Xiaojian Zhu

Microvesicles secreted from human multiple myeloma cells promote angiogenesis

Aim:To investigate whether human multiple myeloma (MM) cells secrete microvesicles (MVs) and whether the MVs secreted from MM cells (MM-MVs) promote angiogenesis.Methods:RPMI8226 human MM cells and EA.hy926 human umbilical vein cells were used. MVs isolated from RPMI8226 cells were characterized under laser confocal microscopy, electron microscopy and with flow cytometry. The fusion of MM-MVs and EA.hy926 cells was studied under confocal microscopy, and the transfer of CD138 to EA.hy926 cells was demonstrated with flow cytometry. The proliferation, invasion and tube formation of EA.hy926 cells in vitro were evaluated using MTT, transwell migration and tube formation assays, respectively. The vasculization of EA.hy926 cells in vivo was studied using Matrigel plug assay. The expression of IL-6 and VEGF was analyzed with PCR and ELISA.Results:MM-MVs from the RPMI 8226 cells had the characteristic cup-shape with diameter of 100–1000 nm. Most of the MM-MVs expressed phosphatidylserine and the myeloma cell marker CD138, confirming that they were derived from myeloma cells. After added to EA.hy926 cells, the MM-MVs transferred CD138 to the endothelial cells and significantly stimulated the endothelial cells to proliferate, invade, secrete IL-6 and VEGF, two key angiogenic factors of myeloma, and form tubes in vitro and in vivo.Conclusion:Our results confirm the presence of MVs in MM cells and support the idea that MM-MVs are newfound mediators for myeloma angiogenesis and may serve as a therapeutic target to treat MM.

miR-146b-5p within BCR-ABL1–Positive Microvesicles Promotes Leukemic Transformation of Hematopoietic Cells

Evidence is accumulating that extracellular microvesicles (MV) facilitate progression and relapse in cancer. Using a model in which MVs derived from K562 chronic myelogenous leukemia (CML) cells transform normal hematopoietic transplants into leukemia-like cells, we defined the underlying mechanisms of this process through gene-expression studies and network analyses of transcription factors (TF) and miRNAs. We found that antitumor miRNAs were increased and several defense pathways were initiated during the early phases of oncogenic transformation. Later, oncomiRs and genes involved in cell cycle, DNA repair, and energy metabolism pathways were upregulated. Regulatory network analyses revealed that a number of TFs and miRNAs were responsible for the pathway dysregulation and the oncogenic transformation. In particular, we found that miR-146b-5p, which was highly expressed in MVs, coordinated the regulation of cancer-related genes to promote cell-transforming processes. Notably, treatment of recipient cells with MV derived from K562 cells expressing mimics of miR-146b-5p revealed that it accelerated the transformation process in large part by silencing the tumor-suppressor NUMB High levels of miR-146b-5p also enhanced reactive oxygen species levels and genome instability of recipient cells. Taken together, our finding showed how upregulation of oncogenic miRNAs in MVs promote hematopoetic cells to a leukemic state, as well as a demonstration for TF and miRNA coregulatory analysis in exploring the dysregulation of cancers and discovering key factors. Cancer Res; 76(10); 2901-11. ©2016 AACR.

Serum deprivation elevates the levels of microvesicles with different size distributions and selectively enriched proteins in human myeloma cells in vitro

Aim:To investigate the effects of serum deprivation (SD) on microvesicles (MVs) secreted from human myeloma cells and the implications for disease progression.Methods:RPMI 8226, U266, and KM3 human myeloma cells were incubated in medium containing 10% (non-SD) or 1% fetal bovine serum (SD) and MVs were isolated. The levels and size distribution of MVs were analyzed with flow cytometry. The protein profiles of MVs were studied using 2D SDS-PAGE, MALDI-TOF-MS, and Western blotting. NF-κB activation was analyzed using EMSA. Angiogenesis was examined in Eahy926 endothelial cells.Results:Exposure of RPMI 8226 cells to SD for 24 h did not alter the number of apoptotic cells. However, SD increased the number of MVs from RPMI 8226, U266, and KM3 cells to 2.5-, 4.3-, and 3.8-fold, respectively. The size distribution of SD MVs was also significantly different from that of non-SD MVs. Three proteins ZNF224, SARM, and COBL in SD MVs were found to be up-regulated, which were involved in cell cycle regulation, signal transduction and metabolism, respectively. Co-culture of SD MVs and RPMI 8226 cells increased NF-κB activation in the target RPMI 8226 cells. Furthermore, SD MVs from RPMI 8226 cells significantly increased the microtubule formation capacity of Eahy926 endothelial cells compared with non-SD MVs.Conclusion:SD elevates the levels of microvesicles with different size distribution and selectively enriched proteins in human myeloma cells in vitro. The selectively enriched proteins, especially ZNF224, may play key roles in regulation of myeloma cells, allowing better adaptation to SD.

Amplification of Functional Myeloid-derived Suppressor Cells during Stem Cell Mobilization Induced by Granulocyte Colony-stimulation-factor

The effects of granulocyte colony-stimulation-factor (G-CSF) on stem cell mobilization and its impact on the amplification of myeloid-derived suppressor cells (MDSCs) of donor mice were examined. A mouse model of stem cell mobilization was established by consecutive subcutaneous injection of 100 μg/kg G-CSF for 5 days. The blood from the donor mice was routinely examined during mobilization. Stem cells and MDSCs were analyzed by flow cytometry. The immunosuppressive molecules derived from MDSCs in serum and spleen, including hydrogen dioxide (H2O2) and nitric oxide (NO), and the activity of nitric oxide synthase (NOS) were determined during the mobilization. Apoptosis of T lymphocytes was assessed by using Annexin-V/PI. During stem cell mobilization, the number of lymphocytes and white blood cells in the peripheral blood was increased, and peaked on the 4th day. The number of stem cells in G-CSF-treated mice was significantly greater than that in controls (P<0.01). The expansions of MSDCs were also observed after G-CSF mobilization, with a more notable rate of growth in the peripheral blood than in the spleen. The activity of NOS and the production of NO were increased in the donor mice, and the serum H2O2 levels were approximately 4-fold greater than the controls. Consequently, apoptosis of T lymphocytes was increased and showed a positive correlation with the elevated percentage of MDSCs. It was concluded that G-CSF could provide sufficient peripheral blood stem cells for transplantation. Exogenous administration of G-CSF caused the accumulation of MDSCs in the peripheral blood and the spleen, which could lead to apoptosis of T lymphocytes and may offer a new strategy for the prevention and treatment of graft versus host disease.SummaryThe effects of granulocyte colony-stimulation-factor (G-CSF) on stem cell mobilization and its impact on the amplification of myeloid-derived suppressor cells (MDSCs) of donor mice were examined. A mouse model of stem cell mobilization was established by consecutive subcutaneous injection of 100 μg/kg G-CSF for 5 days. The blood from the donor mice was routinely examined during mobilization. Stem cells and MDSCs were analyzed by flow cytometry. The immunosuppressive molecules derived from MDSCs in serum and spleen, including hydrogen dioxide (H2O2) and nitric oxide (NO), and the activity of nitric oxide synthase (NOS) were determined during the mobilization. Apoptosis of T lymphocytes was assessed by using Annexin-V/PI. During stem cell mobilization, the number of lymphocytes and white blood cells in the peripheral blood was increased, and peaked on the 4th day. The number of stem cells in G-CSF-treated mice was significantly greater than that in controls (P<0.01). The expansions of MSDCs were also observed after G-CSF mobilization, with a more notable rate of growth in the peripheral blood than in the spleen. The activity of NOS and the production of NO were increased in the donor mice, and the serum H2O2 levels were approximately 4-fold greater than the controls. Consequently, apoptosis of T lymphocytes was increased and showed a positive correlation with the elevated percentage of MDSCs. It was concluded that G-CSF could provide sufficient peripheral blood stem cells for transplantation. Exogenous administration of G-CSF caused the accumulation of MDSCs in the peripheral blood and the spleen, which could lead to apoptosis of T lymphocytes and may offer a new strategy for the prevention and treatment of graft versus host disease.

P-450-dependent epoxygenase pathway of arachidonic acid is involved in myeloma-induced angiogenesis of endothelial cells

P-450-dependent epoxygenase pathway of arachidonic acid and the products of epoxyeicosatrienoic acids (EETs) have been demonstrated to be involved in angiogenesis and tumor progression. This study examined the expression of EETs and the role of the pathway in the angiogenesis of multiple myeloma (MM). MM cell lines of U266 and RPMI8226 were cultured, and the EETs levels (11, 12-EET and 14, 15-EET) in the supernatant were determined by ELISA. Human umbilical vein endothelial cells (HUVECs) were cultured and used for analysis of the angiogenesis activity of the two MM cell lines, which was examined both in vitro and in vivo by employing MTT, chemotaxis, tube formation and matrigel plug assays. 11, 12-EET and 14, 15-EET were found in the supernatant of the cultured MM cells. The levels of the two EETs in the supernatant of U266 cells were significantly higher than those in the RPMI8226 cell supernatant (P<0.05), and the levels paralleled the respective angiogenesis activity of the two different MM cell lines. 17-octadecynoic acid (17-ODYA), as a specific inhibitor of P450 enzyme, suppressed HUVECs proliferation and tube formation induced by MM cells. Furthermore, 17-ODYA decreased the EET levels in the supernatant of MM cells. These results suggest that EETs may play an important role in the angiogenesis of MM, and the inhibitor 17-ODYA suppresses this effect.SummaryP-450-dependent epoxygenase pathway of arachidonic acid and the products of epoxyeicosatrienoic acids (EETs) have been demonstrated to be involved in angiogenesis and tumor progression. This study examined the expression of EETs and the role of the pathway in the angiogenesis of multiple myeloma (MM). MM cell lines of U266 and RPMI8226 were cultured, and the EETs levels (11, 12-EET and 14, 15-EET) in the supernatant were determined by ELISA. Human umbilical vein endothelial cells (HUVECs) were cultured and used for analysis of the angiogenesis activity of the two MM cell lines, which was examined both in vitro and in vivo by employing MTT, chemotaxis, tube formation and matrigel plug assays. 11, 12-EET and 14, 15-EET were found in the supernatant of the cultured MM cells. The levels of the two EETs in the supernatant of U266 cells were significantly higher than those in the RPMI8226 cell supernatant (P<0.05), and the levels paralleled the respective angiogenesis activity of the two different MM cell lines. 17-octadecynoic acid (17-ODYA), as a specific inhibitor of P450 enzyme, suppressed HUVECs proliferation and tube formation induced by MM cells. Furthermore, 17-ODYA decreased the EET levels in the supernatant of MM cells. These results suggest that EETs may play an important role in the angiogenesis of MM, and the inhibitor 17-ODYA suppresses this effect.

Leukemia cell-derived microvesicles induce T cell exhaustion via miRNA delivery

ABSTRACT T cell function in cancer patients is usually impaired due to the constitutive activation of immune checkpoint inhibitors. This state is known as ‘exhaustion’ and is often associated with the inefficient control of tumors or persistent infections. In this work, we investigated the role of leukemia cell-derived microvesicles (MVs) in T cell exhaustion. Following incubation with MVs from various sources, all T cell subtypes exhibited the exhaustion phonotype and impaired cytokine secretion in vitro. Mice models also showed the connection between immune checkpoint inhibitors and MV injection. Sequencing and bioinformatics analyses indicated that a number of transcription factors and microRNAs (miRNAs) were attributable to the dysregulation of pathways and exhaustion in T cells. Further work revealed that functional miR-92a-3p, miR-21-5p, miR-16-5p, miR-126 and miR-182-5p in MVs could be delivered into T cells to induce the exhaustion phenotype. SerpinB2, IL-1β and CXCL5, which are mediators of the NF-κB pathway, were identified as the targets of the miRNAs mentioned above. We demonstrated that leukemia-derived MVs could initiate T cell exhaustion via the progressive temporal delivery of multiple exogenous miRNAs into T cells and the subsequent interaction of these miRNAs with their targets. Therefore, MVs can be expected not only to become new indicators of the T cell status in patients but also to be used as novel targets for personalized patient treatment.

A clinical observation of Chinese chronic myelogenous leukemia patients after discontinuation of tyrosine kinase inhibitors

Whether tyrosine kinase inhibitors (TKIs) can be safely discontinued is a key focus of chronic myelogenous leukemia (CML) at present. We report a clinical observation of TKIs cessation in Chinese CML patients and a probable connection between CML leukemia stem cells (LSCs) and relapse. In all, 22 of 1057 patients consented to participate in this observation. The average time of complete molecular response was 12.73 months after TKI withdrawal. LSCs could be flow cytometrically detected in most of the patients. However, the number of LSCs did not differ between the relapsers and non-relapsers. We evaluated the leukemogenetic ability of the LSCs by transplanting bone marrow into irradiated NOD/SCID mice. The results indicated that part of the bone marrow from the relapsers lead to leukemogensis in the mice. Besides, we found that LSCs-derived microvesicles might serve as a novel factor for the stratification of undetectable minimal residual disease and an early warning sign of relapse. In summary, post-TKI cessation relapse seems to show none association with the number of LSCs. A mouse xenograft model would provide a novel and useful method of analyzing LSCs function and predicting relapse. Microvesicles may provide important information about optimal molecular monitoring schedules in TKI discontinuation strategies.

Monitoring of leukemia stem cells in chronic myeloid leukemia patients

Jieke Cui , Zunmin Zhu , Songya Liu, Qing Li, Li Meng, Hui Cheng, Zhaodong Zhong, Weiming Li, Yong You, Xiaojian Zhu and Ping Zou Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P. R. China; Department of Hematology, Henan Province Peoples Hospital, Zhengzhou, P. R. China; Department of Hematology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P. R. China; Department of Hematology, Wuhan No.1 Hospital, Wuhan, P. R. China

Future Perspectives of Tyrosine Kinase Inhibitors Discontinuation in ChronicMyeloid Leukemia

Stopping tyrosine kinase inhibitors (TKIs) treatment is an emerging goal of chronic myeloid leukemia (CML) management. Several studies have demonstrated the feasibility of stopping treatment. A sustained molecular response on long-term TKIs therapy seems to be necessary prior to attempting treatment-free remission (TFR). However, there were none available characteristics or indicators which can predict the outcome of TKIs discontinuation now. In our opinion, factors which could reflex the progression probability of minimal residual leukemia such as leukemia stem cells and microenvironment might play a pivotal role. Besides, novel methods for further monitoring would also attract much attention of the researchers in this area.

BCR-ABL1-positive microvesicles malignantly transform human bone marrow mesenchymal stem cells in vitro

The intercellular communication between leukemia cells and bone marrow mesenchymal stem cells (BM-MSCs) plays more important role in chronic myeloid leukemia (CML) than we previously understood. Recently, we found that microvesicles released from human leukemia cell line K562 (K562-MVs) containing BCR-ABL1 mRNA malignantly transformed normal hematopoietic transplants. Here, we investigated whether K562-MVs contribute to the transformation of human bone marrow mesenchymal stem cells (BM-MSCs). We showed that K562-MVs could be integrated into co-cultured normal BM-MSCs and dose-dependently enhanced the proliferation of BM-MSCs. Meanwhile, K562-MVs (400 ng/mL) significantly increased the expression of BCR-ABL1 in these BM-MSCs, accompanied by the enhanced secretion of TGF-β1. These BM-MSCs in turn could trigger the TGF-β1-dependent proliferation of K562 cells. Moreover, we confirmed the presence of BCR-ABL1 in circulating MVs from 11 CML patients. Compared to the normal BM-MSCs, the BM-MSCs from CML patients more effectively increased the BCR-ABL1 expression and TGF-β1 secretion in K562 cells as well as the proliferation of K562 cells. Our findings enrich the mechanisms involved in the interaction between leukemia cells and BM-MSCs and provide novel ways to monitor minimal residual disease and worthwhile approaches to treat CML.