Sensitivity Of Leukemia Cells Research Articles

The cytotoxic activities of the major diterpene extracted from Salvia multicaulis (Bardakosh) are mediated by the regulation of heat-shock response and fatty acid metabolism pathways in human leukemia cells

BackgroundLeukemia is one of the most lethal cancers worldwide and represents the sixth-leading cause of cancer deaths. The results of leukemia treatment have not been as positive as desired, and recurrence is common. PurposeThus, there is an urgent requirement for the development of new therapeutic drugs. Salvia multicaulis (Bardakosh) is a widespread species that contains multiple phytochemical components with anti-cancer activities. MethodsWe isolated and characterized the major diterpene candesalvone B methyl ester from S. multicaulis and investigated its action as a cytotoxic agent towards sensitive and drug-resistant leukemia cells by the resazurin reduction assay. Additionally, the targeted genes and the affected molecular mechanisms attributed to the potent cytotoxic activities were discovered by transcriptome-wide mRNA expression profiling. The targets predicted to be regulated by candesalvone B methyl ester in each cell line were confirmed by qRT-PCR, molecular docking, microscale thermophoresis, and western blotting. Moreover, cell cycle distribution and apoptosis were analyzed by flow cytometry. ResultsCandesalvone B methyl ester was cytotoxic with IC50 values of 20.95 ± 0.15 µM against CCRF-CEM cells and 4.13 ± 0.10 µM against multidrug-resistant CEM/ADR5000 leukemia cells. The pathway enrichment analysis disclosed that candesalvone B methyl ester could regulate the heat-shock response signaling pathway via targeting heat shock factor 1 (HSF1) in CCRF-CEM cells and ELOVL fatty acid elongase 5 (ELOVL5) controls the fatty acid metabolism pathway in CEM/ADR5000 cells. Microscale thermophoresis showed the binding of candesalvone B methyl ester with HSF1 and ELOVL5, confirming the results of molecular docking analysis. Down-regulation of both HSF1 and ELOVL5 by candesalvone B methyl ester as detected by both western blotting and RT-qPCR was related to the reversal of drug resistance in the leukemia cells. Furthermore, candesalvone B methyl ester increased the arrest in the sub-G1 phase of the cell cycle in a dose-dependent manner from 1.3 % to 32.3 % with concomitant induction of apoptosis up to 29.0 % in CCRF-CEM leukemic cells upon inhibition of HSF1. ConclusionCandesalvone B methyl ester isolated from S. multicaulis exerted cytotoxicity by affecting apoptosis, cell division, and modulation of expression levels of genes contributing to the heat stress signaling and fatty acid metabolism pathways that could relieve drug resistance of leukemia cells.

Impact of Age on Pharmacogenomics and Treatment Outcomes of B-Cell Acute Lymphoblastic Leukemia.

Acute lymphoblastic leukemia (ALL) can occur across all age groups, with a strikingly higher cure rate in children compared with adults. However, the pharmacological basis of age-related differences in ALL treatment response remains unclear. Studying 767 children and 309 adults with newly diagnosed B-cell ALL enrolled on frontline trials at St Jude Children's Research Hospital, MD Anderson Cancer Center, the Alliance for Clinical Trials in Oncology, and the ECOG-ACRIN Cancer Research Group, we determined the ex vivo sensitivity of leukemia cells to 21 drugs. Twenty-three ALL molecular subtypes were identified using RNA sequencing. We systematically characterized the associations between drug response and ALL genomics in children, adolescents and young adults, and elderly adults. We evaluated the effect of age-related gene expression signature on ALL treatment outcomes. Seven ALL drugs (asparaginase, prednisolone, mercaptopurine, dasatinib, nelarabine, daunorubicin, and inotuzumab ozogamicin) showed differential activity between children and adults, of which six were explained by age-related differences in leukemia molecular subtypes. Adolescents and young adults showed similar patterns of drug resistance as older adults, relative to young children. Mercaptopurine exhibited subtype-independent greater sensitivity in children. Transcriptomic profiling uncovered subclusters within CRLF2-, DUX4-, and KMT2A-rearranged ALL that were linked to age and cytotoxic drug resistance. In particular, a subset of children had adult-like ALL on the basis of leukemia gene expression patterns across subtypes, despite their chronological age. Resistant to cytotoxic drugs, children with adult-like ALL exhibited poor prognosis in pediatric ALL trials, even after adjusting for age and minimal residual diseases. Our results provide pharmacogenomic insights into age-related disparities in ALL cure rates and identify leukemia prognostic features for treatment individualization across age groups.

Expression and Function of circ_0073585 in Acute Myeloid Leukemia

To investigate the expression level, clinical significance and function of circular RNAs (circRNAs) circ_0073585 in the bone marrow of patients with acute myeloid leukemia (AML). The expression levels of circ_0073585 in bone marrow samples of 106 newly diagnosed AML patients and 38 controls were detected by real-time quantitative PCR (RQ-PCR). The differences were compared between the two groups and their clinical significance was analyzed. The diagnostic value of circ_0073585 expression for AML was evaluated by receiver operating characteristic curve(ROC). THP-1 cells with lentivirus overexpressing circ_0073585 vector and empty vector were divided into two groups: circ_0073585-THP-1 and NC-THP-1 group. CCK-8 assay and flow cytometry were used to study the effects of circ_0073585 on THP-1 cell proliferation, survival, apoptosis and drug sensitivity. Compared with the controls, the expression level of circ_0073585 in the bone marrow of AML patients was significantly reduced (P < 0.001). There was a statistically significant difference between the high and low expression groups of circ_0073585 in the white blood cell count, platelet count (P < 0.01) and chromosome risk (P < 0.05). Compared with NC-THP-1 cells, the proliferation and viability of circ_0073585-THP-1 cells were weakened (P < 0.01), the apoptosis rate was increased (P < 0.01), and the sensitivity to homoharringtonine (P < 0.05) and daunorubicin hydrochloride (P < 0.001) was increased. The expression level of circ_0073585 is decreased in AML patients. Overexpression of circ_0073585 can inhibit the proliferation and viability of leukemic cells, promote apoptosis, and increase sensitivity of leukemia cells to chemotherapy drugs.

Identification of exosomal microRNAs and related hub genes associated with imatinib resistance in chronic myeloid leukemia.

Chemotherapy resistance is a major obstacle in cancer therapy, and identifying novel druggable targets to reverse this phenomenon is essential. The exosome-mediated transmittance of drug resistance has been shown in various cancer models including ovarian and prostate cancer models. In this study, we aimed to investigate the role of exosomal miRNA transfer inchronic myeloid leukemia drug resistance. For this purpose, firstly exosomes were isolated from imatinib sensitive (K562S) and resistant (K562R) chronic myeloid leukemia (CML)cells and named as Sexo and Rexo, respectively. Then, miRNA microarray was used to compare miRNA profiles of K562S, K562R, Sexo, Rexo, and Rexo-treated K562S cells. According to our results, miR-125b-5p and miR-99a-5p exhibited increased expression in resistant cells, their exosomes, and Rexo-treated sensitive cells compared to their sensitive counterparts. On the other hand, miR-210-3p and miR-193b-3p were determined to be the two miRNAs which exhibited decreased expression profile in resistant cells and their exosomes compared to their sensitive counterparts. Gene targets, signaling pathways, and enrichment analysis were performed for these miRNAs by TargetScan, KEGG, and DAVID. Potential interactions between gene candidates at the protein level were analyzed via STRING and Cytoscape software. Our findings revealed CCR5, GRK2, EDN1, ARRB1, P2RY2, LAMC2, PAK3, PAK4, and GIT2 as novel gene targets that may play roles in exosomal imatinib resistance transfer as well as mTOR, STAT3, MCL1, LAMC1, and KRAS which are already linked to imatinib resistance. MDR1 mRNA exhibited higher expression in Rexo compared to Sexo as well as in K562S cells treated with Rexo compared to K562S cells which may suggest exosomal transfer of MDR1 mRNA.

Progress in the study of autophagy-related proteins affecting resistance to chemotherapeutic drugs in leukemia.

Leukemia is a life-threatening malignant tumor of the hematopoietic system. Currently, the main treatment modalities are chemotherapy and hematopoietic stem cell transplantation. However, increased drug resistance due to decreased sensitivity of leukemia cells to chemotherapeutic drugs presents a major challenge in current treatments. Autophagy-associated proteins involved in autophagy initiation have now been shown to be involved in the development of various types of leukemia cells and are associated with drug resistance. Therefore, this review will explore the roles of autophagy-related proteins involved in four key autophagic processes: induction of autophagy and phagophore formation, phagophore extension, and autophagosome formation, on the development of various types of leukemias as well as drug resistance. Autophagy may become a promising therapeutic target for treating leukemia.

Rituximab potentially improves clinical outcomes of CAR-T therapy for r/r B-ALL via sensitizing leukemia cells to CAR-T-mediated cytotoxicity and reducing CAR-T exhaustion.

Despite chimeric antigen receptor (CAR) T-cell therapy has achieved great advances in recent year, approximately 50% of relapsed/refractory B cell acute lymphoblastic leukemia (r/r B-ALL) patients treated with CAR-T experience relapse 6 months post CAR-T treatment. CD20 express on 30 to 50% of B-ALL, which makes CD20 Monoclonal Antibody as one of the potential therapy strategies to decrease the tumor burden and improve the efficacy of CAR-T therapy. Adding Rituximab to chemotherapy protocol had been demonstrated to improve the outcome for CD20-positive ALL. However, rare study explored the influence of Rituximab combined with CAR-T therapy. We retrospectively analyzed 20 r/r B-ALL patients who received CAR-T therapy, all of whom had failed multiple lines of therapy. Before CAR-T infusion, we administered Rituximab to 10 patients with high CD20 expression at a dose of 375mg/m2 for 1 day. Meanwhile, we selected 10 patients with the comparable features who underwent CAR-T treatment without Rituximab in the same period as the control group. In vitro, the surface molecule expression and killing of CAR-T post Rituximab-treated B-ALL cells co-incubated with CAR-T cells were detected by flow cytometry. The median follow-up of Rituximab and Control groups were 29.27 and 9.83 months. We found that adding Rituximab may confer a favorable prognosis compared with Control group. The 2-year overall survival (OS) and leukemia-free survival (LFS) rates both were longer in the Rituximab group (90% vs. 26.7%, p=0.0342; 41.7% vs. 25%, p=0.308). In vitro, we observed that Rituximab-treated tumour cells are more sensitive to CAR-T killing and a broad range of cytokines and chemokines were produced when Rituximab-treated Nalm-6 cells co-cultured with 19-22CAR-T cells, such as interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2). To investigate whether Rituximab has an effect on CAR-T persistence, we stimulated CAR-T cells repeatedly in vitro with Rituximab-treated Nalm-6 to evaluate the changes in CAR-T surface exhaustion molecules at different times. We found that the expression of exhaustion molecules (LAG-3, PD-1, TIM-3) on CAR-T cells were significantly lower in the Rituximab group than in the Control group. Rituximab combined with CAR-T therapy is effective for improving the long-term prognosis of B-ALL patients who have failed multiple lines of therapy. In vitro, we observed that rituximab potentially improves CAR-T efficacy by sensitizing ALL to CART-mediated cytotoxicity and reducing CAR-T exhaustion.

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.

Melatonin sensitizes leukemia cells to the MCL1 inhibitors S63845 and A‐1210477 through multiple pathways

AbstractSeveral myeloid cell leukemia sequence 1 protein (MCL1) inhibitors including S64315 have undergone clinical testing for leukemia. Because of the toxicities after MCL1 inhibition, including hematopoietic, hepatic, and cardiac toxicities, there is substantial interest in finding agents that can sensitize leukemia cells to these MCL1 inhibitors. Melatonin is a chronobiotic that promotes chemo‐induced cancer cell death while protecting normal cells from cytotoxic effects. In this study, we found melatonin sensitizes over 10 leukemia cell lines to the MCL1 inhibitors S63845 (S64315 analog) and A‐1210477. Further studies demonstrate that melatonin sensitizes Jurkat cells to S63845 and A‐1210477 independent of melatonin receptors MT1 and MT2, but through multiple mechanisms, including upregulating the death receptor pathway, increasing mitochondrial reactive oxygen species (ROS), inhibiting nuclear factor‐κB (NF‐κB) signaling, and causing cell cycle arrest. First, death receptor pathway inhibition only slightly diminishes the melatonin sensitization of S63845, while inhibiting mitochondrial ROS partially reduces the S63845/melatonin combination‐induced apoptosis and depletion of the mitochondrial pathway totally abolishes it, indicating that both death receptor and mitochondrial apoptosis pathways are involved. Second, transcriptome sequencing analysis found that NF‐κB signaling is downregulated by melatonin that inhibition of NF‐κB signaling by parthenolide also dramatically sensitizes Jurkat cells to S63845. Third, melatonin induces G1 cell cycle arrest and upregulates NOXA while NOXA knockdown diminishes the sensitization to S63845 by melatonin. In addition, a xenograft model suggests that melatonin in combination with S63845 causes shrinkage of leukemic deposit while S63845 or melatonin monotherapy only has limited effects. Thus, our results demonstrate that melatonin efficiently sensitizes various leukemia to the MCL1 inhibitors, potentially allowing the usage of lower doses.

Myelodysplasia-Related Gene Mutations for NGS-Based MRD Assessment in Acute Myeloid Leukemia

Introduction: Measurable residual disease (MRD) plays an increasing role for treatment management of AML patients. While next-generation-sequencing (NGS) based MRD assessment can be well standardized, there is uncertainty about the type of gene mutations that associate with prognosis and are useful for MRD assessment. The 2022 ELN recommendations assign patients with at least one mutation in the genes ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1 or ZRSR2 to the subgroup of myelodysplasia-related gene mutations (MRGM), which is associated with poor prognosis. We aimed to define the prognostic effect of MRD after induction chemotherapy in AML patients with MRGM using MRG mutations for MRD assessment by NGS. Methods: We retrospectively collected bone marrow and peripheral blood samples from AML patients in complete remission (CR) or CR with incomplete hematologic recovery (CRi) after one to two cycles of 7+3-based standard induction chemotherapy (IC) with at least one MRGM detected at diagnosis by myeloid panel sequencing covering 48 AML associated genes. Patients treated with one course of IC were included if they proceeded to allogeneic hematopoietic cell transplantation (alloHCT) already after one cycle. Molecular MRD status was assessed using targeted NGS and bioinformatics error-correction with 0.01% sensitivity as described before using only MRGM as MRD markers. Results: MRD was assessed on 104 adult newly-diagnosed AML patients (median age 58.6) with a total of 166 MRGM, resulting in a median of one MRGM per patient (range 1-4). 43 (41.3%) patients had secondary or therapy-related AML and 20 (19.2%) had myelodysplasia-related cytogenetic abnormalities. 68 (65.4%) patients were MRD positive for at least one MRGM after one (18 patients (17.3%)) or two (86 patients (82.7%)) cycles of intensive chemotherapy, while 36 (34.6%) became MRD negative. Measured variant allele frequencies (VAF) of positive samples ranged from 0.02-43.1% (median VAF 1.34%).MRD positive patients were older and more likely to be male compared to MRD negative patients, while cytogenetic risk, WBC count, Hgb, platelet count and ECOG status at diagnosis were similar to MRD negative patients. 53 (77.9%) MRD positive and 23 (63.9%) MRD negative patients underwent alloHCT in first CR/CRi.Median follow-up was 3.35 years. OS (P = 0.92), RFS (P = 0.99) and CIR (P = 0.98) were similar in MRD positive (at least one MRGM detectable) and negative (no MRGM detectable) patients (Figure 1). OS, RFS and CIR were also similar between MRD positive and negative patients, when MRD negativity was defined by conversion of at least one MRGM to negativity (55 (52.9%) MRD positive, 49 (47.1%) MRD negative), and when ASXL1 was excluded from the analysis. As variants with VAF &amp;gt;5% in CR/CRi samples may indicate clonal hematopoiesis, we excluded all variants with VAF &amp;gt;5% and repeated the analysis with the 88 (84.6%) remaining patients. Again, OS, RFS and CIR were similar for MRD positive and negative patients. We next reasoned that reduction of VAF correlates with the sensitivity of leukemic cells and possibly with depth of remission and long-term outcome. The fold-reduction of VAFs from diagnosis to the time of MRD analysis was calculated for all variants. For patients with several MRGMs, the variant with the largest fold-reduction was considered including undetectable variants. Patients with more or less than a 2-log, 3-log or 4-log reduction (log 10) had similar OS, RFS and CIR, respectively. Evaluating each MRGM individually, only RUNX1-MRD associated with RFS and by trend CIR (comparing MRD positive to negative patients for OS, HR 3.41, 95% CI 0.43-26.82, P = 0.24; RFS, HR 4.37, 95% CI 1.07-17.79, P = 0.04; CIR, HR 3.30, 95% CI 0.79-13.82, P = 0.1). Conclusion: 65.4% of AML-MRGM patients in CR/CRi remained MRD positive when MRGMs were used for MRD assessment by NGS. MRD positivity was associated with age above 60 years and male sex.Using all MRG mutations for MRD assessment at a threshold of 0.01% or by various degrees of log-reduction was not predictive of outcome after intensive induction chemotherapy. This limits the number of potential MRD markers for NGS analysis before alloHCT, although individual markers like RUNX1 may be of prognostic value.

Clonal Medicine Targeting DNA Damage Response Eradicates AML

Clonal diversity of acute myeloid leukemia (AML) plays a key role in poor therapeutic outcomes. AML cells usually accumulate spontaneous DNA damage including highly toxic DNA double-strand breaks (DSBs) induced by metabolic products and replication stress. To repair numerous DSBs and survive, AML cells activate the DNA damage response (DDR) involving the pathways that sense (ATM and ATR kinases) and repair (RAD51-mediated homologous recombination = HR, RAD52-mediated transcription associated homologous recombination = TA-HR and single strand annealing = SSA, DNA-PK -mediated non-homologous end-joining = NHEJ, PARP1/Polq-dependent microhomology-mediated end-joining = MMEJ) DSBs. Thus, DDR is a legitimate therapeutic target. Numerous AML-driving mutations [ FLT3(ITD), TETmut, DNMT3Amut, AML1-ETO, PML-RARa , IDH1mut, cKITmut] regulate DDR and affect the sensitivity of leukemia cells to DDR inhibitors (DDRi). The genetic landscape of malignant clones in a patient may be complicated since individual clones can carry multiple mutations. Thus, individual AML clones may respond differently to DDRi depending on their mutational profile. In our experimental protocol AML cells from individual patients were treated with various DDRi followed by single-cell targeted DNA sequencing (sctDNA-seq) to integrate patient's leukemia clonal composition with response to the inhibitors. We developed a sctDNA-seq myeloid platform interrogating up to 1394 genetic variants of 54 known leukemia driver genes, which unraveled the clonal landscape of AML at a single-cell resolution before and after the treatment. Based on these results we designed a “clonal attack”, a patient-tailored combination of DDRi targeting all AML clones in a patient sample. Here we show that DDRi simultaneously attacking different clones caused clonal attrition and eradicated the disease in vitro and in vivo. For example, in AML-MD2 sample 2 clones carrying EZH2(V679M) + TET2(L1721W) and EZH2(V679M) + TET2(L1721W) + FLT3(D835Y) were resistant/less responsive to ATRi but sensitive to PARPi, ATMi and RAD52i. Conversely, three other clones carrying EZH2(V679M) + TET2(L1721W) + RUNX1(D160Y), EZH2(V679M) + TET2(L1721W) + RUNX1(D160Y) + EZH2(E54*) and EZH2(V679M) + TET2(L1721W) + RUNX1(D160Y)EZH2(E54*) + BCOR1(R1334Tfs*32) + NRAS(G13R) were sensitive to ATRi while less responsive to PARPi, ATMi and RAD52i. Based on this observation, we hypothesized that simultaneous treatment with ATRi + PARPi or ATRi + ATMi should result in elimination of all AML-MD2 clones. In agreement with this hypothesis, in vitro treatment with these combinations was 20 - 30x more effective in eliminating clonogenic growth of Lin-CD34+ AML-MD2 cells when compared to individual inhibitors. This effect was associated with abundant accumulation of DSBs. Combinations of these inhibitors were only modestly toxic to normal hematopoietic cells. Moreover, combination of DDRi displaying similar clonal targeting specificity was only 2x better than individual inhibitors. Next, humanized NRGS immunodeficient mice bearing primary AML-MD2 xenograft were treated with vehicle, PARPi, ATRi and the combination of these drugs. We found that individual treatments reduced the number of hCD45+ AML-MD2 cells in bone marrow and spleen by approximately 2x and 3x, respectively. Remarkably, the combination of PARPi + ATRi eliminated more than 99% of leukemia cells in bone marrows of 7/10 mice and in spleens of 10/10 mice while no obvious toxicity was observed. Clonal targeting by DDR inhibitors, however, may not be applicable to all AML samples. For example, we identified AML patient samples, where clones displayed similar sensitivity pattern or were resistant to DDRi treatment. In conclusion, we postulate that sctDNA-seq combined with in vitro DDRi sensitivity testing (sctDNA-seq/DDRi) is a powerful tool to interrogate clonal sensitivity of AML to these agents. This clonal medicine approach may become a novel therapeutic regimen to overcome clonal complexity of AML in a cohort of patients. The “clonal attack” by DDR inhibitors shifts the paradigm of genotoxic therapies from those using non-discriminative cytotoxic drugs to those selectively attacking DDR vulnerabilities in AML clones with minimal harm to normal cells. Since clonal heterogeneity and DNA damage are hallmarks of cancer, the “clonal attack” may be broadly applicable to the quest for cancer cure.

Overexpression of Nrf2 in Mesenchymal Stem Cells Promotes Migration and Invasion of B- Acute Lymphoblastic Leukemia Cells

Background and objective:B -Acute lymphoblastic leukemia (B-ALL) is one of the most difficult cancers to treat in adults, especially recurrence and drug resistance are still the biggest challenges for B-ALL. In recent years, a new concept has been proposed, that is, the interaction between bone marrow microenvironment and leukemic cells can reduce the sensitivity of leukemic cells to chemotherapy. The components of bone marrow microenvironment (BMM) have been shown to mediate the occurrence and development of leukemia. There is growing evidence that leukemic cells teach the bone marrow microenvironment, change its function and establish leukemia protective interactions with stromal cells and immune cells. Bone marrow mesenchymal stem cells (Bone marrow mesenchymal stem cells, BM-MSCs) are stromal cells in leukemia microenvironment, which can promote the progression of leukemia under certain conditions. Nuclear factor erythroid related factor 2 (Nrf2) is an important transcription factor and a regulator of cellular antioxidant response, which regulates the expression of genes encoding antioxidant enzymes to prevent various oxidative changes. It has been confirmed that the high expression of Nrf2 in leukemic cells is related to drug resistance and poor prognosis of leukemia. However, the interaction mechanism of Nrf2 overexpression in MSCs on B-cell acute lymphoblastic leukemia (B-ALL) cells is not clear. We will for the first time propose the mechanism of Nrf2 overexpression in MSCs on the migration and invasion of B-ALL leukemic cells. Methods :Bone marrow nucleated cells were detected in 16 patients with complete remission (B-ALL/CR), 12 patients with relapsed/refractory (B-ALL/R/R) ALL and 10 normal controls. The expression of Nrf2 was detected byreal-time PCR and Western Blot. In vitro cell experiments, real-time PCR and Western Blot were used to detect the expression of Nrf2 in mesenchymal stem cells (MSCs) alone and in the co-culture of MSCs and cell lines (Nalm-6/RS4:11) express the situation Mouse model experiment in vivo, transwell chamber experiment in vitro, three-dimensional (3D) cell culture model, lentivirus transfection, WB and PCR were used to explore the possible mechanism of Nrf2 overexpression in mesenchymal stem cells on the migration and invasion of B-ALL cells. Results: In clinical samples, the expression of Nrf2 in B-ALL-R/R group was significantly higher than that in ALL-CR group and normal control group, suggesting that the expression of Nrf2 was closely related to the recurrence and drug resistance of ALL. In vitro cell experiment, the expression level of Nrf2 in MSCs co-cultured with cell line (NALM-6/RS4:11) was higher than that in MSC cultured alone(P &amp;lt; 0.05). By regulating the overexpression of Nrf2 in MSCs, it can significantly promote the growth, proliferation, migration and invasion of leukemia cells, and promote the expression of CXCR4 in tumor tissues. We further regulated the expression of Nrf2 in MSCs. The results showed that it significantly promoted the migration and invasion of NALM-6/RS4:11 cells. We concluded that the overexpression of Nrf2 in MSCs promotes the migration and invasion of leukemic cells by activating the activity of SDF-1-CXCR4 axis. In vivo experiments, we used tail vein injection of MSCs and B-ALL leukemia cells to explore the protective effect of Nrf2 overexpression in mesenchymal stem cells on leukemia cells and promote extramedullary infiltration of leukemia. The results showed that the infiltration degree of extramedullary organs of mice after combined infusion of two kinds of cells was significantly higher than that of leukemia cells alone, and the survival time of mice was significantly shortened after combined infusion. After statistical treatment, the difference was statistically significant (P &amp;lt; 0.05). Conclusion:The expression of Nrf2 in MSCs may be a key component in mediating the interaction between MSCs and ALL cells. This result may provide a new entry point for deepening all disease progression mechanisms and finding more promising targeted therapies.On the other hand, activation of PI3K/AKTERK1/2 signaling pathway in B-ALL cells further promoted the evolution of B-ALL. This may provide new ideas for findingpotential therapeutic targets for B-ALL extramedullary infi ltration, and help to further solve the current problem of B-ALL relapse and refractory.

Primary Acute Myeloid Leukemia Cells Trigger Distinct Activation Patterns in Expanded NK Cells

Increasing efforts are devoted to implement immunotherapies for the treatment of acute myeloid leukemia (AML). Recently, natural killer (NK) cell-based immunotherapy has shown initial encouraging results. However, which patients are most likely to benefit from NK cell-based treatments remains poorly understood. Here, we investigate the responses of NK cells to ex vivo co-cultures with 55 primary AML samples using single-cell transcriptomics. We identify a subgroup of AML patients eliciting strong responses in NK cells and define the molecular programs in NK cells and other microenvironmental cell types triggered by diverse AML cells. We performed functional single-cell immune profiling on co-cultures of primary expanded NK cells and 55 bone marrow (BM) samples from AML patients at diagnosis. We used NK cells expanded using irradiated K562-41BB-L-mbIL-21 feeder cells, resulting in a product commonly used in clinical trials. All expanded NK cells were from one single healthy donor displaying an HLA-C1C2 allotype.We investigated NK cell-treated and untreated cultures through multiplexed single-cell RNA sequencing (scRNA-seq) to dissect adaptive changes in both NK and AML BM cells upon their interaction. In total, we investigated 121 samples through scRNA-seq: 11 monocultures of expanded NK cells, 55 AML BM cells and 55 co-cultures of AML BM cells and expanded NK cells. scRNA-seq yielded 95,715 high quality cells (791 cells per sample on average), including 31,882 NK cells (483 cells per sample on average) and 63,833 AML BM cells (580 cells per sample on average). Unsupervised clustering of the cells revealed distinct clusters separating expanded NK cells from AML cells (Fig. 1a). We studied the sensitivity of leukemic cells to NK cytotoxicity using high-throughput flow cytometry. We further integrated the results with genetic and clinical data of the AML patients to characterize the mechanisms of action driving the transcriptomic responses and leukemic cell susceptibility to NK cell killing. After 24 h co-culture, scRNA-seq revealed that AML BM cells induced distinct gene expression states in the NK cells. The observed tumor-induced NK states were predominantly enriched in co-cultured samples and not found in NK cell monocultures which mostly consisted of resting-state NK cells. Across the co-cultures, half of the AML samples triggered at least 30% of NK cells to change from resting to tumor-induced states (Fig. 1b). Out of the 28 AML samples causing the strongest NK cell induction, 54% primarily triggered a type I interferon (IFN) signature, characterised by expression of genes encoding MX1, OAS1, and IRF7. In contrast, the other 46% mainly induced an activated phenotype, including expression of TNFRSF18 ( GITR), TNFRSF9 ( 4-1BB), TIGIT and HAVCR2 ( TIM-3). Killer cell immunoglobulin-like receptors-HLA ligand mismatchesare well known causes of NK alloreactivity. Thus, we explored whether HLA-C matched (C1C2, n=24) and mismatched (C1C1 or C2C2, n=28) AML samples influenced NK cell responses. Interestingly, no significant difference in the NK cell induction states was observed between matched and mismatched samples (Mann-Whitney p = 0.57). NK cell treatment also induced responses in the patients' own T cells. Both CD4+ and CD8+ T cells upregulated IFN-ɣ and type I IFN genes upon co-culture. The type I IFN signature in CD8+ T cells was mainly found in AML samples triggering strong NK cell induction. CD8+ T cells also upregulated cytotoxicity genes including FASLG and TNFSF10 (TRAIL), along with inhibitory molecules such as LAG3, suggesting that NK cells can promote effector functions of T cells. Our results suggest that AML BM cells from different patients trigger a heterogeneous response in expanded NK cells. Only in half of the cases, the leukemic BM cells induced substantial activation of NK cells. The observed variation in NK states was not determined by HLA-C allotypes, suggesting that other tumor cell features are responsible for the responses. This underscores the importance of understanding the molecular drivers of tumor and NK cell interaction. Our data additionally show that NK cell-based immunotherapy may be able to promote the functionality of the patient's own T cells, demonstrating how our ex vivo modeling approach can help to refine the mechanism of action of immunotherapies. Our work paves the way for identifying subgroups of AML patients responding to NK cell-based immunotherapies.

Werner helicase mediates the senescence and cell cycle of leukemia cells by regulating DNA repair pathways

Leukemia is a type of malignant hematological disease that is generally resistant to chemotherapy and has poor therapeutic outcomes. Werner (WRN) DNA helicase, an important member of the RecQ family of helicases, plays an important role in DNA repair and telomere stability maintenance. WRN gene dysfunction leads to premature aging and predisposes humans to various types of cancers. However, the biological function of WRN in cancer remains unknown. In this study, the expression of this RecQ family helicase was investigated in different types of leukemia cells, and the leukemia cell line K562 with high WRN expression was selected to construct a WRN knockdown cell line. The results showed that WRN knockdown inhibited leukemia occurrence and development by regulating the proliferation, cell cycle, differentiation, and aging of cells and other biological processes. The results of transcriptome sequencing revealed that WRN promoted the sensitivity of leukemia cells to the DNA damage inducer Etoposide by regulating cell cycle-related proteins, such as CDC2, cyclin B1, p16, and p21, as well as key proteins in DNA damage repair pathways, such as p53, RAD50, RAD51, and MER11. Our findings show that WRN helicase is a promising potential target for leukemia treatment, providing new ideas for the development of targeted drugs against leukemia.

Clonal Targeting of DNA Damage Response Pathways Eradicates Myeloproliferative Neoplasms

Clonal diversity of myeloproliferative neoplasms (MPN) plays a key role in poor therapeutic outcomes. MPN cells usually accumulate spontaneous DNA damage including highly toxic DNA double-strand breaks (DSBs) induced by metabolic products and replication stress. To repair numerous DSBs and survive, MPN cells activate the DNA damage response (DDR) involving the pathways that sense (ATM and ATR kinases) and repair (RAD51-mediated homologous recombination = HR, RAD52-mediated transcription associated homologous recombination = TA-HR and single strand annealing = SSA, DNA-PK -mediated non-homologous end-joining = NHEJ, PARP1/Polq-dependent microhomology-mediated end-joining = MMEJ) DSBs. Thus, DDR is a legitimate therapeutic target. Numerous MPN-driving mutations [ JAK2(V617F), TETmut, DNMT3Amut, IDH1mut] regulate DDR and affect the sensitivity of leukemia cells to DDR inhibitors (DDRi). The genetic landscape of malignant clones in a patient may be complicated since individual clones can carry multiple mutations. Thus, individual MPN clones may respond differently to DDRi depending on their mutational profile. In our experimental protocol MPN cells from individual patients were treated with various DDRi followed by single-cell targeted DNA sequencing (sctDNA-seq) to integrate patient's leukemia clonal composition with response to the inhibitors. We developed a sctDNA-seq myeloid platform interrogating up to 1394 genetic variants of 54 known leukemia driver genes, which unraveled the clonal landscape of MPN at a single-cell resolution before and after the treatment. Based on these results we designed a “clonal attack”, a patient-tailored combination of DDRi targeting all MPN clones in a patient sample. Here we show that DDRi simultaneously attacking different clones caused MPN clonal attrition in vitro. For example, phylogenetic tree analysis of MPN patient P349 sample detected linear multi-clonal architecture with 3 Lin-CD34+ clones carrying specific sets of mutations. sctDNA-seq followed by fish plot analysis revealed clonal similarities and differences in response to DDRi. The clone carrying KMT2A(L2373H) + SETBP1(H1100R) was more sensitive to ATRi than RAD52i, conversely clones with KMT2A(L2373H) alone and KMT2A(L2373H) + SETBP1(H1100R) + FLT3(R834L) were more sensitive to RAD52i than ATRi. Based on this observation, we hypothesized that simultaneous treatment with ATRi+RAD52i should result in elimination of all 3 MPN P349 clones. Remarkably, the combination of RAD52i + ATRi was &amp;gt;100x more effective in inhibiting clonogenic growth of Lin-CD34+ P349 cells (all clonogenic cells were eradicated). On the other hand, combination of RAD52i + ATMi, the two DDR inhibitors displaying similar pattern of clonal targeting was only 2x better than individual inhibitors. Phylogenetic tree analysis of Lin-CD34+ cells from another MPN patient P350 sample showed linear multi-clonal architecture with 4 clones. Again, sctDNA-seq followed by fish plot analysis revealed clonal similarities and differences in response to DDRi. All 4 clones displayed similar sensitivity to RAD52i and ATMi, but they responded differently to PARPi and ATRi. Clones carrying TET2(P363L) + NRAS(G12D) were more sensitive to ATRi than PARPi, whereas clones with TET2(P363L) + NRAS(G12D) + DNMT3A(W330C) and TET2(P363L) + NRAS(G12D) + DNMT3A(W330C) + IDH2(R132C) responded better to PARPi than ATRi. Importantly, the combination of PARPi + ATRi was &amp;gt;9x more effective in inhibiting clonogenic growth of Lin-CD34+ P349 cells, whereas RAD52i + ATMi was only 2x better than individual inhibitors. In conclusion, we postulate that sctDNA-seq combined with in vitro DDRi sensitivity testing (sctDNA-seq/DDRi) is a powerful tool to interrogate clonal sensitivity of MPN to these agents. This clonal medicine approach may become a novel therapeutic regimen to overcome clonal complexity of MPN in a cohort of patients. The “clonal attack” by DDR inhibitors shifts the paradigm of genotoxic therapies from those using non-discriminative cytotoxic drugs to those selectively attacking DDR vulnerabilities in MPN clones with minimal harm to normal cells. Since clonal heterogeneity and DNA damage are hallmarks of cancer, the “clonal attack” may be broadly applicable to the quest for cancer cure.

Rituximab Improves Clinical Outcomes of CAR-T Therapy for r/r B-ALL Via Sensitizing Leukemia Cells to CAR-T-Mediated Cytotoxicity and Reducing CAR-T Exhaustion

Background: Despite chimeric antigen receptor (CAR) T-cell therapy has achieved great advances in recent year, approximately 50% of relapsed/refractory B cell acute lymphoblastic leukemia (r/r B-ALL) patients treated with CAR-T experience relapse 6 months post CAR-T treatment. CD20 express on 30 to 50% of B-ALL, which makes CD20 Monoclonal Antibody as one of the potential therapy strategies to decrease the tumor burden and improve the efficacy of CAR-T therapy. Adding Rituximab to chemotherapy protocol had been demonstrated to improve the outcome for CD20-positive ALL. However, rare study explored the influence of Rituximab combined with CAR-T therapy. Methods: We retrospectively analyzed 20 r/r B-ALL patients who received CAR-T therapy, all of whom had failed multiple lines of therapy. Before CAR-T infusion, we administered Rituximab to 10 patient with high CD20 expression at a dose of 375mg/m2 for 1 day. Meanwhile, we selected 10 patients with the comparable features who underwent CAR-T treatment without Rituximab in the same period as the control group. In vitro, the surface molecule expression and killing of CAR-T post Rituximab-treated B-ALL cells co-incubated with CAR-T cells were detected by flow cytometry. Results The day 28 after CAR-T cells infusion, 8（80%） and 6（60%） of the 10 patients achieved minimal residual disease negative complete remission (MRD-negative CR) in Rituximab group and Control group, respectively. The median follow-up of Rituximab and Control groups were 29.27 and 9.83 months. The 2-year overall survival (OS) and leukemia-free survival (LFS) rates both were longer in the Rituximab group (90% vs 26.7%, p=0.034; 41.7% vs 25%, P=0.14). Particularly, subgroup analysis showed that Rituximab could markedly improve the OS and LFS for relapsed patients (88.9% vs 25%, P=0.0203; 87.5% vs 15%, P=0.0112). In addition, CAR-T combined with Rituximab improved long-term outcome in patients who had failed multiple lines of therapy (&amp;gt;5) (2-year OS 100% vs 16.7%, P=0.0205; 1-year LFS 50% vs 0%, P=0.011). There was no significant difference between the two groups in hematological toxicities as well as in non-hematological toxicities. All adverse events were manageable（Figure1）. In vitro, we observed that Rituximab-treated tumor cells are more sensitive to CAR-T killing and a broad range of cytokines and chemokines were produced when Rituximab-treated Nalm-6 cells co-cultured with 19-22CAR-T cells, such as interferon-γ(IFN-γ), tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2)(IL-2:272.5 pg/ml vs 84.83 pg/ml, P=0.0243; IFN-γ: 6111 pg/ml vs 796 pg/ml, P=0.0451,TNF-α: 1374 pg/ml vs 629.4 pg/ml, P=0.048)（Figure 2）. To investigate whether Rituximab has an effect on CAR-T persistence, we stimulated CAR-T cells repeatedly in vitro with Rituximab-treated Nalm-6 to evaluate the changes in CAR-T surface exhaustion molecules at different times. We found that the expression of exhaustion molecules (LAG-3, PD-1, TIM-3) on CAR-T cells were significantly lower in the Rituximab group than in the Control group (LAG-3: 57.23% vs 71.8%, P=0.0015; PD-1: 35.57% vs 69.03%, P&amp;lt;0.001; TIM-3:36.53% vs 68.9%, P&amp;lt;0.001). Conclusion: Rituximab combined with CAR-T therapy was effective for improving the long-term outcome of B-ALL patients who have failed multiple lines of therapy. In vitro, we observed that rituximab potentially improved CAR-T efficacy by sensitizing Leukemia Cells to CAR T-mediated cytotoxicity and reducing CAR-T exhaustion.

Cerebral Spinal Fluid Attenuates the Efficacy of Methotrexate Against Acute Lymphoblastic Leukemia Cells

The anti-folate methotrexate is a critical component of acute lymphoblastic leukemia (ALL) therapy. In addition to systemic administration, methotrexate is given intrathecally, or directly into the cerebral spinal fluid (CSF) via lumbar puncture, for central nervous system (CNS) leukemia treatment and prophylaxis. While IT methotrexate played a critical role in improving outcomes for ALL, CNS ALL relapse remains a major cause of treatment failure and therapy related morbidity. However, attempts to develop more efficacious and less toxic CNS ALL therapies have been largely unsuccessful and IT methotrexate has remained the standard of care for 60+ years. Based on our prior work showing that ALL cells are more poised to undergo apoptosis in nutrient poor CSF, we initially hypothesized that ALL chemosensitivity will be increased in CSF (Basile et al., 2020). While this was confirmed for several ALL drugs including cytarabine and anthracyclines, we strikingly found that methotrexate was significantly less efficacious and potent against ALL cells in CSF relative to standard tissue culture media or the more physiologically relevant human plasma-like media (HPLM). CSF also attenuated the sensitivity of ALL cells to other anti-folates including raltitrexed, trimetrexate, and pralatrexate. To define the mechanism(s) underlying this methotrexate resistance induced by CSF, we explored previously well-described mechanisms of methotrexate resistance in leukemia and other cancers. However, to date this work suggests that the molecular etiology of this CSF-induced relative methotrexate resistance is not entirely explained by diminished leukemia proliferation in CSF, altered methotrexate cellular influx/efflux, methotrexate metabolism, folate analog rescue, dysregulated expression of methotrexate target proteins, or compensation by nucleotide salvage pathways. To complement our work examining known mechanisms of methotrexate resistance, we also used a more discovery-based approach and compared the gene expression patterns of leukemia cells in CSF versus tissue culture media. Preliminary bioinformatic analyses identified dysregulation of multiple genes involved in the integrated stress response (ISR) and unfolded protein response (UPR) pathways in leukemia cells in CSF. The ISR/UPR are mechanisms by which cells adapt to diverse stress stimuli in the microenvironment, including potentially nutrient poor CSF which is low in glucose, proteins, and lipids relative to plasma. The hallmark event in this pathway is the phosphorylation of the translation initiation factor eIF2α, which inhibits global protein synthesis and enables the translation of selected genes that together enable cell survival. Supporting our gene expression data, ALL cells in CSF showed increased phosphorylation of eIF2α and a decrease in global protein synthesis. Intriguingly, it has been shown that activation of the UPR can divert metabolites from glycolysis to mitochondrial one-carbon metabolism with resulting resistance to anti-folates such as methotrexate (Reich et al., 2020). Accordingly, we next tested the effect of UPR/ISR activation on leukemia cell sensitivity to methotrexate in tissue culture media. Activation of the UPR with thapsigargin, a sarco/endoplasmic reticulum Ca 2+ ATPase (SERCA) inhibitor that triggers ER stress, increased methotrexate resistance in leukemia cells. Similarly, BtdCPU a small-molecule activator of heme regulated inhibitor (HRI) kinase that phosphorylates eIF2α and activates the ISR, also enhanced leukemia resistance to methotrexate. Building upon these results, current investigations are focused on testing the role of UPR/IST activation in methotrexate resistance in leukemia cells in CSF and modulating this pathway to overcome resistance. While methotrexate is clearly an efficacious and critical component of CNS leukemia treatment and prophylaxis, we have shown that CSF attenuates the overall efficacy of methotrexate in targeting leukemia cells. Moreover, we anticipate that our current work defining the mechanisms driving this resistance may identify novel approaches for maximizing methotrexate efficacy and more completely eradicating leukemia cells in CSF and the CNS. Finally, this work highlights the importance of critically evaluating even long-established standards of care.

Two palladium (II) complexes derived from halogen-substituted Schiff bases and 2-picolylamine induce parthanatos-type cell death in sensitive and multi-drug resistant CCRF-CEM leukemia cells

The use of cisplatin and its derivatives in cancer treatment triggered the interest in metal-containing complexes as potential novel anticancer agents. Palladium (II)-based complexes have been synthesized in recent years with promising antitumor activity. Previously, we described the synthesis and cytotoxicity of palladium (II) complexes containing halogen-substituted Schiff bases and 2-picolylamine. Here, we selected two palladium (II) complexes with double chlorine-substitution or double iodine-substitution that displayed the best cytotoxicity in drug-sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 leukemia cells for further biological investigation. Surprisingly, these compounds did not significantly induce apoptotic cell death. This study aims to reveal the major mode of cell death of these two palladium (II) complexes. We performed annexin V-FITC/PI staining and flow cytometric mitochondrial membrane potential measurement followed by western blotting, immunofluorescence microscopy, and alkaline single cell electrophoresis (comet assay). J4 and J6 still induced neither apoptosis nor necrosis in both leukemia cell lines. They also insufficiently induced autophagy as evidenced by Beclin and p62 detection in western blotting. Interestingly, J4 and J6 induced a novel mode of cell death (parthanatos) as mainly demonstrated in CCRF-CEM cells by hyper-activation of poly(ADP-ribose) polymerase 1 (PARP) and poly(ADP-ribose) (PAR) using western blotting, flow cytometric measurement of mitochondrial membrane potential collapse, nuclear translocation of apoptosis-inducing factor (AIF) by immunofluorescence microscopy, and DNA damage by alkaline single cell electrophoresis (comet assay). AIF translocation was also observed in CEM/ADR5000 cells. Thus, parthanatos was the predominant mode of cell death induced by J4 and J6, which explains the high cytotoxicity in CCRF-CEM and CEM/ADR5000 cells. J4 and J6 may be interesting drug candidates and deserve further investigations to overcome resistance of tumors against apoptosis. This study will promote the design of further novel palladium (II)-based complexes as chemotherapeutic agents.

Bcl-2 family inhibitors sensitize human cancer models to therapy

BH3 mimetics, targeting the Bcl-2 family anti-apoptotic proteins, represent a promising therapeutic opportunity in cancers. ABT-199, the first specific Bcl-2 inhibitor, was approved by FDA for the treatment of several hematological malignancies. We have recently discovered IS21, a novel pan BH3 mimetic with preclinical antitumor activity in several tumor types. Here, we evaluated the efficacy of IS21 and other BH3 mimetics, both as single agents and combined with the currently used antineoplastic agents in T-cell acute lymphoblastic leukemia, ovarian cancer, and melanoma. IS21 was found to be active in T-cell acute lymphoblastic leukemia, melanoma, lung, pancreatic, and ovarian cancer cell lines. Bcl-xL and Mcl-1 protein levels predicted IS21 sensitivity in melanoma and ovarian cancer, respectively. Exploring IS21 mechanism of action, we found that IS21 activity depends on the presence of BAX and BAK proteins: complexes between Bcl-2 and Bcl-xL proteins and their main binding partners were reduced after IS21 treatment. In combination experiments, BH3 mimetics sensitized leukemia cells to chemotherapy, ovarian cancer cells and melanoma models to PARP and MAPK inhibitors, respectively. We showed that this enhancing effect was related to the potentiation of the apoptotic pathway, both in hematologic and solid tumors. In conclusion, our data suggest the use of inhibitors of anti-apoptotic proteins as a therapeutic strategy to enhance the efficacy of anticancer treatment.

AKT inhibition sensitizes acute leukemia cells to S63845-induced apoptosis

ABSTRACTThe MCL1 inhibitors are undergoing clinical testing for multiple leukemia. However, because that MCL1 inhibition has on-target hematopoietic, hepatic and cardiac toxicities, there is substantial interest in finding agents can sensitize leukemia cells to the MCL1 inhibitors. Here we describe that the AKT inhibitors MK-2206 and Gsk690693 sensitize multiple leukemia cells to the MCL1 inhibitor S63845. Further experiments demonstrate that MK-2206 and Gsk690693 sensitize S63845 through the mitochondrial apoptosis pathway. Moreover, MK-2206 downregulates the anti-apoptotic protein BCLXL and induces the BH3-only pro-apoptotic protein BAD dephosphorylation and mitochondrial translocation. Knockdown of BAD significantly inhibits MK-2206-induced sensitization to S63845. Thus, our results suggest that MK-2206 sensitizes multiple leukemia cells to S63845-induced apoptosis, with the mechanisms involving BAD dephosphorylation and BCLXL downregulation.

Ciclopirox olamine sensitizes leukemia cells to natural killer cell-mediated cytolysis by upregulating NKG2DLs via the Akt signaling pathway

The activating receptor natural killer group 2D (NKG2D) expressed by Natural killer (NK) cells functions as a “master-switch” in governing the awakening status of NK cells. The NKG2D-mediated cytotoxicity has been declared to be related with the expression levels of NKG2D ligands (NKG2DLs) expressed on tumor cells. Therefore, selective induction of NKG2DLs could be a reliable approach to enhance the efficacy of NK cell-mediated immunotherapy. Our existing study demonstrated that Ciclopirox Olamine (CPX), an off-patent antifungal agent, effectively elevated the expression of NKG2DLs on leukemia cells and sensitized leukemia cells to NK-cell mediated cytolysis. Induction of ROS production and AKT phosphorylation by CPX is essential for the up-regulation of NKG2DLs expressions. Inhibition of AKT by using AKT inhibitor MK2206 decreased both NKG2DLs expressions and NK cell cytotoxicity. These data indicated that increased sensitivity of CPX-treated leukemia cells to NK cell cytolysis was attributed to higher NKG2DLs expressions, resulting from activated AKT signaling pathway. Our findings support the ongoing development of CPX as an anti-tumor agent and suggest its promising immunotherapeutic value in the medication of leukemia.