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Autophagy inhibition impairs leukemia stem cell function in FLT3-ITD AML but has antagonistic interactions with tyrosine kinase inhibition

ABSTRACT: The FLT3-ITD mutation is associated with poor prognosis in acute myeloid leukemia (AML). FLT3 tyrosine kinase inhibitors (TKIs) demonstrate clinical efficacy but fail to target leukemia stem cells (LSC) and do not generate sustained responses. Autophagy is an important cellular stress response contributing to hematopoietic stem cells (HSC) maintenance and promoting leukemia development. Here we investigated the role of autophagy in regulating FLT3-ITD AML stem cell function and response to TKI treatment. We show that autophagy inhibition reduced quiescence and depleted repopulating potential of FLT3-ITD AML LSC, associated with mitochondrial accumulation and increased oxidative phosphorylation. However, TKI treatment reduced mitochondrial respiration and unexpectedly antagonized the effects of autophagy inhibition on LSC attrition. We further show that TKI-mediated targeting of AML LSC and committed progenitors was p53-dependent, and that autophagy inhibition enhanced p53 activity and increased TKI-mediated targeting of AML progenitors, but decreased p53 activity in LSC and reduced TKI-mediated LSC inhibition. These results provide new insights into the role of autophagy in differentially regulating AML stem and progenitor cells, reveal unexpected antagonistic effects of combined oncogenic tyrosine kinase inhibition and autophagy inhibition in AML LSC, and suggest an alternative approach to target AML LSC quiescence and regenerative potential.

ORGANISM(S): Mus musculus

PROVIDER: GSE169750 | GEO | 2022/10/13

REPOSITORIES: GEO

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Microenvironmental CXCL12 Deletion Enhances Flt3-ITD Acute Myeloid Leukemia Stem Cell Response to Therapy by Reducing p38 MAPK Signaling

Project description:Fms-like tyrosine kinase 3 (Flt3) tyrosine kinase inhibitors (Flt3-TKI) have improved outcomes for patients with Flt3-mutated acute myeloid leukemia (AML) but are limited by resistance and relapse, suggesting persistence of leukemia stem cells (LSC). Here we utilized a Flt3-internal tandem duplication (Flt3-ITD) and Tet2-deleted AML genetic mouse model to characterize Flt3-ITD AML LSC and their resistance to Flt3-TKI. We show that LSC were enriched within the primitive ST-HSC population. CXCl12-expressing osteoprogenitors were increased in the Flt3-ITD AML marrow and FLT3-ITD LSC showed increased expression of the CXCL12 receptor CXCR4. CXCL12 deletion from the microenvironment enhanced AML targeting by combined Flt3-TKI and chemotherapy treatment with enhanced LSC targeting. We found that both treatment and CXCL12 deletion partially reduced p38 mitogen-activated protein kinase (p38) signaling with increased, but not complete, reduction seen with combined treatment and CXCL12 deletion. Our studies suggest that p38 contributes to CXCL12-mediated maintenance of AML LSC following Flt3-TKI and chemotherapy treatment, but that p38 inhibition enhances AML LSC response to treatment to a greater extent than CXCL12 deletion alone. This study supports a role for p38 signaling in CXCL12-mediated protection of AML LSC from treatment and provide a rationale for targeting p38 signaling to enhance Flt3-ITD AML targeting.

2024-01-03 | GSE212428 | GEO

FLT3 inhibition upregulates HDAC8 via FOXO to inactivate p53 and promote maintenance of FLT3-ITD+ acute myeloid leukemia

Project description:Internal tandem duplication (ITD) mutations within the FMS-like receptor tyrosine kinase-3 (FLT3) can be found in up to 25~30% of acute myeloid leukemia (AML) patients and confer a poor prognosis. Although FLT3 tyrosine kinase inhibitors (TKIs) have shown clinical responses, the overall outcome of FLT3-ITD+ AML patients remains poor, and most of them would relapse very shortly. TKIs can not eliminate primitive FLT3-ITD+ AML cells, which are potential sources of relapse. Therefore, elucidating the mechanisms underlying FLT3-ITD+ AML maintenance and drug resistance is essential to develop novel, effective treatment strategies. Here, we demonstrate that FLT3 inhibition induces histone deacetylase 8 (HDAC8) upregulation through FOXO1 and FOXO3-mediated transactivation in FLT3-ITD+ AML cells. Upregulated HDAC8 deacetylates and inactivates p53, leading to leukemia maintenance and drug resistance upon TKIs treatment. Genetic or pharmacological inhibition of HDAC8 re-activates p53, abrogates leukemia maintenance and significantly enhances TKI-mediated elimination of FLT3-ITD+ AML cells. Importantly, in FLT3-ITD+ AML patient-derived xenograft models, the combination of FLT3 TKI (AC220) with a HDAC8 inhibitor (22d) significantly inhibits leukemia progression and effectively reduces primitive FLT3-ITD+ AML cells. Moreover, we extend these findings to an AML subtype harboring another tyrosine kinase activating mutation. In conclusion, our study demonstrates that HDAC8 upregulation as an important mechanism to resist TKIs and promote leukemia maintenance, and suggests that combining HDAC8 inhibition with TKI treatment could be a promising strategy to treat FLT3-ITD+ AML and other tyrosine kinase mutation-harboring leukemias.

2020-02-13 | GSE138057 | GEO

PRMT1-mediated FLT3 arginine methylation is required for maintenance of FLT3-ITD+ Acute Myeloid Leukemia

Project description:The presence of FLT3-ITD mutations in patients with acute myeloid leukemia (AML) is associated with poor clinical outcome. FLT3 tyrosine kinase inhibitors (TKIs), although effective in kinase ablation, do not eliminate FLT3-ITD+ leukemia stem cells (LSCs) which are potential sources of disease relapse, prompting us to ask whether FLT3-ITD protein regulates the AML LSCs survival through a kinase-independent mechanism. Here, we show that expression of PRMT1, the primary type I arginine methyltransferase, significantly increases in LSC-enriched CD34+CD38- populations relative to normal counterparts. Genetic PRMT1 depletion blocked AML CD34+ cell survival, and had more potent effects in AML cells from patients harboring FLT3-ITD. Our genome wide analysis of gene expression and PRMT1 conditional KO mouse study confirmed that PRMT1 preferentially cooperates with FLT3-ITD contributing to AML cell maintenance. Mechanistically, PRMT1 catalyzed FLT3-ITD protein methylation at arginines 972/973, and PRMT1 promoted leukemia cell growth in a FLT3 methylation-dependent manner. Moreover, effects of FLT3-ITD methylation in AML cells were in part due to crosstalk with FLT3-ITD phosphorylation at tyrosine 969 (Y969). Importantly, FLT3 methylation persisted in FLT3-ITD+ AML cells following TKI (AC220) treatment, indicating that methylation occurs independently of kinase activity. Finally, in both patient-derived xenograft (PDX) and murine AML models, combined administration of AC220 with a type I PRMT inhibitor (MS023) enhanced elimination of FLT3-ITD+ AML relative to AC220 treatment alone. Our study demonstrates that PRMT1-mediated FLT3 methylation promotes LSC activity and suggests that combining PRMT1 inhibition with FLT3 TKI treatment could be a promising approach to selectively target FLT3-ITD+ LSCs.

2021-11-10 | GSE122435 | GEO

GRP94 rewires and buffers the FLT3-ITD signaling network and promotes survival of acute myeloid leukemic stem cells

Project description:Internal tandem duplications in the tyrosine kinase receptor FLT3 (FLT3-ITD) are among the most common lesions in acute myeloid leukemia (AML) and there exists a need for new forms of treatment. Using ex vivo drug sensitivity screening, we found that FLT3-ITD+ patient cells are particularly sensitive to HSP90 inhibitors. While it is well known that HSP90 is important for FLT3-ITD stability, we found that HSP90 family members play a much more complex role in FLT3-ITD signaling than previously appreciated. First, we found that FLT3-ITD activates the unfolded protein response (UPR), leading to increased expression of GRP94/HSP90B1. GRP94 rewires FLT3-ITD signaling by binding and retaining FLT3-ITD in the ER, where it aberrantly activates downstream signaling pathways. Second, HSP90 family proteins protect FLT3-ITD+ AML cells against apoptosis by alleviating proteotoxic stress, and treatment with HSP90 inhibitors results in proteotoxic overload that triggers UPR-induced apoptosis. Importantly, leukemic stem cells are strongly dependent upon HSP90 for their survival, and the HSP90 inhibitor ganetespib causes leukemic stem cell exhaustion in mouse PDX models. Taken together, our study reveals a molecular basis for HSP90 addiction of FLT3-ITD+ AML cells and provides a rationale for including HSP90 inhibitors in the treatment regime for FLT3-ITD+ AML.

2020-09-02 | PXD009423 | Pride

Phosphoproteomic characterization of primary AML samples and relevance for response towards FLT3-inhibitors

Project description:Kinase hyperactivity is a common driver of acute myeloid leukemia (AML) and serves as a therapeutic target. The most frequent genetic aberration leading to hyperactive kinase signaling and poor prognosis is internal tandem duplication (ITD) of the FMS-tyrosine-like Kinase 3-gene (FLT3). FLT3-ITD induces ligand independent activation of FLT3 and downstream pathways leading to proliferation, decreased apoptosis and partial differentiation block. Combined with chemotherapy, FLT3-Tyrosine Kinase Inhibitor (FLT3-TKI) midostaurin improves overall survival (OS) of newly diagnosed FLT3-mutated AML patients, whereas single agent gilteritinib proved superior to chemotherapy in relapsed/refractory FLT3-mutated AML patients . As the primary targets of currently approved FLT3-TKIs are tyrosine (Y) kinases, we hypothesized that direct evaluation of tyrosine phosphorylation status could reveal pY phosphorylation profiles associated with FLT3-TKI response. Therefore, we used label-free pTyr-based phosphoproteomics in 35 primary AML samples (18 FLT3-WT, 17 FLT3-ITD), to identify differentially phosphorylated proteins underlying response to the FLT3-TKIs gilteritinib and midostaurin. We identified a total of 3024 unique phosphosites (median 1299 per sample, range 286 – 1612, pS:pT:pY 11.9%:9.5%:78.6%). Due to low number of identified phosphosites, we excluded two samples from further analyses. On the remaining 33 samples, we additionally performed IMAC global phosphoproteomics and on 17 samples protein expression analysis.

2021-09-10 | PXD024235 | Pride

Phosphoproteome Analysis Reveals Differential Mode of Action of Sorafenib in Wildtype and Mutated FLT3 AML Cells

Project description:Constitutively activating internal tandem duplication (ITD) alterations of the receptor tyrosine kinase FLT3 (Fms-like tyrosine kinase 3) are common in acute myeloid leukemia (AML) and classifies FLT3 as an attractive therapeutic target. So far, application of FLT3 small molecule inhibitors such as Sorafenib has resulted only in partial and transient clinical responses in FLT3-ITD+ patients. Only recently, a prolonged event-free survival has been observed in AML patients who were treated with Sorafenib in addition to standard therapy. Here, we studied the Sorafenib effect on proliferation in a panel of 13 FLT3-ITD- and FLT3-ITD+ AML cell lines. Sorafenib IC50 values ranged from 0.001 to 5.6 µM, whereas FLT3-ITD+ cells (MOLM-13, MV4;11) were found more sensitive to Sorafenib than FLT3-ITD- cells. However, we identified two FLT3-ITD- cell lines (MONO-MAC-1 and OCI-AML-2) which were also Sorafenib sensitive. Phosphoproteome analyses revealed that the affected pathways differed in Sorafenib sensitive FLT3-ITD- and FLT3-ITD+ cells. In MV4;11 cells Sorafenib suppressed mTOR signalling by inhibiting direct inhibition of FLT3. In MONO-MAC-1 cells Sorafenib inhibited the MEK/ERK pathway by inhibition of the RET tyrosine kinase. These data suggest that the FLT3 status in AML patients might not be the only predictive factor for a response to Sorafenib.

2017-05-02 | PXD004442 | Pride

Crenolanib in combination with azacitidine abrogates stromal protection and survival of leukemia-initiating cells in FLT3-ITD+ AML

Project description:Effectively targeting leukemia-initiating cells (LIC) in FLT3-internal-tandem-duplication (ITD)-mutated acute myeloid leukemia (AML) remains a crucial goal for achievement of cure. FLT3 tyrosine kinase inhibitors (TKI) have limited impact as single agents and have thus far been unable to eradicate LIC enriched in the CD34+CD38- bone marrow compartment and protected by contact with niche cells.Using primary AML samples in vitro as well as in an in vivo xenograft model, we investigated whether combining the novel FLT3-selective TKI crenolanib with the hypomethylating agent azacitidine (AZA) can eliminate LIC in FLT3-ITD+ AML and determined whether efficacy of this combination is dependent on coexisting genetic mutations in DNMT3A, NPM1 and TET2. Our data show that crenolanib as a single agent was unable to target FLT3-ITD+ LIC in contact with niche cells while the addition of AZA overcame stromal protection and resulted in dramatically reduced clonogenic capacity of FLT3-ITD+ LIC in vitro as well as severely impaired engraftment capacity of FLT3-ITD+ LIC in NSG mice. Strikingly, FLT3-mutated AML samples harboring concurrent TET2 mutations were completely resistant to crenolanib as a single agent. Mutations in DNMT3A or NPM1 had no influence on response to crenolanib while DNMT3A mutations conferred increased sensitivity of FLT3-ITD+ LIC to AZA. Our data suggest that response to crenolanib or AZA as single agents in FLT3-ITD+ AML is highly dependent on coexisting mutations in epigenetic regulators. However, the combination of AZA + crenolanib effectively eliminated FLT3-ITD+ LIC irrespective of additional mutations in NPM1, DNMT3A or TET2.

2017-04-03 | GSE86021 | GEO

Differential expression analysis of primary AML cells treated with AC220 vs DMSO in endothelial cell co-culture.

Project description:Although chemotherapy can successfully induce remission in FLT3/ITD positive acute myeloid leukemia (AML) patients, many, especially those with a high ratio of the FLT3/ITD versus wild type allele (FLT3-AR), exhibit a high relapse rate, requiring hematopoietic stem cell (HSC) transplantation to increase the chance of long-term remission. As the bone marrow tumor microenvironment (TME) has been implicated in drug resistance, we reasoned that AML-TME interactions might be critical for leukemic precursor survival and drug resistance, and that targeting AML-TME interactions might be crucial to improving survival in FLT3/ITD AML patients. In this study, we demonstrate that endothelial cells (ECs), a component of the TME, and the Notch pathway plays a critical role in the protection of FLT3/ITD positive progenitors against AC220 in AML patient samples with high FLT3-AR. We have previously shown that high FLT3-AR disease is distinguished by the presence of the mutation in the least mature CD34+CD33- precursors, where leukemic stem cells (LSCs) reside. Here, we demonstrate that inhibiting Notch signaling overcomes the TME-mediated drug resistance of the LSC-enriched CD34+CD33- precursors, raising the possibility that Notch may serve as a therapeutic target for eradicating LSCs that are thought to be responsible for relapse in this high-risk AML subset.

2019-10-03 | GSE138340 | GEO

Alkynyl nicotinamides with antileukemic activity to treat poor prognosis AM

Project description:FLT3 activating mutations cause myeloproliferative neoplasms by deregulating hematopoietic progenitor cell growth, and acute myeloid leukemia is on the rise. Investigational drugs targeting mutant FLT3, including Quizartinib and Crenolanib, develop inherent and acquired resistance to FLT3 targeted therapy. FLT3 inhibitor resistance in AML is dependent on co-occurring mutations, parallel survival pathways, and/or subsequent FLT3-ITD mutations. Despite the high prevalence of FLT3 mutations and their clinical significance in AML, there are few targeted therapeutic options. We identified two novel naphthyridine-based FLT3 inhibitors (HSN608 and HSN748) that specifically target FLT3-ITD at sub-nanomolar concentrations and are effective against drug-resistant secondary mutations. In the current study, we evaluated these compounds antileukemic activity against FLT3-ITD and gatekeeper mutations in drug-resistant AML, relapsed/refractory AMLs with FLT3 mutations, and in vivo mouse models with combinations of epigenetic mutations TET2 with FLT3-ITD, and AML patients PDX. In these model systems, we demonstrate that HSN748 outperforms the FDA-approved FLT3 inhibitor Gilteritinib in terms of inhibitory activity against FLT3-ITD.

2022-12-07 | MSV000090855 | MassIVE

Human acute myeloid leukemia (AML) cell line LFQ, comparison between doxycycline-inducible control shRNA and Pim2 shRNA

Project description:Acute myeloid leukemia (AML) with the FLT3 internal tandem duplication (FLT3-ITD AML) accounts for 20-30% of AML cases. This subtype usually responds poorly to conventional therapies including FLT3 tyrosine kinase inhibitors (TKIs) due to molecular bypass mechanisms. New therapeutic strategies are therefore urgently needed. Pim kinases are FLT3-ITD oncogenic targets that have been implicated in FLT3 TKI resistance. However, their precise biological function downstream of FLT3-ITD requires further investigation. MOLM-14 is a human FLT3-ITD AML cell line that was transduced with control (scrambled) or anti-Pim2 shRNA using lentivirus. Expression of hairpins was induced by doxycycline during 3 days and the experiments were done in biological triplicates. One million of MOLM-14 shSCR or shPim2 cells were lysed in 200µl lysis buffer (50 mM Tris (pH 8.5), 2% SDS, 20 mM TCEP, 50 mM chloroacetamide) and heated 5 min at 95°C. Proteins (50µg) from whole cell lysate were trypsin-digested overnight using the filtered-aided sample preparation (FASP) method. Liquid chromatography and mass spectrometry analyses were performed on anU3000 RSLC nanoflow-HPLC system coupled to a Q-Exactive Orbitrap mass spectrometer (both from Thermo Fisher Scientific). The analyses of raw data were performed by LFQ on Maxquant software with a maximum of 1% FDR and match between runs enabled within a 0.7 min match time window and 20 min alignment time window. Maxquant LFQ data were analyzed with Perseus, Ingenuity and Excel softwares.

2017-09-18 | PXD005880 | Pride

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