TGF-β Neutralizing Antibody 1D11 Inhibits LIF-JAK-Stat3 Signaling and Enhances Cytarabine Induced Apoptosis in AML Cells in Bone Marrow Microenvironment

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 926-926
Author(s):  
Yoko Tabe ◽  
Yuexi Shi ◽  
Zhihong Zeng ◽  
Linhua Jin ◽  
Yixin Zhou ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stromal Cells ◽  
Molecular Mechanisms ◽  
Leukemia Cell ◽  
Neutralizing Antibody ◽  
Leukemia Cells ◽  
U937 Cells ◽  
Induced Apoptosis ◽  
Cells Cultured

Abstract Abstract 926 We have previously reported pro-survival effects of TGF-β1 in myelo-monocytic leukemia cells (Xu et al.,Br J Haematol.2008). Hypoxia and interactions with bone marrow (BM) stromal cells have emerged as essential components of leukemic BM microenvironment that promote leukemia cell survival and chemoresistance. Our preliminary data indicate that TGF-β neutralizing antibody 1D11 (Genzyme) prevents accumulation of AML cells in a quiescent G0 state under co-culture condition with BM-derived mesenchymal stromal cells (MSC) (Jin et al., ASH abstract 2010). In turn, the chemokine CXCL12 and its receptor CXCR4 play crucial roles in cell migration and stroma/leukemia cell interactions. In this study, we investigated the anti-leukemic effects and molecular mechanisms of action of TGF-β neutralizing antibody 1D11 under hypoxic conditions. We further investigated the anti-leukemic efficacy of 1D11 combined with CXCR4 antagonist plerixafor in the in vivo leukemia models. AML cells (MV4;11 and U937) were propagated under 1% O2 for at least 14 days to assure their sustained proliferation and survival. Isotype control antibody 13C4 combined with ara-C induced no significant change in apoptosis or cell cycle progression. In MV4;11 cells cultured with 2ng/mL rhTGF-β1, 1D11 (10 μg/mL) induced only minimal apoptosis by itself, yet enhanced low-dose cytarabine (AraC, 0.5 μM) induced apoptosis. This effect was more prominent under hypoxia compared to normoxia (% of subG1 fraction, 21% O2: ara-C, 2.6 ± 0.2%, ara-C + 1D11, 10.8 ± 2.5%, p=0.03; 1% O2: ara-C, 11.3 ± 2.7%, AraC + 1D11, 21.4 ± 0.5%, p=0.001). 1D11 with ara-C abrogated rhTGFβ1-induced accumulation of cells in G0/G1 phase (21% O2; cont, 73.8 ± 4.1, rhTGFβ, 82.2 ± 3.2, rhTGFβ + AraC, 65.4 ± 2.5, rhTGFβ + AraC + 1D11, 50.3 ± 1.9, p=0.001: in 1% O2; cont, 71.8 ± 1.3, rhTGFβ, 85.4 ± 1.4, rhTGFβ + AraC, 79.3 ± 5.1, rhTGFβ + AraC + 1D11, 67.1 ± 4.0, p = 0.03). The anti-leukemic efficacy of 1D11 was next examined in an in vivo leukemia model. 1D11 administered at 5 mg/kg IP every other day in combination with ara-C (50 mg/kg IP weekly) decreased leukemia burden of nude mice injected with Baf3/ITD-luciferase leukemia cells (p=0.002). Administration of small molecule CXCR4 inhibitor plerixafor, which successfully diminished cell migration to CXCL12 in vitro, in combination with 1D11 decreased leukemia burden in vivo (p=0.05), and co-administration of ara-C, plerixafor and 1D11 was most effective (bioluminescence intensity, ×107 photons/sec) control, 1.2 ± 0.2; ara-C, 0.94 ± 0.3; plerixafor + 1D11, 0.56 ± 0.1; plerixafor + 1D11 + ara-C, 0.23 ± 0.09, p=0.003). We next examined the molecular mechanisms responsible for chemosensitization through blockade of TGFβ with 1D11. Treatment with rhTGF-β1 induced upregulation of p21 expression as well as pro-survival phosphorylation of Stat3 in MV4;11 and U937 cells, and these effects were abrogated by 1D11. Knock-down of Stat3 by siRNA increased apoptosis induction in U937 cells cultured in the presence of rhTGFβ1. Notably, 4-fold upregulation of the established TGFβ target, leukemia inhibitory factor (LIF) gene mRNA, was observed after rhTGF-β1 treatment and this was reversed by 1D11. These results indicate that 1D11 inhibits rhTGF-β1-induced autocrine stimulation of pro-survival LIF-JAK-Stat3 signal transduction pathway in AML cells. In summary, blockade of TGF-β by 1D11, and abrogation of CXCL12/CXCR4 signaling may enhance the efficacy of chemotherapy against AML cells in the hypoxic BM microenvironment. These findings warrant further investigations in human clinical trials. Disclosures: Konopleva: Genzyme: Research Funding.

ARC Is Regulated by MAPK and PI3K and Confers Drug Resistance and Survival Advantage to AML in Vitro and in Vivo

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 893-893
Author(s):  
Po Yee Mak ◽  
Duncan H Mak ◽  
Yuexi Shi ◽  
Vivian Ruvolo ◽  
Rodrigo Jacamo ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Apoptosis Resistance ◽  
Control Mscs ◽  
Extrinsic Apoptosis ◽  
Induced Apoptosis ◽  
And Control

Abstract Abstract 893 ARC (Apoptosis repressor with caspase recruitment domain) is a unique antiapoptotic protein that has been shown to suppress the activation of both intrinsic and extrinsic apoptosis. We previously reported that ARC is one of the most potent adverse prognostic factors in AML and that high ARC protein expression predicted shorter survival and poor clinical outcome in patients with AML (Carter BZ et al., Blood 2011). Here we report how ARC is regulated and its role in inhibition of AML apoptosis and in cell survival. We provide evidence that ARC expression is regulated by MAPK and PI3K signaling. Inhibition of MAPK and PI3K pathways decreased ARC mRNA and protein levels in AML cells. ARC expression in AML cells is upregulated in co-cultures with bone marrow-derived mesenchymal stromal cells (MSCs) and the upregulation is suppressed in the presence of MAPK or PI3K inhibitors. To investigate the role of ARC in apoptosis resistance in AML, we generated stable ARC overexpressing (O/E) KG-1 and stable ARC knock down (K/D) OCI-AML3 and Molm13 cells and treated them with Ara-C and agents selectively inducing intrinsic (ABT-737) or extrinsic (TRAIL) apoptosis. We found that ARC O/E cells are more resistant and ARC K/D cells more sensitive to Ara-C, ABT-737, and TRAIL-induced apoptosis: EC50s of Ara-C, ABT-737, or TRAIL treatment at 48 hours for ARC O/E KG-1 and control cells were 1.5 ± 0.1 μM vs. 83.5 ± 4.6 nM, 2.2 ± 0.2 μM vs. 60.2 ± 3.1 nM, or 0.97 ± 0.03 μg/mL vs. 0.17 ± 0.08 μg/mL, respectively and for ARC K/D OCI-AML3 and control cells were 0.33 ± 0.02 μM vs. 3.4 ± 0.2 μM, 0.24 ± 0.01 μM vs. 1.3 ± 0.1 μM, or 0.13 ± 0.09 μg/mL vs. 0.36 ± 0.03 μg/mL, respectively. Bone marrow microenvironment is known to play critical roles in AML disease progression and in protecting leukemia cells from various therapeutic agent-induced apoptosis. Leukemia cells were co-cultured with MSCs in vitro study to mimic the in vivo condition. ARC was found to be highly expressed in MSCs and stable ARC K/D MSCs were generated. AML cell lines and primary patient samples were co-cultured with ARC K/D or control MSCs and treated with Ara-C, ABT-737, or TRAIL. Interestingly, ARC K/D MSCs lost their protective activity for leukemia cells treated with these agents. EC50s for OCI-AML3 cells co-cultured with ARC K/D or control MSCs for 48 hours treated with Ara-C, ABT-737, or TRAIL were 1.0 ± 0.04 μM vs. 4.5 ± 0.2 μM, 0.15 ± 0.06 μM vs. 0.53 ± 0.02 μM, or 1.4 ± 0.8 μg/mL vs. 8.1 ± 0.3 μg/mL, respectively. In addition, ARC O/E KG-1 cells grew faster and ARC K/D OCI-AML3 and Molm13 cells and ARC K/D MSCs grew slower than their respective controls. We then injected KG-1 cells into mice and found that NOD-SCID mice harboring ARC O/E KG-1 had significantly shorter survival than mice injected with the vector control KG-1 (median 84 vs. 111 days) as shown in the figure. Collectively, results demonstrate that ARC plays critical roles in AML. ARC is regulated by MSCs through various signaling pathways in AML cells, protects leukemia cells from apoptosis induced by chemotherapy and by agents selectively inducing intrinsic and extrinsic apoptosis. ARC regulates leukemia cell growth in vitro and in vivo. The results suggest that ARC is a potential target for AML therapy. In addition, targeting ARC in MSCs suppresses microenvironmental protection of AML cells. Disclosures: No relevant conflicts of interest to declare.

BMS-936564 (MDX1338): A Fully Human Anti-CXCR4 Antibody Induces Apoptosis in an in Vitro Model of Stromal – Leukemia Cell Interaction for Chronic Lymphocytic Leukemia.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2887-2887
Author(s):  
Manoj Kumar Kashyap ◽  
Deepak Kumar ◽  
Harrison Jones Jones ◽  
Michael Y. Choi ◽  
Johanna Melo-Cardenas ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Leukemia Cell ◽  
Cell Interaction ◽  
Lymphocytic Leukemia ◽  
Leukemia Cells ◽  
Drug Induced ◽  
Induced Apoptosis ◽  
Cells Cultured

Abstract Abstract 2887 Chronic lymphocytic leukemia (CLL) remains incurable despite advances in the biology and treatment of this disease. Current data support the notion that resistance to therapy is promoted by a “protective” tumor microenvironment in which non-leukemia cells produce factors that enhance the resistance of CLL cells to spontaneous or drug-induced apoptosis. One such factor is the chemokine CXCL12, which interacts with its receptor CXCR4 on CLL cells to promote cancer cell survival. To examine the therapeutic potential of blocking CXCL12-CXCR4 interactions, we studied the effect of BMS-936564, a fully human IgG4 anti-CXCR4 antibody, using an in vitro co-culture model of human bone marrow derived stomal-NKter cells – leukemia cell interaction. Such stromal-NKter cells secrete CXCL12 and enhance the resistance of CLL cells to apoptosis in vitro. We observed that primary CLL cells co-cultured with stromal-NKter cells had significantly greater viability than CLL cells cultured alone (20–60% above baseline at 48 hours). Moreover, CLL cells co-cultured with stromal cells had enhanced resistance to drug-induced apoptosis. We found that BMS-936564 antibody at concentrations of 2–200nM could enhance the rate of apoptosis of CLL cells cultured alone or in the presence of stromal cells. CLL cells that expressed unmutated IgVH genes or ZAP-70 appeared equally susceptible to treatment with BMS-936564 as did CLL cells that lack these adverse prognostic markers, as did CLL cells that harbored deletions in 17p13.2 and that were resistant to chemotherapeutic agents, such a fludarabine monophosphate. BMS-936564 antibody inhibited CXCL12 mediated F-Actin polymerization in CLL cells at lower concentrations (20–200nM) compared to AMD-3100 (Mozobil), a small molecule CXCR4 inhibitor (50–150μM). In addition, AMD-3100 did not induce apoptosis in CLL cells (10–300μM). In summary, we observed that the anti-CXCR4 antibody BMS-936564 inhibited CXCL12 mediated activation of the CXCR4 receptor in CLL cells and induced apoptosis in leukemia cells. The pro-apoptotic activity of BMS-936564 was observed in cells cultured alone or together with stromal cells suggesting that this antibody had direct cytotoxic effect on leukemia cells and that it can overcome the protective tumor microenvironment. More over, the activity of BMS-936564 was independent of the presence of poor prognostic factors such as del(17p) suggesting that its mechanism of action is P53 independent. These findings show evidence that the CXCR4-CXCL12 pathway is a valid therapeutic target in CLL and provide additional biological rationale for ongoing clinical trials in CLL and other hematological malignancies using BMS-936564. Disclosures: Kuhne: Bristol-Myers Squibb: Employment. Sabbatini:Bristol-Myers Squibb: Employment. Cohen:Bristol-Myers Squibb: Employment. Shelat:Bristol-Myers Squibb: Employment. Cardarelli:Bristol-Myers Squibb: Employment. Kipps:Abbott: Consultancy, Research Funding.

Disruption of Leukemia/Stroma Cell Interactions by CXCR4 Antagonist CTCE-9908 Enhances Chemotherapy-Induced Apoptosis in AML

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2415-2415
Author(s):  
Hongbo Lu ◽  
Zhihong Zeng ◽  
Yuexi Shi ◽  
Sergej Konoplev ◽  
Donald Wong ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stromal Cells ◽  
Leukemia Cell ◽  
Bone Marrow Microenvironment ◽  
Cell Interactions ◽  
Leukemic Cells ◽  
Dependent Manner ◽  
Induced Apoptosis ◽  
Dose Dependent

Abstract The chemokine receptor CXCR4 is critically involved in the migration of hematopoietic cells towards the stromal derived factor (SDF-1α)-producing bone marrow microenvironment. We and others have previously demonstrated that stroma/leukemia interactions mediate protection of leukemic cells from chemotherapy-induced apoptosis (Konopleva, Leukemia 2002). Using a peptide analog of SDF-1α designated CTCE-9908, we tested the hypothesis that CXCR4 inhibition interferes with stromal/leukemia cell interactions resulting in increased sensitivity to chemotherapy. Our results showed that CTCE-9908 significantly inhibits SDF-1α-induced migration of U937 (43% inhibition) and OCI-AML3 cells (40% inhibition) in a dose-dependent manner. In three of the four primary AML samples which expressed CXCR4 on cell surface and migrated in response to SDF-1α, 50 μg/ml CTCE-9908 reduced SDF-1α-induced migration of leukemic blasts (60%, 19% and 50% inhibition respectively). In in vitro co-culture systems, stromal cells significantly protected OCI-AML3 cells from chemotherapy induced apoptosis [no MS-5, 75.2±5.2% annexinV(+); with MS-5, 59±1.1% annexinV(+)]. Western blot analysis revealed that CTCE-9908 inhibits Akt and Erk phosphorylation in a dose-dependent manner in the OCI-AML3 cell line stimulated by SDF-1α. Blockade of CXCR4 expression with CTCE-9908 markedly abrogated the protective effects of stromal cells on OCI-AML3 [Ara-C, 59±1.1% annexinV(+); Ara-C + CTCE-9908, 76.9±1.35 annexinV(+)]. Most importantly, it decreased stroma-mediated protection from AraC-induced apoptosis in four out of five primary AML samples with surface expression of functional CXCR4 (mean increase, 25.1±9.3% compared to chemotherapy alone). In vivo, subcutaneous administration of 1.25mg CTCE-9908 induced mobilization of leukemic cells from primary AML patient transplanted into NOD/Scid-IL2Rγ-KO mice (from 15% to 27% circulating leukemic cells 1 hour post CTCE-9908 injection). Taken together, our data suggest that SDF-1α/CXCR4 interactions contribute to the resistance of leukemic cells to chemotherapy-induced apoptosis via retention of leukemic cells in the bone marrow microenvironment niches. Disruption of these interactions by the potent CXCR4 inhibitor CTCE-9908 represents a novel strategy for targeting leukemia cell/bone marrow microenvironment interaction. Based on these observations, in vivo experiments are ongoing to characterize the efficacy of chemotherapy combined with CTCE-9908.

Leukemia-Derived Exosomes Reorganize Bone Marrow Microenvironment In AML

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2455-2455
Author(s):  
Bijender Kumar ◽  
Lihong Weng ◽  
Xiaoman Lewis ◽  
Jodi Murakami ◽  
Xingbin Hu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stromal Cells ◽  
Stromal Cell ◽  
Leukemia Cell ◽  
Bone Marrow Microenvironment ◽  
Leukemia Cells ◽  
Control Group ◽  
Hematopoietic Progenitors ◽  
Stromal Compartment

Abstract Increasing evidence suggests that leukemia cells take shelter in the bone marrow (BM) microenvironment (niche), where they hide from chemotherapy and continue to divide. As yet, the identity of niche cells and secreted factors that facilitate leukemia cell growth and assist them in evading chemotherapy is unclear. Further, how leukemia cells alter the bone marrow microenvironment is not known yet. In this study, we provide compelling evidences of a novel role of leukemia-derived exosomes in altering the microenvironment constituents by paracrine mechanisms.As proof-of-concept, we analyzed the cytokines mRNA profiles of primary human and mouse stromal cell co-cultured with primary CD34+CD38- cells from AML patients. Stromal cells co-cultured with leukemia showed increased levels of IL-6, IL-1β, VEGFα, TNF and reduced SDF1 mRNA expression. Similar pattern of gene expression changes were observed from stroma cells co-cultured with leukemia-derived exosomes.By using CFSE labeled exosomes, we observed that leukemia-derived exosomes target marrow stromal and endothelial cells both in-vitro and in-vivo directly. In our in vivo AML model, established using xenografted AML cell lines or primary AML patient samples in Rag2-/- γc-/-mice, we observed expansion of LT-HSC and hematopoietic progenitors compartment. The leukemia animals also showed cellular composition changes in the stromal compartment suggesting osteoblast differentiation was blocked. Interestingly, milder but similar changes were observed in mice treated with leukemia-derived exosomes. Exosomes derived from normal human peripheral blood did not induce significant changes in either hematopoietic or stromal compartments in recipient mice. These data indicate that leukemia cells secrete specialized exosomes to modulate the BM microenvironment. Fluidigm dynamic array analysis of BM stromal cells from leukemic mice revealed that the cell adhesion molecules (NCAM1, VCAM1, CD44, OPN & ICAM1) and factors important for angiogenesis (Angpt1, Angpt 2 &VEGF) were all upregulated in leukemia-modified stromal cells whereas genes important for osteoblast (OCN, OSX), chondrocyte (SOX9) development and HSC maintenance (SDF1 and SCF) were down regulated. These results suggest that leukemia cells can remodel the BM microenvironment by changing the stromal cell composition and influencing expression of important molecular regulators. To evaluate the HSC functions in exosomes-treated mice, we used 5-fluorouracil (5-FU) to suppress hematopoiesis and induce myeloablative stress. Leukemia-derived exosome-pretreated mice succumbed to death earlier compared to the control group (p=0.0001) suggesting that HSCs from leukemia-derived exosome-treated mice may have lower stem cell activity than their counterparts from normal mice. Furthermore, more LT-HSC and hematopoietic progenitors from leukemia-derived exosome-pretreated mice were in active cell cycle (p=0.004 and p=0.01 respectively). These findings support our hypothesis that leukemia cells/exosomes directly or indirectly through leukemia-modified niche, altered the HSCs physiological and quiescence properties. Next we analyzed the ability of leukemia-modified niche to support the normal hematopoiesis. We co-cultured freshly sorted normal CD45.2 LT-HSCs (LSK CD150+CD48-Flk2-) with leukemia cells/exosomes pre-treated stroma cells for 48 hours and transplanted the co-cultured HSC into irradiated CD45.1 mice. 18 weeks after transplantation, we observed a significantly decreased engraftment of the HSCs co-cultured with leukemic cells/exosomes stroma compared with the HSCs co-cultured with normal stroma (p=0.003). Finally, leukemia engrafted better and developed more rapidly (p=0.0026) in mice that received leukemia-derived exosomes pre-treatment. These data suggest that changes induced by leukemia-derived exosomes in the BM niche accelerate leukemia progression and decrease their ability to support HSCs. Collectively, our data demonstrate that the leukemia cells manipulate the bone marrow microenvironment, partly through leukemia-derived exosomes, to suppress the normal hematopoiesis and facilitate growth of the leukemic progeny. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Bone Marrow Stromal Cell Mediated Resistance to Mertk Inhibition in Acute Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2819-2819 ◽  
Author(s):  
Katherine A Minson ◽  
Madeline G Huey ◽  
Amanda A Hill ◽  
Irene Perez ◽  
Xiaodong Wang ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Death ◽  
Acute Leukemia ◽  
Cell Cultures ◽  
Stromal Cells ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Wild Type ◽  
Equity Ownership ◽  
Induced Apoptosis

Abstract MERTK is a receptor tyrosine kinase of the TAM family (TYRO-3, AXL, MERTK) that is ectopically expressed in 30-50% of newly diagnosed pediatric acute lymphoblastic leukemia (ALL) patient samples and aberrantly expressed in 80-100% of pediatric and adult primary acute myeloid leukemia (AML) samples. MERTK inhibition mediated by shRNA or a small molecule inhibitor, MRX-2843, decreased colony-forming potential and induced apoptosis in leukemia cell cultures. Moreover, MERTK inhibition prolonged survival in mouse xenograft models of acute leukemia, but was not curative. In these models, treatment with MRX-2843 effectively reduced peripheral disease burden but was less effective in the bone marrow, suggesting a role for the bone marrow microenvironment in therapeutic resistance. Additionally, Gas6, a MERTK ligand, is a poor prognostic factor in AML, mediates increased resistance to cytotoxic chemotherapy in leukemia cells, and is expressed in the bone marrow. To determine the role of Gas6 produced by bone marrow stromal cells in mediating resistance to MERTK inhibition by MRX-2843, acute leukemia cell lines were cultured in the presence of a Gas6-producing fibroblast-like cell line (HS27) or bone marrow derived stromal cells (BMDSCs) from wild type or Gas6 knockout mice and induction of apoptosis and cell death was determined by flow cytometry after treatment with MRX-2843 or vehicle. Co-culture with the HS27 cell line significantly reduced cell death in Kasumi-1 AML cell cultures in response to treatment with 300nM MRX-2843 compared to leukemia cells alone (29.4% versus 60.5%, p=0.002). Similar results were observed in Nomo1 AML and 697 pre-B ALL cell cultures. To evaluate whether soluble factors mediated this protective effect, Kasumi-1 cells were cultured in HS27-conditioned medium in the presence or absence of MRX-2843. Interestingly, conditioned medium was not sufficient to provide protection from MRX-2843 induced apoptosis (86.0% vs. 85.5% in unconditioned medium). To more directly assess the role of Gas6, BMDSCs isolated from wild-type and Gas6 knockout C57Bl/6 mice were co-cultured with 697 leukemia cells and sensitivity to MRX-2843 was determined. BMDSCs from wild-type mice protected 697 leukemia cells from MRX-2843 induced cell death much more effectively than BMDSCs from Gas6 knockout mice (4.3% apoptotic and dead cells versus 72.4%, respectively). To investigate biochemical mechanisms of Gas6-mediated protection, Kasumi-1 AML cells were cultured with 200nM MRX-2843 or vehicle in the presence or absence of HS27 cells and expression and activation of MERTK, AXL, TYRO-3, and downstream signaling effectors STAT5, AKT, and ERK1/2 were determined by immunoblot. AXL was not expressed in Kasumi-1 cells with or without co-culture. Treatment with MRX-2843 mediated robust inhibition of MERTK activation indicated by reduced levels of phosphorylated protein in both the presence and absence of stromal cell co-culture. In contrast, activation of TYRO-3 was increased after treatment with MRX-2843 in leukemia cells co-cultured with HS27 stromal cells. Similarly, in the absence of co-culture MRX-2843 inhibited activation of STAT5, AKT, and ERK1/2. However, in the presence of HS27 cells there was robust activation of STAT5 that was sustained even after treatment with MRX-2843. In contrast, MRX-2843 inhibited activation of AKT and ERK1/2 in HS27 co-cultures, although higher doses were required. Together these data support a model whereby Gas6 produced by stromal cells mediates leukemia cell resistance to MERTK inhibition in the bone marrow by inducing activation of TYRO-3, thereby promoting downstream signaling and cell survival despite MERTK inhibition. Thus, combined treatment with MRX-2843 and a TAM ligand sink (eg MERTK-Fc), a TYRO-3 inhibitor, or a bone marrow mobilizing agent may be particularly effective therapeutic strategies. Disclosures Wang: Meryx, Inc: Equity Ownership, Patents & Royalties: MRX-2843. Frye:Meryx, Inc: Equity Ownership, Patents & Royalties: MRX-2843. Earp:Meryx, Inc: Equity Ownership, Patents & Royalties: targeting MERTK. DeRyckere:Meryx, Inc: Equity Ownership, Patents & Royalties: targeting MERTK. Graham:Meryx, Inc: Equity Ownership, Patents & Royalties: targeting MERTK.

Bone Marrow Stroma-Produced TGF-beta1 Confers Chemoresistance of Leukemic Cells.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4248-4248
Author(s):  
Yoko Tabe ◽  
Yuanyuan Xu ◽  
Linhua Jin ◽  
Michael Andreeff ◽  
Marina Konopleva
Keyword(s):  
Bone Marrow ◽  
Molecular Mechanisms ◽  
Neutralizing Antibody ◽  
Leukemic Cells ◽  
Cycle Phase ◽  
Serum Starvation ◽  
U937 Cells ◽  
Tgf Beta ◽  
Induced Apoptosis ◽  
Apoptotic Effects

Abstract TGF-beta1 is secreted at high levels by bone marrow stromal cells and osteoblasts, however its role in leukemia/stroma interactions is unknown. We investigated the effects of TGF-beta1 on survival and proliferation of human monoblastic U937 cells. First, the production of TGF-beta1 by bone marrow-derived mesenchymal stem cells (MSCs) and by U937 cells was analyzed by ELISA. U937 cells secreted approximately 0.1 ng/ml of TGF-beta, while TGF-beta1 level was over 20-fold higher in MSC conditioned medium (2.1±1.7 ng/ml at 72 hours). When U937 cells were co-cultured with MSC, TGFbeta concentration was 2.2±0.2 ng/ml. Hence, we selected 2 ng/ml concentration of recombinant TGF-beta to examine the effects on survival and proliferation of U937 cells exposed to chemotherapy or serum starvation. TGF-beta1 significantly reduced Ara-C or serum withdrawal-induced apoptosis of U937 cells in particular when U937 cells were co-cultured with MSCs (AnnexinV(+)%;U937 alone, control 34.5±8.4, TGF-beta1 18.4±4.5, Ara-C 88.6±3.0, Ara-C/TGF-beta1 60.4±8.0, p=0.04; U937 co-cultured with MSC, control 19.4±2.8, TGF-beta1 3.5±1.0, Ara-C 69.0±3.6, Ara-C+TGF-beta1 24.9±3.3, p=0.01). Treatment with rhTGF-beta1 also enhanced percentage of cells in G0/1 cell cycle phase hence promoting quiescence (G0/G1 phase; control 50.1±6.7, TGF-beta1 63.8±5.5, p=0.04). Most importantly, inhibition of TGF-beta1 by neutralizing antibody (TGF-NA) significantly diminished the pro-survival effects of rhTGF-beta1 in serum-deprived U937 cells co-cultured with MSC (AnnexinV(+)%; U937 alone, control 27.9±9.0, TGF-beta1 20.1±3.3, TGF-NA 21.8±2.2, TGF-beta1+ TGF-NA 18.9±4.1; U937 co-cultured with MSC, control 22.2±1.9, TGF-beta1 10.9±2.5, TGF-NA 29.6±5.1, TGF-beta1+ TGF-NA 20.2±0.9, p<0.001). Dissection of molecular mechanisms demonstrated that TGF-beta1 induced anti-apoptotic Bcl-2 protein expression in U937 cells. Furthermore, concomitant exposure of U937 cells to rhTGF-beta1 in MSC co-cultures results in activation of AKT signaling and pro-survival phosphorylation of Bcl-2, implicating their role in anti-apoptotic effects of TGF-beta1. Taken together, these findings demonstrate that TGF-beta1 secreted by BM stroma cells promotes survival of U937 cells and confers chemoresistance of leukemic cells within the bone marrow microenvironment. Since small molecule inhibitors of TGF-beta signaling are undergoing final steps of pre-clinical development, this approach may represent a viable strategy to enhance efficacy of chemotherapy in AML.

scholarly journals The Role of Prep1 in the Regulation of Mesenchymal Stromal Cells

2019 ◽  
Vol 20 (15) ◽  
pp. 3639 ◽  
Author(s):  
Giorgia Maroni ◽  
Daniele Panetta ◽  
Raffaele Luongo ◽  
Indira Krishnan ◽  
Federica La Rosa ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Fate ◽  
Mesenchymal Stromal Cells ◽  
Stromal Cells ◽  
Molecular Mechanisms ◽  
Gene Dosage ◽  
Homeobox Gene ◽  
Fate Decision

Molecular mechanisms governing cell fate decision events in bone marrow mesenchymal stromal cells (MSC) are still poorly understood. Herein, we investigated the homeobox gene Prep1 as a candidate regulatory molecule, by adopting Prep1 hypomorphic mice as a model to investigate the effects of Prep1 downregulation, using in vitro and in vivo assays, including the innovative single cell RNA sequencing technology. Taken together, our findings indicate that low levels of Prep1 are associated to enhanced adipogenesis and a concomitant reduced osteogenesis in the bone marrow, suggesting Prep1 as a potential regulator of the adipo-osteogenic differentiation of mesenchymal stromal cells. Furthermore, our data suggest that in vivo decreased Prep1 gene dosage favors a pro-adipogenic phenotype and induces a “browning” effect in all fat tissues.

Cellular Cholesterol Modulates VEGFR-1 Function on Acute Leukemia Cells.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1847-1847
Author(s):  
Rita Fragoso ◽  
Cristina Casalou ◽  
Sergio Dias
Keyword(s):  
Cell Migration ◽  
Growth Factor ◽  
Acute Leukemia ◽  
Molecular Mechanisms ◽  
Cholesterol Metabolism ◽  
Leukemia Cell ◽  
Protein Translation ◽  
Leukemia Cells ◽  
Cholesterol Levels

Abstract Vascular endothelial growth factor (VEGF) and its receptors play a crucial role in malignancy and in disease, regulating the survival, proliferation, and migration of several cell types, such as endothelium and also leukemia cells. Following our recent report on the role of VEGFR-1 (FLT-1) in ALL (Fragoso R et al, 2006), in the present study we analyzed the molecular mechanisms whereby it modulates acute leukemia cell migration in response to VEGF/Placental Growth Factor (PLGF). First, we observed the formation of cell protrusions on ALL cells after VEGF/PLGF stimulation, with evidence for polymerized actin and FLT-1 co-localization (as determined by phalloidin, immunofluorescence staining, and confocal microscopy). Western blot analysis revealed that PLGF/VEGF stimulation resulted in increased RhoA and Rac1 GTPases expression. Co-treatment with LY200942 significantly decreased RhoA and Rac1 induction and cell migration by PLGF/VEGF, demonstrating this effect is modulated via Pi3 kinase. Next, we investigated the mechanisms whereby FLT-1 and actin co-localize at the cell “leading edge” (protrusions), after VEGF/PLGF stimulation, and the relevance of such co-localization for cell migration. We addressed this question by impairing the formation of lipid rafts/caveolae using drugs that either sequester (nystatin) or deplete (methyl-β-ciclodextrin) total cholesterol. Accordingly, co-treatment of leukemia cells with nystatin or MβCD and PLGF/VEGF blocked cell migration, an effect that was associated with a decrease in FLT-1 polarization and co-localization with actin filaments. Instead, FLT-1 was now found mostly in the cell cytosol. Given that leukemia cells have an increased rate of cholesterol up-take we sought to understand if increased cholesterol levels affected FLT-1 function in leukemia cells. Cholesterol repletion in leukemia cells enhanced leukemia cells migration in response to VEGF/PlGF (about 3 folds). This significant increase was associated with an increase in FLT-1 protein expression that, very interestingly, was particularly concentrated intracellulary in the cytoplasm. At this time we are trying to understand if this increase in FLT-1 expression after cholesterol repletion is associated with increase protein translation or impairment in proteasome activity. Finally, our preliminary in vivo experiments using Nod-Scid mice subjected (n=3) or not (n=3) to high fat diet (that results in increased cholesterol levels in the BM and in the spleen), showed this metabolic condition worsens disease symptoms and significantly decreases mouse survival. These results reveal for the first time some of the molecular mechanisms involved in FLT-1-mediated leukemia migration, namely the involvement of cholesterol metabolism, which may be crucial for new therapeutics delineation.

TGF-β Receptor Kinase Inhibitor LY2109761 Reverses the Anti-Apoptotic Effects of TGF-β1 in Leukemic Cells Co-Cultured with Stromal Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2846-2846
Author(s):  
Yoko Tabe ◽  
Yuanyuan Xu ◽  
Teresa McQueen ◽  
Michael Andreeff ◽  
Marina Konopleva
Keyword(s):  
Cell Proliferation ◽  
Stromal Cells ◽  
Leukemic Cells ◽  
Leukemia Cells ◽  
U937 Cells ◽  
The Novel ◽  
Β Receptor ◽  
Tgf Β1 ◽  
Cells Cultured

Abstract Transforming growth factor β1 (TGF-β1) is an essential regulator of cell proliferation, survival, and apoptosis, depending on the cellular context. TGF-β1 is also known to affect cell-to-cell interactions between tumor and stromal cells through production of the extracellular matrix and stimulation of integrin receptors. We investigated the role of TGF-β1 in the survival of human leukemic cells growing in the context of bone marrow (BM) microenvironment, and the anti-leukemia effects of the novel TGF-β receptor inhibitor LY2109761. BM-derived mesenchymal stem cells (MSC) produced TGF-β in an autocrine fashion. Treatment with rhTGF-β1 (2ng/mL) inhibited the spontaneous and Ara-C-induced apoptosis in U937 cells (% AnnexinV(+), control 34.5±8.4; TGF-β1 18.4±4.5; Ara-C 88.6±3.0; Ara-C/TGF-β1 60.4±8.0, p=0.04). These effects were more prominent in U937 cells co-cultured with MSC (% AnnexinV(+), control 19.4±2.8; TGF-β1 3.5±1.0; Ara-C 69.0±3.6; Ara-C+TGF-β1 24.9±3.3; p=0.01). In U937 cells co-cultured with MSC, rhTGF-β1 conferred higher cell protective effects on leukemia cells attached to MSC than on floating cells. Conversely, the pro-survival effects of TGF-β1 were inhibited by 5mM LY2109761 (%AnnexinV(+); MSC(−), control 31.8±2.3, TGF-β1 19.5±3.0, LY 28.4±4.4, TGF-β1+LY 37.7±2.0; MSC(+), control 22.1±1.7, TGF-β1 7.8±0.9, LY16.1±2.6, TGF-β1+ LY 18.0±1.1, p<0.01). Similar results were obtained using TGF-β1 neutralizing antibody. TGF-β1 induced pro-survival phosphorylation of Akt in U937 cells cultured alone or co-cultured with MSC, which was abrogated by LY2109761. Further, rhTGF-β1 induced a moderate increase in C/EBPβ gene and LAP isoform (cell cycle arrest inducing) of C/EBPβ protein in U937 cells cultured without MSCs, while markedly upregulating C/EBPβ gene and protein, both LIP (cell proliferation inducing) and LAP isoforms, under MSCs co-culture condition, suggesting the novel role of C/EBPβ in TGF-β1-mediated U937 cell survival. In summary, these results indicate that TGF-β1-secreting BM stromal cells promote the survival of U937 leukemia cells via direct cell-to-cell interaction and promote chemoresistance of leukemia cells through the activation of Akt signaling and upregulation of C/EBPβ. The blockade of TGF-β signaling by LY2109761, which effectively inhibited the pro-survival signaling, may enhance the efficacy of chemotherapy against leukemia cells in the BM microenvironment.

Bone Marrow Stromal Cells Induce Bortezomib Resistance in Multiple Myeloma Cells through Downregulation of miRNA-101-3p Targeting Survivin

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1772-1772 ◽  
Author(s):  
Jahangir Abdi ◽  
Yijun Yang ◽  
Patrick Meyer-Erlach ◽  
Hong Chang
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Drug Resistance ◽  
Cell Lines ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Molecular Mechanisms ◽  
Marrow Stromal Cells ◽  
Survivin Gene ◽  
Induced Apoptosis

Abstract INTRODUCTION It is not yet fully understood how bone marrow microenvironment components especially bone marrow stromal cells (BMSCs) induce drug resistance in multiple myeloma (MM). This form of drug resistance has been suggested to pave the way for intrinsic (de novo) resistance to therapy in early stages of the disease and contribute to acquired drug resistance in the course of treatment. Hence, deciphering the molecular mechanisms involved in induction of above resistance will help identify potential therapeutic targets in MM combined treatments. Our previous work showed that BMSCs (normal and MM patient-derived) induced resistance to bortezomib (BTZ) compared with MM cells in the absence of stroma. This resistance was associated with modulation of a transcriptome in MM cells, including prominent upregulation of oncogenes c-FOS, BIRC5 (survivin) and CCND1. However; whether these oncogenes mediate BTZ resistance in the context of BMSCs through interaction with miRNAs is not known. METHODS Human myeloma cell lines, 8226, U266 and MM.1s, were co-cultured with MM patient-derived BMSCs or an immortalized normal human line (HS-5) in the presence of 5nM BTZ for 24 h. MM cell monocultures treated with 5nM BTZ were used as controls. Co-cultures were then applied to magnetic cell separation (EasySep, Stem Cell Technologies) to isolate MM cells for downstream analyses (western blotting and qPCR). Total RNA including miRNAs was isolated from MM cell pellets (QIAGEN miRNeasy kit), cDNAs were synthesized (QIAGEN miScript RT II kit) and applied to miScript miRNA PCR Array (SABioscience, MIHS-114ZA). After normalization of all extracted Ct values to 5 different housekeeping genes, fold changes in miRNA expression were analyzed in co-cultures compared to MM cell monocultures using the 2-ΔΔCt algorithm. Moreover, survivin gene was silenced in MM cells using Ambion® Silencer® Select siRNA and Lipofectamine RNAiMAX transfection reagent. Survivin-silenced cells were then seeded on BMSCs and exposed to BTZ. Percent apoptosis of gated CD138+ MM cells was determined using FACS. For our overexpression and 3'UTR reporter experiments, we transiently transfected MM cells with pre-miR-101-3p, scrambled miRNA or pEZX-3'UTR constructs using Endofectin reagent (all from GeneCopoeia). RESULTS BMSCs upregulated survivin gene / protein (a member of inhibitors of apoptosis family) and modulated an array of miRNAs in MM cells compared to MM cells in the absence of stroma. The more noticeably downregulated miRNAs were hsa-miR-101-3p, hsa-miR-29b-3p, hsa-miR-32-5p, hsa-miR-16-5p (4-30 fold) and highly upregulated ones included hsa-miR-221-3p, hsa-miR-409-3p, hsa-miR-193a-5p, hsa-miR-125a-5p (80-330 fold). We focused on miRNA-101-3p as it showed the highest level of downregulation (30 fold) and has been shown to function as an important tumor suppressor in other malignancies. Real time RT-PCR confirmed downregulation of miRNA-101-3p. Moreover, microRNA Data Integration Portal (mirDIP) identified miRNA-101-3p as a putative target for survivin and Luciferase activity assays confirmed binding of miRNA-101-3p to 3'UTR of survivin. In addition, overexpression of miRNA-101-3p downregulated survivin and sensitized MM cells to BTZ-induced apoptosis. Furthermore, silencing of survivin upregulated miRNA-101-3p and increased BTZ-induced apoptosis in MM cell lines both in the absence of BMSCs (Apoptosis range in BTZ-treated conditions: 57.65% ± 4.91 and 28.66% ± 0.78 for si-survivin and scrambled control, respectively, p<0.05) and in the presence of BMSCs (41.23% ± 1.43 and 14.8% ± 0.66, for si-survivin and scrambled control, respectively, p<0.05). CONCLUSION Our results indicate that BMSCs downregulated miRNA-101-3p and upregulated survivin in MM cells compared to MM cells in the absence of stroma. Silencing of survivin or overexpression of miRNA-101-3p sensitized MM cells to BTZ in the presence of BMSCs. These findings suggest that miRNA-101-3p mediates BTZ response of MM cells in the presence of BMSCs by targeting survivin and disclose a role of survivin-miRNA-101-3p axis in regulation of BMSCs-induced BTZ resistance in MM cells, thus provide a rationale to further investigate the anti-myeloma activity of miRNA-101-3p in combination with BTZ as a potential novel therapeutic strategy in MM. Disclosures No relevant conflicts of interest to declare.

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