Apoptosis In Leukemia Cells Research Articles

Dexamethasone enhances venetoclax-induced apoptosis in acute myeloid leukemia cells.

Acute myeloid leukemia (AML) therapies have been significantly improved by the development of medicines that can target BCL-2. On the other hand, non-recurrent alterations in oncogenic pathways and gene expression patterns have already been linked to therapeutic resistance to venetoclax therapy. Bone marrow mesenchymal stromal cells (BM-MSCs) support leukemic cells in preventing chemotherapy-induced apoptosis by mitochondrial transfer in leukemic microenvironment. In this study, we investigated the enhancement of the antitumor effect of BCL-2 inhibitor venetoclax by dexamethasone. In particular, dexamethasone had no significant effect on the viability of AML cells, but dexamethasone combined with venetoclax could significantly increase the apoptosis of AML cells induced by venetoclax. When AML cells were co-cultured with BM-MSCs, dexamethasone combined with venetoclax showed additional anti-tumor effect compared to venetoclax alone. Venetoclax increased reactive oxygen species level in co-cultured AML cells, contributed to transfer more mitochondria from BM-MSCs to AML cells and protect AML cells from apoptosis. Dexamethasone combined with venetoclax induced more apoptosis, but dexamethasone reduced the venetoclax-induced reactive oxygen species level in AML cells and reduced the transfer of mitochondria from BM-MSCs to AML cells. This may lead to a diminished protective effect of BM-MSCs on AML cells. Together, our findings indicated that venetoclax in combination with dexamethasone could be a promising therapy in AML.

Pinostrobin, a fingerroot compound, regulates miR-181b-5p and induces acute leukemic cell apoptosis

Pinostrobin (PN) is the most abundant flavonoid found in fingerroot. Although the anti-leukemic properties of PN have been reported, its mechanisms are still unclear. MicroRNAs (miRNAs) are small RNA molecules that function in posttranscriptional silencing and are increasingly being used in cancer therapy. The aims of this study were to investigate the effects of PN on proliferation inhibition and induction of apoptosis, as well as the involvement of miRNAs in PN-mediated apoptosis in acute leukemia. The results showed that PN reduced cell viability and induced apoptosis in acute leukemia cells via both intrinsic and extrinsic pathways. A bioinformatics approach and Protein–Protein Interaction (PPI) network analysis revealed that ataxia-telangiectasia mutated kinase (ATM), one of the p53 activators that responds to DNA damage-induced apoptosis, is a crucial target of PN. Four prediction tools were used to predict ATM-regulated miRNAs; miR-181b-5p was the most likely candidate. The reduction in miR-181b-5 after PN treatment was found to trigger ATM, resulting in cellular apoptosis. Therefore, PN could be developed as a drug for acute leukemia; in addition, miR-181b-5p and ATM may be promising therapeutic targets.

Cytosolic JNK-dependent microtubule reassembly protects Jurkat leukemia cells from selenite-induced apoptosis

BackgroundSelenite at high dosage exhibits great potential in curing tumors. It has been shown that selenite inhibits tumor growth through regulation of microtubule dynamics, however, the exact underlying mechanisms remained to be fully elucidated. Methods & resultsWestern blots were carried out to evaluate expression level of different molecules. Our current study discovered that selenite induced microtubule disassembly, cell cycle arrest and finally resulted in apoptosis in Jurkat leukemia cells, while during this process disassembled tubulins were re-organized after long-term exposure to selenite. Furthermore, JNK was activated in the cytoplasm of selenite-treated Jurkat cells, and inhibition of JNK activity successfully prevented the process of microtubule re-assembly. Moreover, inactivation of JNK further enhanced selenite-induced cell cycle arrest and apoptosis. According to the results from cell counting-8 assay, blockage of microtubule re-assembly by colchicine further inhibited Jurkat cell viability after exposure to selenite. Experiments in a xenograft model also proved that selenite could alter JNK activity, destroy microtubule structure and inhibit cell division in vivo. Moreover, TP53, MAPT and YWHAZ were identified to be three most confident interactors that link JNK to microtubule assembly using PPIs analysis. ConclusionOur study indicated that cytosolic JNK-dependent microtubule re-organization took a protective function during selenite-induced apoptosis, while inhibition of this process would finally enhance the anti-tumor effect of selenite.

1,5-AG suppresses pro-inflammatory polarization of macrophages and promotes the survival of B-ALL in vitro by upregulating CXCL14

B-lineage acute lymphoblastic leukemia (B-ALL) is one of the most common malignancies in children. Despite advances in treatment, the role of the tumor microenvironment in B-ALL remains poorly understood. Among the key components of the immune microenvironment, macrophages play a critical role in the progression of the disease. However, recent research has suggested that abnormal metabolites may influence the function of macrophages, altering the immune microenvironment and promoting tumor growth. Our previous non-targeted metabolomic detection revealed that the metabolite 1,5-anhydroglucitol (1,5-AG) level in the peripheral blood of children newly diagnosed with B-ALL was significantly elevated. Except for its direct influence on leukemia cells, the effect of 1,5-AG on macrophages is still unclear. Herein, we demonstrated new potential therapeutic targets by focusing on the effect of 1,5-AG on macrophages. We used polarization-induced macrophages to determine how 1,5-AG acted on M1-like polarization and screened out the target gene CXCL14 via transcriptome sequencing. Furthermore, we constructed CXCL14 knocked-down macrophages and a macrophage-leukemia cell coculture model to validate the interaction between macrophages and leukemia cells. We discovered that 1,5-AG upregulated the CXCL14 expression, thereby inhibiting M1-like polarization. CXCL14 knockdown restored the M1-like polarization of macrophages and induced leukemia cells apoptosis in the coculture model. Our findings offer new possibilities for the genetic engineering of human macrophages to rehabilitate their immune activity against B-ALL in cancer immunotherapy.

Pinostrobin induces acute leukemia cell apoptosis via the regulation of miR-410-5p and SFRP5

AimsThis study attempted to explore the mechanisms involved in pinostrobin (PN)-mediated acute leukemia cell apoptosis regulated by miR-410-5p. Material and methodsNB4 and MOLT-4 cells were cultured and treated with PN at the IC50 concentration. Apoptosis was examined by Annexin V-FITC/PI staining. RT–qPCR was used to measure the expression of caspase-3, BAK, BCL-W, and MCL-1. The target protein of PN was identified using LC–MS/MS followed by bioinformatic analysis. TargetScan, DIANA, and miRDB were used for the prediction of miRNAs involved in the PN-induced apoptosis mechanism. miRNA mimic transfection, RT–qPCR, and western blot analysis were performed to evaluate the regulatory effect of miRNA on its target and the involvement of miRNA in apoptosis induction by PN. In addition, the synergistic effect of PN and daunorubicin (DNR) were investigated by using the MTT assay. Key findingsThe results showed that PN reduced cell viability and induced apoptosis in both leukemia cell lines. From the LC–MS/MS and bioinformatics analysis, SFRP5 and miR-410-5p were selected as a potential PN target protein and miRNA, respectively. After miRNA mimic transfection, miR-410-5p, which is an onco-miRNA, was decreased and led to increased apoptosis in both cell lines, indicating that this miRNA is involved in PN-mediated apoptosis mechanisms. Moreover, PN demonstrated a synergistic effect with DNR, suggesting that PN may be used in combination with conventional chemotherapy drugs. SignificancePN regulates the expression of miR-410-5p and SFRP5 to promote apoptosis in acute leukemia cells. It could be developed as an alternative treatment for leukemia in the future.

MMP9-Associated Tumor Stem Cells, CCL1-Silenced Dendritic Cells, and Cytokine-Induced Killer Cells Have a Remarkable Therapeutic Efficacy for Acute Myeloid Leukemia by Activating T Cells.

Dendritic cells (DC) are specialized antigen-presenting cells, and cytokine-induced killer (CIK) cells have a specific killing activity to a variety of tumors. However, the underlining mechanism and function of DC-CIK cells in acute myeloid leukemia (AML) remain largely elusive. Gene expression profiles of leukemia patients were obtained from TCGA, DC cell components were evaluated using the quanTIseq method, and cancer stem cell scores were estimated using machine learning methods. The transcriptomes were obtained in DC-CIK cells from normal and AML patients by high-throughput sequencing. Large differentially expressed mRNAs were verified by RT-qPCR assay, and MMP9 and CCL1 were selected for subsequent studies in vivo and in vitro experiments. Significant positive correlations were found with DC versus cancer stem cells (p = 0.008) and the expression of MMP9 versus cancer stem cells (p = 0.018). MMP9 and CCL1 were found to be highly expressed in DC-CIK cells from AML patients. DC-CIK cells with MMP9 and CCL1 knockout alone had little effect on leukemia cells, while knockdown of MMP9 and CCL1 in DC-CIK cells increased cytotoxicity, suppressed proliferation, and induced apoptosis of leukemia cells. In addition, we proved that MMP9- and CCL1-silenced DC-CIK cells significantly elevated the CD3+CD4+ and CD3+CD8+ cells and lowered the CD4+PD-1+ and CD8+PD-1+ T cells. Meanwhile, blockage of MMP9 and CCL1 in DC-CIK cells dramatically increased IL-2 and IFN-γ, increased CD107aþ (LAMP-1) and granzyme B (GZMB), and downregulated PD-1, CTLA4, TIM3, and LAG3 T cells from AML patients and AML model mice. Furthermore, activated T cells in DC-CIK cells knocking down MMP9 and CCL1 also prevented proliferation and accelerated apoptosis of AML cells. Our findings demonstrated that blockage of MMP9 and CCL1 in DC-CIK cells could markedly enhance the therapeutic efficiency in AML via activating T cells.

Combined Application of Salinomycin and ATRA Induces Apoptosis and Differentiation of Acute Myeloid Leukemia Cells by Inhibiting WNT/β-Catenin Pathway.

All-trans retinoic acid (ATRA) is only effective in acute promyelocytic leukemia (APL), but not in other subtype of acute myeloid leukemia (AML). Salinomycin targets tumor cells rather than non-tumorigenic cells, and WNT/β-catenin pathway inhibition is one of the mechanisms of its anti-tumor activity. There is a crosstalk between RA and WNT/β-catenin pathway. Here, we investigate the effect of the combination of salinomycin and ATRA (S+RA) in non-APL AML cells. Apoptosis was evaluated by cell viability and Annexin-V assay. Cell differentiation was analyzed by CD11c expression and morphology. To explore the underlying mechanisms, Western blot analysis and mitochondrial transmembrane potentials (ΔΨm) were used. S+RA induced differentiation and apoptosis in AML cell lines and AML primary cells. S+RA inhibited the β-catenin signal pathway as determined by the decreased protein levels of β-catenin, the low-density lipoprotein receptor-related proteins 6 (LRP6), and its downstream proteins such as survivin, c-Myc, caspase-3/7, cdc25A and cyclinD1 and reduced phosphorylation level of GSK3β S9. S+RA also increased the protein levels of CCAAT/enhancer-binding proteins (C/EBPs) and PU.1 and collapsed Δψm. The above molecular and cellular changes induced by S+RA were inhibited by β-catenin specific activator and promoted by β-catenin specific inhibitor. S+RA induced differentiation by β-catenin-inhibition-mediated up-regulation of C/EBPs and PU.1 and suppression of c-Myc. S+RA triggered apoptosis through β-catenin-inhibition-regulated ΔΨm collapse and caspase-3/7 activation. Taken together, our findings may provide novel therapeutic strategies for AML patients by targeting the WNT/β-catenin pathway.

Duocarmycin SA reduces proliferation and induces apoptosis in Acute Myeloid Leukemia cells in vitro

Abstract Acute myeloid leukemia (AML) is a blood cancer that is characterized by the clonal expansion of immature myeloid blasts. Duocarmycin SA (DSA) is an antitumor antibiotic that induces DNA alkylation and has demonstrated cytotoxic activity against several cancers, but not AML. Preliminary data from our lab demonstrated that DSA induced cytotoxic effects on AML cells in vitro. The objective of this study was to investigate the mechanism by which DSA exerts its cytotoxic effects on AML cells in vitro. We hypothesized that DSA will induce cell cycle arrest and contribute to cellular apoptosis. The human AML cell line (Molm-14) was used for all studies and the phenotype of the cells was confirmed by flow cytometry. To test our hypothesis, we performed dose response (MTT), proliferation (CFU and EdU) and apoptosis (Hoffman Modulation and Annexin V/7-AAD) assays. Our results showed that the AML cells were CD45+, CD33+, CD13+, CD14+ and CD4+ and the IC 50of DSA was ~11 pM. DSA induced cell cycle arrest at the G2/M phase, significantly decreased the production of colonies and significantly reduced the proliferation of AML cells in a dose-dependent manner (63.5%, 37.6%, 14.3% and 2.9% of EdU+ cells following treatment with 0, 20, 100 and 500 pM of DSA respectively for 96 hours). Finally, DSA also increased apoptosis of AML cells in a dose-dependent manner (4.5%, 9.4%, 56.7%, and 92.0% at 0, 20, 100 and 500 pM DSA respectively following treatment with DSA for 72 hours). In summary, picomolar concentrations of DSA induces cell cycle arrest, reduces proliferation and colony formation, and induces apoptosis as a mechanism of cell death in AML cells. Thus, highlighting DSA as a potential therapeutic candidate for further evaluation on AML cells. This work was supported by funding from the School of Pharmacy at Loma Linda University.

Naringenin induces the cell apoptosis of acute myeloid leukemia cells by regulating the lncRNA XIST/miR-34a/HDAC1 signaling

Acute myeloid leukemia (AML) is a life-threatening aggressive malignancy of the bone marrow and has posed a great challenge to the clinic, due to a lack of fully understanding of the molecular mechanism. Histone deacetylase 1 (HDAC1) has been reported to be a therapeutic target for treating AML. Naringenin (Nar) may act as an anti-leukemic agent and suppress the expression of HDACs. However, the potential underlying mechanism of Nar in suppressing the activity of HDAC1 remains unclear. Here, we found that Nar induced the apoptosis, decreased the expression of lncRNA XIST and HDAC1, and increased the expression of microRNA-34a in HL60 cells. Sh-XIST transfection could induce cell apoptosis. On the contrary, the forced expression of XIST might reverse the biological actions of Nar. XIST could sponge miR-34a, which targeted to degrade HDAC1. The forced expression of HDAC1 could effectively reverse the effects of Nar. Thus, Nar can induce cell apoptosis by mediating the expression of lncRNA XIST/miR-34a/HDAC1 signaling in HL60 cells.

Abstract #1407741: Pegaspargase-Induced Severe Hyptriglyceridemia

Pegaspargase (PEG) a critical medication for acute lymphoblastic leukemia (ALL). As a long-acting formulation of L-asparaginase, it leads to degradation and depletion of the amino acid asparagine and selective leukemic cell apoptosis. Despite significantly improving treatment response rates, its use can be challenging due to a complex toxicity profile, including thrombosis, hepatotoxicity, hyperglycemia, pancreatitis, and hypertriglyceridemia (HTG). We report a case of a young man who developed severe hypertriglyceridemia secondary to PEG. A 26-year-old man with no significant past medical history presented with refractory upper respiratory symptoms and cervical lymphadenopathy. He was subsequently found to have severe leukocytosis with 70% blasts and 7cm mediastinal mass with superior vena cava compression. Flow cytometry and bone marrow biopsy diagnosed T-cell ALL and he was started on chemotherapy via the GIMEMA LAL1913 protocol (a chemotherapy regimen that includes prephase cyclophosphamide and induction phase with vincristine, idarubicin, dexamethasone, and PEG). About 12 days after having received PEG, the patient developed unexplained acute hyponatremia to 123 mmol/L and other lab tests such as potassium and hepatic function tests were not able to be processed. Further workup revealed pseudohyponatremia and that lab interference was occurring from lipemia. A triglyceride (TG) level was found to be >4425 mg/dL. LDL direct was measured to be 95 mg/dL, and lipid analysis showed absent chylomicrons. Clinically, he had stable mild abdominal tenderness and a serum lipase level resulted marginally above the upper limit of reference range. At this point, he was transitioned to a low-fat diet (<20g per day). Omega-3-acid ethyl esters (EPA/DHA) and fenofibrate were started. In the next 2 weeks his TG steadily decreased to 163 mg/dL. His mild abdominal pain resolved and lipase normalized. The patient is currently undergoing cycle 2 of his chemotherapy and remains on low fat diet, EPA/DHA, and fenofibrate therapy. After 1 week of receiving his second dose of PEG, his triglycerides were 105 mg/dL. Apo E genotyping was performed and revealed normal E3/E3 genotype. He denies any family history of lipid disorders. The incidence of PEG-induced HTG is poorly described in the adult population, and recent studies have shown the condition is becoming more frequently recognized. Its underlying mechanism is not fully understood, but TG levels often rise dramatically and can lead to severe pancreatitis. Clinicians should be aware of this adverse effect and consider baseline lipid analysis prior to induction chemotherapy and TG surveillance, in addition to clinical monitoring for pancreatitis.

Cytostatic Activity of Sanguinarine and a Cyanide Derivative in Human Erythroleukemia Cells Is Mediated by Suppression of c-MET/MAPK Signaling.

Sanguinarine (1) is a natural product with significant pharmacological effects. However, the application of sanguinarine has been limited due to its toxic side effects and a lack of clarity regarding its molecular mechanisms. To reduce the toxic side effects of sanguinarine, its cyanide derivative (1a) was first designed and synthesized in our previous research. In this study, we confirmed that 1a presents lower toxicity than sanguinarine but shows comparable anti-leukemia activity. Further biological studies using RNA-seq, lentiviral transfection, Western blotting, and flow cytometry analysis first revealed that both compounds 1 and 1a inhibited the proliferation and induced the apoptosis of leukemic cells by regulating the transcription of c-MET and then suppressing downstream pathways, including the MAPK, PI3K/AKT and JAK/STAT pathways. Collectively, the data indicate that 1a, as a potential anti-leukemia lead compound regulating c-MET transcription, exhibits better safety than 1 while maintaining cytostatic activity through the same mechanism as 1.

HIF1α-mediated transactivation of WTAP promotes AML cell proliferation via m6A-dependent stabilization of KDM4B mRNA.

Hypoxia inducible factor 1α (HIF1α) is abnormally overexpressed in t(8;21) acute myeloid leukemia (AML) and functions as an oncogene through transactivating DNA methyltransferase 3 alpha leading to DNA hypermethylation. However, it remains unclear whether HIF1α influences RNA N6-methyladenosine (m6A) methyltransferases. Here, we show that HIF1α promotes the expression of Wilms tumor 1-associated protein (WTAP), a main component of the m6A methyltransferase complex, markedly alters the transcriptome-wide m6A distribution and enhances cell proliferation in t(8;21) AML. In agreement with this, WTAP is overexpressed and predicts poor prognosis in t(8;21) AML patients. Moreover, WTAP knockdown inhibits growth, and induces apoptosis and differentiation of leukemia cells. Mechanistically, HIF1α transactivates WTAP gene expression by directly binding to the hypoxia-response element of its promoter region. Pharmacological or genetic intervention in the HIF1α-WTAP axis results in the reduction of m6A level on lysine demethylase 4B (KDM4B) transcripts and increased its degradation, correlated with lower expression of KDM4B and higher trimethylation levels of histone H3 on lysine 9. KDM4B knockdown inhibits leukemia cell growth in vitro and in mice. Thus, HIF1α-mediated WTAP high expression enhances the malignant behavior of leukemia cells and drives a crosstalk between m6A RNA methylation and histone methylation through monitoring m6A-dependant KDM4B translation.

Synergistic Action of MCL-1 Inhibitor with BCL-2/BCL-XL or MAPK Pathway Inhibitors Enhances Acute Myeloid Leukemia Cell Apoptosis and Differentiation.

Acute myeloid leukemia (AML) is a hematological malignancy characterized by excessive proliferation of abnormal myeloid precursors accompanied by a differentiation block and inhibition of apoptosis. Increased expression of an anti-apoptotic MCL-1 protein was shown to be critical for the sustained survival and expansion of AML cells. Therefore, herein, we examined the pro-apoptotic and pro-differentiating effects of S63845, a specific inhibitor of MCL-1, in a single-agent treatment and in combination with BCL-2/BCL-XL inhibitor, ABT-737, in two AML cell lines: HL-60 and ML-1. Additionally, we determined whether inhibition of the MAPK pathway had an impact on the sensitivity of AML cells to S63845. To assess AML cells' apoptosis and differentiation, in vitro studies were performed using PrestoBlue assay, Coulter electrical impedance method, flow cytometry, light microscopy and Western blot techniques. S63845 caused a concentration-dependent decrease in the viability of HL-60 and ML-1 cells and increased the percentage of apoptotic cells. Combined treatment with S63845 and ABT-737 or MAPK pathway inhibitor enhanced apoptosis but also induced differentiation of tested cells, as well as altering the expression of the MCL-1 protein. Taken together, our data provide the rationale for further studies regarding the use of MCL-1 inhibitor in combination with other pro-survival protein inhibitors.

The interaction between Hsp90-mediated unfolded protein response and autophagy contributes to As3+/ Se4+ combination-induced apoptosis of acute promyelocytic leukemia cells

The interaction between the unfolded protein response (UPR) and autophagy plays either pro-survival or pro-apoptotic roles in the treatment of acute promyelocytic leukemia (APL). Our previous study has shown that the combination therapy of arsenite (As3+) and selenite (Se4+) induces apoptosis in APL NB4 cells, although the mechanisms are not clear. Here, we demonstrate that the interaction between heat shock protein 90 (Hsp90)-mediated UPR and autophagy is the core module for As3+/Se4+ combination-induced apoptosis. Hsp90 overexpression and knockdown assays indicate that Hsp90 inhibition by PERK modulates two branches of the UPR, leading to the activation of ATF4 and CHOP, causing the degradation of IRE1α and the dephosphorylation of eIF2α, thereby contributing to switching the cytoprotective UPR into an apoptotic pathway. Assays using pretreatment with inducers and inhibitors of endoplasmic reticulum stress (ERS) and autophagy reveal that autophagy is stimulated by ERS but suppressed by As3+/Se4+ combination via the mTOR signaling pathway. However, inhibition of autophagy decreases GRP78 expression and eIF2α phosphorylation, thereby further promoting ERS-induced apoptosis. Moreover, As3+/Se4+ combination blocks hepatic infiltration in an APL-NCG mouse model of extramedullary infiltration. Taken together, these findings provide novel agents and therapeutic approaches for APL.

TRAF7 inhibits glycolysis to potentiate growth inhibition and apoptosis of myeloid leukemia cells via regulating the KLF2-PFKFB3 axis

Tumor necrosis factor receptor-related factor 7 (TRAF7) can regulate cell differentiation and apoptosis, but its specific functional mechanism in the pathological process of acute myeloid leukemia (AML) closely related to differentiation and apoptosis disorders is largely unclear. In this study, TRAF7 was found to be lowly expressed in AML patients and a variety of myeloid leukemia cells. TRAF7 was overexpressed in AML Molm-13 and chronic myeloid leukemia (CML) K562 cells by transfection with pcDNA3.1-TRAF7. CCK-8 assay and flow cytometry analysis showed that TRAF7 overexpression induced growth inhibition and apoptosis in K562 and Molm-13 cells. Measurements of glucose and lactate suggested that TRAF7 overexpression impaired glycolysis of K562 and Molm-13 cells. Cell cycle analysis indicated that most of K562 and Molm-13 cells were captured in G0/G1 phase by TRAF7 overexpression. PCR and western blot assay revealed that TRAF7 increased Kruppel-like factor 2 (KLF2) expression but decreased 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) expression in AML cells. KLF2 knockdown can counteract TRAF7-triggered PFKFB3 inhibition, and abolish TRAF7-mediated glycolysis inhibition and cell cycle arrest. KLF2 knockdown or PFKFB3 overexpression both can partially neutralize TRAF7-induced growth inhibition and apoptosis of K562 and Molm-13 cells. Moreover, Lv-TRAF7 decreased human CD45+ cells in mouse peripheral blood in the xenograft mice established by NOD/SCID mice. Taken together, TRAF7 exerts anti-leukemia effects by impairing glycolysis and cell cycle progression of myeloid leukemia cells via modulating the KLF2-PFKFB3 axis.

Abstract 1673: Discovery of potent, selective, and orally bioavailable GSPT1 degraders and their pre-clinical anti-tumor activity in acute myeloid leukemia and solid tumors

Abstract Molecular glue degraders (MGDs) of neo-substrates that function by hijacking the CRBN E3 ligase are clinically validated as therapeutics for the treatment of hematological malignancies. Novel MGDs of GSPT1, a translation termination factor, elicit dysregulated protein translation termination and subsequent induction of TP53-independent apoptosis in acute myeloid leukemia (AML) cells through activation of the integrated stress response. In addition, dysregulation of translation termination triggered by GSPT1 degradation appears to be cytotoxic specifically to MYC-driven cancers including solid tumors with translational addiction. Phase 1 clinical trials of three novel GSPT1 MGDs have been recently launched for the treatment of AML and/or MYC-driven solid tumors (NCT02848001, NCT04336982, NCT05546268, and NCT05144334). Herein, we present novel GSPT1 MGDs and their pre-clinical results against AML and solid tumors. Our current lead GSPT1 MGDs induced rapid, potent, and durable degradation of GSPT1, resulting in strong inhibition of tumor cell growth in a variety of cell lines of MYC-driven solid tumor and blood cancer (AML and acute lymphoblastic leukemia). Moreover, in ex-vivo assays using a panel of patient-derived primary AML cells, C-10386 was highly sensitive with EC50s at the nanomolar range. Furthermore, a related analogue (C-14207) showed excellent rodent PK profiles and demonstrated dose-dependent PKPD relationship and excellent efficacy in the NCI-H1155 NSCLC xenograft model. Finally, our current lead compounds showed safer profiles in various normal cells compared to other known GSPT1 degraders. Collectively, we have identified novel GSPT1 MGDs as promising development candidates for the treatment of AML and solid tumors. Citation Format: Min Sung Joo, JaeYung Lee, Eun-Jung Kim, Dong Hyuk Ki, Hunmi Choi, Joonwoo Nam, Jaewoo Park, Keon Wook Kang, Wooseok Han. Discovery of potent, selective, and orally bioavailable GSPT1 degraders and their pre-clinical anti-tumor activity in acute myeloid leukemia and solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1673.

Effect of Scutellarin on Proliferation of Acute Myeloid Leukemia Cells and Its Related Mechanism

To investigate the effect of scutellarin (SCU) on proliferation, cell cycle and apoptosis of acute myeloid leukemia (AML) cells and its related molecular mechanism. Human AML HL-60 cells were cultured in vitro. The cells were treated with SCU at the concentration of 0, 2, 4, 8, 16, 32, 64 μmol/L, and the inhibition rate of cell proliferation was detected by CCK-8 method. Then HL-60 cells were treated with SCU at the concentration of 4, 8, 16 μmol/L, and the negative control group (NC group) was set. The cell cycle distribution and apoptosis were detected by flow cytometry, and the expression of cell cycle, apoptosis and JAK2/STAT3 pathway related proteins were detected by Western blot. SCU significantly inhibited the proliferation of HL-60 cells in a concentration- and time-dependent manner(r =0.958,r =0.971). Compared with NC group, the proportion of cells in G0/G1 phase and apoptosis rate of HL-60 cells in 4, 8, 16 μmol/L SCU group were significantly increased, and the proportion of cells in S phase was significantly decreased (P <0.05). The relative protein expression levels of p21, p53, caspase-3 and Bax were significantly increased, while the relative protein expression levels of CDK2, cyclin E and Bcl-2 were significantly decreased (P <0.05). The ratio of p-JAK2/JAK2 and p-STAT3/STAT3 were significantly decreased (P <0.05). The changes of above-mentioned indexes were concentration dependent. SCU can inhibit the proliferation of AML cells, induce cell cycle arrest and apoptosis, and its mechanism may be related to the regulation of JAK2/STAT3 signaling pathway.

Melatonin promotes differentiation and apoptosis of AML1-ETO-positive cells.

Acute Myeloid Leukemia 1-Eight-Twenty-One (AML1-ETO) is an oncogenic fusion protein that causes acute myeloid leukemia. We examined the effects of melatonin on AML1-ETO by investigating cell differentiation, apoptosis, and degradation in leukemia cell lines. We evaluated Kasumi-1, U937T, and primary acute myeloid leukemia (AML1-ETO-positive) cell proliferation by Cell Counting Kit-8 assay. Flow cytometry and western blotting were used to evaluate CD11b/CD14 levels (differentiation biomarkers) and the AML1-ETO protein degradation pathway, respectively. CM-Dil-labeled Kasumi-1 cells were also injected into zebrafish embryos to determine the effects of melatonin on vascular proliferation and development and to evaluate the combined effects of melatonin and common chemotherapeutic agents. AML1-ETO-positive acute myeloid leukemia cells were more sensitive to melatonin than AML1-ETO-negative cells. Melatonin increased apoptosis and CD11b/CD14 expression in AML1-ETO-positive cells and decreased the nuclear/cytoplasmic ratio, together suggesting that melatonin induced cell differentiation. Mechanistically, melatonin degraded AML1-ETO by activating the caspase-3 pathway and regulating the mRNA levels of AML1-ETO downstream genes. Melatonin reduced the number of neovessels in Kasumi-1-injected zebrafish, suggesting that melatonin inhibits cell proliferation in vivo. Finally, combining drugs with melatonin inhibited cell viability. Melatonin is a potential compound for the treatment of AML1-ETO-positive acute myeloid leukemia.

Synergistic Anti-Cancer Effects of Second-Generation Proteasome Inhibitor Carfilzomib with Doxorubicin and Dexamethasone Via p53-Mediated Apoptosis in Pre-B Acute Lymphoblastic Leukemia Cells

Background: The ubiquitin-proteasome system (UPS) plays a crucial role in regulating the levels and functions of a large number of proteins in the cell, which are important for cancer cell growth and survival. The proteasome is highly activated in B-cell precursor acute lymphoblastic leukemia (BCP-ALL), which is the most common malignancy in children. The attempt to inhibit proteasome as a therapeutic strategy has been successful for some malignancies.&#x0D; Materials and Methods: In this experimental study, human BCP-ALL cell lines NALM-6 and SUP-B15 were treated with carfilzomib with and without the chemotherapeutic agents. The XTT assay evaluated the viability of the cells. Cell cycle analysis and apoptosis assay were assessed by flow cytometry. RQ-PCR and western blotting evaluated the expression of pro-/anti-apoptotic signals. A drug combination study for synergistic or additive effects of carfilzomib with doxorubicin or dexamethasone was performed.&#x0D; Results: We observed that carfilzomib alone induced G2/M cell cycle arrest and caspase-dependent apoptosis in the human BCP-ALL cells (NALM-6 and SUP-B15). Gene and protein expression analysis indicated the upregulation of pro-apoptotic as well as downregulation of the cell survival and proliferative signals (P-value&lt;0.05). The synergy of carfilzomib with doxorubicin or dexamethasone was revealed in BCP-ALL cells.&#x0D; Conclusion: Our results indicated that proteasome inhibition induces p53-mediated apoptosis in BCP-ALL cells. Since carfilzomib has a synergistic effect with anti-leukemic agents doxorubicin and dexamethasone in BCP-ALL cells, this combined-modality approach might be befitting for patients who do not respond well to conventional chemotherapy.

Novel gold(I) complexes induce apoptosis in leukemia cells via the ROS-induced mitochondrial pathway with an upregulation of Harakiri and overcome multi drug resistances in leukemia and lymphoma cells and sensitize drug resistant tumor cells to apoptosis in vitro

Gold complexes could be promising for tumor therapy because of their cytotoxic and cytostatic properties. We present novel gold(I) complexes and clarify whether they also show antitumor activity by studying apoptosis induction in different tumor cell lines in vitro, comparing the compounds on resistant cells and analyzing the mechanism of action. We particularly highlight one gold complex that shows cytostatic and cytotoxic effects on leukemia and lymphoma cells already in the nanomolar range, induces apoptosis via the intrinsic signaling pathway, and plays a role in the production of reactive oxygen species. Furthermore, not only did we demonstrate a large number of resistance overcomes on resistant cell lines, but some of these cell lines were significantly more sensitive to the new gold compound. Our results show promising properties for the gold compound as anti-tumor drug and suggest that it can subvert resistance mechanisms and thus targets resistant cells for killing.