scholarly journals SETDB1 mediated histone H3 lysine 9 methylation suppresses MLL-fusion target expression and leukemic transformation

Haematologica ◽  
2019 ◽  
Vol 105 (9) ◽  
pp. 2273-2285 ◽  
Author(s):  
James Ropa ◽  
Nirmalya Saha ◽  
Hsiangyu Hu ◽  
Luke F. Peterson ◽  
Moshe Talpaz ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Target Genes ◽  
Critical Role ◽  
High Expression ◽  
Leukemia Cells ◽  
Biological Impact ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Epigenetic regulators play a critical role in normal and malignant hematopoiesis. Deregulation, including epigenetic deregulation, of the HOXA gene cluster drives transformation of about 50% of acute myeloid leukemia. We recently showed that the Histone 3 Lysine 9 methyltransferase SETDB1 negatively regulates the expression of the pro-leukemic genes Hoxa9 and its cofactor Meis1 through deposition of promoter H3K9 trimethylation in MLL-AF9 leukemia cells. Here, we investigated the biological impact of altered SETDB1 expression and changes in H3K9 methylation on acute myeloid leukemia. We demonstrate that SETDB1 expression is correlated to disease status and overall survival in acute myeloid leukemia patients. We recapitulated these findings in mice, where high expression of SETDB1 delayed MLL-AF9 mediated disease progression by promoting differentiation of leukemia cells. We also explored the biological impact of treating normal and malignant hematopoietic cells with an H3K9 methyltransferase inhibitor, UNC0638. While myeloid leukemia cells demonstrate cytotoxicity to UNC0638 treatment, normal bone marrow cells exhibit an expansion of cKit+ hematopoietic stem and progenitor cells. Consistent with these data, we show that bone marrow treated with UNC0638 is more amenable to transformation by MLL-AF9. Next generation sequencing of leukemia cells shows that high expression of SETDB1 induces repressive changes to the promoter epigenome and downregulation of genes linked with acute myeloid leukemia, including Dock1 and the MLL-AF9 target genes Hoxa9, Six1, and others. These data reveal novel targets of SETDB1 in leukemia that point to a role for SETDB1 in negatively regulating pro-leukemic target genes and suppressing acute myeloid leukemia.

LR11 Plays a Critical Role in Leukemogenesis of Acute Myeloid Leukemia by Regulating Adhesion and Homing Ability to Bone Marrow.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2409-2409
Author(s):  
Keigo Nishii ◽  
Chiaki Nakaseko ◽  
Masahiro Takeuchi ◽  
Naomi Shimizu ◽  
Chikako Ohwada ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Cell Growth ◽  
Myeloid Leukemia ◽  
Critical Role ◽  
Leukemia Cells ◽  
Adhesion Assay ◽  
U937 Cells ◽  
Donor Cells ◽  
Acute Myeloid

Abstract Abstract 2409 Introduction: Membrane-anchored uPAR plays a role in regulating the engraftment and mobilization of murine hematopoietic stem/progenitor cells (HSPCs) to bone marrow (BM). Acute myeloid leukemia (AML) patients with higher proportions of uPAR-positive cells posed higher relapse risk after chemotherapy. LR11 (also called SorLA or SORL1) is a regulator of uPAR function through complex formation with uPAR., and the LR11 expression is highly induced in AML cells, and circulating soluble form of LR11 (sLR11) levels are significantly increased in AML patients and ameliorated by chemotherapy (Sakai et al. 2012). Although LR11 is over-expressed in AML, the role of over-expressed LR11 in AML leukemogenesis remains unknown. Recently we found that LR11 mRNA expression levels are drastically increased in murine transformed granulocyte macrophage progenitors (GMPs) with MLL-AF9 fusion gene. Here, we show the pathological significance of LR11 expressions in the progression of AML using mouse leukemia model. Materials and Methods: Stably LR11-knockdown (LR11-KD) U937 cells were generated by transfection of shRNA expression vector specific for LR11. For generation of mouse AML model, the GMPs transformed by MLL-AF9 (MA9-GMPs) or human leukemic cells were transplanted into syngeneic mice or immune-deficient mice, respectively. For colony replating assays, MA9-GMPs were cultured in methylcellulose medium and colonies were counted and pooled, and then 1×104 cells were replated in the same medium. For cell growth assays, 5th round MA9-GMPs were transferred to liquid culture. An adhesion assay was performed using human mesenchymal stromal cells (MSC)-coated plates. Results: U937 cells expressed high level of LR11 mRNA and protein, but there was no difference in cell growth between control and LR11-KD U937 cells in vitro. We transplanted LR11-KD or control U937 cells into recipient mice, and monitored the percent of peripheral blood (PB) leukemia cells by flow cytometry. All the recipient mice transplanted with control U937 cells were died of leukemia by 3 weeks after transplantation, whereas the survival of mice transplanted with LR11-KD U937 cells were prolonged significantly (the median survival: 17.5 days for control cells vs. 28 days for LR11-KD cells, Figure. 1). The percent of leukemia cells in PB of the mice transplanted with LR11-KD U937 cells on day 13 after transplantation were significantly lower than those of mice transplanted with control U937 cells (1.2 ± 1.1% vs. 10.2 ± 5.8%, respectively). We next examined the effect of LR11 on the malignant phenotype by cell growth assay and colony replating assay using the MA9-GMPs from Lr11+/+ and Lr11−/− mice. There was no difference in the cell growth and colony forming ability between Lr11+/+ and Lr11−/− MA9-GMPs. However, the donor chimerism of mice transplanted with Lr11−/− MA9-GMPs was significantly lower than that of mice transplanted with Lr11+/+ MA9-GMPs (the percentage of chimerism on day 28 and on day 35 after transplantation: 54.6 ± 2.1% and 66.3 ± 11.0% for Lr11+/+ donor cells vs. 0.7 ± 2.1% and 0.5 ± 0.1% for Lr11−/− donor cells). We finally examined the cell motility analysis. In the adhesion assay, the attached cell numbers to MSC-coated plates were significantly reduced to 0.7-fold in the LR11-KD U937 cells compared with control U937 cells. In homing assay, we transplanted LR11-KD U937 cells and control cells into recipient mice. The number of LR11-KD U937 cells in recipient BM 16 hours after transplantation was significantly decreased compared with those of control cells (0.011 ± 0.004% for control cells vs. 0.003 ± 0.001% for LR11-KD cells, Figure 2). Conclusion: These data showed that LR11 plays a critical role in the pathogenesis of AML by enhancing the cell adhesion and homing ability to BM. Disclosures: No relevant conflicts of interest to declare.

scholarly journals NLRP3 Inflammasome Promotes the Progression of Acute Myeloid Leukemia via IL-1β Pathway

2020 ◽  
Author(s):  
Chaoqin Zhong ◽  
Ruiqing Wang ◽  
Mingqiang Hua ◽  
Chen Zhang ◽  
Fengjiao Han ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Nlrp3 Inflammasome ◽  
Myeloid Leukemia ◽  
Therapeutic Option ◽  
Leukemia Cells ◽  
Dependent Manner ◽  
Hematopoietic Stem ◽  
Cycle Regulation ◽  
Acute Myeloid

Abstract Background: NLRP3 inflammasome has been reported to be associated with the pathogenesis of multiple solid tumors. However, the role of NLRP3 inflammasome in acute myeloid leukemia (AML) remains unclear. Methods: NLRP3 inflammasome expression in AML bone marrow samples was investigated via quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays and further determined in a cohort of AML bone marrow via Western blot analysis. Cell proliferation and flow cytometry assays were performed to confirm the roles of NLRP3 in AML proliferation, cell cycle regulation, and apoptosis. A mouse model with up-regulated NLRP3 expression was constructed by lentiviral transfection and a model with down-regulated expression was established by hematopoietic stem cell transplantation.Results: NLRP3 inflammasome is over-expressed and highly activated in AML bone marrow leukemia cells, which is correlated with poor prognosis. The activation of NLRP3 inflammasome in AML cells promotes leukemia cells proliferation, inhibits apoptosis and increases resistance to chemotherapy, while inactivation of NLRP3 by caspase-1 or NF-κB inhibitor shows leukemia-suppressing effects. Bayesian networks analysis and cell co-culture tests further suggests that NLRP3 inflammasome acts through IL-1β but not IL-18 in AML. Knocking down endogenous IL-1β or anti-IL-1β antibody inhibits leukemia cells whereas IL-1β cytokine enhances leukemia proliferation. In AML murine model, up-regulation of NLRP3 increases the leukemia burden in bone marrow, spleen and liver, and shortens the survival time; furthermore, knocking out NLRP3 inhibits leukemia progression. Conclusions: Collectively, all these evidences demonstrated that NLRP3 inflammasome promotes AML progression in an IL-1β dependent manner, and targeting NLRP3 inflammasome may provide a novel therapeutic option for AML.

Rac1 Gtpase Promotes Hematopoietic Stem Cell Migration, Self-Renewal and Participates in Leukemia Initiation and Maintenance

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2923-2923
Author(s):  
Shuying Chen ◽  
Qing Rao ◽  
Haiyan Xing ◽  
Jing Yu ◽  
Huan Li ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Cell Migration ◽  
Myeloid Leukemia ◽  
Leukemia Cells ◽  
Bone Marrow Niche ◽  
Hematopoietic Stem ◽  
Rac1 Gtpase ◽  
Acute Myeloid

Abstract Acute myeloid leukemia (AML) is a hematological malignancy resulting from the transformation of normal hematopoietic stem cell (HSC). Except for the intrinsic factors, it is acceptable that some extrinsic events from microenvironment could be the important co-factors in the development of leukemia. In addition to the specific component, as an extrinsic factor, interaction between HSC and bone marrow niche regulates HSCs fate. Disruption on the interactions also influences hematopoiesis. It has become evident that Rac members of Rho GTPases family are important molecules regulating HSCs interactions with hematopoietic microenvironment and activation of Rac1 are observed in a serials of leukemia cells. We previously reported that Rac1 is highly expressed in leukemia cells and found that activation of Rac1 GTPase lead to an increase in leukemia cells migration, chemotherapy resistance, quiescence and trafficking to bone marrow niche. Furthermore, we showed that Rac1 mediated the localization in niche is further attributable to the maintenance of LSC quiescence. In this study, we investigated the effects of active Rac1 GTPase in the transformation of HSC and determined if the activation of Rac1GTPase could promote the interaction of HSC with osteoblastic niche and further contribute to the leukomogenesis. By forced expression of a constitutively active form of Rac1 GTPase (Rac1 V12）in c-Kit+ hematopoietic stem/progenitor cell, we show that activation of Rac1 GTPase promotes cell migration, adhesion and colony formation, and also lead to an increase in the frequency of cells in quiescent state. Gene expression analysis shows that activation of Rac1 up-regulates the expression of several molecules that mediated the interaction of LSC with osteoblastic niche, as well as the cell cycle inhibitors such as p21, p27, and p57. Furthermore, we established a mouse model of acute myeloid leukemia by transduction murine c-kit+HSPC with Rac1 V12 combined with AML1-ETO9a, followed by transplantation into lethally irradiated mice. To investigate the role of Rac1 activation in leukemogenesis in vivo, we treated the AML1-ETO-Rac1 leukemia cells with Rac1 GTPase inhibitor EHT1846 and then transplanted into recipient mice. After 40 μM EHT1846 treatment, no engraftment of AML cells in recipient mice was observed. Kaplan-Meier analyses indicate that treatment with EHT1846 significantly prolongs survival of the transplanted mice. 20μM dose of EHT1846 was less effective. These data indicated that active Rac1 might be an important contributing factor to leukemogenesis. In addition, short-term homing assays showed that EHT 1846 treatment causes a marked inhibition of AML cell homing into both bone marrow and spleen as compared with controls, indicating that Rac1 mediated homing could be an important step and participated in the leukemogensis. Altogether, our data suggest that activation of Rac1 GTPase is critical for the interaction between HSCs with BM niche and even be contributed to leukemia development. Disclosures Wang: Novartis: Consultancy; Bristol Myers Squibb: Consultancy.

scholarly journals Biological Associations and Clinical Impact of Differential Expression of the Pre-Mir-29a/b-1 and Pre-Mir-29b-2/C Clusters in Acute Myeloid Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5110-5110
Author(s):  
Florian Ramdohr ◽  
Marius Bill ◽  
Madlen Jentzsch ◽  
Karoline Schubert ◽  
Juliane Grimm ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Differential Expression ◽  
Hematopoietic Stem Cell ◽  
Myeloid Leukemia ◽  
Clinical Impact ◽  
High Expression ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Abstract Expression levels of miR-29 family members (i.e. miR-29a, miR-29b, & miR-29c) are deregulated in various neoplastic diseases, including acute myeloid leukemia (AML), known to affect DNA-methylation profiles by targeting epigenetic modifiers, & have been shown to be important for normal hematopoietic stem cell function. Mir-29 is organized in two distinctively regulated bi-cistronic clusters: the miR-29a/b-1 cluster & the miR-29b-2/c cluster. Here we evaluated the biological associations & clinical impact of the differential expression of pre-miR-29a/b-1 & pre-miR-29b-2/c clusters in AML. We analysed121 AML patients (pts) (median age 63 years [y], range 37-75 y) who have been consolidated with hematopoietic stem cell transplantation following non-myeloablative conditioning (nma-HCT; Fludarabin 30 mg/m2 on day -4 till -2 & 2 Gy total body irradiation) between 2000 & 2014 with pretreatment bone marrow material (BM) available. Disease status at nma-HCT was first (CR1 62%) or second complete remission (CR2 18%) or CR with incomplete peripheral recovery (CRi 20%). The mutation status (mut) of the ASXL1, CEBPA, DNMT3A IDH1, IDH2, NPM1, & TP53 gene & the FLT3-ITD & EVI1 expressionstatusas well as common surface marker expressions were assessed at diagnosis. European LeukemiaNet (ELN) classification was favorable (25%), intermediate-I (23%), intermediate-II (21%), adverse (27%) or unknown (4%). Pretreatment pre-miR-29a/b-1 & pre-miR-29b-2/c clusters expressionin bone marrow (BM)was measured by quantitative reverse transcription polymerase chain reaction & normalized to 18S. The median normalized gene expression defined high & low pre-miR-29a/b-1 & pre-miR-29b-2/c clusterexpressers. Median follow-up was 4.4y for pts alive. At diagnosis a high pre-miR-29a/b-1 expression did not associate with clinical characteristics. High pre-miR-29a/b-1 expressers were less likely to be TP53 mut (p=.01). Pts with high pre-miR-29b-2/c expression at diagnosis had higher BM blast counts (p=.01), were more likely to have a normal cytogenetics (CN, p=.03) & were less likely to be TP53 (p=.004) or ASXL1 mutated (p=.03). When we combined the expression status information of the two miR-29 clusters we found that AML blasts of pts with high expression of both clusters were less likely to be CD34 (p=.05) or CD117 (p=.04) positive & more likely to be CD11b positive (p=.05). These pts more often had CN-AML (p=.04) & better ELN genetic risk (p=.03). High expressers of both miR-29 clusters were also more likely to be DNMT3A mut (p=.01) & less likely to be EVI1 positive (p=.007). Noteworthy, none of the pts with high expression of both clusters had a TP53 (p=.16) or ASXL1 mutation (p=.08). Pts with a high expression of both miR-29 clustershad a significant longer relapse free survival (RFS, p=.01, Figure 1a) & overall survival (OS, p=.03) compared to pts with low expression of one or both miR-29 clusters. In conclusion, high expression of pre-miR-29a/b-1 & pre-miR-29b-2/c associated with different clinical & genetic characteristic at AML diagnosis. High expressers of both clusters were more often DNMT3A mutated, a gene targeted by miR-29. Furthermore, none of these patients harbored TP53 mutations, a gene known to be indirectly activated by miR-29 family members. These findings provide new insights into the miR-29 associated AML biology, which may contribute to the observed impact on AML pts outcomes. While we observed a trend for better survival for each miR-29 cluster, pts with high expression of the pre-miR-29a/b-1 & the pre-miR-29b-2/c clusterhad significantly longer RFS & OS. Figure 1 Figure 1. Disclosures Poenisch: Mundipharma: Research Funding.

scholarly journals SETDB1 Mediated H3K9 Methylation Suppresses MLL-Fusion Target Expression and Leukemic Transformation

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 110-110
Author(s):  
Andrew G. Muntean ◽  
James Ropa ◽  
Nirmalya SAHA ◽  
Hsiang-Yu Hu ◽  
Justin Serio ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Target Genes ◽  
Bone Marrow Cells ◽  
Hematopoietic Cells ◽  
High Expression ◽  
Leukemic Transformation ◽  
Acute Myeloid

Genes encoding epigenetic proteins are mutated in about 70% of Acute Myeloid Leukemia patients underscoring their role in leukemic transformation. Epigenetic deregulation of the HOXA gene cluster drives transformation of about 50% of acute myeloid leukemia (AML), such as those harboring MLL rearrangements, NPM mutations and others. Indeed, expression of Hoxa9 and its co-factor Meis1 is sufficient to transform bone marrow cells into a lethal AML. We have shown that epigenetic regulation of Hoxa9 and Meis1 is mediated through the Polymerase Associated Factor 1 complex (PAF1c). The PAF1c binds to RNA polymerase II and recruits enzymes that alter epigenetic landscapes and influence gene transcription. We and others have shown that the PAF1c directly binds and recruits MLL and MLL fusion proteins to target genes such as Hoxa9 and Meis1 to deliver H3K4 methylation or H3K79 methylation activity respectively. Importantly, the PAF1c-MLL1 interaction is necessary for the growth of MLL-fusion leukemia cells but appears dispensable for normal hematopoietic stem and progenitor cells (HSPCs) function. This suggests the PAF1c is differentially required in leukemic cells compared to its normal counterparts. Thus, we aimed to 1) define the role of the PAF1c in normal hematopoiesis, and 2) identify mechanisms regulating PAF1c function that may be deregulated in leukemia. To understand the role of the PAF1c in hematopoiesis, we conditionally deleted the PAF1c subunit Cdc73 in HSPCs in hematopoietic cells. Conditional hematopoietic deletion of Cdc73 leads to lethality within a week due to a depletion of c-kit+ cells. Characterization revealed a cell autonomous requirement for Cdc73 to prevent apoptosis in HSPCs. Gene expression profiling on both c-kit+ hematopoietic cells and AML cells revealed that Hoxa9/Meis1 gene programs are differentially responsive to loss of Cdc73. This work revealed an essential role for the PAF1c subunit in maintaining viability of HSPCs and points to AML specific functions for the PAF1c. Thus, we utilized immunoprecipitation followed by mass spectroscopy to identify novel PAF1c interactions in AML cells. We found a novel interaction with several H3K9 methyltransferases including SETDB1. We demonstrate that the PAF1c-SETDB1 interaction reduces expression of Hoxa9 and Meis1 by promoting deposition of H3K9me3. These findings mirrored human AML patient samples that showed SETDB1 expression was inversely correlated with HOXA9 and MEIS1 expression. Further, SETDB1 expression is correlated to disease status and overall survival in AML patients. We recapitulated these findings in mice, where high expression of SETDB1 delayed MLL-AF9 mediated disease progression by promoting differentiation of AML cells. We also explored the biological impact of treating normal and malignant hematopoietic cells with an H3K9 methyltransferase inhibitor, UNC0638. While AML cells demonstrate cytotoxicity to UNC0638 treatment, normal bone marrow cells exhibit an expansion of HSPCs. Consistent with these data, we show that bone marrow treated with UNC0638 is more amenable to transformation by MLL-AF9. Next generation sequencing of AML cells shows that high expression of SETDB1 induces repressive changes to the promoter epigenome and downregulation of genes linked with AML, including Dock1 and the MLL-AF9 target genes Hoxa9, Six1, and others. These data reveal novel targets of SETDB1 in AML that point to a role for SETDB1 in negatively regulating pro-leukemic target genes and suppressing AML. Disclosures Maillard: Genentech: Consultancy; Regeneron: Consultancy.

A leukemic stem cell with intrinsic drug efflux capacity in acute myeloid leukemia

Blood ◽  
2001 ◽  
Vol 98 (4) ◽  
pp. 1166-1173 ◽  
Author(s):  
Gerald G. Wulf ◽  
Rui-Yu Wang ◽  
Ingrid Kuehnle ◽  
Douglas Weidner ◽  
Frank Marini ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Myeloid Leukemia ◽  
Side Population ◽  
Fluorescence Emission ◽  
Drug Efflux ◽  
Hematopoietic Stem ◽  
Immunodeficient Mice ◽  
Acute Myeloid

The hematopoietic stem cell underlying acute myeloid leukemia (AML) is controversial. Flow cytometry and the DNA-binding dye Hoechst 33342 were previously used to identify a distinct subset of murine hematopoietic stem cells, termed the side population (SP), which rapidly expels Hoechst dye and can reconstitute the bone marrow of lethally irradiated mice. Here, the prevalence and pathogenic role of SP cells in human AML were investigated. Such cells were found in the bone marrow of more than 80% of 61 patients and had a predominant CD34low/− immunophenotype. Importantly, they carried cytogenetic markers of AML in all 11 cases of active disease examined and in 2 out of 5 cases in complete hematological remission. Comparison of daunorubicin and mitoxantrone fluorescence emission profiles revealed significantly higher drug efflux from leukemic SP cells than from non-SP cells. Three of 28 SP cell transplants generated overt AML-like disease in nonobese diabetic–severe combined immunodeficient mice. Low but persistent numbers of leukemic SP cells were detected by molecular and immunological assays in half of the remaining mice. Taken together, these findings indicate that SP cells are frequently involved in human AML and may be a target for leukemic transformation. They also suggest a mechanism by which SP cells could escape the effects of cytostatic drugs and might eventually contribute to leukemia relapse.

scholarly journals 7-Ketocholesterol Promotes Oxiapoptophagy in Bone Marrow Mesenchymal Stem Cell from Patients with Acute Myeloid Leukemia

Cells ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 482 ◽  
Author(s):  
Jessica Liliane Paz ◽  
Debora Levy ◽  
Beatriz Araujo Oliveira ◽  
Thatiana Correia de Melo ◽  
Fabio Alessandro de Freitas ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Cholesterol Oxidation ◽  
Specific Cell ◽  
Hematopoietic Stem ◽  
Shh Pathway ◽  
Number Of Cells ◽  
Acute Myeloid

7-Ketocholesterol (7-KC) is a cholesterol oxidation product with several biological functions. 7-KC has the capacity to cause cell death depending on the concentration and specific cell type. Mesenchymal stem cells (MSCs) are multipotent cells with the ability to differentiate into various types of cells, such as osteoblasts and adipocytes, among others. MSCs contribute to the development of a suitable niche for hematopoietic stem cells, and are involved in the development of diseases, such as leukemia, to a yet unknown extent. Here, we describe the effect of 7-KC on the death of bone marrow MSCs from patients with acute myeloid leukemia (LMSCs). LMSCs were less susceptible to the death-promoting effect of 7-KC than other cell types. 7-KC exposure triggered the extrinsic pathway of apoptosis with an increase in activated caspase-8 and caspase-3 activity. Mechanisms other than caspase-dependent pathways were involved. 7-KC increased ROS generation by LMSCs, which was related to decreased cell viability. 7-KC also led to disruption of the cytoskeleton of LMSCs, increased the number of cells in S phase, and decreased the number of cells in the G1/S transition. Autophagosome accumulation was also observed. 7-KC downregulated the SHh protein in LMSCs but did not change the expression of SMO. In conclusion, oxiapoptophagy (OXIdative stress + APOPTOsis + autophagy) seems to be activated by 7-KC in LMSCs. More studies are needed to better understand the role of 7-KC in the death of LMSCs and the possible effects on the SHh pathway.

scholarly journals Gpr44 Mediates the Selenium-Dependent Anti-Leukemic Effect in Acute Myeloid Leukemia

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1835-1835
Author(s):  
Fenghua Qian ◽  
Fenghua Qian ◽  
Diwakar Tukaramrao ◽  
Jiayan Zhou ◽  
Nicole Palmiero ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Murine Model ◽  
Myeloid Leukemia ◽  
Hematopoietic Stem ◽  
Cell Counts ◽  
Pparγ Agonist ◽  
Acute Myeloid

Abstract Objectives The relapse of acute myeloid leukemia (AML) remains a significant concern due to persistent leukemia stem cells (LSCs) that are not targeted by existing therapies. LSCs show sensitivity to endogenous cyclopentenone prostaglandin J (CyPG) metabolites that are increased by dietary trace element selenium (Se), which is significantly decreased in AML patients. We investigated the anti-leukemic effect of Se supplementation in AML via mechanisms involving the activation of the membrane-bound G-protein coupled receptor 44 (Gpr44) and the intracellular receptor, peroxisome proliferator-activated receptor gamma (PPARγ), by endogenous CyPGs. Methods A murine model of AML generated by transplantation of hematopoietic stem cells (HSCs- WT or Gpr44−/−) expressing human MLL-AF9 fusion oncoprotein, in the following experiments: To investigate the effect of Se supplementation on the outcome of AML, donor mice were maintained on either Se-adequate (Se-A; 0.08–0.1 ppm Se) or Se-supplemented (Se-S; 0.4 ppm Se) diets. Complete cell counts in peripheral blood were analyzed by hemavet. LSCs in bone marrow and spleen were analyzed by flow cytometry. To determine the role of Gpr44 activation in AML, mice were treated with Gpr44 agonists, CyPGs. LSCs in bone marrow and spleen were analyzed. Mice transplanted with Gpr44−/- AML cells were compared with mice transplanted with wild type AML cells and the progression of the disease was followed as above. To determine the role of PPARγ activation in AML, PPARγ agonist (Rosiglitazone, 6 mg/kg, i.p, 14 d) and antagonist (GW9662, 1 mg/kg, i.p. once every other day, 7 injections) were applied to Se-S mice transplanted with Gpr44−/- AML cells and disease progression was followed. Results Se supplementation at supraphysiological levels alleviated the disease via the elimination of LSCs in a murine model of AML. CyPGs induced by Se supplementation mediate the apoptosis in LSCs via the activation of Gpr44 and PPARγ. Conclusions Endogenous CyPGs produced upon supplementation with Se at supraphysiological levels improved the outcome of AML by targeting LSCs to apoptosis via the activation of two receptors, Gpr44 and PPARg. Funding Sources NIH DK 07,7152; CA 175,576; CA 162,665. Office of Dietary Supplements, USDA Hatch funds PEN04605, Accession # 1,010,021 (KSP, RFP).

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