Sensitivity Of Acute Myeloid Leukemia Research Articles

MiR-217 Targeting PI3K/Akt Pathway Enhances Sensitivity of Adriamycin to Acute Myeloid Leukemia

To investigate the effects of miR-217 on proliferation and adriamycin sensitivity of acute myeloid leukemia (AML) cells. The mimic NC and miR-217 mimic vectors were constructed and transfected into HL-60 cells, and transfection efficiency was detected by qPCR. The cells were treated with different concentrations of adriamycin for 24 h and 48 h. CCK-8 assay was used to detect the chemical sensitivity of adriamycin and screen the optimal concentration and time of adriamycin treatment. Cells were divided into control group, mimic NC group, miR-217 mimic group, adriamycin group and miR-217 mimic+adriamycin group. Apoptosis was detected by flow cytometry, and the expressions of miR-217, PI3K and Akt3 were detected by qPCR. Western blot was used to detect the expression of PI3K/Akt pathway proteins PI3K, Akt3 and apoptosis proteins Bcl-2, Bax, and double luciferase was used to verify the relationship between miR-217 and Akt3. MiR-217 mimic could enhance the sensitivity of HL-60 cells to adriamycin. The optimal concentration and treatment time of adriamycin were 160 ng/ml and 48 h, respectively. Compared with control group, apoptosis rate, miR-217 and Bax protein levels were significantly increased in miR-217 mimic and adriamycin groups (P < 0.01), while Bcl-2 protein, PI3K, Akt3 mRNA and protein levels were significantly decreased (P < 0.01). Compared with adriamycin group, apoptosis rate, miR-217 and Bax protein levels were significantly increased in miR-217 mimic+adriamycin group (P < 0.01), while Bcl-2 protein, PI3K, Akt3 mRNA and protein levels were significantly decreased (P < 0.01). Dual luciferase assay showed that there was a targeted regulatory relationship between miR-217 and Akt3. MiR-217 regulates the PI3K/Akt pathway targeting Akt3, inhibits cell proliferation, promotes cell apoptosis and enhances the sensitivity of adriamycin to AML cells.

Poly(ferulic acid) nanocarrier enhances chemotherapy sensitivity of acute myeloid leukemia by selectively targeting inflammatory macrophages

Macrophages, as a subset of innate immune cells, play a pivotal role in the initiation, maintenance, and resolution of inflammatory responses during tissue damage repair, defense against infections, and tumor progression. However, the mechanisms by which macrophages regulate inflammation in acute myeloid leukemia (AML) and their involvement in the chemotherapeutic effect remain elusive. In this study, we have identified that AML cells stimulate macrophage expansion by activating the colony-stimulating factor 1 receptor (CSF1R) pathway. The expanded macrophages activate nuclear factor kappa-B (NFκB) to induce the expression of inflammatory factors, thereby maintaining leukemic cell quiescence and promoting cell survival following chemotherapy. Furthermore, we have successfully utilized a poly(ferulic acid) nanocarrier to selectively target macrophages for inhibiting the NFκB-mediated inflammation, ultimately enhancing chemotherapy efficacy against AML. Taken together, our findings highlight the crucial role of macrophage-induced inflammation in conferring chemoresistance to AML, and demonstrate the potential of a targeted nanocarrier specifically designed for inflammatory macrophages to improve the AML chemotherapeutic outcomes.

Disregulation of CTCF Boundary at the HOX Locus Enhances Sensitity to Multiple Drug Treatment in Myeloid Malignancies

Dysregulation of HOX genes is a dominant mechanism of leukemic transformation by altering self-renewal and differentiation properties of HS/PCs leading to leukemic transformation. The overexpression of posterior HOXA9 gene is also a poor prognostic marker in leukemia patients. Recent studies revealed that CTCF insulator constrains temporal HOX gene expression patterns within confined chromatin domains suggesting that CTCF mediated chromatin boundary activity may involve in regulating HOX gene patterns during AML prognosis.To investigate the role of CTCF in aberrant HOX gene expression and AML prognosis, we employed CRISPR-Cas9 genome editing technology to delete 47 base pairs of the core CTCF motif located between HOXA7 and HOXA9 genes (CBS7/9) in different subtype of AML cells with either MLL-rearrangement or NPM1 mutation. RNA-seq analysis revealed that transcription factors, HOXA9 , RUNX1 , and ZEB1 , as well as MAPK signaling pathway, all of them are involved in AML survival, prognosis and chemo-resistance, are significantly dowregulated in response to the CBS7/9 boundary deletion. Given that these genes and pathways are involved in AML prognosis and chemo-resistance, we then examined whether perturbation of CBS7/9 chromatin boundary resulted in alteration of drug resposes of AML cells. Both WT AML cells and the CBS7/9 defected AML cells derived from MLL-AF9 rearranged MOLM-13 and NPM mutated OCI-AML3 cells were treated with 1 mM of Ara-C or 100 nM of bromodomain (BET) inhibitors. Compared to the WT controls, the defected CBS7/9 boundary resulted in a significantly increase in AML sensitivity to both Ara-C and BET inhibitor treatment in both MOLM-13 and OCI-AML3 cells as evidence by significantly reducing percentage of proliferating cells.To further examine if treatment related drug sensitivity in AML cells is depended on the levels of HOXA9 expression, we overexpressed HOXA9 cDNA in the CBS7/9 deleted MOLM-13 and OCI-AML3 cells. Gain-of-function (GOF) expression of HOXA9 in the CBS7/9 defected AML cells rescued and restored the resistance to the Ara-C treatment of the CBS7/9 KO cells to the levels compatible to that of the WT control MOLM-13 and OCI-AML3 cells, but HOXA9 overexpression did not rescued the resistance of the CBS7/9 KO AML cells to the BET inhibitor treatment. The data suggest that HOXA9 is directly associated with cytotoxic drug Ara-C resistance, but not BET inhibitor mediated drug responses. KO of CBS7/9 specifically decreased enrichment of H3K9ac and H4K5ac, as well as recruitment of BRD4 to the posterior HOXA domain. Furthermore, overexpression of HOXA9 gene in the CBS7/9 KO AML cells indeed rescued the mRNA transcripts affected by CBS7/9 deletion to the levels compatible to that of WT control MOLM-13 or OCI-AML3 cells. Among rescued genes, ZEB1, STAT5A, and RUNX1 play essential roles in pathogenesis of myeloid malignancies and chemo-drug sensitivity.Finally, in order to further explore biological role of CTCF boundaries in AML pathogenesis, we analyze the whole genome sequencing data of 183 primary AML patients obtained from public available Cosmic Database for somatic mutations occurred in the CTCF binding sites. Several core CTCF motifs in the HOXA locus, including CBS5/6 and CBS7/9 boundaries, are highly mutated in AML patients. Thus, disruption of CTCF boundary located between HOXA7 and HOXA9 genes perturbs HOXA9 oncogene transcription and regulates chemo- or epigenetic drug sensitivity of acute myeloid leukemia. Alteration of CTCF boundaries in the oncogene loci may provide a novel therapeutic target for treatment of myeloid malignancies. DisclosuresNo relevant conflicts of interest to declare.

MiR-199a-5p Affects Sensitivity of Acute Myeloid Leukemia to Adriamycin by Targeting DRAM1

To compare the expression of miR-199a-5p between ADM-resistant AML cell (K562/ADM)and ADM-sensitive AML cell (K562), and to investigate the effect of miR-199a-5p on regulating AML drug resistance as well as its molecular mechanism. MTT method was used to detect the proliferation inhibition effect of ADM on K562 and K562/ADM cells, the IC50 was calculated. miR-199a-5p expression in cell lines (K562 and K562/ADM) and bone marrow sample (refractory/relapsed AML patients and complete remission AML patients) was detected by RT-qPCR. K562/ADM and K562 cells were transfected by miR-199a-5p mimic and miR-199a-5p inhibitor respectively to ensure that miR-199a-5p expression in K562/ADM cells was increased and that in K562 cells was decreased. Then proliferation inhibition effect of ADM on both cells was detected by CCK-8 and mRNA and protein DRAM1 expression in both cells was measured by real time RT-PCR and Western blot respectively. Dual luciferase reporter assay was used to detect wether there were direct binding sites between miR-199a-5p and DRAM1 3' UTR. CCK-8 was used to measure the proliferation inhibition effect of ADM on K562/ADM cells when DRAM1 was downregulated by siRNA. The IC50 of ADM for K562/ADM and K562 cells was 146.14±0.079 and 3.08±0.056 μg/ml respectively. As compared with patients in complete remission group, MiR-199a-5p expression in refractory/ relapsed AML patients significantly decreased, and the MiR-199a-5p expression in K562/ADM cells was also dramatically downregulated, compared with K562 cells (P＜0.05). When the expression of miR-199a-5p was upregulated in K562/ADM cells, the proliferation inhibition effect of ADM on cells elevated and both DRAM1 mRNA and protein expressions decreased. Conversely, when miR-199a-5p expression was downregulated in K562 cells, the proliferation inhibition effect of ADM on cells obviously reduced and both DRAM1 mRNA and protein expression increased (P＜0.05). Dual luciferase reporter Assay showed a direct interaction between miR-199a-5p and its binding site within DRAM1 mRNA. Both DRAM1 mRNA and protein expression in K562/ADM were markedly higher than those in K562 cells (P＜0.05). The ADM chemosensitivity of K562/ADM cells was improved significantly when DRAM1 expression was downregulated (P＜0.05). miR-199a-5p is downregulated in chemoresistant AML cells. miR-199a-5p expression plays an important role in regulating the sensitivity of AML cells to ADM treatment. DRAM1 is a functional target gene for miR-199a-5p modulating AML chemoresistance.

A mechanism for increased sensitivity of acute myeloid leukemia to mitotoxic drugs

Mitochondria play a central and multifunctional role in the progression of tumorigenesis. Although many recent studies have demonstrated correlations between mitochondrial function and genetic makeup or originating tissue, it remains unclear why some cancers are more susceptible to mitocans (anticancer drugs that target mitochondrial function to mediate part or all of their effect). Moreover, fundamental questions of efficacy and mechanism of action in various tumor types stubbornly remain. Here we demonstrate that cancer type is a significant predictor of tumor response to mitocan treatment, and that acute myeloid leukemias (AML) show an increased sensitivity to these drugs. We determined that AML cells display particular defects in mitochondrial metabolism that underlie their sensitivity to mitocan treatment. Furthermore, we demonstrated that combinatorial treatment with a mitocan (CCCP) and a glycolytic inhibitor (2-deoxyglucose) has substantial synergy in AML cells, including primary cells from patients with AML. Our results show that mitocans, either alone or in combination with a glycolytic inhibitor, display anti-leukemia effects in doses much lower than needed to induce toxicity against normal blood cells, indicating that mitochondria may be an effective and selective therapeutic target.

Role of drug transporters in the sensitivity of acute myeloid leukemia to sorafenib.

BackgroundChemoresistance often limits the success of the pharmacological treatment in acute myeloid leukemia (AML) patients. Although positive results have been obtained with tyrosine kinase inhibitors (TKIs), such as sorafenib, especially in patients with Fms-like tyrosine kinase 3 (FLT3)-positive AML, the success of chemotherapy is very heterogeneous. Here we have investigated in vitro whether the transportome (set of expressed plasma membrane transporters) is involved in the differential response of AML to sorafenib.MethodsThe sensitivity to sorafenib-induced cell death (MTT test and anexin V/7-AAD method) was evaluated in five different cell lines: MOLM-13, OCI-AML2, HL-60, HEL and K-562. The transportome was characterized by measuring mRNA using RT-qPCR. Drug uptake/efflux was determined by flow cytometry using specific substrates and inhibitors.ResultsThe cytostatic response to sorafenib was: MOLM-13>>OCI-AML2>HL-60>HEL≈K-562. Regarding efflux pumps, MDR1 was highly expressed in HEL>K-562≈MOLM-13, but not in OCI-AML2 and HL-60. BCRP and MPR3 expression was low in all cell lines, whereas MRP4 and MRP5 expression was from moderate to high. Flow cytometry studies demonstrated that MRP4, but not MRP5, was functional. The expression of the organic cation transporter 1 (OCT1), involved in sorafenib uptake, was MOLM-13>OCI-AML2≈HL-60 and non detectable in HEL and K-562. Transfection of HEL cells with OCT1 increased the sensitivity of these cells to sorafenib, whereas inactive genetic variants failed to induce this change.ConclusionTogether with changes in the expression/function of receptors targeted by TKIs, the expression of plasma membrane transporters involved in sorafenib uptake/efflux may affect the response of leukemia cells to this drug.

VEGFR2-Mediated Reprogramming of Mitochondrial Metabolism Regulates the Sensitivity of Acute Myeloid Leukemia to Chemotherapy.

Metabolic reprogramming is central to tumorigenesis, but whether chemotherapy induces metabolic features promoting recurrence remains unknown. We established a mouse xenograft model of human acute myeloid leukemia (AML) that enabled chemotherapy-induced regressions of established disease followed by lethal regrowth of more aggressive tumor cells. Human AML cells from terminally ill mice treated with chemotherapy (chemoAML) had higher lipid content, increased lactate production and ATP levels, reduced expression of peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), and fewer mitochondria than controls from untreated AML animals. These changes were linked to increased VEGFR2 signaling that counteracted chemotherapy-driven cell death; blocking of VEGFR2 sensitized chemoAML to chemotherapy (re-)treatment and induced a mitochondrial biogenesis program with increased mitochondrial mass and oxidative stress. Accordingly, depletion of PGC-1α in chemoAML cells abolished such induction of mitochondrial metabolism and chemosensitization in response to VEGFR2 inhibition. Collectively, this reveals a mitochondrial metabolic vulnerability with potential therapeutic applications against chemotherapy-resistant AML.Significance: These findings reveal a mitochondrial metabolic vulnerability that might be exploited to kill chemotherapy-resistant acute myeloid leukemia cells. Cancer Res; 78(3); 731-41. ©2017 AACR.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

MiR-424 and miR-27a increase TRAIL sensitivity of acute myeloid leukemia by targeting PLAG1.

Although microRNAs have been elaborated to participate in various physiological and pathological processes, their functions in TRAIL resistance of acute myeloid leukemia (AML) remain obscure. In this study, we detected relatively lower expression levels of miR-424&27a in TRAIL-resistant and semi-resistant AML cell lines as well as newly diagnosed patient samples. Overexpression of miR-424&27a, by targeting the 3′UTR of PLAG1, enhanced TRAIL sensitivity in AML cells. Correspondingly, knockdown of PLAG1 sensitized AML cells to TRAIL-induced apoptosis and proliferation inhibition. We further found that PLAG1 as a transcription factor could reinforce Bcl2 promoter activity, causing its upregulation at the mRNA level. Both downregulated PLAG1 and elevated expression of miR-424&27a led to Bcl2 downregulation and augmented cleavage of Caspase8, Caspase3 and PARP in the presence of TRAIL. Restoration of Bcl2 could eliminate their effects on AML TRAIL sensitization. Overall, we propose that miR-424&27a and/or PLAG1 might serve as novel therapeutic targets in AML TRAIL therapy.

Sensitivity of Acute Myeloid Leukemia (AML) cells to a urokinase‐activated recombinant anthrax toxin

We tested efficacy of a urokinase‐activated recombinant anthrax toxin (PrAgU2/FP59) on 11 human AML cell lines. PrAgU2/FP59 consists of PrAgU2, the cell binding domain in which the furin activation site is replaced by a urokinase plasminogen activator (uPA) activation site and FP59, the catalytic domain, consisting of Pseudomonas aeruginosa exotoxin A. PrAgU2 binds cells, is cleaved by uPA, heptamerizes, binds 3 molecules of FP59 and undergoes endocytosis releasing FP59 in the cytosol. FP59 ADP ribosylates EF2 causing protein synthesis inhibition and cell death. Introduction of the uPA activation site selectively targets this toxin to tumor cells expressing an active uPA system.7/11 AML cell lines were highly sensitive to PrAgU2/FP59 (IC50 = 0.5–33 pM, % cell kill &gt; 95%) while 4/11 cell lines were moderately sensitive to PrAgU2/FP59 (IC50 = 160–410 pM, % cell kill &gt; 70%). Addition of pro‐uPA increased AML sensitivity to PrAgU2/FP59 by an average of 40 fold. Addition of a neutralizing anti‐uPA antibody decreased toxicity of PrAgU2/FP59 to AML cells by an average of 14 fold, demonstrating requirement for active uPA for selective activation of PrAgU2/FP59.AML cells are sensitive to the cytotoxic effects of a urokinase‐targeted recombinant anthrax toxin with sensitivity depending on the expression of active uPA. PrAgU2/FP59 is a promising tumor selective therapeutic for the potential treatment of AML.

Granulocyte colony-stimulating factor enhances the in vitro cytotoxicity of gemtuzumab ozogamicin against acute myeloid leukemia cell lines and primary blast cells

To evaluate the effects of granulocyte colony-stimulating factor (G-CSF) on the in vitro sensitivity of acute myeloid leukemia (AML) cell lines and primary AML blast cells to gemtuzumab ozogamicin (GO). AML cell lines and primary blasts from 10 patients with AML were first incubated for 72 hours in the presence of G-CSF (5 or 100 ng/mL) and then exposed to increasing concentrations of GO (1-1,000 ng/mL) for an additional 72 hours. Pretreatment with G-CSF translated into significant enhancement of GO-induced cytotoxicity in the GO-sensitive HL-60 and NB-4 cells. Conversely, the response of GO-insensitive KG-1a, TF-1, and K562 cells was unaffected by in vitro priming with G-CSF. In vitro exposure to G-CSF augmented GO-induced apoptosis in 7 of 10 primary AML samples and rendered blast cells from three refractory patients sensitive to killing effect of GO. The G-CSF-induced increase of the cytocidal activity of GO was independent of effects on the cell cycle and on the expression levels of CD33 antigen. Of potential interest, G-CSF induced dose-dependent inhibition of P-glycoprotein (P-gp/ABCB1) function in the GO-sensitive HL-60 and NB-4 cells and in blasts from three patients with AML that we tested. Collectively, our findings point to G-CSF as a potential sensitizing agent that can be exploited therapeutically to improve the clinical efficacy of GO.

Cell cycle regulatory protein expression in fresh acute myeloid leukemia cells and after drug exposure.

Characteristics of treatment-induced cell cycle arrest are important for in vitro and in vivo sensitivity of acute myeloid leukemia (AML) cells to cytotoxic drugs. We analyzed the expression of the major G1 cell cycle regulators (p21Cip1, p27Kip1, cyclins D, cyclin E and pRb) in 41 fresh AML cell samples. The level of p27 expression was the only factor correlated with the response to chemotherapy, a high level of p27 expression being predictive of complete remission. There was a close relation between expression of pRb, cyclin D2 and FAB subtype, illustrated by the absence of both proteins in most samples having a monocytic component (M4, M5). We also assessed the expressions of pRb, cyclin E, p21 and p27 and the activity of cdk2, the major regulator of S-phase entry, after exposure to cytosine-arabinoside (AraC) and daunorubicin (DNR), and found these proteins could characterize time- and dose-dependent cellular response to each drug. We observed hyperphosphorylated pRb, increased levels of cyclin E and a high cdk2 activity, but no p21 induction, in AML cells exposed to 10(-6) M AraC. After exposure to 10(-5) M AraC, corresponding to the serum concentration reached in high-dose AraC regimens (HDAraC), a strong p21 induction was observed, associated with similarly overexpressed cyclin E and even higher cdk2 activity than after 10(-6) M AraC, while apoptosis was significantly increased. These data suggest that cdk2 activity is likely to play a role in AraC-induced apoptosis in AML cells. This mechanism may account for high efficacy of HDAraC in cells showing little sensitivity to conventional AraC doses.

Modulation of in vitro chemosensitivity in acute myelogenous leukemia cell line by GM-CSF: opposing effects observed with different cytotoxic drugs and time exposure

In some studies the GM-CSF (granulocyte-macrophage colony-stimulating factor) increased the in vitro sensitivity of acute myeloid leukemia (AML) cells to cytosine arabinoside (Ara-C), however, in clinical trials no favorable effects were shown. We used a GM-CSF responsive AML cell line (AML 193) to test the effects of growth stimulation on in vitro efficacy of Ara-C and methotrexate (MTX). In 6 days continuous exposure, dose dependent Ara-C cytotoxicity was counteracted by GM-CSF. Conversely, MTX cytotoxicity was increased significantly. However, in a short term treatment (24 h, high doses) the GM-CSF increased both MTX and Ara-C cytotoxicity. These effects might depend on different drug regimens and cell features.