Galectin-3 Is the Molecular Target for Overcoming Multidrug Resistance Due to the Cell Protection by Bone Marrow Leukemia Microenvironment in Chronic Myeloid Leukemia,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3746-3746
Author(s):  
Mio Yamamoto ◽  
Junya Kuroda ◽  
Tsutomu Kobayashi ◽  
Nana Sasaki ◽  
Hisao Nagoshi ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Drug Resistance ◽  
Cell Death ◽  
Chronic Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Chemotherapeutic Agents ◽  
Leukemic Cells ◽  
Galectin 3 ◽  
The Impact

Abstract Abstract 3746 Recent advances in molecular targeted therapy using tyrosine kinase (TK) inhibitors (TKIs) for Bcr-Abl TK have greatly improved treatment outcomes for chronic myeloid leukemia (CML). However, complete elimination of CML clones has been rarely achieved by TKIs due to both intrinsic and extrinsic cell mechanisms. In this study, we investigated the molecular mechanisms for bone marrow microenvironment (BMME)-mediated leukemia progression and drug resistance in CML. CML cell lines MYL and K562 acquired drug resistance to imatinib mesylate (IM), dasatinib (Das), doxorubicin (DOX), cytarabine (CA), etoposide (VP16), or vincristine (VCR) through co-culture with HS-5, an immortalized human bone marrow stromal cell (BMSC)-derived cell line. We used microarray-based assays to investigate the changes in gene expression profiles in Philadelphia (Ph)-positive MYL as a result of co-culture with HS-5 and of adhesion to fibronectin (FN). In MYL with HS-5 or with FN, 902 and 910 genes, respectively, were upregulated more than 2.0-fold compared with control. Among the 284 genes commonly upregulated in MYL with HS-5 and with FN, we focused on galectin-3 (Gal-3) as one of the candidate mediators of BMME-mediated leukemia progression because of its pleiotropic cellular function. The levels of galectin-3 mRNA increased 3.84-fold as a result of co-culture with HS-5, and 2.83-fold as a result of adhesion to FN in MYL. The induction of Gal-3 by the co-culture with HS-5 or the adhesion to FN was also confirmed at the protein level, not only in MYL, but also in all Ph+ leukemic cell lines examined (K562, KBM5, KCL22, BV173), while Gal-3 protein expression was either absent or extremely low in normal liquid culture. To investigate the clinical significance of Gal-3 in CML, we examined its expression in BM-derived primary CML cells. Approval was obtained from the institutional review board at Kyoto Prefectural University of Medicine for a study using patient-derived samples, and the study was conducted in accordance with the ethical principles of the Declaration of Helsinki. Of the leukemic cells of 20 CML patients, those of all but one CML-blast crisis phase patient were positive for Gal-3. Ph+ cells from the CML-chronic phase were especially highly positive for Gal-3. In contrast, the frequency of Gal-3-positive cells from most acute leukemia patients was as low as that of BM hematopoietic cells from healthy volunteers. These results suggest that in the clinical setting Gal-3 expression in the BM milieu is more predominant in CML. To further characterize the role of Gal-3 in CML, Gal-3 overexpressing subcell lines of MYL and K562 were generated by transfection of pEF1Galec3.neo plasmid and designated as MYL/G3 and K562/G3, respectively. Gal-3 overexpression was found to confer moderately higher in vitro proliferation potency in medium containing 10% FCS as well as in low nutrient 1% FCS-containing medium compared with the cells transfected with the mock plasmid. We also examined the impact of Gal-3 overexpression on cell death induced by chemotherapeutic agents. Both MYL/G3 and K562/G3 were less sensitive than their parental cells to cell death induced by chemotherapeutic agents. This diminished sensitivity to cell death caused by chemotherapeutic agents was due to a reduction in apoptosis, as reflected by the reduced frequency of subG1 populations detected in DNA content analyses (FACS SubG1 analysis of results for 48-hour treatment: MYL 54.9%, MYL/G3 15.7% with IM 0.25uM; MYL 47.1%, MYL/G3 23.1% with Das 1.0nM; MYL 40.2%; MYL/G3 13.4% with DOX 200nM; MYL 45.7%; MYL/G3 19.4% with CA 150nM; MYL 50.9%; MYL/G3 19.1% with VP16 4uM; MYL 75.0%; MYL/G3 49.5% with VCR 8nM). We next examined the effect of an inhibitor for Gal-3, fractionated citrus pectin powder (FPP), on MYL and MYL/G3. As expected, MYL and MYL/G3 showed similar sensitivity to cell death induced by FPP, while the addition of FPP overcame resistance to IM-induced cell death in MYL/G3. Furthermore, the addition of FPP was found to have overcome HS-5-induced resistance against IM in MYL. Molecular sequelae of Gal-3 overexpression in leukemic cells were also investigated. Both co-culture with HS-5 and Gal-3 overexpression activated Akt and Erk, induced accumulation of Mcl-1 in MYL and K562. Collectively, our study disclosed that leukemia microenvironment-specific Gal-3 may be a candidate therapeutic target to help overcome BMME-mediated therapeutic resistance in CML. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Molecular analysis of relapse in chronic myeloid leukemia after allogeneic bone marrow transplantation

Blood ◽  
1987 ◽  
Vol 70 (3) ◽  
pp. 873-876 ◽  
Author(s):  
TS Ganesan ◽  
GL Min ◽  
JM Goldman ◽  
BD Young
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Transplantation ◽  
Chronic Myeloid Leukemia ◽  
Marrow Transplantation ◽  
Myeloid Leukemia ◽  
Allogeneic Bone Marrow Transplantation ◽  
Allogeneic Bone Marrow ◽  
Leukemic Cells ◽  
Allogeneic Bone ◽  
Leukemic Clone

Abstract Four patients with Philadelphia (Ph′) positive chronic myeloid leukemia (CML) were studied before, after, and on relapse following allogeneic bone marrow transplantation (BMT). Southern analysis of DNA from cells collected before and at relapse after BMT was performed in order to investigate the origin of the leukemia at relapse. Using minisatellite probes we showed that the relapse occurred in cells of host origin in all four patients and this was confirmed with a Y chromosome specific probe in two male patients who had a female donor. Furthermore, using two probes for the breakpoint cluster region (bcr) on chromosome 22, we showed that leukemic cells at relapse bore identical rearrangements to those in the disease at time of presentation of each patient. We conclude that relapse in all four patients is due to re-emergence of the original leukemic clone.

scholarly journals Molecular analysis of relapse in chronic myeloid leukemia after allogeneic bone marrow transplantation

Blood ◽  
1987 ◽  
Vol 70 (3) ◽  
pp. 873-876
Author(s):  
TS Ganesan ◽  
GL Min ◽  
JM Goldman ◽  
BD Young
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Transplantation ◽  
Chronic Myeloid Leukemia ◽  
Marrow Transplantation ◽  
Myeloid Leukemia ◽  
Allogeneic Bone Marrow Transplantation ◽  
Allogeneic Bone Marrow ◽  
Leukemic Cells ◽  
Allogeneic Bone ◽  
Leukemic Clone

Four patients with Philadelphia (Ph′) positive chronic myeloid leukemia (CML) were studied before, after, and on relapse following allogeneic bone marrow transplantation (BMT). Southern analysis of DNA from cells collected before and at relapse after BMT was performed in order to investigate the origin of the leukemia at relapse. Using minisatellite probes we showed that the relapse occurred in cells of host origin in all four patients and this was confirmed with a Y chromosome specific probe in two male patients who had a female donor. Furthermore, using two probes for the breakpoint cluster region (bcr) on chromosome 22, we showed that leukemic cells at relapse bore identical rearrangements to those in the disease at time of presentation of each patient. We conclude that relapse in all four patients is due to re-emergence of the original leukemic clone.

scholarly journals E4F1 deficiency results in oxidative stress–mediated cell death of leukemic cells

2011 ◽  
Vol 208 (7) ◽  
pp. 1403-1417 ◽  
Author(s):  
Elodie Hatchi ◽  
Genevieve Rodier ◽  
Matthieu Lacroix ◽  
Julie Caramel ◽  
Olivier Kirsh ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Tumor Regression ◽  
Fetal Liver ◽  
Leukemia Cell ◽  
Leukemic Cells ◽  
Viral Oncoprotein ◽  
Mitochondrial Defects

The multifunctional E4F1 protein was originally discovered as a target of the E1A viral oncoprotein. Growing evidence indicates that E4F1 is involved in key signaling pathways commonly deregulated during cell transformation. In this study, we investigate the influence of E4F1 on tumorigenesis. Wild-type mice injected with fetal liver cells from mice lacking CDKN2A, the gene encoding Ink4a/Arf, developed histiocytic sarcomas (HSs), a tumor originating from the monocytic/macrophagic lineage. Cre-mediated deletion of E4F1 resulted in the death of HS cells and tumor regression in vivo and extended the lifespan of recipient animals. In murine and human HS cell lines, E4F1 inactivation resulted in mitochondrial defects and increased production of reactive oxygen species (ROS) that triggered massive cell death. Notably, these defects of E4F1 depletion were observed in HS cells but not healthy primary macrophages. Short hairpin RNA–mediated depletion of E4F1 induced mitochondrial defects and ROS-mediated death in several human myeloid leukemia cell lines. E4F1 protein is overexpressed in a large subset of human acute myeloid leukemia samples. Together, these data reveal a role for E4F1 in the survival of myeloid leukemic cells and support the notion that targeting E4F1 activities might have therapeutic interest.

KRN5500, a Spicamycin Derivative, Exerts Anti-Myeloma Effects through Impairing Both Myeloma Cells and Osteoclasts.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1669-1669
Author(s):  
Hirokazu Miki ◽  
Shuji Ozaki ◽  
Osamu Tanaka ◽  
Shingen Nakamura ◽  
Ayako Nakano ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Drug Resistance ◽  
Cell Death ◽  
Cell Growth ◽  
Cell Lines ◽  
G1 Arrest ◽  
Dependent Manner ◽  
Osteolytic Bone Disease ◽  
Rpmi 8226

Abstract Multiple myeloma (MM) is a plasma cell malignancy characterized by devastating bone destruction due to enhanced bone resorption and suppressed bone formation. Although high-dose chemotherapy and new agents such as thalidomide, lenalidomide, and bortezomib have shown marked anti-MM activity in clinical settings, MM remains incurable due to drug resistance mediated by interactions with osteoclasts or stroma cells. Moreover, osteolytic bone disease continues to be a major problem for many patients. Therefore, alternative approaches are necessary to overcome drug resistance and inhibit osteoclasts activity in MM. KRN5500 is a new derivative of spicamycin produced by Streptomyces alanosinicus (Kirin Pharma, Tokyo, Japan), which potently inhibits protein synthesis and induces cell death in human tumor cell lines. Phase I studies of KRN5500 in patients with solid tumors such as colon cancer and gastric cancer showed acceptable toxicity with Cmax values of 1000––3000 nM. In this study, we investigated the effects of KRN5500 against MM cells and osteoclasts in vitro and in vivo. MM cell lines such as RPMI 8226, MM.1S, INA-6, KMS12-BM, UTMC-2, TSPC-1, and OPC were incubated with various concentrations of KRN5500 for 3 days. Cell proliferation assay showed marked inhibition of cell growth with G1 arrest in these MM cells (IC50: 4–100 nM). KRN5500 (100 nM) also induced 30–90% of cell death in primary MM cells (n=7). Annexin V/propidium iodide staining showed that KRN5500 induced apoptosis of MM cells in a dose- and time-dependent manner. Western blot analysis confirmed activation of caspase-8, -9, and −3, cleavage of poly (ADP-ribose) polymerase (PARP), and down-regulation of Mcl-1. We next examined the effect of KRN5500 against MM cell lines and primary MM cells in the presence of bone marrow stroma cells and osteoclasts. Co-culture of these cells enhanced viability of MM cells; however, KRN5500 still induced strong cytotoxicity to MM cells. Of interest, KRN5500 specifically mediated apoptosis in osteoclasts but not stroma cells as assessed by TUNEL staining. More than 90% of osteoclasts were killed even at a low concentration of KRN5500 (20 nM). Finally, we evaluated the effect of KRN5500 against MM cells and osteoclasts in vivo. Two xenograft models were established in SCID mice by either subcutaneous injection of RPMI 8226 cells or intra-bone injection of INA-6 cells into subcutaneously implanted rabbit bones (SCID-rab model). These mice were treated with intraperitoneal injection of KRN5500 (5 mg/kg/dose) or saline thrice a week for 3 weeks after tumor development. In a subcutaneous tumor model, KRN5500 inhibited the tumor growth compared with control mice (increased tumor size, 232 ± 54% vs 950 ± 422%, p<0.001, n=6 per group). In a SCID-rab model, KRN5500 also inhibited MM cell growth in the bone marrow (increase of serum human sIL6-R derived from INA-6, 134 ± 19% vs 1112 ± 101%, p<0.001, n=5 per group). Notably, the destruction of the rabbit bones was also prevented in the KRN5500-treated mice as evaluated by radiography. Therefore, these results suggest that KRN5500 exerts anti-MM effects through impairing both MM cells and osteoclasts and that this unique mechanism of action provides a valuable therapeutic option to improve the prognosis in patients with MM.

Different Kinetic Pattern of Chronic Myeloid Leukemia: Lymphoblastic and Myeloblastic Blastic Crisis

1980 ◽  
Vol 66 (3) ◽  
pp. 295-303
Author(s):  
Wanda Piacibello ◽  
Massimo Aglietta ◽  
Felice Gavosto
Keyword(s):  
Bone Marrow ◽  
Acute Lymphoblastic Leukemia ◽  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Lymphoblastic Leukemia ◽  
Kinetic Studies ◽  
Leukemic Cells ◽  
Cell Kinetic ◽  
Blastic Crisis ◽  
Kinetic Pattern

Cell kinetic studies were performed in 8 ease of lymphoid blastic crisis (BC) of chronic myeloid leukemia at the onset of BC and during subsequent relapses. The results were compared with those found in 7 myeloblastic BC. While in the myeloblastic transformation the labeling index (LI) was always higher in bone marrow than in peripheral blood blasts, suggesting a predominant bone marrow proliferation of the leukemic cells, in the lymphoid transformation a higher LI was often found in peripheral blasts. Moreover, the lymphoblastic transformations were frequently characterized by lymphadenopathy. These findings point to the similarities between lymphoid BC and acute lymphoblastic leukemia, suggesting the possibility that a blastic event may originate in an extramedullary site and that an extramedullary BC is more likely to be lymphoid in nature.

Transplantation of Immunodeficient Mice with Chronic Myeloid Leukemia (CML) Cells from Chronic Phase Patients Reveals a Hierarchy of CD34+ Aldehyde Dehydrogenase-Positive Cells with Short- and Long-Term Repopulating Activity and Transient Responsiveness to Imatinib Mesylate in Vivo.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2960-2960
Author(s):  
Oliver Christ ◽  
Wolfgang Eisterer ◽  
Xiaoyan Jiang ◽  
Emily Pang ◽  
Karen Leung ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Chronic Myeloid Leukemia ◽  
Imatinib Mesylate ◽  
Aldehyde Dehydrogenase ◽  
Myeloid Leukemia ◽  
Chronic Phase ◽  
Leukemic Cells ◽  
Majority Population ◽  
Normal Human

Abstract Transplantation of sublethally irradiated NOD/SCID or NOD/SCID-β2microglobulin (β2m) null mice with cells from most chronic phase chronic myeloid leukemia (CML) patients results in the regeneration in the mice of primarily normal human hematopoietic cells. This is due to the usual predominance of normal cells within the most primitive subsets of bone marrow or blood cells in these patients. To date, no markers that allow the most primitive normal and leukemic cells to be differentially isolated from chronic phase CML samples have been identified except those reflecting an increased turnover of the leukemic cells. As an alternative approach to characterizing chronic phase CML stem cells, we have identified particular patient samples that contain predominantly leukemic LTC-ICs and have found that transplants of these samples regenerate a predominance of leukemic cells in both NOD/SCID and NOD/SCID-β2m null mice. To investigate the biological and phenotypic properties of CML cells that have short- and longterm repopulating activity, we transplanted sublethally irradiated NOD/SCID and NOD/SCID-β2m null mice with FACS-sorted subsets of lin- CML cells from 2 such samples and then monitored their output of cells in the bone marrow of the mice for up to 12 weeks. The CD34+CD38+ CML cells produced a rapid but transient wave of mainly myeloid progeny that peaked at 3 weeks whereas the CD34+CD38− cells produced a more delayed but persistent wave of cells in both types of mice that included some lymphoid progeny although the latter represented a markedly reduced proportion of the total relative to the cells produced by normal human bone marrow. These patterns were seen in both recipient genotypes but cell output was enhanced in NOD/SCID-β2m null mice as expected for short-term repopulating cells. In additional studies with 3 patients’ samples, both types of repopulating cells were found primarily in the aldehyde dehydrogenase-positive fraction based on their staining with BODIPY-labeled amino acetaldehyde. To test the feasibility of the CML xenograft model for evaluating novel treatments in vivo, groups of NOD/SCID mice repopulated to high levels with leukemic cells (49±8%) 7 weeks after being transplanted with 3x107 CD34+ CML cells, were injected with 50 mg/kg imatinib mesylate (or not) i.p. twice daily for 10 days. Bone marrow samples obtained from the imatinib mesylate-treated mice 2, 4, 12 and 22 weeks after initiation of this treatment, initially showed a more rapid and greater decline of human leukemic cells (>2-fold as assessed by both FACS and quantitative real-time PCR); however by 5 months after completion of the treatment, the level of human cells in the bone marrow of both the imatinib mesylate-treated and untreated mice was the same. Taken together, these findings demonstrate that the CML clone in chronic phase patients contains a similar hierarchy of short and longterm repopulating cells as is found in normal adult bone marrow, and that the CML repopulating cells have, in addition to their ability to sustain the clone, a greater innate resistance to the toxic effects that imatinib mesylate has in vivo on the majority population of more differentiated CML cells.

Inhibition of Cellular Aminopeptidases as Novel Therapy for AML.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2588-2588
Author(s):  
Christopher Jenkins ◽  
Chris Pepper ◽  
Ken Mills ◽  
Alan Burnett
Keyword(s):  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Human Cancer ◽  
Myeloid Cells ◽  
Chemotherapeutic Agents ◽  
Molecular Therapy ◽  
Leukemic Cells ◽  
Therapeutic Window ◽  
Acute Myeloid

Abstract CHR 2797 is one of a new class of enzyme inhibitors with a pleiotropic effect against a number of human cancer cells. It is thought to inhibit the M1 family of metalloenzymes that include aminopeptidases, and is under investigation for the treatment of acute myeloid leukemia. Aminopeptidases catalyse the hydrolysis of the terminal amino acids from short chain polypeptides and they are involved in the continuous cycle of protein formation and degradation in cells. As malignant cells are thought to be more highly dependant on this protein cycling, interrupting this pathway is therefore a potential therapeutic target for novel agents. The effects of the aminopeptidase inhibitor CHR 2797 were investigated in AML cells in-vitro. Leukemic cells and cell lines were treated with CHR 2797 at a range of 0.0002 – 20μM and IC50 values were calculated from the WST-1 proliferation experiments. The AML cell lines HL60, KG1, K562 and U937 had an average IC50 of 1μM with a range between 0.01 and 10μM. Primary diagnostic AML samples (n=40) were analysed and an IC50 range of between 0.01 and >40μM were detected, with a median of 0.8μM. The effects of CHR 2797 were also analysed on normal bone marrow samples (n=10). The IC50 range was between 6.2 and >40μM with a median of 15μM, demonstrating a potential therapeutic window between the treatment of the leukemic cells and toxicity to the normal samples. The level of synergy or antagonism with conventional therapeutic agents was calculated using a combination index. Synergy was demonstrated in 70% of cell samples in combination with ARA-C, and 80% with Velcade. Synergy was also shown in 60% of cells samples with ATRA, even in non-promyelocytic leukemia types. Annexin V and cell cycle analysis confirmed apoptosis after treatment with CHR 2797 in many cases. A degree of differentiation of acute promyelocytic cells to mature myeloid cells was also stimulated with the treatment. The effects of CHR 2797 on cellular aminopeptidases were also measured. CD13 is a cell surface protein which is expressed selectively on myeloid cells and is also classified as an aminopeptidase N. Its activity can be measured by the conversion of the substrate ala-MCA to the protein MCA that can be detected on a fluorometric plate reader. CHR 2797 was demonstrated to reduce CD13 activity in a time and dose responsive manner. The reduction in activity was demonstrated immediately following addition of the drug, and a persistent effect was shown over four days of cell culture. A reduction in CD13 activity was also shown with a concentration of CHR 2797 of under 0.5μM; and with a 10μM dose the activity in many AML samples was reduced by >90%. New treatments are needed for acute myeloid leukemia to improve survival and reduce the toxicity of conventional therapy. This study demonstrates that CHR 2797 might be an effective molecular therapy for AML, either alone or in combination with other chemotherapeutic agents.

scholarly journals Impact of Bone Marrow miR-21 Expression on Acute Myeloid Leukemia T Lymphocyte Fragility and Dysfunction

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2053
Author(s):  
Douâa Moussa Agha ◽  
Redouane Rouas ◽  
Mehdi Najar ◽  
Fatima Bouhtit ◽  
Hussein Fayyad-Kazan ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Death ◽  
Acute Myeloid Leukemia ◽  
T Lymphocytes ◽  
T Lymphocyte ◽  
Myeloid Leukemia ◽  
Myeloid Cell ◽  
Leukemic Cells ◽  
Hematopoietic Malignancy ◽  
Acute Myeloid

Background: Acute myeloid leukemia (AML) is a hematopoietic malignancy in which antitumor immunity is impaired. The therapeutic management of AML requires understanding the mechanisms involved in the fragility and immune dysfunction of AML T lymphocytes. Methods: In this study, T lymphocytes from healthy donors (HD) and AML patients were used. Extracellular vesicles (EVs) from leukemic cells were screened for their microRNA content and impact on T lymphocytes. Flow cytometry, transcriptomic as well as lentiviral transduction techniques were used to carry out the research. Results: We observed increased cell death of T lymphocytes from AML patients. EVs from leukemia myeloid cell lines harbored several miRNAs, including miR-21, and were able to induce T lymphocyte death. Compared to that in HD, miR-21 was overexpressed in both the bone marrow fluid and infiltrating T lymphocytes of AML patients. MiR-21 induces T lymphocyte cell death by upregulating proapoptotic gene expression. It also increases the immunosuppressive profile of T lymphocytes by upregulating the IL13, IL4, IL10, and FoxP3 genes. Conclusions: Our results demonstrate that miR-21 plays a significant role in AML T lymphocyte dysfunction and apoptosis. Targeting miR-21 may be a novel approach to restore the efficacy of the immune response against AML.

scholarly journals Carbenoxolone Decreases the Microenvironment-Induced Chemoresistance of Acute Myeloid Leukemia Cells

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1474-1474
Author(s):  
Farah Kouzi ◽  
Frederic Picou ◽  
Jerome Bourgeais ◽  
Nathalie Gallay ◽  
Fabrice Gouilleux ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Gap Junctions ◽  
Gap Junction ◽  
Cell Lines ◽  
Culture System ◽  
Myeloid Leukemia ◽  
Connexin 43 ◽  
Leukemic Cells ◽  
Leukemia Cells ◽  
Hematopoietic Stem

Abstract Introduction Bone marrow niche of acute myeloid leukemia (AML) is a highly specialized microenvironment that regulates leukemic progression by favoring leukemic cell quiescence and chemoresistance. Niche components, especially mesenchymal stromal/stem cells (MSCs), have pro-survival effects on leukemia cells by protecting them from chemotherapy-induced apoptosis. The protection mechanisms of AML cells by the microenvironment are extensively studied to identify pharmacological targets to prevent AML relapse after chemotherapy. Direct intercellular communications between hematopoietic stem cells and MSCs involve connexins, such as connexin 43 (Taniguchi Ishikawa E et al. Connexin-43 prevents hematopoietic stem cell senescence through transfer of reactive oxygen species to bone marrow stromal cells. Proc Natl Acad Sci U S A. 2012,109:9071-6). The connexins are key components of gap junctions and we postulated in this study that blocking their assembly could modify cell-cell interactions in the leukemic niche and consequently the chemoresistance. To this end we evaluated the effects of carbenoxolone (CBX), a glycyrrhetinic acid derivative known to block gap junctions (Rozental R et al. How to close a gap junction channel. Efficacies and potencies of uncoupling agents. Methods Mol Biol 2001;154:447-76), already evaluated in the treatment of human diseases. Methods Primary AML blasts isolated from bone marrow patients and 8 AML cell lines (KG1-a, KG1, HL-60, THP-1, MOLM-13, MV4-11, ML2, NB4) were exposed to CBX to assess cell viability and proliferation (Trypan blue exclusion and MTT assays). To study the combined drug effects of CBX and cytarabine (Ara-C), isobolograms were determined by co-treatment of AML cell lines with various doses of these two molecules. The metabolic effects of CBX on AML live cells were investigated with Seahorse® analyzer to measure oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) and high-throughput metabolic profiling was performed by OmniLog® technology. Direct cell-cell interactions were studied in a co-culture system of AML cells and bone marrow primary MSCs combining or not CBX (150 µM) and Ara-C (1 µM). After 48h (37°C, 5% CO2), AML cells adherent to MSCs were collected and the two populations were discriminated by flow cytometry studies (AML cells: CD45+CD90- / MSCs: CD45-CD90+) to quantify cell number apoptosis/necrosis (AnnexinV/7AAD assay). Gap junction inhibition by CBX was checked by calcein transfer (dye transferred mainly by gap junction channels) from labeled MSCs to AML cells in the co-culture system. Statistical analyses were performed with Mann-Whitney-Wilcoxon test. Results Treatment of AML cell lines with CBX reduced cell growth and viability in a time- and dose-dependent manner and the CBX IC50 was around 150 µM. Moreover, the exposure for 48h of primary AML blast to this dose of CBX induced a two time decrease in the number of viable cells. Interestingly, the isobolograms of the 8 AML cells lines identified three different profiles of resistance to chemotherapy and a synergistic effect between CBX and Ara-C. Regarding the energy metabolism, the analysis of all AML cell lines showed a major reduction of OCR and ECAR after treatment with CBX (150 µM, 48h) regardless their chemoresistance to Ara-C. Moreover, treated AML cells lacked their metabolic capacities for utilization of numerous substrates. In the co-culture experiments, contact with MSCs induced resistance to Ara-C; the apoptosis/necrosis rate observed after Ara-C exposure was 4.3- and 6.4-times decreased by MSC-contact for KG1a cells (n=5, p=0.0115) and primary blasts (n=5, p=0.0001), respectively. Co-treatment of leukemic cells with CBX and Ara-C reversed these deleterious effects of MSC-contact; the apoptosis/necrosis rate observed in MSC-contact leukemic cells was 5- and 2-times increased by CBX co-treatment for KG1a cells (n=5, p=0.007) and primary blasts (n=5, p=0.042), respectively. Finally, CBX induced a 48%-decrease in calcein transfer between leukemic cells and MSCs, highlighting its role as a gap junction inhibitor. Conclusion Niche-induced chemoresistance is associated with the mechanism of AML relapse after initial well-conducted chemotherapy. Combined to chemotherapy, CBX could be of interest to reduce the deleterious effects of leukemic niche by targeting gap junctions. Disclosures No relevant conflicts of interest to declare.

scholarly journals Shikonin Overcomes Drug Resistance and Induces Necroptosis By Regulating the Mir-92a-1-5p/Mlkl Axis in Chronic Myeloid Leukemia Cells

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1633-1633
Author(s):  
Xianbo Huang ◽  
Jie Jin ◽  
Wenbin Qian ◽  
Xiujin Ye
Keyword(s):  
Cell Death ◽  
Chronic Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Metabolic Reprogramming ◽  
Luciferase Reporter ◽  
Wide Range ◽  
Tki Resistance ◽  
Poor Outcomes

BACKGROUND: Resistance to cell death and metabolic reprogramming are common features of tumor cells. Although the introduction of selective BCR/ABL tyrosine kinase inhibitors (TKIs) has dramatically improved the outcomes and survival rates of chronic myeloid leukemia (CML) patients, some patients (20-30%) develop TKI resistance. The most aggressive and treatment-resistant CML is the subtype harboring BCR/ABL with the T315I mutation, and this subtype is refractory to nearly all TKI-induced apoptosis. Thus, alternative approaches that induce apoptosis-independent cell death are thought to compensate for apoptotic-resistant cells. Recently, necroptosis (also called programmed necrosis), which is generally driven by RIPK1/RIPK3/MLKL activation, has been demonstrated to be a new type of programmed cell death mode that is different from apoptosis. Thus, a deeper understanding of the molecular mechanisms regulating necroptosis might lead to the development of new therapeutic strategies that could remarkably improve the treatment-responses and outcomes of patients with TKI-resistant CML. RESULTS: Shikonin, a compound purified from traditional Chinese medicine, has been reported to induce cell death in various tumor cell lines via a wide range of mechanisms. In our current study, we found that shikonin can effectively inhibit proliferation and induce necrosis-like morphological alterations (Fig. A and B) accompanied by RIPK1/RIPK3/MLKL signaling activation ((Fig. C) in CML cell lines, including the T315I mutant type (32Dp210-T315I). The effects of shikonin can be attenuated by the necroptosis-specific inhibitor (essentially a RIPK1 inhibitor) Nec-1, but not by the pan-apoptosis inhibitor z-VAD-fmk, indicating the occurrence of necroptosis in these cells ((Fig. B and C). Our data also show that shikonin has in vivo anti-CML activity via necroptosis induction in 32Dp210-T315I cells xenografted into NOD/SCID mice via subcutaneous injection ((Fig. D). miRNAs play an important role in tumorigenesis mainly via regulation of gene expression. Our next generation sequencing-based microRNA expression profiling showed significant dysregulation of miR-92a-1-5p expression in a shikonin-treated CML cell line (K562) (Fig. E). We then measured the miR-92a-1-5p expression levels in bone marrow samples from CML patients and patients with nonhematologic malignant diseases. The data showed that the miR-92a-1-5p expression level was higher in primary cells obtained from CML-BC patients than in those from non-CML-CP patients, suggesting that miR-92a-1-5p upregulation is correlated with poor outcomes (Fig. F). Bioinformatics analyses and a dual luciferase reporter gene assay proved that MLKL, a downstream factor in the necroptosis pathway that usually acts as the necroptosis executor, is a direct target of miR-92a-1-5p (Fig. G). Overexpression of miR-92a-1-5p in vitro led to decreased MLKL protein abundance in CML cells (Fig. G). Inhibition of miR-92a-1-5p via use of a specific antago-miRNA could inhibit CML xenograft tumor growth and induce necroptosis via MLKL upregulation in vivo (Fig. H). Hence, we believe that miR-92a-1-5p plays a role in promoting the proliferation and survival of CML via downregulating the abundance of MLKL, the necroptosis executor. CONCLUSIONS: In conclusion, our study proves that shikonin can overcome TKI resistance and induce necroptosis in CML cells, mainly via a mechanism involving RIPK1/RIPK3/MLKL activation. Our study also suggests that miR-92a-1-5p is frequently overexpressed in CML patients with poor outcomes and that it can promote tumor survival by inhibiting MLKL expression. For the first time, we demonstrated that miR-92a-1-5p inhibition via antago-miRNA can potentially be used to treat CML via necroptosis induction. Since necroptosis has not yet been considered to be a therapeutic strategy for tumor treatment, our research confirms that it might indeed serve as a new modality to better control drug-resistant CML. Figure Disclosures No relevant conflicts of interest to declare.

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