osteoprotegerin and Hodgkin-Disease

The mitogen-activated protein kinase (MAPK) (also called extracellular signal-regulated kinase [ERK]) pathway has been implicated in malignant transformation and in the regulation of cellular growth and proliferation of several tumor types, but its expression and function in Hodgkin disease (HD) are unknown. We report here that the active phosphorylated form of MAPK/ERK is aberrantly expressed in cultured and primary HD cells. Inhibition of the upstream MAPK kinase (also called MEK) by the small molecule UO126 inhibited the phosphorylation of ERK and demonstrated a dose- and time-dependent antiproliferative activity in HD cell lines. UO126 modulated the levels of several intracellular proteins including B-cell lymphoma protein 2 (Bcl-2), myeloid cell leukemia-1 (Mcl-1) and caspase 8 homolog FLICE-inhibitory protein (cFLIP), and induced G2M cell-cycle arrest or apoptosis. Furthermore, UO126 potentiated the activity of apoliprotein 2/tumor necrosis factor-related apoptosis-inducing ligand (APO2L/TRAIL) and chemotherapy-induced cell death. Activation of CD30, CD40, and receptor activator of nuclear kappabeta (RANK) receptors in HD cells by their respective ligands increased ERK phosphorylation above the basal level and promoted HD cell survival. UO126 inhibited basal and ligand-induced ERK phosphorylation, and inhibited ligand-induced cell survival of HD cell lines. These findings provide a proof-of-principle that inhibition of the MEK/ERK pathway may have therapeutic value in HD.

Topics: Antineoplastic Agents; Apoptosis Regulatory Proteins; Butadienes; CD40 Antigens; Cell Division; Cell Survival; Enzyme Inhibitors; Glycoproteins; Hodgkin Disease; Humans; Ki-1 Antigen; Lymph Nodes; MAP Kinase Signaling System; Membrane Glycoproteins; Mitogen-Activated Protein Kinase Kinases; Mitogen-Activated Protein Kinases; Nitriles; Osteoprotegerin; Phosphorylation; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; TNF-Related Apoptosis-Inducing Ligand; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha

Topics: Carrier Proteins; Cell Survival; Glycoproteins; Hodgkin Disease; Humans; Membrane Glycoproteins; Neoplasm Proteins; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Tumor Cells, Cultured

Bone destruction, caused by aberrant production and activation of osteoclasts, is a prominent feature of multiple myeloma. We demonstrate that myeloma stimulates osteoclastogenesis by triggering a coordinated increase in the tumor necrosis factor-related activation-induced cytokine (TRANCE) and decrease in its decoy receptor, osteoprotegerin (OPG). Immunohistochemistry and in situ hybridization studies of bone marrow specimens indicate that in vivo, deregulation of the TRANCE-OPG cytokine axis occurs in myeloma, but not in the limited plasma cell disorder monoclonal gammopathy of unknown significance or in nonmyeloma hematologic malignancies. In coculture, myeloma cell lines stimulate expression of TRANCE and inhibit expression of OPG by stromal cells. Osteoclastogenesis, the functional consequence of increased TRANCE expression, is counteracted by addition of a recombinant TRANCE inhibitor, RANK-Fc, to marrow/myeloma cocultures. Myeloma-stroma interaction also has been postulated to support progression of the malignant clone. In the SCID-hu murine model of human myeloma, administration of RANK-Fc both prevents myeloma-induced bone destruction and interferes with myeloma progression. Our data identify TRANCE and OPG as key cytokines whose deregulation promotes bone destruction and supports myeloma growth.

Topics: Acid Phosphatase; Animals; Carrier Proteins; Disease Progression; Glycoproteins; Hodgkin Disease; Humans; Isoenzymes; Leukemia, Lymphocytic, Chronic, B-Cell; Membrane Glycoproteins; Mice; Mice, SCID; Osteoprotegerin; Paraproteinemias; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Reference Values; Reverse Transcriptase Polymerase Chain Reaction; Tartrate-Resistant Acid Phosphatase; Time Factors

The malignant Hodgkin and Reed-Sternberg (H/RS) cells of Hodgkin disease (HD) express several members of the tumor necrosis factor (TNF) receptor family, including CD30 and CD40, and secrete several cytokines and chemokines. However, little is known about what regulates cytokine and chemokine secretion in H/RS cells. Although H/RS cells are predominantly of B-cell origin, they frequently share phenotypic and functional features with dendritic cells (DCs). Previous studies reported that receptor activator of nuclear factor kappaB (NF-kappaB) (RANK), a member of the TNF receptor family, is expressed on DCs, and that RANK ligand (RANKL) enhances DC survival and induces them to secrete cytokines. This study reports that, similar to DCs, cultured H/RS cells expressed RANK. However, unlike DCs, H/RS cells also expressed RANKL. Soluble RANKL activated NF-kappaB and induced messenger RNA expression of interferon-gamma, interleukin-8 (IL-8), IL-13, IL-9, IL-15, and RANTES, in addition to the receptors for IL-9, IL-13, IL-15, and CCR4. RANKL increased IL-8 and IL-13 levels in the supernatants of H/RS cell lines, an effect that was blocked by soluble RANK. Furthermore, soluble RANK decreased the basal level of IL-8 in one cell line, suggesting that IL-8 was induced by an autocrine RANKL/RANK loop. RANKL had no effect on H/RS cell survival in culture, and it did not modulate the expression of bcl-2, bcl-xL, bax, or inhibitors of apoptosis proteins. These data provide evidence of further functional similarities between DCs and H/RS cells. The coexpression of RANK and RANKL in H/RS cells suggests that they may regulate cytokine and chemokine secretion in H/RS cells by an autocrine mechanism.

Topics: Antigens, Surface; Autocrine Communication; Carrier Proteins; Cell Survival; Cytokines; Glycoproteins; Hodgkin Disease; Humans; Membrane Glycoproteins; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Reed-Sternberg Cells; Tumor Cells, Cultured; Up-Regulation