scholarly journals Deregulated Notch and Wnt signaling activates early-stage myeloid regeneration pathways in leukemia

2019 ◽  
Vol 217 (3) ◽  
Author(s):  
Yoon-A Kang ◽  
Eric M. Pietras ◽  
Emmanuelle Passegué

Targeting commonly altered mechanisms in leukemia can provide additional treatment options. Here, we show that an inducible pathway of myeloid regeneration involving the remodeling of the multipotent progenitor (MPP) compartment downstream of hematopoietic stem cells (HSCs) is commonly hijacked in myeloid malignancies. We establish that differential regulation of Notch and Wnt signaling transiently triggers myeloid regeneration from HSCs in response to stress, and that constitutive low Notch and high Wnt activity in leukemic stem cells (LSCs) maintains this pathway activated in malignancies. We also identify compensatory crosstalk mechanisms between Notch and Wnt signaling that prevent damaging HSC function, MPP production, and blood output in conditions of high Notch and low Wnt activity. Finally, we demonstrate that restoring Notch and Wnt deregulated activity in LSCs attenuates disease progression. Our results uncover a mechanism that controls myeloid regeneration and early lineage decisions in HSCs and could be targeted in LSCs to normalize leukemic myeloid cell production.

2020 ◽  
Vol 21 (17) ◽  
pp. 6247
Author(s):  
Yongsheng Ruan ◽  
Hye Na Kim ◽  
Heather Ogana ◽  
Yong-Mi Kim

Leukemia is an aggressive hematologic neoplastic disease. Therapy-resistant leukemic stem cells (LSCs) may contribute to the relapse of the disease. LSCs are thought to be protected in the leukemia microenvironment, mainly consisting of mesenchymal stem/stromal cells (MSC), endothelial cells, and osteoblasts. Canonical and noncanonical Wnt pathways play a critical role in the maintenance of normal hematopoietic stem cells (HSC) and LSCs. In this review, we summarize recent findings on the role of Wnt signaling in leukemia and its microenvironment and provide information on the currently available strategies for targeting Wnt signaling.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lars Velten ◽  
Benjamin A. Story ◽  
Pablo Hernández-Malmierca ◽  
Simon Raffel ◽  
Daniel R. Leonce ◽  
...  

AbstractCancer stem cells drive disease progression and relapse in many types of cancer. Despite this, a thorough characterization of these cells remains elusive and with it the ability to eradicate cancer at its source. In acute myeloid leukemia (AML), leukemic stem cells (LSCs) underlie mortality but are difficult to isolate due to their low abundance and high similarity to healthy hematopoietic stem cells (HSCs). Here, we demonstrate that LSCs, HSCs, and pre-leukemic stem cells can be identified and molecularly profiled by combining single-cell transcriptomics with lineage tracing using both nuclear and mitochondrial somatic variants. While mutational status discriminates between healthy and cancerous cells, gene expression distinguishes stem cells and progenitor cell populations. Our approach enables the identification of LSC-specific gene expression programs and the characterization of differentiation blocks induced by leukemic mutations. Taken together, we demonstrate the power of single-cell multi-omic approaches in characterizing cancer stem cells.


Haematologica ◽  
2020 ◽  
Vol 106 (1) ◽  
pp. 111-122 ◽  
Author(s):  
Sandrine Jeanpierre ◽  
Kawtar Arizkane ◽  
Supat Thongjuea ◽  
Elodie Grockowiak ◽  
Kevin Geistlich ◽  
...  

Chronic myelogenous leukemia arises from the transformation of hematopoietic stem cells by the BCR-ABL oncogene. Though transformed cells are predominantly BCR-ABL-dependent and sensitive to tyrosine kinase inhibitor treatment, some BMPR1B+ leukemic stem cells are treatment-insensitive and rely, among others, on the bone morphogenetic protein (BMP) pathway for their survival via a BMP4 autocrine loop. Here, we further studied the involvement of BMP signaling in favoring residual leukemic stem cell persistence in the bone marrow of patients having achieved remission under treatment. We demonstrate by single-cell RNA-Seq analysis that a sub-fraction of surviving BMPR1B+ leukemic stem cells are co-enriched in BMP signaling, quiescence and stem cell signatures, without modulation of the canonical BMP target genes, but enrichment in actors of the Jak2/Stat3 signaling pathway. Indeed, based on a new model of persisting CD34+CD38- leukemic stem cells, we show that BMPR1B+ cells display co-activated Smad1/5/8 and Stat3 pathways. Interestingly, we reveal that only the BMPR1B+ cells adhering to stromal cells display a quiescent status. Surprisingly, this quiescence is induced by treatment, while non-adherent BMPR1B+ cells treated with tyrosine kinase inhibitors continued to proliferate. The subsequent targeting of BMPR1B and Jak2 pathways decreased quiescent leukemic stem cells by promoting their cell cycle re-entry and differentiation. Moreover, while Jak2-inhibitors alone increased BMP4 production by mesenchymal cells, the addition of the newly described BMPR1B inhibitor (E6201) impaired BMP4-mediated production by stromal cells. Altogether, our data demonstrate that targeting both BMPR1B and Jak2/Stat3 efficiently impacts persisting and dormant leukemic stem cells hidden in their bone marrow microenvironment.


Blood ◽  
2011 ◽  
Vol 118 (9) ◽  
pp. 2420-2429 ◽  
Author(s):  
Christoph Schaniel ◽  
Dario Sirabella ◽  
Jiajing Qiu ◽  
Xiaohong Niu ◽  
Ihor R. Lemischka ◽  
...  

Abstract The role of Wnt signaling in hematopoietic stem cell fate decisions remains controversial. We elected to dysregulate Wnt signaling from the perspective of the stem cell niche by expressing the pan Wnt inhibitor, Wnt inhibitory factor 1 (Wif1), specifically in osteoblasts. Here we report that osteoblastic Wif1 overexpression disrupts stem cell quiescence, leading to a loss of self-renewal potential. Primitive stem and progenitor populations were more proliferative and elevated in bone marrow and spleen, manifesting an impaired ability to maintain a self-renewing stem cell pool. Exhaustion of the stem cell pool was apparent only in the context of systemic stress by chemotherapy or transplantation of wild-type stem cells into irradiated Wif1 hosts. Paradoxically this is mediated, at least in part, by an autocrine induction of canonical Wnt signaling in stem cells on sequestration of Wnts in the environment. Additional signaling pathways are dysregulated in this model, primarily activated Sonic Hedgehog signaling in stem cells as a result of Wif1-induced osteoblastic expression of Sonic Hedgehog. We find that dysregulation of the stem cell niche by overexpression of an individual component impacts other unanticipated regulatory pathways in a combinatorial manner, ultimately disrupting niche mediated stem cell fate decisions.


2016 ◽  
Vol 65 (1) ◽  
pp. 69-81 ◽  
Author(s):  
Geoffrey Brown ◽  
Aleksandra Marchwicka ◽  
Alan Cunningham ◽  
Kai-Michael Toellner ◽  
Ewa Marcinkowska

2016 ◽  
Vol 44 (9) ◽  
pp. S47
Author(s):  
Anne-Katrine Frank ◽  
Anton Willer ◽  
Tanja Lyholm Jensen ◽  
Teresa D'Altri ◽  
Nicolas Rapin ◽  
...  

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1708-1708
Author(s):  
Gesine Bug ◽  
Hilal Gul ◽  
Kerstin Schwarz ◽  
Manuela Kampfmann ◽  
Xiaomin Zheng ◽  
...  

Abstract Histone deacetylase inhibitors (HDI) have attracted considerable attention because of their ability to overcome the differentiation block in leukemic blasts either alone, or in combination with differentiating agents such as all-trans retinoic acid (ATRA). We have previously reported favorable effects of the potent HDI valproic acid (VPA) in combination with ATRA in a small subset of patients with advanced acute myeloid leukemia (AML) leading to blast cell reduction and improvement of hemoglobin. This effect was accompanied by hypergranulocytosis most likely due to an enhancement of non-leukemic myelopoiesis and suppression of malignant hematopoiesis rather than enforced differentiation of leukemic cells. These data prompted us to investigate the impact of VPA on normal hematopoietic stem cells (HSC). Differentiation of cord blood-derived, purified CD34+ cells was assessed by FACS analysis after a 7-days suspension culture in presence of early acting cytokines and 30–150μg/mL VPA. VPA prevented differentation of CD34+ cells in a dose-dependent manner: concomitant with an increase of CD34+ cells from 17 to 47%, the proportion of monocytic CD14+ cells decreased from 27 to 3% (n=3). In addition, VPA induced a 30-fold amplification of CD34+ bone marrow (BM) cells within 10 days as determined by colony assays (n=3). To evaluate the functional capacity of VPA-treated HSC, murine Sca1+/lin−s cells were harvested from colony assays and replated. VPA treatment allowed up to four cycles of replating in contrast to VPA-naïve control cells. Further analysis demonstrated that the stimulatory effect of VPA on the in vitro growth and colony formation capacity of HSC was mainly due to accelerated cell cycle progression. VPA strongly increased the proportion of cells in S phase compared to untreated controls (38 vs. 17%, resp.), as detected by propidium iodid staining and BRDU incorporation as well as reduced expression of the CDK-inhibitor p21cip-1/waf using murine HSC after 7 days of culture. Downregulation of p21cip-1/waf was confirmed in CD34+ BM cells showing maximum inhibition after 48 hours of VPA treatment and no recovery thereafter. Recent results indicate that VPA exerts inhibitory activity on GSK3beta by phosphorylation on Ser-9 and stimulates Akt in human neuroblastoma cells. GSK3beta is an effector of the Wnt-signaling pathway located upstream of beta-catenin. Wnt-signaling can directly stimulate the proliferation of HSC, expand the HSC pool and lead to upregulation of HoxB4. Here we show that VPA increased the inhibition-associated phosphorylation of GSK3beta on Ser-9 in human CD34+ BM cells after 48 hours as well as in murine Sca1+/lin− cells after 7 days. Exposure to VPA enhanced beta-catenin and Akt activity not only in CD34+ HSC but also in KG-1 and TF-1 cells with maximum activation after 48 hours of VPA stimulation. Moreover, VPA lead to an 8-fold increase of the HoxB4 level in CD34+ BM cells as determined by real time PCR at 48 hours. In conclusion, we show that VPA i.) expands HSC as assesed by phenotype and function; ii.) accelerates cell cycle progression of HSC accompanied by the down-regulation of p21cip-1waf; iii.) activates the GSK3beta depending beta-catenin pathway and Akt and iv.) up-regulates HoxB4. Our data strongly suggest that VPA is able to influence some of the signaling pathway considered relevant for proliferation and self-renewal which might request reconsideration of their employment for the treatment of AML.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1209-1209
Author(s):  
Chun Shik Park ◽  
Koramit Suppipat ◽  
H. Daniel Lacorazza

Abstract Abstract 1209 Chronic myeloid leukemia (CML) is a myeloproliferative disease that originate in hematopoietic stem cells (HSCs) as a result of the t(9;22) translocation, giving rise to the Ph (Philadelphia chromosome) and BCR-ABL oncoprotein. Although treatment of CML patients with tyrosine kinase inhibitor can efficiently eliminate most leukemic cells, chemoresistant leukemic stem cells (LSCs) can survive and drive recurrence of CML in these patients. A number of genes have been described to promote or inhibit proliferation of LSCs. Some of them have similar roles in normal HSCs. The transcription factor ELF4 promotes cell cycle entry of quiescent HSCs during homeostasis (Lacorazza et al., 2006). Thus, to investigate the function of ELF4 in CML initiation and maintenance, we developed a BCR-ABL-induced CML-like disease using retroviral transfer of BCR-ABL in Elf4-null bone marrow (BM) cells. We first investigated whether ELF4 is required for the induction of CML. Recipient mice of BCR-ABL-transduced WT BM cells developed CML and died with a latency 16–23 days, whereas recipient mice of BCR-ABL-transduced Elf4-/- BM cells showed longer latency of 45–47 days (n=20; p<0.0005). Progression of leukemia was monitored in peripheral blood, BM and spleen by flow cytometry. In mice transplanted with BCR-ABL-transduced Elf4-null BM cells, Gr-1+ leukemic cells expanded the first two weeks after BM transplantation followed by a decline at expense of a secondary expansion of B220+ cells. In contrast, Gr-1+ leukemic cells continuously expanded in mice receiving BCR-ABL-transduced WT BM cells. These results suggest that loss of ELF4 causes a profound abrogation in BCR-ABL-induced CML, while allowing progression of B-cell acute lymphocytic leukemia. Since loss of Elf4 led to impaired maintenance of myeloid leukemic cells, we postulated that ELF4 may affect survival of LSCs. Thus, we analyzed the frequency of Lin-c-Kit+Sca-1+ (LSK) cells that are BCR-ABL positive in BM and spleen. We found that BCR-ABL+ LSK cells were significantly reduced in recipients of BCR-ABL-transduced Elf4-/- BM cells. These studies indicate that ELF4 is essential to maintain the LSC pool in CML acting as a molecular switch between myeloid and lymphoid blast crisis. Disclosures: No relevant conflicts of interest to declare.


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