Immunostimulatory CpG-oligonucleotides cause proliferation, cytokine production, and an immunogenic phenotype in chronic lymphocytic leukemia B cells.
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Bacterial DNA and synthetic CpG-oligodeoxynucleotides (ODNs) derived thereof have attracted attention because they activate cells of the immune system in a sequence-dependent manner. Here we investigated the potential of CpG-ODNs to cause proliferation, cytokine production, and regulation of surface molecules in human B-chronic lymphocytic leukemia (CLL) cells. CpG-ODN induced proliferation in both B-CLL cells and normal B cells; however, only B-CLL cells increased proliferative responses when CpG-ODN was added to co-cultures of CD40-ligand transfected mouse fibroblasts (CD40LF) and B cells. Production of interleukin-6 and tumor necrosis factor alpha was detectable at borderline levels, using CpG-ODN as the only stimulus. In contrast, when CpG-ODN was added to co-cultures of B cells and CD40LF, a strong increase in cytokine production occurred in B-CLL cells as well as in normal B cells. The surface molecules CD40, CD58, CD80, CD86, CD54, and MHC class I molecules were up-regulated in B-CLL cells, whereas CD95 expression was not influenced by CpG-ODN stimulation. The same pattern of surface molecule regulation was observed in normal B cells, but up-regulation of CD40 was significantly stronger in B-CLL cells. Costimulation with CpG-ODN and CD40LF resulted in further up-regulation of CD58, CD80, CD86, and MHC class I molecules. In contrast, CD95 expression induced by CD40-ligation was inhibited by CpG-ODN. CpG-ODN activated B-CLL cells acquired a strong stimulatory capacity toward T cells in allogeneic mixed lymphocyte reaction. This effect was completely inhibited by a combination of anti-CD80 and anti-CD86 monoclonal antibody. Taken together, these findings suggest the possible use of CpG-ODN for immunotherapeutic strategies in patients with B-CLL. (+info)
A primitive hematopoietic cell is the target for the leukemic transformation in human philadelphia-positive acute lymphoblastic leukemia.
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BCR-ABL is a chimeric oncogene generated by translocation of sequences from the chromosomal counterpart (c-ABL gene) on chromosome 9 into the BCR gene on chromosome 22. Alternative chimeric proteins, BCR-ABL(p190) and BCR-ABL(p210), are produced that are characteristic of chronic myelogenous leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(1)-ALL). In CML, the transformation occurs at the level of pluripotent stem cells. However, Ph(1)-ALL is thought to affect progenitor cells with lymphoid differentiation. Here we demonstrate that the cell capable of initiating human Ph(1)-ALL in non-obese diabetic mice with severe combined immunodeficiency disease (NOD/SCID), termed SCID leukemia-initiating cell (SL-IC), possesses the differentiative and proliferative capacities and the potential for self-renewal expected of a leukemic stem cell. The SL-ICs from all Ph(1)-ALL analyzed, regardless of the heterogeneity in maturation characteristics of the leukemic blasts, were exclusively CD34(+ )CD38(-), which is similar to the cell-surface phenotype of normal SCID-repopulating cells. This indicates that normal primitive cells, rather than committed progenitor cells, are the target for leukemic transformation in Ph(1)-ALL. (+info)
Hodgkin and Reed-Sternberg-like cells in B-cell chronic lymphocytic leukemia represent the outgrowth of single germinal-center B-cell-derived clones: potential precursors of Hodgkin and Reed-Sternberg cells in Hodgkin's disease.
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In rare cases of B-cell chronic lymphocytic leukemia (B-CLL), large cells morphologically similar to or indistinguishable from Hodgkin/Reed-Sternberg (HRS) cells of Hodgkin's disease (HD) can be found in a background of otherwise typical B-CLL. To test these HRS-like cells for a potential clonal relationship to the B-CLL cells, single cells were micromanipulated from immunostained tissue sections, and rearranged immunoglobulin genes were amplified from HRS-like cells and B-CLL cells and sequenced. The same variable (V) gene rearrangements with shared and distinct somatic mutations were found in HRS-like and B-CLL cells from 1 patient, which indicates derivation of these cells from 2 distinct members of a germinal-center B-cell clone. Separate clonal V gene rearrangements were amplified from HRS-like and B-CLL cells from 2 other patients, showing concomitant presence of 2 distinct expanded B-cell clones. Epstein-Barr virus (EBV) was detected in the HRS-like cells of these 2 latter cases, indicating clonal expansion of an EBV-harboring B cell in the setting of B-CLL. There is evidence that HRS-like cells in B-CLL, like HRS cells in HD, derive from germinal-center B cells. In all cases, somatic mutations have been detected in the rearranged V genes of the HRS-like cells, and in 1 of the EBV-positive HRS-like cell clones, somatic mutations rendered an originally functional V gene rearrangement nonfunctional. We speculate that the HRS-like cells in B-CLL represent potential precursors for HRS cells causing HD. (+info)
Regulation of drug sensitivity by ribosomal protein S3a.
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When bcl-2 is immunoprecipitated from (32)P-labeled cell extracts of all-trans retinoic acid (ATRA)-treated acute myeloblastic leukemia (AML) blasts, a phosphorylated protein of approximately 30 kd is coprecipitated. This protein has been identified as ribosomal protein S3a. The biologic effects of S3a include favoring apoptosis and enhancing the malignant phenotype. We sought to determine whether S3a, like bcl-2, influenced the response of cells to chemotherapeutic drugs and ATRA. Cell lines were studied in which S3a was genetically increased or disrupted; increased S3a was regularly associated with increased plating efficiency and increased sensitivity to either cytosine arabinoside (ara-C) or doxorubicin (DNR). S3a did not affect the sensitivity of cells to paclitaxel. Pulse exposures to either (3)HTdR or ara-C showed a greater percentage of clonogenic cells in the S phase of the cell cycle in cells with increased S3a than in controls. Cells with increased S3a responded to ATRA by increased ara-C or DNR sensitivity, whereas cells with reduced S3a protein were either protected by ATRA or not affected. We studied cryopreserved blast cells from patients with AML or chronic myelomonocytic leukemia (CMML). S3a protein levels were heterogeneous in these populations. In 32 cryopreserved blast populations, S3a levels were significantly correlated with both bcl-2 and with cell growth in culture. As in cell lines, high S3a in cryopreserved blasts was associated with ATRA-induced sensitization to ara-C. No significant association was seen between S3a levels and response to treatment. (+info)
Myeloma progenitors in the blood of patients with aggressive or minimal disease: engraftment and self-renewal of primary human myeloma in the bone marrow of NOD SCID mice.
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The myelomagenic capacity of clonotypic myeloma cells in G-CSF mobilized blood was tested by xenotransplant. Intracardiac (IC) injection of NOD SCID mice with peripheral cells from 5 patients who had aggressive myeloma led to lytic bone lesions, human Ig in the serum, human plasma cells, and a high frequency of clonotypic cells in the murine bone marrow (BM). Human B and plasma cells were detected in BM, spleen, and blood. Injection of ex vivo multiple myeloma cells directly into the murine sternal BM (intraosseus injection [IO]) leads to lytic bone lesions, BM plasma cells, and a high frequency of clonotypic cells in the femoral BM. This shows that myeloma has spread from the primary injection site to distant BM locations. By using a cellular limiting dilution PCR assay to quantify clonotypic B lineage cells, we confirmed that peripheral myeloma cells homed to the murine BM after IC and IO injection. The myeloma progenitor undergoes self-renewal in murine BM, as demonstrated by the transfer of human myeloma to a secondary recipient mouse. For 6 of 7 patients, G-CSF mobilized cells from patients who have minimal disease, taken at the time of mobilization or after cryopreservation, included myeloma progenitors as identified by engraftment of clonotypic cells and/or lytic bone disease in mice. This indicates that myeloma progenitors are mobilized into the blood by cyclophosphamide/G-CSF. Their ability to generate myeloma in a xenotransplant model implies that such progenitors are also myelomagenic when reinfused into patients, and suggests the need for an effective strategy to purge them before transplant. (+info)
Molecular analysis of immunoglobulin genes in diffuse large B-cell lymphomas.
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Diffuse large B-cell lymphoma (DLBCL) is a common type of non-Hodgkin's lymphoma (NHL) that is highly heterogeneous from both clinical and histopathologic viewpoints. The immunoglobulin (Ig) heavy (H) chain variable region genes were examined in 71 patients with untreated primary DLBCL. Fifty-eight potentially functional V(H) genes were detected in 53 DLBCL cases; V(H) genes were nonfunctional in 9 cases and were not detected in an additional 9 cases. The use of V(H) gene families by DLBCL tumors was unbiased without overrepresentation of any particular V(H) gene or gene family. Analysis of Ig mutations in comparison to the most closely related germline gene disclosed mutated V(H) genes in all but 1 DLBCL case. More than 2% difference from the most similar germline sequence was detected in 52 potentially functional and the 8 nonfunctional V(H) gene sequences, whereas less than 2% difference from the germline sequence was observed in 3 V(H) gene isolates. Only 3 V(H) gene isolates were unmutated. No correlation was found between V(H) gene use, mutation level, and International Prognostic Index (IPI) or survival. Six of 8 tested tumors showed evidence of ongoing somatic mutations. Evidence for positive or negative antigen selection pressure was observed in 65% of mutated DLBCL cases. Our findings indicate that the etiology and the driving forces for clonal expansion are heterogeneous, which may explain the well-known clinical and pathologic heterogeneity of DLBCL. (Blood. 2000;95:1797-1803) (+info)
Synergy of SF1 and RAR in activation of Oct-3/4 promoter.
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The Oct-3/4 transcription factor is expressed in the earliest stages of embryogenesis, and is thus likely to play an important role in regulation of initial decisions in development. For the first time, we have shown that SF1 and Oct-3/4 are co-expressed in embryonal carcinoma (EC) P19 cells, and their expression is down-regulated with very similar kinetics following retinoic acid (RA) induced differentiation of these cells, suggesting a functional relationship between the two. Previously, we have shown that the Oct-3/4 promoter harbors an RA-responsive element, RAREoct, which functions in EC cells as a binding site for positive regulators of transcription, such as RAR and RXR. In this study we have identified in the Oct-3/4 promoter two novel SF1-binding sites: SF1(a) and SF1(b). The proximal site, SF1(a), is located within the RAREoct, and the distal site, SF1(b), is located between nucleotide -193 and -209 of the Oct-3/4 promoter. Both sites contribute to activation of Oct-3/4 promoter in EC cells, with SF1(a) playing a more crucial role. SF1, and its isoforms ELP2 and ELP3 bind to both SF1 sites and activate the Oct-3/4 promoter. This activation depends on the presence of SF1 DNA-binding domain. Thus, Oct-3/4 is the first EC-specific gene reported that is regulated by SF1. Interestingly, SF1 and RAR form a novel complex on the RAREoct sequence that synergistically activate the Oct-3/4 promoter. Both RARE and SF1 cis regulatory elements, as well as the SF1 DNA-binding domain, are needed for this synergism. SF1 and Oct-3/4 transcription factors play a role in the same developmental regulatory cascade. (+info)
Contemporary theories of cervical carcinogenesis: the virus, the host, and the stem cell.
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Cervical cancer is a complex disease that, by its association with human papillomavirus (HPV), has elicited research in a broad range of areas pertaining to its basic diagnostic and clinical aspects. The complexity of this association lies not only in the fundamental relationship between virus and cancer but also in its translation to pathologic diagnosis and clinical management. Offshoots from the relationship of virus to pathology include studies targeting the link between papillomavirus infection and cervical epithelial abnormalities, the molecular epidemiology of papillomavirus infection, and the potential use of HPV testing as either a screening technique or a tool for managing women who have Pap smear abnormalities. A second variable that is critical to the pathogenesis of cervical neoplasia is the cervical transformation zone. The wide range of invasive and noninvasive lesion phenotypes associated with HPV infection in this region indicate that not only the virus but also specific host target epithelial cells in the transformation zone play an important part in the development of cervical neoplasia. Further understanding of this relationship between the virus and the host epithelium will hinge on determining the subtypes of epithelial cells in the transformation zone and their phenotypic response to infection. New technologies, such as expression arrays, promise to clarify, if not resolve, the complexity of molecular interactions leading to the multiplicity of tumor phenotypes associated with HPV infection of the uterine cervix. (+info)