scholarly journals Pro-Apoptotic Potential of Pseudevernia furfuracea (L.) Zopf Extract and Isolated Physodic Acid in Acute Lymphoblastic Leukemia Model In Vitro

Pharmaceutics ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2173
Author(s):  
Martin Kello ◽  
Tomas Kuruc ◽  
Klaudia Petrova ◽  
Michal Goga ◽  
Zuzana Michalova ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Cycle ◽  
Dna Damage ◽  
Acute Lymphoblastic Leukemia ◽  
Lymphoblastic Leukemia ◽  
Jurkat Cells ◽  
Pseudevernia Furfuracea ◽  
Wide Range ◽  
Stress Survival

Acute lymphoblastic leukemia (ALL) is the most frequently diagnosed type of leukemia among children. Although chemotherapy is a common treatment for cancer, it has a wide range of serious side effects, including myelo- and immunosuppression, hepatotoxicity and neurotoxicity. Combination therapies using natural substances are widely recommended to attenuate the adverse effects of chemotherapy. The aim of the present study was to investigate the anti-leukemic potential of extract from the lichen Pseudevernia furfuracea (L.) Zopf (PSE) and isolated physodic acid (Phy) in an in vitro ALL model. A screening assay, flow cytometry and Western blotting were used to analyze apoptosis occurrence, oxidative stress, DNA damage and stress/survival/apoptotic pathway modulation induced by the tested substances in Jurkat cells. We demonstrate for the first time that PSE and Phy treatment-induced intrinsic caspase-dependent cell death was associated with increased oxidative stress, DNA damage and cell cycle arrest with the activation of cell cycle checkpoint proteins p53, p21 and p27 and stress/survival kinases p38 MAPK, JNK and PI3K/Akt. Moreover, using peripheral T lymphocytes, we confirmed that PSE and Phy treatment caused minimal cytotoxicity in normal cells, and therefore, these naturally occurring lichen secondary metabolites could be promising substances for ALL therapy.

scholarly journals BRD4 PROTAC degrader ARV-825 inhibits T-cell acute lymphoblastic leukemia by targeting 'Undruggable' Myc-pathway genes

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Shuiyan Wu ◽  
You Jiang ◽  
Yi Hong ◽  
Xinran Chu ◽  
Zimu Zhang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Acute Lymphoblastic Leukemia ◽  
Caspase 3 ◽  
Lymphoblastic Leukemia ◽  
Rna Seq ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Bet Protein

Abstract Background T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disease with a high risk of induction failure and poor outcomes, with relapse due to drug resistance. Recent studies show that bromodomains and extra-terminal (BET) protein inhibitors are promising anti-cancer agents. ARV-825, comprising a BET inhibitor conjugated with cereblon ligand, was recently developed to attenuate the growth of multiple tumors in vitro and in vivo. However, the functional and molecular mechanisms of ARV-825 in T-ALL remain unclear. This study aimed to investigate the therapeutic efficacy and potential mechanism of ARV-825 in T-ALL. Methods Expression of the BRD4 were determined in pediatric T-ALL samples and differential gene expression after ARV-825 treatment was explored by RNA-seq and quantitative reverse transcription-polymerase chain reaction. T-ALL cell viability was measured by CCK8 assay after ARV-825 administration. Cell cycle was analyzed by propidium iodide (PI) staining and apoptosis was assessed by Annexin V/PI staining. BRD4, BRD3 and BRD2 proteins were detected by western blot in cells treated with ARV-825. The effect of ARV-825 on T-ALL cells was analyzed in vivo. The functional and molecular pathways involved in ARV-825 treatment of T-ALL were verified by western blot and chromatin immunoprecipitation (ChIP). Results BRD4 expression was higher in pediatric T-ALL samples compared with T-cells from healthy donors. High BRD4 expression indicated a poor outcome. ARV-825 suppressed cell proliferation in vitro by arresting the cell cycle and inducing apoptosis, with elevated poly-ADP ribose polymerase and cleaved caspase 3. BRD4, BRD3, and BRD2 were degraded in line with reduced cereblon expression in T-ALL cells. ARV-825 had a lower IC50 in T-ALL cells compared with JQ1, dBET1 and OTX015. ARV-825 perturbed the H3K27Ac-Myc pathway and reduced c-Myc protein levels in T-ALL cells according to RNA-seq and ChIP. In the T-ALL xenograft model, ARV-825 significantly reduced tumor growth and led to the dysregulation of Ki67 and cleaved caspase 3. Moreover, ARV-825 inhibited cell proliferation by depleting BET and c-Myc proteins in vitro and in vivo. Conclusions BRD4 indicates a poor prognosis in T-ALL. The BRD4 degrader ARV-825 can effectively suppress the proliferation and promote apoptosis of T-ALL cells via BET protein depletion and c-Myc inhibition, thus providing a new strategy for the treatment of T-ALL.

scholarly journals Phloridzin Docosahexaenoate (PZ-DHA) : A Novel Naturally Derived Drug Active in T-Cell Acute Lymphoblastic Leukemia (T-ALL)

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5197-5197
Author(s):  
Niroshaathevi Arumuggam ◽  
Nicole Melong ◽  
Catherine K.L. Too ◽  
Jason N. Berman ◽  
H.P. Vasantha Rupasinghe
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Xenograft Model ◽  
Jurkat Cells ◽  
Interferon Α ◽  
Omega 3 ◽  
Cell Acute Lymphoblastic Leukemia

Abstract T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignant disease that accounts for about 15% of pediatric and 25% of adult ALL. Although risk stratification has provided more tailored therapy and improved the overall survival of T-ALL patients, clinical challenges such as suboptimal drug responses, morbidity from drug toxicities, and drug resistance still exist. Plant polyphenols have therapeutic efficacy as pharmacological adjuvants to help overcome these challenges. They can be acylated with fatty acids to overcome issues concerning bioavailability, such as poor intestinal absorption and low metabolic stability. Phloridzin (PZ), a flavonoid found in apple peels, was acylated with an omega-3 fatty acid, docosahexaenoic acid (DHA), to generate a novel ester called phloridzin docosahexaenoate (PZ-DHA). The cytotoxic effect of PZ-DHA was studied in the human Jurkat T-ALL cell line. PZ-DHA significantly reduced the viability and cellular ATP levels of treated cells. PZ-DHA was found to selectively induce apoptosis in Jurkat cells, while sparing normal murine T-cells. Apoptosis was further confirmed by demonstrating the ability of PZ-DHA to induce morphological alterations, DNA fragmentation, caspase activation, and the release of intracellular lactate dehydrogenase. PZ-DHA also significantly inhibited cell division in Jurkat cells. Furthermore, interferon-α-induced phosphorylation of the transcription factor, STAT3, was downregulated following PZ-DHA treatment. The in vitro efficacy of PZ-DHA was recapitulated in vivo in an established zebrafish xenograft model, where the proliferation of transplanted Jurkat cells was inhibited when PZ-DHA was added to the embryo water. Overall, these findings provide evidence for PZ-DHA as a novel therapeutic agent with activity in T-ALL. Studies examining the effect of PZ-DHA on patient-derived ALL cells engrafted in zebrafish are currently underway. Disclosures No relevant conflicts of interest to declare.

scholarly journals The Rational Design and Biological Mechanisms of Nanoradiosensitizers

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 504 ◽  
Author(s):  
Hainan Sun ◽  
Xiaoling Wang ◽  
Shumei Zhai
Keyword(s):  
Oxidative Stress ◽  
Cell Cycle ◽  
Dna Damage ◽  
Rational Design ◽  
Design Strategies ◽  
Biological Mechanisms ◽  
Normal Tissues ◽  
Current State

Radiotherapy (RT) has been widely used for cancer treatment. However, the intrinsic drawbacks of RT, such as radiotoxicity in normal tissues and tumor radioresistance, promoted the development of radiosensitizers. To date, various kinds of nanoparticles have been found to act as radiosensitizers in cancer radiotherapy. This review focuses on the current state of nanoradiosensitizers, especially the related biological mechanisms, and the key design strategies for generating nanoradiosensitizers. The regulation of oxidative stress, DNA damage, the cell cycle, autophagy and apoptosis by nanoradiosensitizers in vitro and in vivo is highlighted, which may guide the rational design of therapeutics for tumor radiosensitization.

scholarly journals Synergistic activity of rapamycin and dexamethasone in vitro and in vivo in acute lymphoblastic leukemia via cell-cycle arrest and apoptosis

2012 ◽  
Vol 36 (3) ◽  
pp. 342-349 ◽  
Author(s):  
Chong Zhang ◽  
Yong-Ku Ryu ◽  
Taylor Z. Chen ◽  
Connor P. Hall ◽  
Daniel R. Webster ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Acute Lymphoblastic Leukemia ◽  
Cell Cycle Arrest ◽  
Lymphoblastic Leukemia ◽  
Synergistic Activity ◽  
Cycle Arrest

The Wee1 Inhibitor, MK-1775, Sensitizes Leukemic Cells to Different Antineoplastic Drugs Interfering with DNA Damage Response Pathway

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1276-1276 ◽  
Author(s):  
Andrea Ghelli Luserna Di Rora ◽  
Ilaria Iacobucci ◽  
Neil Beeharry ◽  
Simona Soverini ◽  
Cristina Papayannidis ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Acute Lymphoblastic Leukemia ◽  
Cell Viability ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Genetic Alterations ◽  
Additive Effect ◽  
Proliferation Index ◽  
Induction Of Apoptosis

Abstract Due to inadequate treatments, the survival rate of adult Acute Lymphoblastic Leukemia (ALL) patients with the exclusion of patients with particular genetic alterations, like the Philadelphia positive patients, is still very low. Moreover even the rate of patient that responds to specific treatment develops relapses during their life. Thus there is a need to improve the efficacy of conventional therapy and to discover novel specific targets. In eukaryotic cells Wee1, ATR/Chk1 and ATM/Chk2 are three pathways involved in cell cycle regulation, DNA damages response and DNA repair. Wee1 is a checkpoint kinase, involved mainly in the regulation of G2/M transition through the inhibitory phosphorylation of both Cyclin-dependent kinase 1 (CDK1) and 2 (CDK2) respectively. This study evaluates the effectiveness of MK-1775, a selective Wee1 inhibitor, as a monotherapy and as chemosensitizer agent for the treatment of B-/T-Acute Lymphoblastic Leukemia. Human B (BV-173, SUPB-15, NALM-6, NALM-19 and REH) and T (MOLT-4, RPMI-8402 and CEM) ALL cell lines were tested in this study. MK-1775 alone strongly reduced the cell viability in a dose and time-dependent manner in all the cell lines treated. The anti-proliferative activity of MK-1775 was accompanied by an increase in apoptotic cells (AnnexinV/Pi staining) and by DNA damage markers (gH2AX and Parp-1 cleavage). Moreover the inhibition of Wee1 disrupted the cell cycle profile by arresting the cells in late S and in G2/M phase. We hypothesized that targeting Chk1, a kinase upstream, of Wee1, would be more effective in reducing cell proliferation. Indeed, the concomitant inhibition of Chk1 and Wee1 kinases, using the PF-0477736 in combination with MK-1775, synergized in the reduction of the cell viability, inhibition of the proliferation index and induction of apoptosis. Moreover the immunofluorescence staining for the DNA damage marker gH2AX and the mitotic marker phosphor-Histone H3 showed that co-treatment with MK-1775 and PF-0477736 induced cell death by mitotic catastrophe. We undertook further studies to understand the immediate clinical potential of the compound, thus MK-1775 was combined with different drugs (Clofarabine, Bosutinib Authentic, and a particular isomer of this compound).The combination between MK-1775 and clofarabine showed an additive effect in terms of reduction of the cell viability and induction of apoptosis. Finally the Wee1 inhibitor was combined with the tyrosine kinase inhibitors Bosutinib and Bos-isomer (Bos-I). Both the isomers in combination with MK-1775 showed an additive effect in term of reduction of the cell viability. Interestedly the cytotoxic effect of Bos-I was stronger on the Philadelphia-negative cell lines in comparison to the positive counterpart. Western blot analysis highlighted that this compound, but not the Bosutinib authentic, interfered with the Chk1/Chk2 and Wee1 pathway. This supported our previous studies showing that Bosutinib and its isomer possess off-target effects against both Wee1 and Chk1 kinases and thus maybe used as a chemosensitizer (Beeharry et al. Cell Cycle 2014). The results of this study in our opinion identify the Wee1 kinase as a promising target for the treatment of ALL not only as a monotherapy but also as chemosensitizer agent to increase the cytotoxicity of different kind of drugs already used in clinical trials. Disclosures Soverini: Novartis, Briston-Myers Squibb, ARIAD: Consultancy. Martinelli:Novartis: Consultancy, Speakers Bureau; Ariad: Consultancy; AMGEN: Consultancy; ROCHE: Consultancy; BMS: Consultancy, Speakers Bureau; MSD: Consultancy; Pfizer: Consultancy.

scholarly journals Gold Nanoparticles Promote Oxidant-Mediated Activation of NF-κB and 53BP1 Recruitment-Based Adaptive Response in Human Astrocytes

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Jennifer Mytych ◽  
Anna Lewinska ◽  
Jacek Zebrowski ◽  
Maciej Wnuk
Keyword(s):  
Oxidative Stress ◽  
Cell Cycle ◽  
Gold Nanoparticles ◽  
Adaptive Response ◽  
Inverse Correlation ◽  
Galactosidase Activity ◽  
Promising Candidate ◽  
Human Astrocytes ◽  
Wide Range

Nanogold-based materials are promising candidate tools for nanobased medicine. Nevertheless, no conclusive information on their cytotoxicity is available. In the present study, we investigated the effects of gold nanoparticles (AuNPs) on human astrocytesin vitro. Nanogold treatment in a wide range of concentrations did not result in cytotoxicity. In contrast, nanogold provoked changes in the astrocyte cell cycle and induced senescence-associatedβ-galactosidase activity. AuNPs promoted oxidative stress and caused activation of NF-κB pathway. After nanogold treatment, an inverse correlation between the formation of 53BP1 foci and micronuclei generation was observed. The robust 53BP1 recruitment resulted in reduced micronuclei production. Thus, nanogold treatment stimulated an adaptive response in a human astrocyte cell.

scholarly journals Evaluation of the combined effects of doxorubicin and bortezomib on the human acute lymphoblastic leukemia cell line

2019 ◽  
Vol 32 (2) ◽  
pp. 87-91
Author(s):  
Agnieszka Korga ◽  
Ewelina Humeniuk ◽  
Grzegorz Adamczuk ◽  
Magdalena Iwan ◽  
Marta Ostrowska ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Acute Lymphoblastic Leukemia ◽  
Synergistic Effect ◽  
Synergistic Effects ◽  
Lymphoblastic Leukemia ◽  
Antineoplastic Agent ◽  
Leukemia Cell ◽  
Leukemia Cell Line ◽  
Wide Range ◽  
Human Acute Lymphoblastic Leukemia

Abstract Increasing numbers of oncological patients and growing drug resistance ensure that new methods of cancer treatment are intensively sought. Combining drugs for a synergistic effect is one of several possible ways to mitigate this problem. This leads to reducing the effective drug dose and the occurrence of side effects. Doxorubicin (DOX) is an antineoplastic agent that has several mechanisms of action. DOX intercalates between base pairs of DNA helix, inhibits topoisomerase II and also forms reactive oxygen species. Bortezomib (BZT) is an antitumor agent belonging to the group of proteasome inhibitors. It has been observed that BZT triggers an oxidative stress response in vitro and in vivo. Accumulation of oxidatively damaged proteins and the simultaneously blocking of the proteasome can be very damaging to the tumour cell. For this reason, the aim of the study was to assess the potentially synergistic effect of DOX and BZT on human acute lymphoblastic leukemia (ALL). In the work, the cells were treated with both agents and their combinations and the effect was evaluated on the basis of morphological assessment, MTT assay and level of reduced glutathione measurement. The study has shown that on acute lymphoblastic leukemia cells, synergistic effects came about in the combination of 1nM BZT with a wide range of concentrations of DOX. Herein, the visible, coactive effect of DOX and BZT was observed on oxidative stress levels. This phenomenon can be essential in blunting the possibility of rapid manifestation of resistance seen in BZT monotherapy. In addition, the needed very low concentrations of DOX reduce the risk of therapy side effect.

scholarly journals Efficacy of JAK1/2 and BCL2 inhibition on human T cell acute lymphoblastic leukemia in vitro and in vivo

2019 ◽  
Author(s):  
Kirsti L. Walker ◽  
Sabrina A. Kabakov ◽  
Fen Zhu ◽  
Myriam N. Bouchlaka ◽  
Sydney L Olson ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Combination Treatment ◽  
Lymphoblastic Leukemia ◽  
Jurkat Cells ◽  
Human T Cell ◽  
Liquid Chromatography Tandem Mass ◽  
Cell Acute Lymphoblastic Leukemia

AbstractRelapsed/refractory T cell acute lymphoblastic leukemia (T-ALL) is difficult to salvage especially in heavily pretreated patients, thus novel targeted agents are sorely needed. Hyperactivated JAK/STAT and BCL2 overexpression promote increased T-ALL proliferation and survival, and targeting these pathways with ruxolitinib and venetoclax may provide an alternative approach to achieve clinical remissions. Ruxolitinib and venetoclax show a dose-dependent effect individually, but combination treatment synergistically reduces survival and proliferation of Jurkat and Loucy cells in vitro. Using a xenograft CXCR4+ Jurkat model, the combination treatment fails to improve survival, with death from hind limb paralysis. Despite on-target inhibition by the drugs, histopathology demonstrates increased leukemic infiltration into the central nervous system (CNS), which expresses CXCL12, as compared to liver or bone marrow. Liquid chromatography-tandem mass spectroscopy shows that neither ruxolitinib nor venetoclax can effectively cross the blood-brain barrier, limiting efficacy against CNS T-ALL. Deletion of CXCR4 on Jurkat cells by CRISPR/Cas9 results in prolonged survival and a reduction in overall and neurologic clinical scores. While combination therapy with ruxolitinib and venetoclax shows promise for treating T-ALL, additional inhibition of the CXCR4-CXCL12 axis will be needed to eliminate both systemic and CNS T-ALL burden and maximize the possibility of complete remission.

scholarly journals Targeting serine hydroxymethyltransferases 1 and 2 for T-cell acute lymphoblastic leukemia therapy

Leukemia ◽  
2021 ◽  
Author(s):  
Yana Pikman ◽  
Nicole Ocasio-Martinez ◽  
Gabriela Alexe ◽  
Boris Dimitrov ◽  
Samuel Kitara ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Cell Cycle Arrest ◽  
Lymphoblastic Leukemia ◽  
Cycle Arrest ◽  
Folate Pathway ◽  
The One

AbstractDespite progress in the treatment of acute lymphoblastic leukemia (ALL), T-cell ALL (T-ALL) has limited treatment options, particularly in the setting of relapsed/refractory disease. Using an unbiased genome-scale CRISPR-Cas9 screen we sought to identify pathway dependencies for T-ALL which could be harnessed for therapy development. Disruption of the one-carbon folate, purine and pyrimidine pathways scored as the top metabolic pathways required for T-ALL proliferation. We used a recently developed inhibitor of SHMT1 and SHMT2, RZ-2994, to characterize the effect of inhibiting these enzymes of the one-carbon folate pathway in T-ALL and found that T-ALL cell lines were differentially sensitive to RZ-2994, with the drug inducing a S/G2 cell cycle arrest. The effects of SHMT1/2 inhibition were rescued by formate supplementation. Loss of both SHMT1 and SHMT2 was necessary for impaired growth and cell cycle arrest, with suppression of both SHMT1 and SHMT2 inhibiting leukemia progression in vivo. RZ-2994 also decreased leukemia burden in vivo and remained effective in the setting of methotrexate resistance in vitro. This study highlights the significance of the one-carbon folate pathway in T-ALL and supports further development of SHMT inhibitors for treatment of T-ALL and other cancers.

Identification of FoxM1 As Therapeutic Target in TKI-Resistant Ph+ ALL

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 874-874
Author(s):  
Maike Buchner ◽  
Lars Klemm ◽  
Chen Zhengshan ◽  
Huimin Geng ◽  
Markus Muschen
Keyword(s):  
Cell Cycle ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Therapeutic Target ◽  
Lymphoblastic Leukemia ◽  
Single Agent ◽  
Cyclin B1 ◽  
Wide Range ◽  
Tki Treatment ◽  
B Cell Precursors

Abstract Abstract 874 Background: Despite initial responsiveness of primary Philadelphia chromosome positive acute lymphoblastic leukemia (Ph+ALL) to tyrosine kinase inhibition (TKI), the majority of patients will relapse and develop TKI-resistant disease. Foxm1 belongs to the forkhead box transcription factor family and is a key regulator of malignant growth by promoting cell cycle and survival through increased DNA damage repair. Foxm1 has been implicated in the progression and chemoresistance in a wide range of solid tumors, including hepatocellular carcinoma and breast cancer. Foxm1 is expressed in dividing cells and regulates the expression of critical regulators for G2/M entry of the cell cycle including Cdc25B, cyclin-B1, Plk-1 and Aurora B kinase. In addition it decreases protein stability of p27kip and p21cip and regulates the expression of antioxidant defense machinery of the cell, e.g. by superoxide dismutase expression. Results: We compared Foxm1 expression levels in Ph+ ALL patient samples and CD19+ B cell precursors from healthy donors and found 12-fold higher levels in the leukemic cells (p=0.011). More importantly, Foxm1 levels at the time of diagnosis in a clinical trial for patients with high risk acute lymphoblastic leukemia (ALL) were predictive of poor outcome (COG P9906; n=207). Comparative analysis of microarray data from matched sample pairs at diagnosis and relapse revealed a significant upregulation of Foxm1 in the relapse samples (n=42; p=0.0025). To further study the role of Foxm1 in Ph+ ALL, we developed a genetic model for inducible inactivation of Foxm1 in Ph+ ALL. To this end, B cell precursors of Foxm1fl/fl mice were transformed with BCR-ABL1 and transduced with a tamoxifen (4-OHT)-inducible Cre. Interestingly, 4-OHT-mediated deletion of Foxm1 resulted in reduced cell viability and an arrest in G0/G1 with a significant decrease of the S-phase of the cell cycle following deletion of Foxm1. The ability to form colonies in vitro was significantly decreased by deletion of Foxm1. In addition, Foxm1−/− ALL cells revealed a strikingly higher sensitivity towards TKI-treatment (Imatinib dose-response curve) compared to the control cells. As a potential therapeutic agent to pharmacologically inhibit Foxm1 function, we evaluated the effects of a previously described ARF peptide that binds and inhibits Foxm1 function. We treated TKI-resistant (BCR-ABL1T315I) and TKI-sensitive patient-derived xenograft Ph+ ALL cells with various ARF peptide concentrations and found significant growth inhibition after 72h (IC50 16.8±4.3μM, n=4), regardless of TKI responsiveness. In addition, treatment of ARF peptide in combination with TKI reduced the viability from 65.7%±1.7 after TKI treatment alone (10μM) to 19%±0.8 after 48h (TKI 10μM ARF peptide 12μM). Ph+ ALL cells treated with similar concentrations of a mutated ARF control peptide revealed 77%±0.9 viable cells and ARF peptide treatment alone decreased the viability to 29.6%±0.4. Hence treatment with the ARF peptide alone induces apoptosis in patient-derived Ph+ ALL cells and enhances the effect of TKI, which confirms the findings of the ALL mouse model for human Ph+ ALL xenografts. In a complementary approach, we used the natural antibiotic Thiostrepton, which functions via Foxm1 blockade. To test the ability of Thiostrepton as a potential anti-leukemia agent, we studied patient-derived TKI-resistant (BCR-ABL1T315I) Ph+ ALL cells. Treatment of these patient derived Ph+ALL cells induced cytotoxicity in nanomolar concentrations of Thiostrepton along with a significant downregulation of Foxm1 protein levels. By contrast, Non-BCR-ABL1 tumor cells including lymphoma cells were not responsive to Thiostrepton treatment at similar concentrations. Conclusion: Our analyses reveal that Foxm1 is a valid therapeutic target for the treatment of TKI sensitive and resistant Ph+ ALL, including BCR-ABL1T315I. We show that Foxm1 has a crucial function in Ph+ ALL and impacts a) leukemia proliferation, b) colony formation, and c) TKI-resistance. These findings identify Foxm1 a rational target for combination therapy with TKI or as a single agent for TKI-resistant Ph+ ALL. Disclosures: No relevant conflicts of interest to declare.

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