Zhen Yu

Bone marrow stromal cells protect myeloma cells from bortezomib induced apoptosis by suppressing microRNA-15a expression.

Despite unsurpassed anti-tumor activity of bortezomib for multiple myeloma (MM), drug resistance has emerged as a challenge, especially when MM cells adhere to the stroma. This study aimed to determine whether bone marrow stromal cells (BMSCs) have a role in the development of chemoresistance in MM. Our data demonstrate that the secretion of interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), and cell-to-cell contact with microenvironment-derived stromal cells from patients with multiple myeloma (MM-BMSCs) significantly decreased the sensitivity of myeloma cells to bortezomib treatment. Mechanistically, we found that microRNA (miRNA)- 15a expression was up-regulated in U266 and NCI-H929 cells treated by bortezomib, which was inhibited by MM-BMSCs. miRNA-15a transfected myeloma cells were arrested in G1/S checkpoint and secreted less VEGF compared to control transfected cells, although no significant difference was found in VEGF mRNA levels. In conclusion, our data suggest that via suppressing miRNA-15a expression, BMSCs provide survival support and protect myeloma cells from bortezomib induced apoptosis.

Umbilical Cord-Derived Mesenchymal Stem Cells Isolated by a Novel Explantation Technique Can Differentiate into Functional Endothelial Cells and Promote Revascularization

Stem cells transplantation holds great promise for the treatment of ischemic diseases through functional revascularization. Umbilical cord-derived mesenchymal stem cells (UC-MSCs) are also an ideal candidate for cell-based bioengineering. Herein, we report on the development of a simple and effective protocol to isolate UC-MSCs, and confirm their endothelial potential both in vitro and in vivo. UC-MSCs were isolated by a novel explantation technique and induced to differentiate into endothelial-like cells. Then UC-MSCs were transplanted into ischemic mouse model and cultured on 3D gel/MMT-CS composite scaffolds. Morphological and proliferation assessments show that sufficient UC-MSCs can be generated during a relatively short culture period with explantation technique. Increased expression of endothelial-specific markers (KDR and vWF), and functional markers (ac-LDL uptake and UEA-1 binding), indicate that functional endothelial progenitor cells are induced after 9 days of in vitro culture. In an ischemic hindlimb mouse model, the ratio of ischemic/nonischemic limb perfusion 4 weeks after MSCs transplantation reached 0.84 +/- 0.09. The capillary density of this group was 2.57-fold greater than that of sham-injected mice (P < 0.05). Immunofluorescence and immunohistological analyses indicate that MSCs may act to salvage the ischemic tissue by incorporating into the local vasculature. In vitro, UC-MSCs were observed to incorporate into 3D gel/MMT-CS composite scaffolds, to secrete extracellular matrix, to remain viable, and to retain their proliferation capacity. In conclusion, UC-MSCs isolated by novel yet simple explantation technique are well suited for application in the development of novel stem cell-based revascularization therapies.

MicroRNA-223 expression is uniformly down-regulated in B cell lymphoproliferative disorders and is associated with poor survival in patients with chronic lymphocytic leukemia

Abstract MicroRNA-223 (miR-223) expression has been demonstrated to be stage-specific in B cell differentiation and associated with the outcome of chronic lymphocytic leukemia (CLL). However, the expression pattern of miR-223 in B cell lymphoproliferative disorders and its association with the outcome of Chinese patients with CLL have not been investigated. In this study, we demonstrated that miR-223 expression was significantly decreased in CLL, mantle cell lymphoma (MCL) and splenic marginal zone lymphoma (SMZL). In CLL, miR-223 expression decreased significantly with progression from early to advanced clinical stages and was significantly lower in patients with elevated β2-microglobulin, unmutated immunoglobulin variable heavy chain (IgVH) gene or with disease progression or death. Using a cut-off determined by receiver operating characteristic (ROC) analysis optimizing concordance with IgVH mutational status, miR-223-negative and -positive groups were defined for 22 and 31 patients, respectively. The median progression-free survival (PFS) and overall survival of the miR-223-negative group were 13 and 40 months, respectively, significantly shorter than for the miR-223-positive group (both not reached; p = 0.002 and p = 0.018, respectively). Multivariate analysis revealed that the absence of miR-223 was the only independent factor capable of predicting shorter PFS. In conclusion, miR-223 is uniformly down-regulated in B-LPDs and is a useful prognostic factor for patients with CLL.

Suppressing miRNA-15a/-16 expression by interleukin-6 enhances drug-resistance in myeloma cells

The bone marrow microenvironment facilitates the survival, differentiation, and proliferation of myeloma (MM) cells. This study identified that microRNA-15a and -16 expressions tightly correlated with proliferation and drug sensitivity of MM cells. miRNA-15a/-16 expression in MM cells was significantly increased after treatment with cytotoxic agents. The interaction of bone marrow stromal cells (BMSC) with MM cells resulted in decreased miRNA-15a/-16 expression and promoted the survival of the MM cells. Interleukin-6 (IL-6) produced by BMSCs suppressed the expression of miRNA-15a and 16 in a time- and dose- dependent pattern, with the suppression on miRNA-15a being more significant than on miRNA-16. miRNA-15a-transfected MM cells were found to be arrested in G1/S checkpoint, and the transfected MM cells had decreased growth and survival. In conclusion, our data suggest that via suppressing miRNA-15a and -16 expressions, IL-6 secreted by BMSCs promotes drug-resistance in myeloma cells.

B7-H1 up-regulation on dendritic-like leukemia cells suppresses T cell immune function through modulation of IL-10/IL-12 production and generation of Treg cells

Dendritic-like leukemia cells (DLLC) originating from leukemic cells could potentially induce a T cell-mediated anti-leukemia immune response. It has been demonstrated that B7-H1, a newly identified homologue of CD80/CD86, is abundant in human carcinomas and dendritic cells (DC), can exert co-stimulatory and immune regulatory functions. We demonstrated that B7-H1 was significantly expressed on AML cells and was strongly enhanced after differentiation to DLLC. Blockade of B7-H1 expressed on DLLC results in increased T cell proliferation and Th1 cytokine production, and decreased Th2 cytokine production. Importantly, autologous CTLs induced by DLLC treated with B7-H1 mAb showed significantly increased specific cytotoxcity against AML blasts. We further demonstrated that a significant decrease in IL-12 production, increase in IL-10 production by DLLC, and an increased CD4(+)CD25(+)Foxp3(+) T regulatory population lead to the defective T cell immune response that is induced by B7-H1 up-regulation on DLLC. Our data suggest that up-regulated B7-H1 on DLLC acts as a strong inhibitor of anti-leukemia T cell response, and that blockade of B7-H1 can improve DLLC-mediated anti-leukemia immunity.

miR-29c down-regulation is associated with disease aggressiveness and poor survival in Chinese patients with chronic lymphocytic leukemia

Abstract Aberrant expression of microRNAs in chronic lymphocytic leukemia (CLL) has been reported to be associated with clinical outcome and improve prognostic stratification. The aim of this study was to explore the association of miR-29c expression with clinical parameters and survival in 53 Chinese patients with CLL. We showed that the miR-29c expression level decreased significantly from early to advanced clinical stages, and was significantly lower in patients with β2-microglobulin higher than 3.5 mg/L or with disease progression or death. With the cut-off determined by receiver operating characteristic (ROC) curve analysis, optimizing concordance with immunoglobulin heavy chain (IgVH) mutation status, miR-29c negative and positive groups were defined as including 17 and 36 patients, respectively. The miR-29c negative group had a higher percentage of patients with trisomy 12 or deletion of 11q or 17p (70.6% vs. 34.3%; p = 0.014) compared to the miR-29c positive group. The median progression-free survival and overall survival of the miR-29c negative group were 21 and 92 months, respectively, significantly shorter than in the miR-29c positive group (both not reached; p = 0.002 and p = 0.042, respectively), and miR-29c down-regulation was an independent prognostic factor for PFS. In conclusion, down-regulation of miR-29c is associated with higher tumor burden and significantly predicts short survival in Chinese patients with CLL.

TOSO is overexpressed and correlated with disease progression in Chinese patients with chronic lymphocytic leukemia

Recently, a gene named TOSO was identified as being overexpressed and associated with the anti-apoptotic characteristic of chronic lymphocytic leukemia (CLL). However, the association of TOSO expression with clinical features of CLL has not been fully described, especially in Chinese patients. TOSO expression was detected by quantitative RT-PCR in CD19+ sorted cells in a cohort of 81 untreated patients with CLL. The results showed that the expression of TOSO in CLL was significantly higher than that in healthy controls (p = 0.027) and other B-cell lymphoproliferative diseases (p = 0.033). The expression level of TOSO was significantly correlated with Binet staging, IGVH mutation status, age, and time to treatment in CLL. A negative correlation was observed between age and TOSO expression (Spearmans, p = 0.025). No correlation was observed between the expression of TOSO and CD38 or ZAP-70. Cox regression analysis indicated that high expression of TOSO (more than 8.4) was an independent indicator for shorter treatment-free survival in CLL. We conclude that TOSO is specifically overexpressed and associated with progressive disease, and might be an important prognostic factor in CLL.

Intratumoral genetic heterogeneity and number of cytogenetic aberrations provide additional prognostic significance in chronic lymphocytic leukemia

Purpose:Chronic lymphocytic leukemia (CLL) is a heterogeneous disease with cytogenetic aberrations that are still considered the gold standard of prognostic factors. However, heterogeneity remains within each cytogenetic group, especially in patients with concomitant cytogenetic aberrations.Methods:A panel of DNA probes was used to detect cytogenetic aberrations, including RB1/D13S25 at 13q14, ATM at 11q22, TP53 at 17p13, CEP12 and IGH translocation at 14q32, by fluorescence in situ hybridization. A comprehensive method integrating the number of cytogenetic aberrations and intratumoral genetic heterogeneity was used to analyze the prognosis for patients with concomitant aberrations.Results:Within the conventional favorable or neutral prognostic groups (i.e., with del 13q, trisomy 12, and/or t(14q32)), the coincidence of these three aberrations worsened survival in terms of time to first therapy, progression-free survival, and overall survival. However, within the conventional unfavorable prognostic group (i.e., del 11q or del 17p), patients with a minor unfavorable clone had an unexpected survival advantage compared with patients with a major unfavorable clone. A new cytogenetic prognostic system that integrates the number of cytogenetic aberrations and intratumoral genetic subclones was more precise than the conventional system.Conclusion:The number of cytogenetic aberrations and the size of intratumoral genetic subclones should be comprehensively considered to determine the prognosis for CLL.Genet Med 19 2, 182–191.

Immunotherapy Strategies Against Multiple Myeloma

Multiple myeloma is a monoclonal B-cell malignancy characterized by an accumulation of malignant plasma cells in the bone marrow, the presence of a monoclonal protein in the serum and/or urine, decreased normal immunoglobulin levels, and lytic bone disease. Patients with multiple myeloma benefit from combination therapy including novel therapeutic agents followed by autologous stem cell transplantation prolonged maintenance therapy. However, multiple myeloma remains incurable; most patients with multiple myeloma will eventually become resistant to chemotherapy, and progression or relapse of the disease is inevitable. Immunotherapy represents a novel therapeutic approach with few adverse effects and good targeting capability that might be a powerful pool to allow long-term control of minimal residual disease. This article reviews the literature evaluating 4 major immunotherapeutic approaches for multiple myeloma including cellular immunotherapy, humoral immunotherapy, radio immunotherapy, and immunomodulation.

SOX11 regulates the pro-apoptosis signal pathway and predicts a favorable prognosis of mantle cell lymphoma

Sex-determining region Y-box 11 (SOX11) is an important diagnostic marker in mantle cell lymphoma (MCL). However, the direct oncogenic mechanisms and downstream effector pathways implicated in SOX11-driven transformation remain poorly understood. In the present study, we analyzed SOX11 expression in B-NHL, and used lentivirus-mediated RNA interference targeting SOX11 to investigate the resulting changes in cellular processes and the underlying mechanisms in MCL cell lines. We found that patients with higher SOX11 expression have superior overall survival (OS) and progression-free survival (PFS) compared to those with lower SOX11 expression. SOX11 silencing promotes proliferation and inhibiting apoptosis of MCL cell through caspase-9-3-7-PARP signaling, and desensitizes MCL cell to bortezomib. Conclusively, our data suggest that SOX11 represents a useful prognostic marker in mantle cell lymphoma.