Apoptosis In Myeloid Leukemia Cells Research Articles

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.

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.

Decitabine Enhances Acute Myeloid Leukemia Cell Apoptosis through SH3BGRL Upregulation.

SH3-domain-binding glutamic acid-rich protein-like protein (SH3BGRL) is downregulated in acute myeloid leukemia (AML). Clinically, DNA demethylating drug decitabine (DAC) combined with traditional chemotherapies reveals better efficacy on AML patients than the conventional chemotherapies alone. Our previous results revealed that human SH3-domain-binding glutamic acid-rich protein-like protein (SH3BGRL) plays a tumor suppressive role in AML but whether there is a connection between DAC and SH3BGRL expression remains elusive. Here, we tentatively treated AML cell lines U937, MV4, and HL-60 with DAC and Western Blots, RT-PCR was used to detect the expression of SH3BGRL. Cell proliferation and apoptosis were determined using Annexin V/7- AAD staining. Real-time RT-PCR and Western blot were used to determine the expression of SH3BGRL mRNA and protein. Methylation-specific PCR was used to quantify the DNA methylation in AML cell lines. DAC had cytotoxicity in HL-60, MV4, and U937. In U937 cell lines, treatment with DAC showed the upregulation of cleaved caspase3, PARP, and SH3BGRL. Upon treatment, up-regulation of SH3BGRL mRNA and protein was dose-dependent and this activity was partially inhibited in endogenous SH3BGRL knockdown cell lines. Thus, our results demonstrated a possibly cytotoxic role of DAC on AML cells by upregulation of SH3BGRL expression at epigenetic modulation level and the methylation status in the SH3BGRL promoter region could be a supplemental diagnostic marker to the precise administration of DAC to AML patients.

Induced effect of zinc oxide nanoparticles on human acute myeloid leukemia cell apoptosis by regulating mitochondrial division.

Zinc oxide nanoparticles (ZnO NPs) have exhibited excellent anti-tumor properties; the present study aimed to elucidate the underlying mechanism of ZnO NPs induced apoptosis in acute myeloid leukemia (AML) cells by regulating mitochondrial division. THP-1 cells, an AML cell line, were first incubated with different concentrations of ZnO NPs for 24 hr. Next, the expression of Drp-1, Bcl-2, Bax mRNA, and protein was detected, and the effects of ZnO NPs on the levels of reactive oxygen species (ROS), mitochondrial membrane potential (Δψm), apoptosis, and ATP generation in THP-1 cells were measured. Moreover, the effect of Drp-1 inhibitor Mdivi-1 and ZnO NPs on THP-1 cells was also detected. The results showed that the THP-1 cells survival rate decreased with the increment of ZnO NPs concentration and incubation time in a dose- and time-dependent manner. ZnO NPs can reduce the cell Δψm and ATP levels, induce ROS production, and increase the levels of mitochondrial division and apoptosis. In contrast, the apoptotic level was significantly reduced after intervention of Drp-1 inhibitor, suggesting that ZnO NPs can induce the apoptosis of THP-1 cells by regulating mitochondrial division. Overall, ZnO NPs may provide a new basis and idea for treating human acute myeloid leukemia in clinical practice.

Inhibitors of poly ADP-ribose polymerase (PARP) induce apoptosis of myeloid leukemic cells: potential for therapy of myeloid leukemia and myelodysplastic syndromes.

Inhibitors of poly ADP-ribose polymerase (PARP) induce apoptosis of myeloid leukemic cells: potential for therapy of myeloid leukemia and myelodysplastic syndromes.

Direct-Acting Small Molecule Activators of PP2A (SMAPs) in Myeloid Malignancies: Understanding Mechanisms of Cytotoxicity to Inform Rational Combinatorial Therapeutic Strategies

The protein phosphatase 2A (PP2A) functions as a tumor suppressor by counteracting oncogenic kinase signaling. Suppression of PP2A activity represents a critical process in the development and maintenance of many neoplasms, including myeloid malignancies; PP2A inhibition de-represses numerous proliferative and survival signaling pathways. However, complete loss of PP2A is lethal to cells. As such, indirect reactivation of PP2A has emerged as a promising therapeutic strategy for myeloid leukemias. Yet the broad applicability of such a strategy remains uncertain, as it relies on targeting endogenous PP2A inhibitors. In the present work we investigated the effects of direct acting small molecule activators of PP2A (SMAPs) (Sandokar et al. JCI 2017) on myeloid leukemia cells and uncovered a novel link between PP2A reactivation and NOXA-mediated apoptosis. This mechanism explains our observation of cooperativity between SMAPs and the BH3 mimetic ABT-199 (venetoclax). Additionally, we found that SMAPs elicit a protective stress response that can be overcome by inhibition ofprotein kinase R (PKR)-like endoplasmic reticulum kinase (PERK).Given the known role of PP2A inactivation in both acute and chronic myeloid leukemia (AML and CML), we first tested the activity of SMAPs against cell lines derived from both diseases. Across all cell lines tested (CML- K562, Meg-01; AML- MOLM-14, HL-60, OCI-AML3, THP-1) SMAPs caused a dose-dependent decrease in cell viability. It is known that reactivation of PP2A induces apoptosis in myeloid leukemia cells, though this area has yet to be thoroughly investigated. Therefore, we first sought to clarify the mode of cell death in response to PP2A reactivation. Both by biochemical and flow cytometric analyses, SMAPs showed activation of the intrinsic apoptotic cascade. Furthermore, SMAP-mediated cell death was blocked by co-treatment with the caspase inhibitor z-VAD-FMK (50 μM). We previously demonstrated the target specificity of SMAPs for PP2A with methods including expression of SV40 small T antigen and PP2A alpha subunit drug-binding mutants (Sandokar et al. JCI 2017). Here, we confirmed that pre-treatment with the PP2A inhibitor okadaic acid at a dose that retains selectivity for PP2A (10 nM) attenuated SMAP-induced cell death and cleavage of PARP and caspase-3.Next, we investigated the effectors of SMAP-mediated apoptosis. To this end, we performed Western blots to detect changes in abundance and/or phosphorylation of a panel of Bcl-2 family member proteins. Interestingly, a strong upregulation of the pro-apoptotic protein NOXA occurred consistently across AML and CML cell lines. Further RT-PCR studies showed this increase to occur at the transcript level. Knockdown studies confirmed the importance of NOXA for SMAP-mediated apoptosis. These data represent the first reported link between PP2A and NOXA regulation. Since SMAPs target the NOXA-MCL1 axis of the Bcl-2 family, we next tested their efficacy in combination with the Bcl-2-selective BH3 mimetic ABT-199. We found co-treatment with SMAPs and ABT-199 to exhibit enhanced cell death compared to either agent alone.Concurrent with NOXA elevation, SMAP treatment modulated protein expression and phosphorylation levels for several known pathways downstream of PP2A. Interestingly, we additionally observed increased phosphorylation of eukaryotic translation initiation factor 2 subunit alpha (eIF2α) in SMAP-treated cells which correlated with upregulation of mRNA and protein for the downstream transcription factor ATF4. Blockade of eIF2α phosphorylation with PERK inhibitor GSK2656157 (350 nM) prevented ATF4 elevation and enhanced SMAP-induced apoptosis. This result supports the idea that the integrated stress response (ISR) via PERK-eIF2α-ATF4 acts to counter apoptosis in the context of PP2A reactivation in myeloid leukemia cells. Thus, the efficacy of SMAPs and other PP2A-activating therapeutics may be enhanced by combination with both BH3 mimetics and inhibitors of the ISR. DisclosuresNarla:Mount Sinai School of Medicine: Patents & Royalties: patents on the small molecule PP2A activators (GN).

Thymoquinone Suppresses Cell Proliferation and Enhances Apoptosis of HL60 Leukemia Cells through Re-Expression of JAK/STAT Negative Regulators.

Objective:The natural compound, thymoquinone (TQ) has demonstrated potential anticancer properties in inhibiting cell proliferation and promoting apoptosis in myeloid leukemia cells, breast cancer cells, and others. However, the effect mechanism of TQ on AML cells still not fully understood. In this study, the authors examined the effects of TQ on the expression of JAK/STAT-negative regulator genes SOCS-1, SOCS-3, and SHP-1, and their consequences on cell proliferation and apoptosis in HL60 leukemia cells. Methods:MTT and trypan blue exclusion tests were conducted to determine the 50% inhibitory concentration (IC50) and cell proliferation. FITC Annexin and Guava® reagent were used to study the cell apoptosis and examine the cell cycle phases, respectively. The expression of JAK/STAT-negative regulator genes, SOCS-1, SOCS-3, and SHP-1, was investigated using reverse transcriptase- quantitative PCR (RT-qPCR). Results:TQ demonstrated a potential inhibition of HL60 cell proliferation and a significant increase in apoptotic cells in dose and time-dependent manner. TQ significantly induced cycle arrest at G0-G1 phase (P < 0.001) and enhanced the re-expression of JAK/STAT-negative regulator genes. Conclusion:TQ potentially inhibited HL60 cell proliferation and significantly increased apoptosis with re-expression of JAK/STAT-negative regulator genes suggesting that TQ could be a new therapeutic candidate for leukemia therapy.

Inhibition of Wnt/Beta-Catenin Pathway Impairs Natural Killer (NK) Cells Induced Apoptosis of Myeloid Leukemia Cells

Introduction:NK cells play an important role in the immune response to cancer due to their ability to induce T-cell independent apoptosis of neoplastic cells. NK cells recognize tumor cells through the interaction of several distinct cell surface receptors, with the net result of inducing NK cell activation and cytotoxic attack on tumor cells. It is hypothesized that a failure of NK surveillance is a contributing factor in the development of acute myeloid leukemia (AML). The discovery of pathways that regulate AML cell apoptosis in response to NK cells activation may represent a potential therapeutic target. It is known that the Wnt/beta-catenin pathway regulates cellular proliferation, differentiation and resistance to apoptosis in AML cells. However, its contribution to the resistance of AML cells in response to NK cell-induced apoptosis resistance is currently unknown. Objective:The objective of the current study is to determine if inhibition of the Wnt/beta catenin pathway impacts NK cell-induced apoptosis of AML cells. Methods:HL-60 leukemia cells were treated with different concentrations of the Wnt/beta-catenin pathway inhibitor XAV-939 (tankyrase inhibitor) to determine the lowest dose capable of inhibiting the Wnt/beta-catenin pathway without inducing cell apoptosis. Inhibition of the pathway was confirmed by evaluating beta-catenin protein by intracellular flow cytometry and real-time PCR for downstream factors MYC and TCF4. Next, differentiation of HL-60 cells into mature granulocytes was evaluated by analyzing expression of CD11b by flow cytometry after stimulation with dimethyl sulfoxide (DMSO), as another marker of Wnt/Beta-catenin pathway inhibition. After confirming pathway inhibition, HL-60 cells were incubated with healthy donor derived NK cells in a 2:1 ratio for 24 hours in the presence or absence of XAV-939. Apoptosis was evaluated by annexin staining. Expression of NK cell inhibitory proteins were determined by flow cytometry. A panel of 84 genes for hematopoietic transcription factors was evaluated by PCR array (RT2 Profiler PCR Array Gene Expression - Qiagen) in HL-60 cells after exposure to XAV-939 for 2 and 6 hours. Expression of apoptosis related genes in HL-60 cells after exposure to XAV-939 was determined by real-time PCR. Results:The dose of 1mM XAV-939 was selected to evaluate is effect in the HL-60 cell line. Suppression of pathway signaling was confirmed by a decrease in expression of Beta-catenin,MYC,TCF4and blockade of HL-60 differentiation into neutrophils. After coincubation with NK cells, there was a decrease in HL-60 cell death with concomitant exposure to XAV-939 (70% [untreated] vs. 30% [XAV-939]; p&amp;lt;0.05) (figure 1). There was no change in NK cell surface receptors or their putative ligands in HL-60 cells as evaluated by flow cytometry. Analysis of expression of hematopoietic transcription factor in HL-60 cells showed a downregulation of several transcription factors after exposure to XAV-939, includingJUNDandTCF7L2. Since there was a decrease in apoptotic cell death, we next evaluated expression of genes related to apoptotic pathways and could demonstrate a decrease in expression ofFASandTNFR1after exposure to XAV-939 (p&amp;lt;0.05) (figure 2A and 2B). Conclusions:These results suggest that inhibition of the Wnt/beta-catenin pathway decreases apoptosis of myeloid leukemia cells mediated by NK cells, and this effect may be secondary to a decreased expression ofFASandTNFR1in the leukemic cells. Figure Disclosures Santos: Novartis:Other: Speaker fee;Bristol-Myers Squibb:Other: Speaker fee.

Epigallocatechin gallate induces CHD5 gene demethylation to promote acute myeloid leukemia cell apoptosis in vitro by regulating p19Arf-p53-p21Cip1 signaling pathway

To investigate the mechanism by which epigallocatechin gallate (EGCG) induces CHD5 gene demethylation and promotes the apoptosis of acute myeloid leukemia KG-1 and THP-1 cell lines. KG-1 and THP-1 cells treated with 25, 50, 75, 100 or 150 μg/mL EGCG for 48 h were examined for CHD5 gene methylation using MSP and for cell proliferation using MTT assay. The changes in cell cycle and apoptosis of the two cell lines after treatment with EGCG for 48 h were detected using flow cytometry. The mRNA and protein expressions of DNMT1, CHD5, p19Arf, p53 and p21Cip1 in the cells were detected using RT-quantitative PCR and Western blot. EGCG dose-dependently reversed hypermethylation of CHD5 gene and reduced the cell viability in both KG-1 and THP-1 cells (P < 0.05). EGCG treatment caused obvious cell cycle arrest in G1 phase, significantly increased cell apoptosis, downregulated the expression of DNMT1 and upregulated the expressions of CHD5, p19Arf, p53 and p21Cip1 in KG-1 and THP-1 cells (P < 0.05). EGCG reduces hypermethylation of CHD5 gene in KG-1 and THP-1 cells by downregulating DNMT1 to restore its expression, which results in upregulated expressions of p19Arf, p53 and p21Cip1 and induces cell apoptosis.

Aprepitant Sensitizes Acute Myeloid Leukemia Cells to the Cytotoxic Effects of Cytosine Arabinoside in vitro and in vivo.

PurposeAcute myeloid leukemia (AML) is a complex malignancy characterized by the clonal expansion of immature myeloid precursors. The standard treatment for newly diagnosed AML is chemotherapy consisting of cytosine arabinoside (Ara-C) and anthracyclines with disappointing clinical outcomes and severe adverse effects, such as symptomatic bradycardia, neurotoxicity. Thus, it is promising to treat AML through combination drug therapy to reduce the adverse effects of chemotherapeutics. In our recent published PNAS paper, we reported that NK-1R antagonists, both Aprepitant and SR140333, induce apoptosis of myeloid leukemia cells by inducing oxidative stress through mitochondrial calcium overload. We, therefore, tested the hypothesis of the combination Ara-C with NK-1R antagonist could enhance the efficacy of Ara-C.MethodsMTT assay was employed to detect the cell proliferation. Flow cytometry was applied to detect the cell cycle and necrosis. PI uptake and LDH release assay were used to detect the disintegration of the plasma membrane. Xenograft model was constructed to explore the effect of combination Ara-C with Aprepitant in vivo.ResultsOur results showed that Aprepitant sensitizes HL60 cells to the cytotoxic effects of Ara-C more than 5-fold by enhancing G0/G1 cell cycle arrest and necrosis in vitro. Furthermore, Nec-1, a specific inhibitor of necroptosis, could recover the cell proliferative viability significantly. Attractively, once every 2-days regimen of Ara-C (5 mg/kg) and Aprepitant (10 mg/kg) via in situ injection dramatically reduced the tumor volume from 2175.0 ± 341.9 mm3 in the vehicle group to 828.4 ± 232.4 mm3 in the combination group without obvious toxicity in human myeloid leukemia xenograft mice.ConclusionTaken together, reduced dose of Ara-C combination with moderate Aprepitant provides more effective therapeutical methods for AML treatment in vitro and in vivo with the elimination of the toxicity of Ara-C, which may pay new avenue for the usage of the routine chemotherapy drug Ara-C with low dose to enhance efficacy and reduce toxicity in clinical practice.

Effects of triptolide and BET protein inhibitor JQ1 on the proliferation and apoptosis of MLL-rearranged acute myeloid leukemia cells and their mechanisms

Objective To investigate the effects of triptolide (TPL) and BET protein inhibitor JQ1 on proliferation inhibition and apoptosis induction of MLL-rearranged acute myeloid leukemia (AML) cell line MV4-11, and to explore their synergistic mechanisms. Methods MV4-11 cells in logarithmic growth phase were treated with different concentrations (100, 200, 300, and 400 nmol/L) of JQ1, 4 nmol/L TPL or different concentrations of JQ1 combined with 4 nmol/L TPL for 48 h. Cell proliferation was detected by CCK-8 method, apoptosis was detected by flow cytometry (FCM), mitochondrial membrane potential was detected by JC-1 method, and expressions of mitochondrial apoptosis pathway-related proteins were detected by Western blot. Results The 50% inhibitory concentration (IC50) value of MV4-11 cells treated with JQ1 for 48 h was (283.9±10.7) nmol/L. However, 4 nmol/L TPL significantly enhanced the inhibitory effect of JQ1 on proliferation of MV4-11 cells, the IC50 value of MV4-11 cells treated with JQ1 combined with TPL was (148.1±2.6) nmol/L, and the difference was statistically significant (t = 25.31, P = 0.029). The result of FCM assay showed that compared with the JQ1 alone group [(9.6±2.3)%, (12.6±1.4)%, (19.5±3.3)%, and (22.7±2.1)%], 4 nmol/L TPL combined with different concentrations (100, 200, 300, and 400 nmol/L) of JQ1 acted on MV4-11 cells for 48 h, the proportions of apoptotic cells were (16.4±1.9)%, (27.5±2.1)%, (32.9±3.6)%, and (35.5±3.0)%, respectively, the difference was statistically significant (F = 9.25, P < 0.01). After treated with 4 nmol/L TPL and JQ1 for 12 h, the level of cell membrane potential in MV4-11 cells was significantly lower than that of JQ1 single agent group, and the difference was statistically significant (P < 0.05). After treated by 4 nmol/L TPL combined with JQ1 for 24 h, the levels of anti-apoptotic proteins bcl-2 and Mcl-1 decreased, and the level of pro-apoptotic protein bax increased. Conclusion TPL can significantly enhance the proliferation inhibition and apoptosis induction effects of BET protein inhibitor JQ1 on MLL-rearranged AML cells, and the mechanism may be related to enhancing the mitochondrial apoptosis pathway. Key words: Gene rearrangement; Leukemia, myeloid, acute; Triptolide; BET protein inhibitor JQ1

Diverse autophagy and apoptosis in myeloid leukemia cells induced by 20(s)-GRh2 and blue LED irradiation.

Autophagy is an important mechanism for cell death regulation. To improve the anticancer effect during the treatment of leukemia and promote the apoptosis of leukemic cells, it is important to define the relationship between autophagy and apoptosis. A key bioactive compound in traditional Chinese medicine, 20(s)-Ginsenoside (GRh2), demonstrated an advancement in leukemia treatment. Blue LED therapy (BL) is a physical treatment method that can induce leukemic cell death. In this study, we tested the effect of 20(s)-GRh2, BL, and their combination (BL–GRh2) on the activation of leukemic cell apoptosis and autophagy. Both treatments, whether used individually or simultaneously, induce apoptosis through the induction of reactive oxygen species (ROS), disrupted mitochondrial membrane potential (MMP) and regulated the expression of apoptosis-related genes and proteins. Furthermore, using western blotting to analyze the autophagy markers LC3B and P62, we detected the activation of autophagy. In cells treated with autophagy inhibitor 3-MA, both autophagy and apoptosis were inhibited, either by BL alone or by BL–GRh2. However, apoptosis in 20(s)-GRh2-treated cells was enhanced. In cells treated with apoptosis suppressor Z-VAD-FMK, autophagy was inhibited in the BL and BL–GRh2-treated cells, although it was enhanced in cells treated with 20(s)-GRh2 alone. Moreover, we observed a stronger induction of apoptosis by BL–GRh2 in myeloid leukemia cells. Our data indicate that autophagy induced by different factors can play diverse roles on the same cells. Our results also indicate that the combination of traditional Chinese medicine with physical therapy may be a new strategy for anti-cancer therapy.

TAK-733, a Selective MEK Inhibitor, Enhances Voreloxin-induced Apoptosis in Myeloid Leukemia Cells.

MEK inhibitors are new promising anticancer drugs. The aim of this study was to investigate the effect of the combination treatment of voreloxin with the MEK inhibitor TAK-733 on HL60 myeloid leukemia cells. MAPK activity, cell viability, apoptosis, oxidative stress induction and AIF (apoptosis-inducing factor) distribution were assessed in HL60 cells cultured with each drug alone or with both drugs. TAK-733 alone at 5 μM significantly reduced MAPK activity and did not influence viability and apoptosis in HL60 cells. Voreloxin at concentration of 0.03-0.48 μM reduced cell viability and increased apoptosis rate. Incubation with both drugs caused further inhibition of cell viability and increased apoptosis associated with generation of reactive oxygen species (ROS) and nuclear translocation of AIF. Combination of TAK-733 and voreloxin can exert a synergistic anticancer effect in myeloid leukemia cells.

Cytotoxic T lymphocytes promote cytarabine-induced acute myeloid leukemia cell apoptosis via inhibiting Bcl-2 expression.

Acute myeloid leukemia (AML) remains difficult to cure due to its drug tolerance and refractoriness. Immunotherapy is a growing area of cancer research, which has been applied for the treatment of numerous types of cancer, including leukemia. The present study generated AML cell-specific cytotoxic T lymphocytes (CTLs) in vitro and investigated the effect of combining CTL treatment with one of the most commonly used drugs for the treatment of hematological malignancies, cytarabine, on AML cell apoptosis. Firstly, it was observed that monocyte-depleted peripheral blood lymphocytes from healthy donors could be used to generate large numbers of CD3+CD8+ CTLs through immune stimulation. These CD3+CD8+ CTLs could effectively recognize and induce the apoptosis of human Kasumi-3 AML cells. In addition, cytarabine-induced AML cell apoptosis was enhanced by CTL treatment. Western blotting revealed that Bcl-2 expression was downregulated in AML cells following cytarabine and CTL treatment, indicating that the synergistic effect of this treatment on AML cell apoptosis is due to the downregulation of Bcl-2. These results highlight the potential application of CTL immunotherapy for the treatment of AML. Further studies optimizing the specificity and potency of CTLs, and identifying favorable combinations with other chemotherapeutic drug are required.

Potential Efficacy of Human IL-1RAP Specific CAR-T cell in Eliminating Leukemic Stem Cells of Chronic Myeloid Leukemia

The purpose of this report was to evaluate the effect of IL1RAP sepecifc CAR-T cell on inducing IL1RAP positive chronic myeloid leukemia cell apoptosis. Leukemic stem cells (LSCs) as the main initiating factor of leukemia relapse still cannot be eradicated thoroughly. Even though Tyrosine kinase inhibitors (TKI) revolutionized the therapy of chronic myeloid leukemia (CML), it alone does not cure this disease for the no response to quiescent LSCs. Human IL1RAP identified by Landberg N and we can be used as a specific surface marker and tumor burden indicator of LSC in CML. Therefore, IL1RAP chimeric antibody receptor (CAR) T cell specific targeting LSCs might be a novel strategy to CML therapy. Here, we demonstrated that IL1RAP CAR T cell showed more powerful cytotoxicity to kill IL1RAP positive CML cell lines than that to directly block IL1RAP expression by shRNA. Furthermore, compared with shRAN group and blank vector treated group, higher rate of apoptosis and lower proliferation of leukemia cells were showed in IL1RAP CAR T cell co-cultured group. In conclusion, in the present study a potential creative therapeutic target to eliminate LSCs and assistant strategy to cure CML was proved.

Short-Course High-Dose Methylprednisolone Induces Differentiation and Apoptosis of Myeloid Leukemic Cells

Differentiation therapy with all-trans retinoic acid significantly improved the outcome of patients with acute promyelocytic leukemia (APL).Therefore, researchers are still exploring the possibility of differentiation therapy for patients with acute myeloblastic leukemia (AML) other than APL. On the other hand, based on in vitro experiments on induction of differentiation of mouse myeloid leukemic cells with certain steroid hormones, we have demonstrated that short-course (3 to 7 days) high-dose methylprednisolone (HDMP) treatment can induce terminal differentiation of leukemic cells in children with APL and in other subtypes of AML (AML-M1, AML-M2, AML-M4 and AML-M7). HDMP treatment has also been shown to induce apoptosis of myeloid leukemic cells in vivo and in vitro.

Effects of itraconazole plus doxorubicin on proliferation and apoptosis in acute myeloid leukemia cells

To explore the effects of itraconazole (ITC) plus adriamycin (ADM) on proliferation and apoptosis of acute myeloid leukemia cells in vitro. The growth inhibition effects of different concentrations of ITC, ADM or ITC (2, 6, 15 µmol/L) plus ADM (0.30, 0.75 µmol/L) were detected by CCK8 assay in KG1α and primary adult acute leukemia cells. Different concentrations of ITC for 7, 14 and 21 days were applied for observing the effect on colony formation. After 48 h treatments with 6 µmol/L ITC, 0.75 µmol/L ADM or ITC (6 µmol/L) plus ADM (0.75 µmol/L), the morphological changes of cells were observed by Wright staining. Flow cytometry was used to detect cell apoptotic rate, mitochondrial membrane potential and cell cycle arrest. And the expression levels of Sonic Hedgehog (Shh) signal pathway-related proteins Shh and glima-associated oncogene homdog1 (Gli1) were determined by Western blot. ITC and ADM inhibited the proliferation of KG1α and primary adult acute leukemia cells and ITC reduced the colony-formation ability of KG1α cells both in dose-dependent manners. Compared with control or single drug group, the changes of cell morphology were more apparent in combined group. Weeb coefficient test revealed a synergistic effect (D ≤ 70%C) of 0.75 µmol/L ADM plus 6 µmol/L ITC. When KG1α cells were treated with 6 µmol/L ITC plus 0.75 µmol/L ADM, the apoptotic rate was 31.72% ± 1.58%. And it was significantly higher than that in control, ITC and ADM groups (4.17% ± 0.74%, 4.33% ± 1.12%, 9.53% ± 1.15%, P < 0.01). Detection of mitochondrial membrane potential showed that low red-fluorescent cells (P3) of combined group were obviously higher than that in control, ADM and ITC single drug groups (18.80% ± 0.96% vs 5.00% ± 0.38%, 9.70% ± 0.43%, 7.10% ± 0.77%, P < 0.01) . KG1α cells were obviously arrested in G2 phase in combined group and it showed no statistical significance compared with control or single drug group. Western blot showed that the expression levels of Shh and Gli1 decreased with rising concentration of ITC. ITC plus ADM can obviously inhibit cell proliferation and increase KG1α cell apoptotic rate, mitochondrial damage and G2 phase retardation. And ITC inhibits the Shh signal pathways.

Inhibition of protein kinase CK2 with the clinical-grade small ATP-competitive compound CX-4945 or by RNA interference unveils its role in acute myeloid leukemia cell survival, p53-dependent apoptosis and daunorubicin-induced cytotoxicity

BackgroundThe involvement of protein kinase CK2 in sustaining cancer cell survival could have implications also in the resistance to conventional and unconventional therapies. Moreover, CK2 role in blood tumors is rapidly emerging and this kinase has been recognized as a potential therapeutic target. Phase I clinical trials with the oral small ATP-competitive CK2 inhibitor CX-4945 are currently ongoing in solid tumors and multiple myeloma.MethodsWe have analyzed the expression of CK2 in acute myeloid leukemia and its function in cell growth and in the response to the chemotherapeutic agent daunorubicin We employed acute myeloid leukemia cell lines and primary blasts from patients grouped according to the European LeukemiaNet risk classification. Cell survival, apoptosis and sensitivity to daunorubicin were assessed by different means. p53-dependent CK2-inhibition-induced apoptosis was investigated in p53 wild-type and mutant cells.ResultsCK2α was found highly expressed in the majority of samples across the different acute myeloid leukemia prognostic subgroups as compared to normal CD34+ hematopoietic and bone marrow cells. Inhibition of CK2 with CX-4945, K27 or siRNAs caused a p53-dependent acute myeloid leukemia cell apoptosis. CK2 inhibition was associated with a synergistic increase of the cytotoxic effects of daunorubicin. Baseline and daunorubicin-induced STAT3 activation was hampered upon CK2 blockade.ConclusionsThese results suggest that CK2 is over expressed across the different acute myeloid leukemia subsets and acts as an important regulator of acute myeloid leukemia cell survival. CK2 negative regulation of the protein levels of tumor suppressor p53 and activation of the STAT3 anti-apoptotic pathway might antagonize apoptosis and could be involved in acute myeloid leukemia cell resistance to daunorubicin.

Omacetaxine mepesuccinate for the treatment of chronic myeloid leukemia.

Omacetaxine mepesuccinate is a protein synthesis inhibitor that causes apoptosis of chronic myeloid leukemia cells without binding to the BCR-ABL tyrosine kinase that is implicated in the pathogenesis of this disease. It has been approved for the treatment of chronic myeloid leukemia in patients with resistance to two or more tyrosine kinase inhibitors and is emerging as an important agent in countering the highly resistant T315I mutation. This review will focus on the preclinical pharmacology, pharmacokinetics and clinical utility of omacetaxine mepesuccinate in the current milieu of tyrosine kinase inhibitor-dominant therapy of chronic myeloid leukemia.

High-dose Glucocorticoid for the Treatment of Myeloid Sarcoma

Myeloid sarcoma is a tumor of myeloblast or poorly differentiated myeloid cells that can occur in extramedullary sites, as isolated tumor, concomitantly with or after the diagnosis of acute myeloblastic leukemia. Despite considerable improvement achieved in the outcome of patients with acute myeloblastic leukemia by using intensive chemotherapy and/or hematopoietic stem cell transplantation, it is generally considered to be poor in patients with myeloid sarcoma. The aim of this review is to indicate the potential therapeutic effects of high-dose glucocorticoid treatment which induce differentiation and apoptosis of myeloid leukemic cells, as a new treatment approach for patients with myeloid sarcoma. We have shown that short-course (3 to7 days) high-dose methylprednisolone treatment that might also induce differentiation and apoptosis of leukemic cells in the extramedullary sites resulted in dramatic decreases in the size of myeloid sarcoma in children with or without marrow infiltration. From the results of our long-term clinical studies, we suggest that to use short- course high-dose glucocorticoids combined with intensive chemotherapy protocol would be a promising treatment strategy for patients with myeloid sarcoma. However, in further studies, the prognostic significance of different localization of myeloid sarcoma and the long term effect of the addition of highdose glucocorticoid to intensive AML chemotherapy protocols should be explored in larger series.