly contributed to improving the prognosis of patients with acute myeloid leukemia (AML), many patients developed drug resistance and eventually succumbed to AML. Thus, resistance to AraC is a major obstacle to improve the efficacy of chemotherapy in AML. Hence, this study aimed to demonstrate that artesunate (ART) can reliably induce cell death in vitro and block AraC resistance. METHODS: AML cell lines resistant to AraC were first constructed by repeated dosing for 5 months. Further, we analyzed whether ART intervention affected the sensitivity of AraC-resistant cells to AraC by cell function experiments, mainly including CCK-8 to assess cell viability, flow cytometry to examine apoptosis, and Western blotting to measure the Janus kinase (JAK)/signal transducers and activators of transcription 3 (STAT3) pathway protein expression. Furthermore, whether JAK/STAT3 pathway knockdown has a blocking effect on the efficacy of ART was also assessed. RESULTS: Co-treatment of ART and AraC increased the sensitivity of AML cells to AraC. Also, it effectively reversed the resistance of AML cells to AraC that is shown by the significantly reduced proliferation and increased apoptosis rates. ART intervention suppressed the activation of the JAK/STAT3 signaling pathway in AraC-resistant AML cells, suggesting that the function of ART in reversing AraC resistance is indeed dependent on the JAK/STAT3 signaling pathway. CONCLUSIONS: In summary, ART enhanced the sensitivity of AML/AraC-resistant cells to AraC by modulating the JAK/STAT3 pathway.

DUSP1 Signaling Pathway Regulates Cytarabine Sensitivity in Acute Myeloid Leukemia.

Objectives: Dual specificity phosphatase 1 (DUSP1) is high-expressed in various cancers and plays an important role in the cellular response to agents that damage DNA. We aimed to investigate the expressions and mechanisms of DUSP1 signaling pathway regulating cytarabine (Ara-C) resistance in acute myeloid leukemia (AML). Methods: Immunohistochemistry was performed on bone marrow biopsy specimens from AML and controls to explore the expression of DUSP1. Western blot and Q-PCR were used to detect the protein and mRNA expression levels. MTT assay was used to detect the proliferation of cells. Cell apoptosis was detected by flow cytometry. The immune protein-protein interaction (PPI) network of DUSP1 was analyzed in the platform of Pathway Commons, and immune infiltration analysis was used to study the immune microenvironment of AML. Results: We found that the expression levels of DUSP1 in AML patients exceeded that in controls. Survival analysis in public datasets showed that AML patients with higher levels of DUSP1 had poor clinical outcomes. Further public data analysis indicated that DUSP1 was overexpressed in NRAS mutated AML. DUSP1 knockdown by siRNA could sensitize AML cells to Ara-C treatments. The phosphorylation level of mitogen-activated protein kinase (MAPK) pathway was significantly elevated in DUSP1 down-regulated NRAS G13D mutated AML cells. The PPI analysis showed DUSP1 correlated with immune gene CREB1 and CXCL8 in NRAS mutated AML. We also revealed a correlation between tumor-infiltrating immune cells in RAS mutated AML microenvironment. Conclusion: Our findings suggest that DUSP1 signaling pathways may regulate Ara-C sensitivity in AML.

A novel anticancer quinolone, (R)-WAC-224, has anti-leukemia activities against acute myeloid leukemia.

Approximately 60%-80% of patients who achieve complete remission eventually relapse after conventional chemotherapy and have poor prognoses despite the recent advances of novel anticancer agents. Continuing development of more effective novel treatments for acute myeloid leukemia (AML) is necessary. We developed (R)-WAC-224 (R-WAC), which is an anticancer quinolone, targeting topoisomerase II. This study evaluated the anti-leukemia potential of R-WAC or racemic WAC-224 (WAC) in vitro and in vivo. R-WAC significantly inhibited the human AML cell line proliferation (MV4-11, HL60, and KG1a), which was comparable to daunorubicin and cytarabine, not affected by P-glycoprotein overexpression. WAC did neither increase serum troponin-T nor decrease the crypt numbers in the small intestine, indicating WAC was less toxic than doxorubicin. R-WAC monotherapy demonstrated prolonged survival in the AML mice model and inhibited tumor growth in the MV4-11 xenograft mice model. Moreover, the combination of R-WAC and cytarabine demonstrated more active anti-leukemia effects than daunorubicin and cytarabine. Finally, R-WAC inhibited the colony-forming abilities using primary AML cells. These results indicate that R-WAC is a promising therapeutic agent for AML.