Inhibition of USP10 induces myeloma cell apoptosis by promoting cyclin D3 degradation.

The cell cycle regulator cyclin D3 (CCND3) is highly expressed in multiple myeloma (MM) and it promotes MM cell proliferation. After a certain phase of cell cycle, CCND3 is rapidly degraded, which is essential for the strict control of MM cell cycle progress and proliferation. In the present study, we investigated the molecular mechanisms regulating CCND3 degradation in MM cells. By utilizing affinity purification-coupled tandem mass spectrometry, we identified the deubiquitinase USP10 interacting with CCND3 in human MM OPM2 and KMS11 cell lines. Furthermore, USP10 specifically prevented CCND3 from K48-linked polyubiquitination and proteasomal degradation, therefore enhancing its activity. We demonstrated that the N-terminal domain (aa. 1-205) of USP10 was dispensable for binding to and deubiquitinating CCND3. Although Thr283 was important for CCND3 activity, it was dispensable for CCND3 ubiquitination and stability modulated by USP10. By stabilizing CCND3, USP10 activated the CCND3/CDK4/6 signaling pathway, phosphorylated Rb, and upregulated CDK4, CDK6 and E2F-1 in OPM2 and KMS11 cells. Consistent with these findings, inhibition of USP10 by Spautin-1 resulted in accumulation of CCND3 with K48-linked polyubiquitination and degradation that synergized with Palbociclib, a CDK4/6 inhibitor, to induce MM cell apoptosis. In nude mice bearing myeloma xenografts with OPM2 and KMS11 cells, combined administration of Spautin-l and Palbociclib almost suppressed tumor growth within 30 days. This study thus identifies USP10 as the first deubiquitinase of CCND3 and also finds that targeting the USP10/CCND3/CDK4/6 axis may be a novel modality for the treatment of myeloma.

[Specific induction of anti-leukemia effects by umbilical cord cell-derived CD8+ T cytotoxic lymphocytes].

OBJECTIVE: To explore the specific anti-leukemia immune response of CD8+ cytotoxic T lymphocyte (CTL) derived from cord blood (CB) ex vivo and evaluate the feasibilities and values of the CTL for specific immunotherapy. METHODS: Dendritic cells (DC) were induced from mononuclear cells (MNC) by combination cytokines in 10 CB samples. Loading U937 cell lysate antigen on the mature DC, they could stimulate the lymphocytes of the same origin to generate CTL. MidiMACS was used to isolate CD8+ CTL. Analysis of DC was performed by inverted microscopy, scanning electron microscopy and flow cytometry. Methyl thiazolyl tetrazolium (MTT) assay was used to evaluate the cytotoxicity of the CTL. RESULTS: Cocultured with GM-CSF, IL-4, TNF-alpha and PGE2, CB-MNC could be induced into functional DC with typical morphology. The mean cytotoxicity of CD8+ CTL to U937 cells was significant stronger than that of CD8- CTL and TL at the same E: T ratios. The mean cytotoxicity rate of CD8+ CTL to U937 cells was higher than that to K562 cells [(66.36 +/- 12.43)% vs (41.97 +/- 14.24)%] at E: T ratio of 40: 1 (P < 0.05). The cytotoxicity of CD8- CTL to K562 cells showed no difference from that to U937 cells (P > 0.05). CONCLUSION: Mature CB-DC loading U937 cell antigens could induce CB-T lymphocytes to generate leukemia-specific CD8+ CTL. The cytotoxicity of the CD8+ CTL is specific against U937 cells and is more potent than that of CD8- CTL.

Construction and expression of dendritic cell nucleic acid vaccine containing CML28 gene in human dendritic cells.

This study was aimed to construct nucleic acid vaccine containing the coding region of the CML28 gene and to express it in human dendritic cells. The full length of CML28 cDNA was amplified from K562 by RT-PCR and subcloned into pGEM-T vector. The CML28 fragment was digested and subsequently inserted into the EcoRI-Xba I sites of pcDNA3.1HisA to construct the recombinant expression vector pcDNA3.1HisA-CML28, which was identified by restrition analysis and sequencing. Human dendritic cells (DC) were separated from peripheral blood mononuclear cells (PBMC) by culture with rhGM-CSF, rhIL-4 and assessed by flow cytometry. The constructed plasmid pcDNA3.1 HisA-CML28 was transfected into DC by electroporation. Western blot was used to detect the expression of fusion protein His-CML28. The results showed that recombinant plasmid pcDNA3.1HisA-CML28 contained the correct full CML28 cDNA identified by restriction analysis and sequencing, and can express the fusion protein His-CML28 in DCs. It is concluded that nucleic acid vaccine containing CML28 gene was constructed and expressed in DC successfully.

[Evaluation of recent thymic output function in benzene-exposed workers].

OBJECTIVE: To analyze the content of signal joint T-cell receptor excision DNA circles signal joint T-cell receptor excision DNA circles (sjTRECs) within peripheral blood mononuclear cells (PBMCs), thereby to infer the level of naive T cells and the recent thymic output function in benzene-exposed workers. METHODS: Quantitative detection of sjTRECs in DNA of peripheral blood mononuclear cells from 11 normal individuals and 62 benzene-exposed workers were performed by real-time polymerase chain reaction (PCR) and TaqMan technique. RESULTS: The median value of sjTRECs copies/1,000 PBMCs was 7.81 in normal individuals whereas it was 2.56 copies/1 000 PBMCs in age-unadjusted benzene-exposed workers (P < 0.01). And its levels were obviously different between two different age groups: that in 30-year-old group (1.76 copies/1,000 PBMCs, n = 23) was less than

[The treatment with allogeneic peripheral blood stem cell transplantation for benzene-induced severe aplastic anemia].

OBJECTIVE: To evaluate the efficacy of treatment with allogeneic peripheral blood stem cell transplantation for benzene-induced severe aplastic anemia. METHODS: HLA-compatible sibling (pregnancy) allogeneic peripheral blood stem cell transplantation (Allo-PBSCT) was successfully performed for a patient with severe aplastic anemia caused by benzene poisoning. 9.41 x 10(8) nucleated cells/kg, 12.49 x 10(6) CD(34) positive cells/kg and CFU-GM 8.2 x 10(5)/kg were infused. The patient was treated with cyclophosphamide (120 mg/kg), total body radiation (8 Gy) and anti-lymphocyte globulin (60 mg/kg) before transplantation. Donor buffy coat cells (9.02 x 10(8) nucleated cells/kg, 10.62 x 10(6) CD(34) positive cells/kg, 6.3 x 10(5) CFU-GM/kg) were infused again on day 18 after transplantation to prevent from graft failure. Graft versus host disease prophylaxis consisted of both methotrexate and cyclosporin A. RESULTS: The lowest ANC was 0, the lowest platelet was 3 x 10(9)/L after transplantation. The patient achieved an ANC of greater than 0.5 x 10(9)/L from 21st day, and the platelet of greater than 50 x 10(9)/L from 28th day after transplantation. Grade I cGVHD was found the fourth month after grafting. Examination of recipient's bone marrow cells showed a normal 46, XX (presumably marrow donor) karyotype. Blood group changed from B to O. CONCLUSION: This is the first case reported in China showing a successful treatment of benzene-induced severe aplastic anemia with allo-PBSCT. Allo-PBSCT may be an effective remedy for this kind of patients.

[Effect of immunocyte therapy on benzene-induced bone marrow haemopoietic dysfunction].

OBJECTIVE: To explore the effect of treatment with immunocyte therapy on benzene-induced haemopoietic dysfunction. METHODS: Mono-nuclear cells (MNC) were separated from 40 - 50 ml peripheral blood in patients and mixed with interleukin-2 and granulocyte macrophage colony stimulating factor (GM-CSF) for six day cultivation. The new formed immunocytes were collected and transfused into the patients. Bone marrow aspiration and biopsy were taken before and after therapy for all patients with severe benzene poisoning. Blood samples were stained by flow cytometry for detecting CD(4) and CD(8) positive cells. RESULTS: Of 20 patients with chronic benzene poisoning, 9 were severe benzene poisoning. All examination including blood count, bone marrow biopsy and T cell subpopulation restored to normal after immunocyte therapy. Laboratory tests (liver and kidney function, and myocardial enzymes) were observed periodically and showed normal during therapy. Follow-up study (the longest time was more than 15 months) showed that bone marrow haemopietic function of all treated patients were in normal range. CONCLUSION: Bone marrow haemopoietic dysfunction caused by benzene poisoning may be closely related to disorder of immune function. Immunocyte therapy may significantly improve bone marrow haemopoietic dysfunction induced by benzene poisoning.