Ryuichi Kamiyama

Overexpression of tumor necrosis factor (TNF)-α and interferon (IFN)- γ by bone marrow cells from patients with myelodysplastic syndromes

To clarify whether regulatory cytokines inhibit hematopoiesis in patients with myelodysplastic syndromes (MDS), malignancies characterized by the formation of cytopenias despite the presence of cellular bone marrow, expression of TNF-α and IFN-γby bone marrow cells was investigated using specific reverse transcriptase-polymerase chain reaction assays. An enhanced expression of the mRNA for TNF-α was observed in most of the samples from MDS patients (11/14, 79%), whereas no enhancement was observed in bone marrow samples from AML (0/6), CML (0/2) or control cases (0/8). The expression of IFN-γ was also enhanced in some of MDS cases (5/12, 42%) while AML (0/5), CML (0/2) and control cases (0/6) showed very low levels of IFN-γ mRNA expression. Immunohistochemical examination confirmed the scattered presence of TNF-α or IFN-γ producing cells in the bone marrow of MDS patients. The majority of these cells were CD68-positive macrophage lineage cells. These results suggested that disruption of hematopoiesis in MDS might be caused by enhanced production of inhibitory regulatory cytokines especially TNF-α and occasionally IFN-γ by bone marrow macrophages.

1α,25-Dihydroxyvitamin D3 and Its Potent Synthetic Analogs Downregulate Tissue Factor and Upregulate Thrombomodulin Expression in Monocytic Cells, Counteracting the Effects of Tumor Necrosis Factor and Oxidized LDL

BackgroundWe have recently found that a hormonally active form of vitamin D, 1&agr;,25-dihydroxyvitamin D3 [1,25(OH)2D3], exerts anticoagulant effects by upregulating the expression of an anticoagulant glycoprotein, thrombomodulin (TM), and downregulating the expression of a critical coagulation factor, tissue factor (TF), in monocytic cells including human peripheral monocytes. In this study, we investigated the counteracting effects of 1,25(OH)2D3 and its potent analogs on TF induction and TM downregulation by tumor necrosis factor and oxidized LDL in monocytic cells and the modulatory effects of potent analogs on TF and TM expression. Methods and ResultsEffects of 1,25(OH)2D3 and its potent synthetic analogs (22R)-22-methyl-20-epi-1,25(OH)2D3 (KY3) and 22-oxacalcitriol on TF and TM antigen levels, cell surface activities, and mRNA levels in monocytic cells were examined. 1,25(OH)2D3 and its potent analogs showed anticoagulant effects in monocytic cells by downregulating TF and upregulating TM expression, counteracting the effects of tumor necrosis factor and oxidized LDL. KY3 was most potent in its regulatory effect on TF and TM expression. ConclusionsBecause KY3 has the highest affinity for vitamin D receptor, our findings suggest that TF and TM regulation by 1,25(OH)2D3 analogs is also mediated by vitamin D receptor. The 1,25(OH)2D3 analogs KY3 and 22-oxacalcitriol may have the potential to serve as an agent for preventing and treating atherosclerotic and other cytokine-mediated thrombotic diseases and as a tool for studying the molecular mechanisms of TF and TM regulation.

Localization of Fas and Fas ligand in bone marrow cells demonstrating myelodysplasia

Frequent apoptosis in the bone marrow of patients with myelodysplastic syndromes (MDS) was demonstrated on frozen sections using the terminal deoxytransferase (TdT)-mediated dUTP nick end labeling (TUNEL) method. The overall mean percentage of TUNEL-positive cells was about 17% in the bone marrow of MDS, while bone marrow from control cases exhibited a mean of 3.4% (P < 0.001). to elucidate the mechanism of apoptosis in bone marrow cells of mds, the expression of fas antigen and fas ligand (fasl) was examined by rt-pcr and immunohistochemistry. all mds cases showed expression of fas mrna (12/12) and most exhibited an expression of fasl mrna (10/12) by rt-pcr. basically, control cases did not show positive signals for fas and fasl mrna, however, a very weak band was detected in three cases (3/10) for fas and in one case (1/10) for fasl mrna by rt-pcr. immunohistochemical examination revealed positive staining for fas (11/12) and fasl (12/12) in the bone marrow of mds, while all the bone marrow samples from control cases were negative for anti-fas (0/15) and for anti-fasl (0/15) antibody. double staining clarified that tunel-positive apoptotic cells expressed fas antigen on the cell surface, although not all fas-positive cells were tunel positive. the fas-positive cells of mds bone marrow included hematopoietic cells expressing cd34 antigen, neutrophil elastase, a marker for myeloid series of cells, or glycophorin a, a marker for erythroid cells. however, cd68-positive cells which were macrophage lineage cells, did not express fas antigen strongly. in contrast, positive staining for fasl was detected in hematopoietic cells and cd68-positive cells in the bone marrow of mds. these results suggest that the fas–fasl system plays an important role in inducing apoptosis in the bone marrow of mds and works in an autocrine (hematopoietic cell–hematopoietic cell interaction) and/or paracrine (hematopoietic cell–stromal cell interaction) manner.

Age‐related hypermethylation of the hMLH1 promoter in gastric cancers

To determine whether methylation of the hMLH1 promoter is related to increasing age and gastric carcinogenesis, we examined hMLH1 methylation and expression in 100 gastric cancers. hMLH1 methylation and aberrant protein expression were observed in 9 and 13 cancers, respectively. Normal and intestinal metaplastic tissues adjacent to cancers with hypermethylation did not exhibit any hMLH1 methylation, indicating that it may be specific to gastric cancers. The frequency of hMLH1 methylation significantly increased with age. These results suggest that hMLH1 methylation plays an important role in gastric carcinogenesis in old people.

IQGAP1, a negative regulator of cell-cell adhesion, is upregulated by gene amplification at 15q26 in gastric cancer cell lines HSC39 and 40A.

AbstractOur previous comparative genomic hybridization (CGH) study revealed a novel amplified region at 15q26 in two cell lines established from diffuse types of gastric cancer (GC). In this amplified region, FES and IGF1R, known targets on 15q26, were located telomeric to the amplicon in the two cell lines, HSC39 and 40A, suggesting that another tumor-associated gene exists in this region. While screening expressed sequence tags (ESTs) for novel genes in this region, we identified the IQGAP1 amplification. IQGAP1 has been reported to encode a ras GAP-related protein, and its interaction with cadherin and/or β-catenin induces a dissociation of β-catenin from the cadherin-catenin complex, one of the mechanisms for cell-cell adhesion. Northern and Western blot analyses revealed that amplification of this gene was accompanied by corresponding increases in mRNA and protein expression. Moreover, immunocytochemical staining showed that overexpressed IQGAP1 accumulated at the membrane, suggesting its colocalization with β-catenin. Taken together, these findings suggest that IQGAP1 may be one of the target genes in the 15q26 amplicon correlated with a malignant phenotype of gastric cancer cells, such as diffuse and invasive characteristics, through the disruption of E-cadherin-mediated cell-cell adhesion.

The proto-oncogene Bcl6 inhibits apoptotic cell death in differentiation-induced mouse myogenic cells

The Bcl6 gene is located at chromosomal band 3q27, a breakpoint for translocation that frequently occurs in B cell lymphomas. Bcl6 has been found to be preferentially expressed in germinal center B cells, and expression of this gene has been shown to be essential for germinal center formation in vivo. The physiological function of Bcl6 and its role in lymphomagenesis, however, are not yet known. Since significant expression of Bcl6 has been demonstrated in skeletal muscle, we have utilized a differentiation-inducible mouse myogenic cell line, C2C12, to elucidate the function of the Bcl6 gene product. Expression of Bcl6 mRNA was very low in growing myocytes, but was increased in differentiating myocytes cultured in serum-starved medium. Incubation of these cells with cytokines or chemicals that are known to block differentiation suppressed this increased Bcl6 message abundance, indicating that Bcl6 induction is related to the process of terminal differentiation in muscle cells. While a fraction of myocytes is known to undergo apoptosis after serum-starvation to induce differentiation, adenovirus-mediated overexpression of Bcl6 enhanced the viability of the differentiating cells by preventing the apoptosis. High levels of Bcl6 antisense mRNA expression induced substantial apoptosis during the differentiation of C2C12 cells, but this was effectively prevented by infection with adenovirus that expressed Bcl6 sense mRNA. These results indicate that Bcl6 acts to prevent apoptotic cell death in differentiating myocytes. The deregulation of expression of this anti-apoptotic gene may also contribute to the development of B cell lymphomas.

MUCOEPIDERMOID CARCINOMA OF THE THYMIC REGION

A case of mucoepidermold carcinoma in thymus in a 59‐year‐old Japanese female is presented. She died of cardiac tamponade due to tumor invasion after a 5 years clinical course. At autopsy the main tumor was found in the thymic region with metastases to the sternum, regional lymph nodes, pericardial, and left pleural cavity. The mucoepidermold carcinoma might be probably originated from a hens egg‐sized cyst which was located in the upper posterior aspect of the tumor‐Involved thymus. No teratomatous components were present. The cyst was most likely to be of thymic or bronchogenic cyst origin, though it was not determined, in view of the lining with pseudo‐stratified ciliated columnar epithelium of the cystic wall and the surrounding with the thymic tissue outside. Moreover, there was thymic hyperplasia with germinal center that was compatible with SLE‐like symptoms in her past history and autoimmune nature of the autopsy findings of pulmonary fibrosis.

Identification of negative regulatory regions within the first exon and intron of the BCL6 gene.

Chromosomal translocations involving BCL6 gene are frequent in human B-cell lymphomas. Chromosomal breaks preferentially occur within a 3-kb region containing the first exon and intron. Recent reports have revealed that internal deletions or point mutations also are common in this region, suggesting that structural alteration of this region may be a crucial event in the development of lymphomas. In this study, we identified two regions in the BCL6 gene that negatively regulate BCL6 expression. One region, ES, is located within the first exon between nucleotides +472 and +543, and a second region, IS, is located between +783 and +918 of the first intron. A consensus nucleotide sequence for the binding of the BCL6 protein itself was found within the ES region. An electrophoretic mobility shift assay and a co-transfection experiment using a BCL6 expression vector showed that transcription of the BCL6 gene was negatively regulated by the BCL6 gene product. The IS region which is included in the regions commonly deleted in B-cell lymphomas had a silencer activity. Structural alterations of these two regions may play roles in the deregulated expression of the BCL6 gene in B-cell lymphomas.

Expression of inducible nitric oxide synthase (NOS) in bone marrow cells of myelodysplastic syndromes

Nitric oxide (NO) is a biological mediator which is synthesized from L-arginine by a family of nitric oxide synthases (NOS). We have studied the expression of the inducible NOS (iNOS) by bone marrow cells from the patients with myelodysplastic syndromes (MDS) at the mRNA level by RT-PCR assay and at the protein level by immunohistochemical staining using a specific anti-iNOS monoclonal antibody. The iNOS message was present in 92% of bone marrow tissues from MDS patients (11 out of 12) by an examination using RT-PCR. Basically, iNOS message was negative or very weak in control (1/9) and AML (0/7) cases. This was supported by immunohistochemical findings that the iNOS was positive in most of the bone marrow samples from MDS patients (9 out of 12), while bone marrow cells of control (0 out of 12) and AML (0 out of 5) cases were basically negative. Double immunostaining for CD68 antigen, which is a marker for macrophage lineage cells, and iNOS was performed on MDS bone marrow sections. iNOS was dominantly localized to bone marrow macrophages, although a part of myeloid cells were also positively stained with anti-iNOS antibody in a part of cases. These results indicated that there is some in vivo induction of iNOS expression for local NO production that might be involved in the dysregulation of hematopoiesis in bone marrow of MDS.

Bone marrow analysis of the myelodysplastic syndromes: histological and immunohistochemical features related to the evolution of overt leukemia

SummaryBone marrow trephines from 31 patients with an initial diagnosis of myelodysplastic syndromes (MDS) were examined and analyzed histologically and immunohistochemically. In those cases terminating in overt leukemia (6/31, 19%), the number of bone marrow mast cells was significantly reduced, compared with those which did not evolve to overt leukemia. The bone marrow lymphoid cells that may participate in immunosurveillance against the proliferation of blast cells were also significantly reduced in cases terminating in overt leukemia. However, S-100 protein-positive cells, which include histiocytes and suppressor T-cells, were increased in cases terminating in overt leukemia. The results indicated that examination of the bone marrow to determine the proportions of mast cells and lymphoid cells which may be involved in host defense systems may be useful in predicting the evolution to overt leukemia in MDS. In the present series, patients with a hypocellular marrow (5/31, 16%) did not progress to overt leukemia and had a significantly lower bone marrow reticulin content, a significantly lower megakaryocyte count, a relatively higher mast cell count and a significantly higher lymphoid cell count than those with a normocellular or hypercellular marrow. These findings may reflect the initial features of MDS or, possibly, that hypocellular MDS is an independent entity with a low potential for biastic proliferation.