The Wilms' tumor gene WT1 is overexpressed in leukemias and various types of solid tumors, and the WT1 protein was demonstrated to be an attractive target antigen for immunotherapy against these malignancies. Here, we report the outcome of a phase I clinical study of WT1 peptide-based immunotherapy for patients with breast or lung cancer, myelodysplastic syndrome, or acute myeloid leukemia. The WT1 gene was isolated as a gene responsible for Wilms' tumor, a pediatric renal cancer, and encodes a zinc finger transcription factor, which is involved in cell proliferation and differentiation, apoptosis, and organ development (3-6). Although the WT1 gene was first categorized as a tumor suppressor gene, we have proposed that the wild-type WT1 gene functions as an oncogene rather than a tumor-suppressor gene on the basis of the following findings. The first is high expression of the wild-type WT1 gene in both leukemias and solid tumors (7-18), the second is growth inhibition of leukemic and solid tumor cells by treatment with WT1 antisense oligomers (14,19), and the third is block of differentiation, but induction of proliferation, of wild-type WT1 gene-transfected myeloid progenitor cells in response to granulocyte colony-stimulating factor (20, 21). The last two are block of thymocyte differentiation but induction of thymocyte proliferation in the transgenic mice with the lck promoter-driven WT1 gene (22), and WT1 gene expression in the majority of dimethylbenzanthracene-induced erythroblastic leukemia and a stronger tendency of the cells with high levels of WT1 to develop into leukemias (23).Expression of the wild-type WT1 gene has been found in most cases of acute myelocytic leukemia (AML), acute lymphocytic leukemia, chronic myelocytic leukemia, and myelodysplastic syndrome (MDS) at higher levels than those in normal bone marrow (BM) or peripheral blood (7-13). Furthermore, various types of solid tumors, including lung, breast, thyroid, and colorectal cancers, expressed the wild-type WT1 gene at higher levels compared to those in corresponding normal tissues (15-18). These results indicated that the wild-type WT1 gene product may be a promising target for cancer immunotherapy (24,25).We tested the potential of the WT1 gene product to serve as a target antigen for tumor-specific immunotherapy. Human WT1-specific CTLs have been found to induce lysis of endogenously WT1-expressing tumor cells in vitro, but not to cause damage to physiologically WT1-expressing normal cells (24,(26)(27)(28). We used a mouse in vivo system to demonstrate that immunization of mice with either MHC class I-restricted WT1 peptide or WT1 cDNA induced WT1-specific CTLs. We also showed that the immunized mice rejected challenges of WT1-expressing tumor cells, whereas the induced CTLs did not affect normal healthy tissues that physiologically expressed WT1 nor damaged the normal tissues (25, 29). These results indicated that the WT1 protein could be a novel tumor rejection antigen for cancer immunotherapy (24)(25)(26)(27)(28)(29)(30)(31)(32).In...

Tetraspanins CD9 and CD81 facilitate the fusion between gametes, myoblasts, or virus-infected cells. Here, we investigated the role of these tetraspanins in the fusion of mononuclear phagocytes. Expression of CD9 and CD81 and their complex formation with integrins were up-regulated when blood monocytes were cultured under normal conditions. Under fusogenic conditions in the presence of Con A, CD9 and CD81 up-regulation was inhibited, and their complex formation with integrins was down-regulated. Anti-CD9 and -CD81 antibodies, which were previously shown to inhibit the fusion of gametes, myoblasts, and virus-infected cells, unexpectedly promoted the fusion of monocytes and alveolar macrophages. However, these effects were not due to altered cell adhesion, aggregation, or cytokine production. When stimulated in vitro or in vivo, alveolar macrophages and bone marrow cells of CD9- and CD81-null mice formed larger numbers of multinucleated cells than those of wild-type mice. Finally, CD9/CD81 double-null mice spontaneously developed multinucleated giant cells in the lung and showed enhanced osteoclastogenesis in the bone. These results suggest that CD9 and CD81 coordinately prevent the fusion of mononuclear phagocytes.

Interleukin (IL)-10 has been shown to reduce many inflammatory reactions. We investigated the in vivo effects of IL-10 on a bleomycin-induced lung injury model. Hemagglutinating virus of Japan (HVJ)-liposomes containing a human IL-10 expression vector (hIL10-HVJ) or a balanced salt solution as a control (Cont-HVJ) was intraperitoneally injected into mice on day -3. This was followed by intratracheal instillation of bleomycin (0.8 mg/kg) on day 0. Myeloperoxidase activity of bronchoalveolar lavage fluid and tumor necrosis factor-alpha mRNA expression in bronchoalveolar lavage fluid cells on day 7 and hydroxyproline content of the whole lung on day 21 were inhibited significantly by hIL10-HVJ treatment. However, Cont-HVJ treatment could not suppress any of these parameters. We also examined the in vitro effects of IL-10 on the human lung fibroblast cell line WI-38. IL-10 significantly reduced constitutive and transforming growth factor-beta-stimulated type I collagen mRNA expression. However, IL-10 did not affect the proliferation of WI-38 cells induced by platelet-derived growth factor. These data suggested that exogenous IL-10 may be useful in the treatment of pulmonary fibrosis.

Small cell lung cancer (SCLC) invades locally and metastasizes distantly extremely early when compared with nonsmall cell lung cancer (NSCLC). The underlying molecular mechanisms, however, have not been elucidated. Accumulating evidence suggests that downregulation of several members of tetraspanins is associated with progression of solid tumors, thus indicating poor prognosis. Here we screened 30 lung cancer cell lines for expression of tetraspanins, CD9, CD63, CD81, CD82, CD151, and NAG-2. Flow cytometry revealed that, among these proteins, CD9 is broadly expressed in NSCLC lines, but is absent or highly reduced in most SCLC lines (Po0.0001). Using the Boyden chamber and videomicroscopic cell motility assays, we showed that stable transfection of CD9 into an SCLC line, OS3-R5, reduced cell motility on fibronectin. Furthermore, by transient transfection of green fluorescent protein (GFP)-tagged CD9 into three other SCLC lines, we observed that SCLC cells expressing GFP-CD9 were uniformly less motile than untransfected cells. CD9 or GFP-CD9 was associated with b1 integrins and distributed at the tumor cell periphery and cell-cell contacts, suggesting that CD9 modifies b1 integrin function to reduce motility. These findings suggest that low expression of CD9 may contribute to the highly invasive and metastatic phenotype of SCLC.

Tetraspanins facilitate the formation of multiple molecular complexes at specialized membrane microdomains and regulate cell activation and motility. In the present study, the role of tetraspanin CD9 in LPS-induced macrophage activation and lung inflammation was investigated in vitro and in vivo. When CD9 function was ablated with mAb treatment, small interfering RNA transfection, or gene knockout in RAW264.7 cells or bone marrow-derived macrophages, these macrophages produced larger amounts of TNF-α, matrix metalloproteinase-2, and -9 upon stimulation with LPS in vitro, when compared with control cells. Sucrose gradient analysis revealed that CD9 partly colocalized with the LPS-induced signaling mediator, CD14, at low-density light membrane fractions. In CD9 knockout macrophages, CD14 expression, CD14 and TLR4 localization into the lipid raft, and their complex formation were increased whereas IκBα expression was decreased when compared with wild-type cells, suggesting that CD9 prevents the formation of LPS receptor complex. Finally, deletion of CD9 in mice enhanced macrophage infiltration and TNF-α production in the lung after intranasal administration of LPS in vivo, when compared with wild-type mice. These results suggest that macrophage CD9 negatively regulates LPS response at lipid-enriched membrane microdomains.

To elucidate the pathophysiology of pulmonary fibrosis, we investigated the involvement of p38 mitogen-activated protein kinase (MAPK), which is one of the major signal transduction pathways of proinflammatory cytokines, in a murine model of bleomycin-induced lung fibrosis. p38 MAPK and its substrate, activating transcription factor (ATF)-2, in bronchoalveolar lavage fluid cells were phosphorylated by intratracheal exposure of bleomycin, and the phosphorylation of ATF-2 was inhibited by subcutaneous administration of a specific inhibitor of p38 MAPK, FR-167653. FR-167653 also inhibited augmented expression of tumor necrosis factor -alpha, connective tissue growth factor, and apoptosis of lung cells induced by bleomycin administration. Moreover, daily subcutaneous administration of FR-167653 (from 1 day before to 14 days after bleomycin administration) ameliorated pulmonary fibrosis and pulmonary cachexia induced by bleomycin. These findings demonstrated that p38 MAPK is involved in bleomycin-induced pulmonary fibrosis, and its inhibitor, FR-167653, may be a feasible therapeutic agent.

CD9 and CD81 are closely related tetraspanins that regulate cell motility and signaling by facilitating the organization of multimolecular membrane complexes, including integrins. We show that CD9 and CD81 are down-regulated in smoking-related inflammatory response of a macrophage line, RAW264.7. When functions of CD9 and CD81 were ablated with monoclonal antibody treatment, small interfering RNA transfection, or gene knock-out, macrophages were less motile and produced larger amounts of matrix metalloproteinase (MMP)-2 and MMP-9 than control cells in vitro. In line with this, CD9/CD81 double-knock-out mice spontaneously developed pulmonary emphysema, a major pathological component of chronic obstructive pulmonary disease (COPD). The mutant lung contained an increased number of alveolar macrophages with elevated activities of MMP-2 and MMP-9 and progressively displayed enlarged airspace and disruption of elastic fibers in the alveoli. Secretory cell metaplasia, a finding similar to goblet cell metaplasia in cigarette smokers, was also observed in the epithelium of terminal bronchioles. With aging, the double-knockout mice showed extrapulmonary phenotypes, including weight loss, kyphosis, and osteopenia. These results suggest that the tetraspanins CD9 and CD81 regulate cell motility and protease production of macrophages and that their dysfunction may underlie the progression of COPD.Chronic obstructive pulmonary disease (COPD), 5 a disease defined by incompletely reversible airflow limitation, results from abnormal inflammatory response to chronic cigarette smoking. Pulmonary emphysema is a major component of COPD, and a dominant hypothesis in its pathophysiology is that persistent infiltration of inflammatory cells and production of proteases, including matrix metalloproteinases (MMPs) in the lung, lead to tissue destruction and airspace enlargement (1, 2). In patients with emphysema, there was an increase in bronchoalveolar lavage fluid (BALF) concentrations and macrophage expression of MMP-9 (3). Studies of human samples have shown increases of MMP-2 and MMP-9 in smoking-related emphysema (4). Alveolar macrophages secrete elastolytic enzymes, including MMP-2, MMP-9, and MMP-12, and play a pivotal role in the pathophysiology of COPD. There was a marked increase in the numbers of macrophages in airways, lung parenchyma, BALF, and sputum in patients with emphysema (2). Macrophages are activated by cigarette smoke to release inflammatory mediators such as TNF-␣, chemokines, and reactive oxygen species as well as MMPs, providing a cellular mechanism that links smoking with inflammation in COPD (2). It was recently proposed that lowered activity of histone deacetylases (HDACs), which are suppressors of inflammatory genes, accounts for the persistent activation of macrophages in COPD patients (5).The tetraspanin proteins include at least 33 members, including CD9, CD63, CD81, CD82, and CD151 in mammals. They are characterized by the structure that spans the plasma membrane four times and have a propensity to form co...

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