Diffuse large B-cell lymphoma-derived exosomes push macrophage polarization toward M2 phenotype via GP130/STAT3 signaling pathway.

Growing evidence shows that cancer progression links with both heterogeneity of the tumor microenvironment and dysregulated activity of immune cells. Cancer-secreted exosomes are being recognized as indispensable mediators of the exchange cargo between cancer and immune cells. The M2-phenotype tumor-associated macrophages have the function of promoting tumor progression and drug resistance. Diffuse large B-cell lymphoma(DLBCL) is a highly heterogeneous and very common malignant non-Hodgkin's lymphoma. Here, we demonstrate that different subtype DLBCL cell-derived exosomes are internalized by macrophages, which can affect macrophages polarization. The mechanism of DLBCL-derived exosomes on macrophage polarization remains unclear currently. This study showed that DLBCL-secreted exosomes could induce the transformation of macrophages to a protumor M2-like phenotype, and block the drug-induced apoptosis of DLBCL cells in an indirect co-culture system. Different DLBCL-derived exosomes could change the phenotype of macrophages through the STAT3 signaling, which upregulated the expression of oncogenic genes and classical markers of M2-like phenotype macrophages, such as IL-10, CD206, and CD163. The addition of DLBCL-derived exosomes resulted in the activation of the STAT3 signaling pathway of M0/M2 macrophages in an indirect co-culture system. GP130 was highly enriched in DLBCL-derived exosomes, which triggered the activation of STAT3 of macrophages and subsequently induced the downstream targets such as BCL2, SURVIVIN, and BAX. The parallel changes of STAT3 and GP130 in macrophages confirmed that GP130 of DLBCL-derived exosomes promoted macrophage polarization by activating STAT3 signaling. Furthermore, all of these effects could be reversed by the GP130 inhibitor SC144. The data indicated that DLBCL-derived exosomes could trigger macrophages polarization into a pro-survival M2-like phenotype, which was at least partially through the GP130/STAT3 signaling pathway. Collectively, this study showed that DLBCL-derived exosomes could promote macrophages transformation to protumor M2-like phenotype in the tumor microenvironment.

Impact of Global and Gene-Specific DNA Methylation in de Novo or Relapsed Acute Myeloid Leukemia Patients Treated with Decitabine.

In this investigation, global DNA methylation patterns and the specific methylation status of 5 genes were studied in DNA from peripheral blood (PB) and impact on progression free survival (PFS) and overall-survival (OS) in patients with de novo or relapsed acute myeloid leukemia (AML) treated with decitabine-based regimens waas assessed. DNA was isolated from PB samples at the time of -1, 1, and 7 days of chemotherapy. Global methylation was determined by ELISA, and the CpG island DNA methylation profile of 5 genes using a DNA methylation PCR system. Our data demonstrated that patients with a high level of 5-mC had a poor prognosis after demethylation therapy and those who have low levels of 5-mC in PB achieved higher CR and better SO, but there was no significant correlation found between the 5-mC levels and other clinical features before treatment except the disease status. Higher methylation status of Sox2 and Oct4 genes was associated with differential response to demethylation therapy. A relatively low methylation percentage in one or both of these two genes was also associated with longer OS after decitabine based chemotherapy. We also suggest that global DNA and Oct-4/Sox2 methylation might impact on the pathogenesis of leukemia and play an important role in the initiation and progression. Moreover, dynamic analysis of 5-mC and Oct-4/Sox2 in peripheral blood nucleated cells of leukemia patients may provide clues to important molecular diagnostic and prognostic targets.

[Sensitivity to bortezomib of RPIM8226 cells after co-cultured with down-regulated Cav-1 expression HUVECs].

OBJECTIVE: To investigate the sensitivity to bortezomib of RPMI8226 cells after co-cultured with down-regulated Caveolin (Cav)-1 expression of HUVECs by transfection with Cav-1 shRNA (HUVECs(Cav-1 low)). METHODS: Exposure to bortezomib with or without 50 nmol/L dexamethasone at different concentration, the proliferation of RPMI8226 was analyzed by MTT assay when it was cultured alone or co-cultured with HUVECs(Cav-1 low). Cav-1 expression was detected by using of Western blot and cell cycle, apoptosis and the level of reactive oxygen species (ROS) were analyzed by flow cytometry. RESULTS: Cav-1 expression was notably down-regulated in HUVECs(Cav-1 low) (0.2199±0.0288 vs 1.3195±0.2393) (P<0.01). The IC(50) of bortezomib for RPMI8226 cultured alone, co-cultured with HUVECs orHUVECCav- 1 low were 20 nmol/L, 50 nmol/L and 65 nmol/L, respectively. The percentages of G0/G1 phase in RPMI8226 cultured alone, co-cultured with HUVECs and HUVECs(Cav-1 low) were 28.49%, 30.41%, and 36.15% respectively. The protection of RPMI 8226 against apoptosis by HUVECs was demonstrated that the apoptosis/death rates were 66.8%, 10.7% and 8.6% in RPMI8226 cultured alone, co-cultured with HUVECs and HUVECs(Cav-1 low) after exposure to 20 nmol/L bortezomib for 24 h. RPMI8226 could induce the oxidative stress of HUVECs before and after co-culture. The ROS level was raised from 15.0% to 35.2% in RPMI8226, from 80.4% to 91.0% in HUVECs, and from 84.6% to 96.8% in HUVECs(Cav-1 low). CONCLUSION: The down-regulated Cav-1 expression of HUVECs could promote proliferation and induce apoptosis of RMPI8226 cells, lead to G0/G1 phase arrest, and reduce the sensitivity to bortezomib.

[Eukaryotic expression and biological activity of recombinant human IL-17B protein].

AIM: To construct pCEP4/hIL-17B recombinant expression vector and express it stably in eukaryotic cells and investigate the biological activity in vitro. METHODS: The CDS region of human IL-17B gene was cloned by RT-PCR. After identification by sequencing, the hIL-17B gene was inserted into expression vector of pCEP4 to construct the recombinant vector pCEP4/hIL-17B, then transfected into 293T cells. The transgenic 293T cell line stably expressing rhIL-17B protein was selected in the presence of Hygromycin B. After FCS-free cultivation and sub-cloning, The IL-17B/mFc gene and protein expression was confirmed by RT-PCR, ELISA and Western blot analysis. To investigate the ability of combination with IL-17B receptor on human leukemic monocytic cell line, THP-1, by Flow cytometrical analysis (FACS) and of stimulation to secret cytokines in vitro. RESULTS: The recombinant pCEP4/hIL-17B and its transgenic 293T cells stably expressing rhIL-17B protein were obtained successfully. FACS analysis showed its high affinity with its receptor and it can stimulated THP-1 cell line to excrete IL-1ß and TNF-α in vitro and consistently caused a dose-dependent influx of neutrophil into the peritoneal cavity by intraperitoneal injection in vivo. CONCLUSION: The obtainment of transgenic 293T cell line stably expressing rhIL-17B protein paved the way for further study on biological functions of hIL-17B.

[Preparation of three functional monoclonal antibodies against human FL molecule and analysis of their bioactivity].

AIM: To Prepare three functional monoclonal antibodies(mAbs) against human FL molecule and analyze their bioactivity. METHODS: The cell line L929-FL transfected with human FL gene was used as immunogen. The hybridomas secreting the antibodies against human FL were obtained by fusing splenoecytes from the immunized mice with murine myeloma cells(Sp2/0). Their subclasses were analyzed using fast-strip method. The monoclonal antibodies were produced in mouse peritoneal cavity and purified by Protein G affinity chromatography. The inhibitory effect of mAbs against FL on leukemia cell lines U937 and HL-60 was detected by MTT. The apoptosis of U937 and HL-60 cells stained by annexin-V/PI was determined by FCM. RESULTS: Three hybridomas named 3C2, 3C6 and 8D10 were successfully obtained, which secreted monoclonal antibodies against human FL molecule stably. Their subclasses were the mouse IgG2a with kappa light chains. The three monoclonal antibodies recognized the FL molecule on U937 and HL-60 cells that also coexpressed Flt3 molecule. When U937 and HL-60 cells were cultured in presence of 3C2, 3C6 and 8D10, their proliferation was reduced as compared to that in control in MTT assay(P < 0.05). The analysis of annexin-V/PI binding to U937 and HL-60 cells by FCM showed the mAbs had the apoptotogenic activity of the monoclonal antibodies against human FL molecule. CONCLUSION: 3C2, 3C6 and 8D10 are three funtional monoclonal antibodies against human FL molecule. They may be of some value in the study of the roles of FL/Flt3 interaction in leukemia pathogenesis.

[Prokaryotic expression, purification and biological activity of recombinant human IL-17/His protein].

AIM: To investigate the biological activity of recombinant human IL-17 protein in vitro. METHODS: The gene region of human IL-17 was cloned by RT-PCR. After identification by sequencing, the hIL-17 gene encoding function domain was cloned into expression plasmid PQE3.0 and transfect into E.coli M15. By the induction of Isopropyl-beta-D-Thiogalacto-Pyranoside (IPTG), recombinant IL-17/His protein was effectively expressed in E.coli M15. The recombinant protein was identified by Western blot. RESULTS: After denaturation, renaturation and purification by HiTrap affinity column, the recombinant protein stimulated HeLa, a human uterine cervix cancer cell line, to excrete IL-6 and GM-CSF in vitro. CONCLUSION: IL-17/His recombinant protein is of high biological activity, which can be used to make further study of auto-immune diseases.

[Establishment of human acute monocytic leukemia model in severe combined immunodeficient (SCID) mice and the analysis of pathological changes].

AIM: To establish a model of human M5 leukemia and investigate the pathomorphological change in severe combined immunodeficient (SCID) mice after being transplanted with SHI-1 cells. METHODS: Various dose of SHI-1 cells were transplanted i.p. into SCID mice. Serial tail vein samples at regular intervals were prepared for detecting the expression of CD14, CD137L on SHI-1 cells by flow cytometry (FCM). All dying mice were dissectted and the liver, spleen, kidney and bone marrow were examined to detect the appearance and distribution of the SHI-1 cells by FCM and/or immunohistochemistry. RESULTS: Tumors appeared in the abdomenion of the mice treated with various dose of SHI-1 cells. However, the dissemination of SHI-1 cells in murine tissues was found only in the groups of middle/high dose. SHI-1 cells were firstly found in tail vein samples 3 weeks after transplantation, and the time of engraftment was related to the dose of cells. CONCLUSION: The SHI-1/SCID mice was constructed, which provided a useful tool to investigate acute monocytic leukemia(AML).

A functional anti-human 4-1BB ligand monoclonal antibody that enhances proliferation of monocytes by reverse signaling of 4-1BBL.

4-1BB Ligand (4-1BBL), a transmembrane molecule, member of the tumor necrosis factor ligand superfamily, is an important costimulatory molecule in the immune response. In this study a functional anti-human 4-1BBL MAb 1F1 was obtained and the specificity of this MAb was verified by flow cytometry and Western blotting. This MAb effectively recognized the 4-1BBL molecule expressed on a series of malignant cell lines as well as on DC and monocytes and it inhibited the proliferation of T lymphocytes, costimulated by soluble 4-1BBL and agonist anti-human CD3 MAb. Furthermore, we demonstrated that MAb 1F1 induced an impressive proliferation of monocytes from peripheral blood by triggering the reverse signal through 4-1BBL. This functional anti-human 4-1BBL MAb provides a valuable tool for further study of biological functions as well as signal transduction of 4-1BBL/4-1BB.