Yoshihiro Yakushijin

Stromal cells in lymph nodes attractB-lymphoma cells via production ofstromal cell-derived factor-1

Abstract: Stromal cell‐derived factor‐1 (SDF‐1) is a chemokine produced by bone marrow stromal cells which plays an important role in B‐lymphopoiesis and the homing of hematopoietic stem cells to the bone marrow. In the present study, we investigated the role of SDF‐1 and its receptor, CXCR4, in the chemotactic interaction between non‐Hodgkin B‐lymphoma cells and lymph node stromal cells. SDF‐1 mRNA was abundantly expressed in stromal cells isolated from the lymph nodes of patients with malignant lymphoma. All B‐lymphoma cells freshly isolated from these patients and most laboratory B‐lymphoma cell lines, including follicular, diffuse large, and Burkitts lymphoma cells, expressed surface CXCR4 and migrated in the presence of recombinant human SDF‐1α. Chemotaxis assays revealed that CXCR4‐positive (but not CXCR4‐negative) B‐lymphoma cells migrated towards lymph node stromal cells, and this migration was almost completely inhibited by the addition of anti‐CXCR4 monoclonal antibody to the lymphoma cells or of anti‐SDF‐1 neutralizing antibody to the culture supernatant of the stromal cells. Down‐regulation of surface CXCR4 was detected in B‐lymphoma cells which migrated towards the stromal cells but not in those which showed no migratory response. In addition, contact between the lymphoma cells and the stromal cells resulted in down‐regulation of surface CXCR4 on the lymphoma cells. These data strongly suggest that SDF‐1/CXCR4 is the main chemokine system involved in the chemotactic interaction between B‐lymphoma cells and lymph node stromal cells.

Novel RUNX1-PRDM16 fusion transcripts in a patient with acute myeloid leukemia showing t(1;21)(p36;q22).

The t(1;21)(p36;q22) is a recurrent chromosome abnormality associated with therapy‐related acute myeloid leukemia (AML). Although involvement of RUNX1 has been detected by fluorescence in situ hybridization analysis, the partner gene has not been reported previously. We identified a novel RUNX1 partner gene, MDS1/EVI1‐like‐gene 1 (PRDM16), in an AML patient with t(1;21). Alternative splicing of the fusion gene generates five different fusion transcripts. In two of them, the PRDM16 reading frame is maintained in the fusion with RUNX1, suggesting that the RUNX1–PRDM16 gene fusion results in the production of a protein that is highly homologous to the RUNX1–MDS1/EVI1 chimeric protein. It is suggested that PRDM16 and MDS1/EVI1 share a common molecular mechanism for the leukemogenesis of RUNX1‐associated leukemia. Characterization of the RUNX1–PRDM16 fusion protein and comparison with the RUNX1–MDS1/EVI1 protein will facilitate the understanding of the mechanisms underlying RUNX1‐associated leukemia.

T-Cell Immune Response to Human Herpesvirus-6 in Healthy Adults

The proliferative response of peripheral blood mononuclear cells (PBMC) from healthy adults to human herpesvirus‐6 (HHV‐6) was examined. It was found that PBMC from 13 of 14 HHV‐6‐seropositive adults apparently proliferated in response to stimulation with HHV‐6 antigen in contrast to the lack of response of cord blood mononuclear cells. In order to confirm the presence of HHV‐6‐specific memory T cells in the peripheral blood of healthy adults, we established HHV‐6‐specific T‐cell clones from an HHV‐6‐seropositive individual. CD4+ T‐cell clones generated from HHV‐6‐stimulated PBMC were found to proliferate upon stimulation with HHV‐6 in the presence of autologous antigen‐presenting cells, but not in response to herpes simplex virus type 1 antigen or mock‐infected control antigen, These results indicate that a T‐cell immune response against HHV‐6 infection is generally present in healthy adult populations.

Regression of rectal mucosa‐associated lymphoid tissue (MALT) lymphoma after antibiotic treatments

Only a few reports have described regression of rectal mucosa‐associated lymphoid tissue (MALT) lymphoma after antibiotic treatment are generally found to be successful for gastric tumors. We examined eight rectal MALT lymphomas treated with antibiotic treatments to determine whether they regressed after treatment. We also discuss the relationship between rectal MALT lymphomas and MALT1 gene genetic abnormalities. Eight patients who had undergone antibiotic treatments were followed up with colonoscopy after initiation of the treatment. In five of the eight cases (63%) endoscopic examination showed that the rectal tumor had disappeared, which was confirmed histologically. Polymerase chain reaction for immunoglobulin heavy chain identified a monoclonal band in seven of eight cases (88%). Of the eight cases analyzed with fluorescence in situ hybridization (FISH) for MALT1 translocation, two demonstrated MALT1 gene genetic abnormality. These cases tended to be resistant to antibiotic treatment. Investigation and analysis of a large number of rectal MALT lymphomas are needed to establish suitable standards for antibiotic treatment.

Non-Hodgkin's lymphoma developing in a pacemaker pocket

A 29-year-old man developed diffuse large B-cell lymphoma in a subpectoral pacemaker pocket that 6 years previously had been created in the chest for a titanium-covered pulse generator. The patient had an 8-cm—diameter dark red tumor with necrotic tissue on a keloidal surgical scar in the left side of the chest. Left axillary lymphadenopathy also was present. Laboratory studies showed an increased level of soluble interleukin 2 receptor and a normal level of lactose dehydrogenase. A biopsy specimen showed a diffuse large B-cell phenotype and monoclonal immunoglobulin H gene rearrangement. A gallium scintigraphy study showed abnormal accumulation in the left chest and left axilla. On the basis of these findings, we diagnosed diffuse large B-cell lymphoma, stage II. The patient received THP-COP chemotherapy (pirarubicin, cyclophosphamide, vincristine, and prednisolone) and radiotherapy, achieved complete remission, and was free of disease for 16 months after treatment. This case suggests that there was a relationship between the development of non-Hodgkin’s lymphoma and the presence of chronic inflammation in the pulse generator pocket.

CD4 down-modulation by ganglioside and phorbol ester inhibits human herpesvirus 7 infection.

Recently, data demonstrating that CD4 is an essential component of the receptor for human herpesvirus 7 (HHV-7) as well as for human immunodeficiency virus have been accumulating. Since gangliosides and phorbol esters are known to induce selective down-modulation of cell surface CD4 expression, it might be expected that treatment with these agents would interfere with HHV-7 infection of CD4+ T cells. The present study, undertaken to verify this possibility, demonstrated that addition of monosialoganglioside-GM1 or 12-O-tetradecanoylphorbol 13-acetate effectively induced disappearance of CD4 from the cell surface and also reduced HHV-7 infectivity, as judged by the CPE on virus-infected cells and studies of indirect immunofluorescence, TCID50 and semi-quantitative PCR of the HHV-7 genome. Taken together with previous studies, the present data strongly suggest that the CD4 molecule is a critical component of the receptor for HHV-7.

Ki-67 is a strong predictor of central nervous system relapse in patients with mantle cell lymphoma (MCL)

BACKGROUND Central nervous system (CNS) relapse is an uncommon but challenging complication in patients with mantle cell lymphoma (MCL). Survival after CNS relapse is extremely poor. Identification of high-risk populations is therefore critical in determining patients who might be candidates for a prophylactic approach. PATIENTS AND METHODS A total of 608 patients (median age, 67 years; range 22-92) with MCL newly diagnosed between 1994 and 2012 were evaluated. Pretreatment characteristics and treatment regimens were evaluated for their association with CNS relapse by competing risk regression analysis. RESULTS None of the patients received intrathecal prophylaxis. Overall, 33 patients (5.4%) experienced CNS relapse during a median follow-up of 42.7 months. Median time from diagnosis to CNS relapse was 20.3 months (range: 2.2-141.3 months). Three-year cumulative incidence of CNS relapse was 5.6% [95% confidence interval (95% CI) 3.7% to 8.0%]. Univariate analysis revealed several risk factors including blastoid variant, leukemic presentation, high-risk MCL International Prognostic Index and high Ki-67 (proliferation marker). Multivariate analyses revealed that Ki-67 ≥ 30 was the only significant risk factor for CNS relapse (hazard ratio: 6.0, 95% CI 1.9-19.4, P = 0.003). Two-year cumulative incidence of CNS relapse in patients with Ki-67 ≥ 30 was 25.4% (95% CI 13.5-39.1), while that in the patients with Ki-67 < 30 was 1.6% (95% CI 0.4-4.2). None of the treatment modalities, including rituximab, high-dose cytarabine, high-dose methotrexate or consolidative autologous stem-cell transplant, were associated with a lower incidence of CNS relapse. Survival after CNS relapse was poor, with median survival time of 8.3 months. There was no significant difference in the survival by the site of CNS involvement.

Follicular dendritic cell tumor as an unknown primary tumor

A 70-year-old Japanese man presented to our hospital with a 1-month history of progressive general fatigue and anorexia. A physical examination revealed severe anemic condition, mild persistent splenomegaly, and no palpable surface lymph nodes. He had pleural effusion and ascites, though no malignant cells were detected in the effusion. He eventually died without any diagnosis of his disease. Immunohistochemical staining of his tumor after autopsy showed atypical cells that were negative for epithelial membrane antigen (EMA), keratin (AE1/3), keratin-20, vimentin, factor VIII, leukocyte common antigen (LCA/T200; CD45), myeloperoxidase (MPO), terminal deoxynucleotidyl tranferase (TdT), lysozyme, CD1a, CD3, CD4, CD10, CD15, CD20 (L26), CD21, CD23, CD34, CD43, CD56, CD68, CD79a, CD138, and EBER-1 in situ. Only a few scattered cells expressed CD30, but they showed no staining for anaplastic large-cell lymphoma kinase (ALK). A few scattered cells expressed S-100 antigen and the majority of cells dominantly expressed dendritic cell-associated antigens (CD35, FDC, Ki-M1p). In conclusion, we found this unknown primary tumor to be consistent with a follicular dendritic cell tumor with anaplastic features.

Existence of Leukemic Clones Resistant to Both Imatinib Mesylate and Rituximab before Drug Therapies in a Patient with Philadelphia Chromosome-Positive Acute Lymphocytic Leukemia

Imatinib mesylate and rituximab are molecularly targeted drugs against the BCR-ABL fusion protein and the CD20 antigen, respectively. Although these drugs have excellent anticancer effects, a major concern is drug resistance. We have investigated the case of a patient with Philadelphia chromosome-positive and CD20+ acute lymphocytic leukemia who acquired resistance to imatinib and rituximab. Imatinib therapy resulted in prompt cytogenetic remission, but resistance developed shortly thereafter. Sequencing of the kinase domain of the ABL gene and allele-specific polymerase chain reaction analysis revealed a point mutation resulting in an E255V substitution that was present before the therapy. After the patient received mild chemotherapy followed by rituximab administration, hematologic and cytogenetic remission was sustained for 5.5 months. The recurrent leukemic cells after the rituximab therapy showed not only the E255V mutation in the ABL gene but also loss of the CD20 antigen due to impaired transcription of the CD20 gene. The results of 2-color flow cytometry analysis showed that a small population of CD20- leukemic cells existed before the imatinib therapy. These results suggest that leukemic subclones carrying a genetic perturbation of the targeted molecules for both imatinib and rituximab were present before the therapies. The preexistence of primary resistant clones suggests the inability of combination therapy with 2 molecularly targeted drugs to overcome drug resistance in leukemia.

Role of activation‐induced cytidine deaminase in the progression of follicular lymphoma

Activation‐induced cytidine deaminase (AID/AICDA) is required for somatic hypermutation and class‐switch recombination of the immunoglobulin gene, and for c‐myc translocation of germinal center‐derived B‐cell lymphoma. In the present study, we attempted to clarify the significance of AID associated with c‐myc in the progression of follicular lymphoma (FL) using RT‐PCR and quantitative real‐time PCR. Tissues from the patients with grade 3 FL expressed relatively higher levels of c‐myc and AID. The samples taken from a patient with FL who died within 2 years after the start of treatment showed either no or low expression of AID, despite expressing high levels of c‐myc. In order to examine the role of AID expression in rapidly progressive FL, the full‐length AID transcript was transfected into AID‐negative cell lines established from different patients with rapidly progressive FL. This led to the establishment of AID‐expressing transfectants with a low proliferation rate and a significantly increased incidence of G0/G1 arrest compared with controls. Our results indicate that AID may act as a negative regulator of cell survival in FL when sufficient c‐myc is expressed. Switch‐off or low expression of AID after c‐myc amplification may correlate with the clinical outcomes of FL. (Cancer Sci 2012; 103: 415–421)