HGF/SF and its receptor c-MET play a minor role in the dissemination of human B-lymphoma cells in SCID mice

The MET protooncogene, c-MET, encodes a cell surface tyrosine kinase receptor. The ligand for c-MET is hepatocyte growth factor (HGF), also known as scatter factor (SF), which is known to affect proliferation and motility of primarily epithelial cells. Recently, HGF/SF was also shown to affect haemopoiesis. Studies with epithelial and transfected NIH3T3 cells indicated that the HGF/SF–c-MET interaction promotes invasion in vitro and in vivo. We previously demonstrated that HGF/SF induces adhesion of c-MET-positive B-lymphoma cells to extracellular matrix molecules, and promoted migration and invasion in in vitro assays. Here, the effect of HGF/SF on tumorigenicity of c-MET-positive and c-MET-negative human B-lymphoma cell lines was studied in C.B-17 scid/scid (severe combined immune deficient) mice. Intravenously (i.v.) injected c-MET-positive (BJAB) as well as c-MET-negative (Daudi and Ramos cells) B-lymphoma cells formed tumours in SCID mice. The B-lymphoma cells invaded different organs, such as liver, kidney, lymph nodes, lung, gonads and the central nervous system. We assessed the effect of human HGF/SF on the dissemination of the B-lymphoma cells and found that administration of 5 μg HGF/SF to mice, injected (i.v.) with c-MET-positive lymphoma cells, significantly (P = 0.018) increased the number of metastases in lung, liver and lymph nodes. In addition, HGF/SF did not significantly influence dissemination of c-MET-negative lymphoma cells (P = 0.350 with Daudi cells and P = 0.353 with Ramos cells). Thus the effect of administration of HGF/SF on invasion of lymphoma cells is not an indirect one, e.g. via an effect on endothelial cells. Finally, we investigated the effect of HGF/SF on dissemination of c-MET-transduced Ramos cells. In response to HGF/SF, c-MET-transduced Ramos cells showed an increased migration through Matrigel in Boyden chambers compared to wild-type and control-transduced Ramos cells. The dissemination pattern of c-MET-transduced cells did not differ from control cells in in vivo experiments using SCID mice. Also no effect of HGF/SF administration could be documented, in contrast to the in vitro experiments. From our experiments can be concluded that the HGF/SF–c-MET interaction only plays a minor role in the dissemination of human B-lymphoma cells. © 1999 Cancer Research Campaig

Contribution of human hematopoietic stem cells to liver repair

Immune-deficient mouse models of liver damage allow examination of human stem cell migration to sites of damage and subsequent contribution to repair and survival. In our studies, in the absence of a selective advantage, transplanted human stem cells from adult sources did not robustly become hepatocytes, although some level of fusion or hepatic differentiation was documented. However, injected stem cells did home to the injured liver tissue and release paracrine factors that hastened endogenous repair and enhanced survival. There were significantly higher levels of survival in mice with a toxic liver insult that had been transplanted with human stem cells but not in those transplanted with committed progenitors. Transplantation of autologous adult stem cells without conditioning is a relatively safe therapy. Adult stem cells are known to secrete bioactive factors that suppress the local immune system, inhibit fibrosis (scar formation) and apoptosis, enhance angiogenesis, and stimulate recruitment, retention, mitosis, and differentiation of tissue-residing stem cells. These paracrine effects are distinct from the direct differentiation of stem cells to repair tissue. In patients at high risk while waiting for a liver transplant, autologous stem cell therapy could be considered, as it could delay the decline in liver function

Differentiation of hematopoietic progenitor cells towards the myeloid and B-lymphoid lineage by hepatocyte growth factor (HGF) and thrombopoietin (TPO) together with early acting cytokines

Objectives: The effect of stem cell factor (SCF), flt3-ligand (FL), and interleukin (IL)-3 (SF3) in combination with hepatocyte growth factor (HGF), thrombopoietin (TPO), and Hyper-IL-6 on maintenance and differentiation of early human peripheral blood-derived progenitor cells was investigated. Methods: Single sorted CD34(+) 38(-) cells were cultured with various combinations of these growth factors in order to identify the most effective cytokine combination. Then, lineage-depleted cells were stimulated for 7 d in bulk culture before they were assessed by flow cytometry and in functional assays. Results: The highest number of clones in the single-cell assay was obtained after culture with SF3 + TPO + HGF. Cell expansion with SF3 + TPO + HGF yielded an increase of the total cell number (11-fold), the number of CD34(+) cells (sevenfold), colony forming cells (CFC; 13-fold), granulocytes (CD15/66b(+); 45-fold) and B-cells (CD19/20(+); 55-fold). However, the number of long-term culture initiating cells (LTC-IC) decreased from 779 +/- 338 per 1 x 10(5) CD34(+) cells on day 0 to 253 +/- 115 on day 7. In parallel, the number of pluripotent mouse repopulating cells decreased by the factor 11, and no significant change in the proportion of human myeloid or lymphoid cells found in the mouse bone marrow was noted. Conclusion: The observation that mature cells of different lineages are generated and that transplantable multipotent hematopoietic cells are lost during culture suggests the differentiation of early hematopoietic progenitors toward lineage committed cells by the tested cytokines. The detection of cells expressing B-lymphoid markers after culture indicates a possible role in the propagation of B-cells

The role of hepatocyte growth factor and its receptor c-met in interactions between lymphocytes and stromal cells in secondary human lymphoid organs

Secondary lymphoid tissue consists of two major populations of cells: lymphoid cells and stromal cells. It is generally accepted that these two cell populations influence each other however, factors mediating these processes are poorly understood. In this paper we characterize one of the possible means of communication between stroma and lymphocytes namely through hepatocyte growth factor/c-met receptor interactions. Hepatocyte growth factor (HGF) is a pleiotropic factor that is mainly produced by mesenchymal cells and acts on cells of epithelial origin which express the HGF receptor c-met. Here we demonstrate that biologically active HGF is constitutively produced by fibroblast-like stromal cells from human lymphoid tissues. HGF secretion from stromal cells was increased by direct contact with activated T cells. This increase was abrogated when activated T cells were separated physically from stromal cells. Using neutralizing antibody or cytokine inhibitors we provide evidence that enhancement of HGF production was due to additive effects of T-cell membrane-associated interleukin-1 (IL-1) and CD40 ligand. Finally, we also show that B lymphocytes activated with CD40L/anti-µ or phorbol 12-myristate 13-acetate (PMA) express c-met receptor. Co-culture of activated B cells with stromal cells from spleen leads to enhanced production of immunoglobulins. This can be partially inhibited by introduction of anti-HGF neutralizing antibodies to the culture system. Substitution of stromal cells with recombinant HGF did not produce enhancement of immunoglobulin secretion. On the other hand stimulation of c-met receptor with HGF leads to enhanced integrin-mediated adhesion of activated B cells to vascular cell adhesion molecule (VCAM-1) and fibronectin. On the basis of the above experiments we conclude that HGF production by fibroblast-like stromal cells can be modulated by activated T cells, thus providing signals for the regulation of adhesion of c-met expressing B cells to extracellular matrix proteins. In this way HGF may indirectly influence immunoglobulin secretion by B cells

The role of inflammation in lymphoma

Human lymphomas usually develop in specialized tissue microenvironments characterized by different populations of accessory stromal and lymphoid cells that interact with malignant cells. A clinical role of the tumor microenvironment has recently emerged, bringing new knowledge and suggesting new ideas and targets for treatment. This chapter analyzes the microenvironment in human lymphomas highlighting the role of inflammation in their pathogenesis. Microenvironmental specificity is detailed according to different models including classic Hodgkin lymphoma (HL), follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL), peripheral T-cell lymphoma, unspecified and angioimmunoblastic T-cell lymphoma (AITL)

Hepatocyte growth factor and carotid intima-media thickness in relation to circulating CD34-positive cell levels

Hepatocyte growth factor (HGF) may act as a possible biochemical index for vascular damage, although evidence for the association between HGF and carotid intima-media thickness (CIMT) is limited. Since both HGF and circulating CD34-positive cells play an important role in endothelial repair, circulating CD34-positive cell levels may influence the association between HGF and CIMT. Methods: We conducted a cross-sectional study of 269 elderly Japanese men aged 60-69 years who had undertaken an annual medical checkup from 2014 to 2015. Results: The median value for circulating CD34-positive cells was 0.93 cells/μL. Among the study population, 135 men showed low circulating CD34-positive cell levels (? 0.93 cells/μL). By multivariable linear regression analysis, HGF was found to be significantly positively associated with CIMT only to participants with low circulating CD34-positive cell levels, with a multi-adjusted β of 0.26 (p = 0.005) and 0.002 (0.986) for low and high circulating CD34-positive cell levels, respectively. In addition, a significant interaction was observed between HGF and circulating CD34-positive cell levels (low and high) on CIMT (multivariable p value of 0.049). A positive association exists between HGF and CIMT in elderly Japanese men, limited to participants with low circulating CD34-positive cell levels. Conclusion: A positive association exists between HGF and CIMT in community-dwelling elderly Japanese men, which is limited to participants with low numbers of circulating CD34-positive cells. Our findings indicate that circulating CD34-positive cell levels could determine the influence of HGF on CIMT in elderly Japanese men