Axl, a prognostic and therapeutic target in acute myeloid leukemia mediates paracrine crosstalk of leukemia cells with bone marrow stroma

Blood ◽  
2013 ◽  
Vol 122 (14) ◽  
pp. 2443-2452 ◽  
Author(s):  
Isabel Ben-Batalla ◽  
Alexander Schultze ◽  
Mark Wroblewski ◽  
Robert Erdmann ◽  
Michael Heuser ◽  
...  

Key PointsAxl inhibition by BGB324 is active in FLT3-mutated and FLT3 wild-type AML, and presence of Axl and Gas6 are required for therapeutic efficacy. AML cells educate BMDSCs to secrete Gas6, which mediates leukemia cell proliferation and therapy resistance.

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3944-3944 ◽  
Author(s):  
Yao-Te Hsieh ◽  
Enzi Jiang ◽  
Jennifer Pham ◽  
Hye-Na Kim ◽  
Hisham Abdel-Azim ◽  
...  

Abstract Despite aggressive chemotherapy and early allogeneic transplantation, acute myeloid leukemia (AML) frequently relapses, so that over-all disease-free survival remains below 50%. Strategies to overcome the chemoresistance of relapse-initiating residual AML blasts are, therefore, warranted. Evidence has been provided that AML cells are sheltered from the insult of chemotherapeutic agents by interacting with bone marrow stroma. Integrin alpha4beta1 (VLA4) mediates adhesion of hematopoietic cells to bone marrow stroma cells and extracellular matrix and has been implicated in cell adhesion-mediated chemotherapy resistance. Based on the evidence thereof provided for ALL blasts, VLA4 is here proposed as a therapeutic target for refractory AML. For this purpose, VLA4 was functionally blocked in vitro and in vivo on patient-derived AML cells using an anti-functional humanized VLA4 antibody, Natalizumab (NZM). VLA4-positive (>90%) patient-derived (primary) AML cells were plated on immobilized human VCAM1 or human stromal cell line HS-5 and treated with control (IgG4) or Natalizumab (NZM) for 2 days. NZM de-adhered 94.0%±7.6 AML cells from its counter receptor VCAM-1, yet only 31.3%±13.8 from HS-5, indicating that stroma cells offer ligands for a wider panel of adhesion receptors besides VLA4. We tested also whether VLA4 blockade is beneficial against AML when combined with chemotherapy. For this purpose, primary AML cells were incubated with NZM and incubated on uncoated tissue culture plates or HS-5 stromal layers in the presence or absence of Ara-C (1µM) for two days. AML cells showed higher viability under Ara-C therapy when incubated with HS-5 cells compared to controls, indicating the chemoprotective effect of the stromal layer. The viability of the AML cells treated with combined Ara-C and NZM was similar to the controls, indicating that HS-5-mediated chemo-protection was completely abrogated by NZM. Significantly more AML cells treated with Ara-C+NZM stained AnnexinV+/7AAD- than after Ara-C+control Ig4 treatment (44.4%±5.6 vs. 29.8%±4.8, p=0.03) indicating increased apoptosis of AML cells. On its own, NZM did not induce apoptosis. Next, we tested NZM as a single agent in our NOD/SCIDIL2Rγ deficient (NSG) xenograft model of primary AML. Luciferase-labeled AML cells were intrafemorally injected into NSG mice (1x105 cells / mouse). NZM (5mg/kg) was given intraperitoneally once per week for 4 weeks. NZM-treated animals survived significantly longer than control Ig-treated animals (Median Survival Time, MST=107 days vs. MST=76 days; *p=0.008 by Log-rank Test.To determine effects of NZM on leukemia cell burden/distribution in different organs, primary AML cells were injected into NSG mice and allowed to engraft for 3 days, subsequently treated with a single dose of NZM or Ig control. 72 hours later, AML cell burden in femurs and spleens of NZM-treated animals was significantly decreased compared to control treated mice, however AML cells were not increased into the peripheral blood, so that whether leukemia cells were selectively killed ormobilized and then retained in non-hematopoietic organs remains to be determined. Further studies addressing molecular mechanisms of increased apoptosis after combined VLA4 blockade and chemotherapy are ongoing. Our data suggest that the paradigm of leukemia cell targeting by VLA4 blockade, previously demonstrated by us for ALL, can also be applied to AML. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4818-4818
Author(s):  
Yanwen Zheng ◽  
Zhengwei Mao ◽  
Bin Yin

Abstract Abstract 4818 Acute myeloid leukemia (AML) is a detrimental disease with difficult diagnosis and treatment. Understanding the biology of AML at the molecular and cellular levels would be essential to successful management of the disease. However, the notoriously known difficulty in manipulation of leukemia cells has long hindered the dissection of AML pathogenesis. The advent of CdSe/ZnS quantum dots (QDs) represents an important advancement in the research field of nanotechnology, which have recently also been applied for imaging of live cells. Here, we have introduced a non-genetic approach of marking blood cells, by taking advantage of QD technology. We compared QDs complexed with different vehicles, including a peptide Tat (QDs-Tat), cationic polymer Turbofect (QDs-Tf) and liposome Lipofectamine 2000 (QDs-Lip), in their abilities to mark cells. QDs-Tat showed the highest efficiency in delivery into hematopoietic cells, among the three vehicles. We then examined QDs-Tat labelling of leukemia cell lines, and found that QDs-Tat could label 293T, bone marrow (BM) cells, THP-1, MEG-01 and HL-60 with a decreasing efficiency. The efficiency of QDs-Tat delivery was dependent on the concentration of QDs-Tat applied, but not the length of incubation time. In addition, more uniform intracellular distributions of QDs in 293T and leukemia cells were obtained with QDs-Tat, compared with the granule-like formation obtained with QDs-Lip. Clearly, QD fluorescence was sharp and tolerant to repetitive photo excitations, and could be detected in 293T for up to one week following labelling. In summary, our results suggest that QDs have provided a photostable, non-genetic and transient approach that labels normal and malignant hematopoietic cells in a cell type-, vehicle-, and QD concentration-dependent manner. We expect for potentially wide applications of QDs as an easy and fast tool assisting investigations of various types of blood cells in the near future. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1585-1585
Author(s):  
Dimitrios Mougiakakos ◽  
Regina Jitschin ◽  
Martina Braun ◽  
Andreas Mackensen

Abstract Introduction: Acute myeloid leukemia (AML) represents the most common form of acute leukemia in adults. Despite the enormous efforts during the last decades treatment resistance is still observed at a high rate. Previous studies have shown that bone marrow stroma promotes an increased resilience of AML blasts towards chemotherapeutics. Furthermore, current data suggest that alterations of the malignant cells’ metabolism could represent a strong determinant for the disease’s (including AML) course and/or treatment resistance. In fact, a deregulated metabolism could lead to a reduced sensitivity towards therapy and it remains to be elucidated whether this is a mechanism contributing to the blast-protective effects elicited by the bone marrow stroma. Here, we sought out to characterize the impact of stroma cells on the AML blasts’ metabolism. Methods and Results: The human bone marrow stroma cell-line HS-5 was utilized for establishing the in vitro niche model. We compared in our assays AML cell lines (THP-1, OCI-AML, and KG-1) as well as primary blasts cultured on a HS-5 monolayer or alone. In line with previous observations we could detect an increased proportion of AML cells in the S-phase of the cell cycle upon co-culture with HS-5. When evaluating the cells’ metabolism we observed a shift towards glycolysis despite presence of oxygen, i.e. aerobic glycolysis or the “Warburg”-effect. Basal glycolysis as well as maximal glycolytic capacity upon blocking ATP production in the mitochondrial respiratory chain was increased. Respiration (including basal respiration, coupling efficacy, and maximal respiratory capacity) was not significantly affected. However, mitochondrial biogenesis appeared reduced. Increased glycolysis was accompanied by an increased up-take of fluorescently labeled glucose as well as an increased expression of glucose transporters. The expression of several glycolytic molecules found to be increased upon HS-5 co-culture. Noticeably, cell-to-cell contact was not a pre-requisite for the metabolic shift. Our data was further corroborated by direct observations from AML patients: AML blasts isolated from the bone marrow exhibited an up-regulated glycolysis as compared to their counterparts from the periphery collected at the same time point. Conclusion: Taken together, our data indicates a stromal cell-mediated metabolic shift in AML blasts towards aerobic glycolysis. This metabolic phenotype is linked to an unfavorable prognosis and increased chemo resistance. The underlying molecular pathways remain to be elucidated and could represent a promising target for future interventions. Disclosures No relevant conflicts of interest to declare.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5040-5040
Author(s):  
Bing Xu ◽  
Rongwei Li ◽  
Huijuan Dong ◽  
Feili Chen ◽  
Yuejian Liu ◽  
...  

Abstract Background Disulfiram(DS), an old drug clinically used for alcoholism, was reported to have antitumor effects, recent studies have found that Copper(Cu) can significantly enhance the DS-induced cell death in vitro in a variety of tumor cells. Our previous studies also demonstrated that disulfiram/copper (DS/Cu) couldtarget human leukemia cell lines(like KG1α,Molt4) through the activation of JNK, in vitro. However, there is few report about the ability of DS/Cu in killing cancer cells in vivo. Aims This study aims to explore the effect of DS/Cu on acute myeloid leukemia cell line KG1αin vivo and clarify the underlining mechanism. Methods 6-8 week old female NOD/SCID mice were sublethally irradiated with 2Gy X-ray the day before transplantation, followed by intravenous injection of KG1α cells (1×107 cells) suspended in 0.2 mL of PBS. 5 weeks after transplantation mice were randomly divided into three treatment groups: vehicle (0.9% saline), a combination of DS and Cu daily for 2 weeks, Ara-C alone twice before killing. Mice were sacrificed after 2 weeks treatment with tissues of spleen, liver, bone marrow being observed using histopathology method to detect the invasion of leukemia. The DS/Cu-induced p-c-jun activation was also examined by western blot using tissues of spleen, liver, bone marrow. Statistical analysis was carried out with one-way ANOVA to assess statistical significance (*p < 0.05). Results 4 weeks after transplantation, mice were dispirited with low appetite, down-bent gait, wrinkled fur, slow move, just like suffered from leukemia. What’s more, immature blasts like morphology similar to KG1α were found in the peripheral blood of the mice(11%±3.41). All the mice were sacrificed after 2 weeks treatment, mice in control group were observed with slightly larger spleen and liver with the morphology of invasion of leukemia such as a granular appearance than the other two groups. Histopathology examination showed that leukemia cells infiltrate liver, spleen and bone marrow, and the immunohistochemistry examination found that the leukemia cells in spleen, liver and bone marrow expressed human specific antigen CD45 with the highest expression level in the control group. Moreover, solid tumor could be observed in the peritoneal cavity of two mice in the control group with expression of human specific antigen CD45detected by immunohistochemistry examination. Western blot in this study showed DS/Cu complex induced phosphorylation of c-Jun expression in the spleen, liver and bone marrow. Conclusion DS/Cu complex could effectively target the acute myeloid leukemia cells in the acute leukemia NOD/SCID mice while inhibiting the invasion of leukemia to some extent, and the activation of JNK might play a functional role in DS/Cu mediated antileukemic effects. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 352-352
Author(s):  
Bijender Kumar ◽  
Mayra Garcia ◽  
Lihong Weng ◽  
Xiaoman Lewis ◽  
Jodi Murakami ◽  
...  

Abstract Increasing evidence suggests that leukemia cells take shelter in the bone marrow (BM) niche, where they hide from chemotherapy and continue to divide. As yet, how leukemia cells alter the BM niche to facilitate their growth and assist them in evading chemotherapy is unclear. In this study, we provide compelling evidences that acute myeloid leukemia (AML), through exosome secretion, transformed the BM niche to facilitate their own growth and suppress normal hematopoiesis. Using AML xenograft and MLL-AF9 knock-in mouse model, we show that leukemia cells as well as AML-derived exosomes stimulate the growth of BM stromal progenitors and blocked the osteolineage development in our stromal compartment analysis. Histological analysis and micro-CT examination confirmed loss or thinning of the bone in both leukemia and leukemic exosome-treated animals. Expression of cell adhesion molecules (NCAM1, VCAM1, CD44, OPN & ICAM1) and factors important for angiogenesis (Angpt1, Angpt2 and VEGF) are upregulated, whereas genes important for HSC maintenance (CXCL12 and SCF), osteoblast (OCN, OSX, Notch3 and IGF1) and chondrocyte (ACAN, SOX9) development are suppressed. While we observed increases in phenotypic LT-HSC in AML-derived exosomes treated mice, these mice show reduced multilineage reconstitution ability, increased cell cycle entry and higher sensitivity to myeloablative stress suggesting that HSCs from exosome-treated mice have lower stem cell activity than their counterparts from normal mice.In addition, leukemia-modified stroma cells exhibit marked reduction in ability to support normal HSCs. Pre-treatment of AML-derived exosome “prime” the animal for leukemia cell invasion and accelerate leukemia progression. Conversely,disruption of exosome secretion by targeting Rab27a in AML cells significantly delays leukemia progression. These data strongly support the notion that leukemia-modified niches favor leukemic cell proliferation and suppress normal hematopoiesis. Disclosures No relevant conflicts of interest to declare.


2015 ◽  
Vol 15 ◽  
pp. S189-S190
Author(s):  
Meritxell Nomdedeu ◽  
Maria Carmen Lara-Castillo ◽  
Amaia Etxabe ◽  
Marta Pratcorona ◽  
Marina Díaz-Beyá ◽  
...  

2015 ◽  
Vol 15 (1) ◽  
Author(s):  
Meritxell Nomdedeu ◽  
María Carmen Lara-Castillo ◽  
Amaia Etxabe ◽  
Josep María Cornet-Masana ◽  
Marta Pratcorona ◽  
...  

2021 ◽  
Vol 22 (15) ◽  
pp. 8092
Author(s):  
Katja Seipel ◽  
Carolyn Graber ◽  
Laura Flückiger ◽  
Ulrike Bacher ◽  
Thomas Pabst

The FMS-like tyrosine kinase 3 (FLT3) gene is mutated in one-third of patients with de novo acute myeloid leukemia (AML). Mutated FLT3 variants are constitutively active kinases signaling via AKT kinase, MAP kinases, and STAT5. FLT3 inhibitors have been approved for the treatment of FLT3-mutated AML. However, treatment response to FLT3 inhibitors may be short-lived, and resistance may emerge. Compounds targeting STAT5 may enhance and prolong effects of FLT3 inhibitors in this subset of patients with FLT3-mutated AML. Here STAT5-inhibitor AC-4-130, FLT3 inhibitor midostaurin (PKC412), BMI-1 inhibitor PTC596, MEK-inhibitor trametinib, MCL1-inhibitor S63845, and BCL-2 inhibitor venetoclax were assessed as single agents and in combination for their ability to induce apoptosis and cell death in leukemic cells grown in the absence or presence of bone marrow stroma. Synergistic effects on cell viability were detected in both FLT3-mutated and FLT3-wild-type AML cells treated with AC-4-130 in combination with the MCL1 inhibitor S63845. AML patient samples with a strong response to AC-4-130 and S63845 combination treatment were characterized by mutated FLT3 or mutated TET2 genes. Susceptibility of AML cells to AC-4-130, PTC596, trametinib, PKC412, and venetoclax was altered in the presence of HS-5 stroma. Only the MCL1 inhibitor S63845 induced cell death with equal efficacy in the absence or presence of bone marrow stroma. The combination of the STAT5-inhibitor AC-4-130 and the MCL1 inhibitor S63845 may be an effective treatment targeting FLT3-mutated or TET2-mutated AML.


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