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What's New In Research - January 15, 2003
01.15.03
Paracrine interactions of basic fibroblast growth factor and interleukin-6 in multiple myeloma.
Bisping G, Leo R, Wenning D, Dankbar B, Padro T, Kropff M, Scheffold C, Kroeger M, Mesters RM, Berdel WE, Kienast J.
Dept of Medicine, Hematology and Oncology, University Hospital, Muenster, Germany.
Blood 2002 Nov 27; [epub ahead of print]

Myeloma cells express basic fibroblast growth factor (bFGF), an angiogenic cytokine triggering marrow neovascularization in multiple myeloma (MM). In solid tumors and some lymphohematopoietic malignancies, angiogenic cytokines have also been shown to stimulate tumor growth via paracrine pathways. Since interleukin-6 (IL-6) is a potent growth and survival factor for myeloma cells, we have studied the effects of bFGF on IL-6 secretion by bone marrow stromal cells (BMSC) and its potential reverse regulation in myeloma cells. Both myeloma-derived cell lines and myeloma cells isolated from the marrow of MM patients were shown to express and secrete bFGF. Cell sorting studies identified myeloma cells as the predominant source of bFGF in MM marrow. BMSC from MM patients and control subjects both expressed high affinity FGF receptors R1 through R4. Stimulation of BMSC with bFGF induced a time- and dose-dependent increase in IL-6 secretion (median 2-fold, P<.001), which was completely abrogated by anti-bFGF antibodies. Conversely, stimulation with IL-6 enhanced bFGF expression and secretion by myeloma cell lines (2-fold, P=.02) as well as MM patient cells (up to 3.6-fold, median 1.5-fold, P=.002). This effect was inhibited by anti-IL-6 antibody. When myeloma cells were co-cultured with BMSC in a non-contact transwell system, both IL-6 and bFGF concentrations in co-culture supernatants increased 2- to 3-fold over the sum of basal concentrations in the monoculture controls. The IL-6 increase was again partially, but significantly inhibited by anti-bFGF. The data demonstrate a paracrine interaction between myeloma and marrow stromal cells triggered by mutual stimulation of bFGF and IL-6.


Downstream effectors of oncogenic ras in multiple myeloma cells.
Hu L, Shi Y, Hsu JH, Gera J, Van Ness B, Lichtenstein A.
Department of Hematology-Oncology, VA West LA-UCLA Medical Center, Los Angeles, CA, USA.
Blood 2002 Dec 19; [epub ahead of print]

Ectopic expression of mutated K-ras or N-ras in the IL-6-dependent ANBL6 multiple myeloma cell line induces cytokine-independent growth. To investigate the signaling pathways activated by oncogenic ras that may stimulate IL-6-independent growth, we compared ANBL6 cells stably transfected with mutated K or N-ras genes to wild type ras-expressing control cells identically transfected with an empty vector. Upon depletion of IL-6, both mutated ras-containing myeloma lines demonstrated constitutive activation of MEK/ERK, PI3-kinase/AKT, mTOR/p70S6 kinase, and NF-kB pathways. In contrast, STAT3 was not constitutively tyrosine phosphorylated in mutant ras-expressing cells. We used several maneuvers in attempts to selectively target these constitutively active pathways. The mTOR inhibitors rapamycin and CCI-779, the PI3-kinase inhibitor Ly294002, and the MEK inhibitor PD 98059 all significantly curtailed growth of mutant ras-containing cells. Farnesyl transferase inhibitors, used to target ras itself, had modest effects only against mutant N-ras-containing cells. Growth of mutant N-ras containing myeloma cells was also inhibited by acute expression of the IKB super repressor gene which abrogated NF-kB activation. These results indicate several pathways are activated downstream of oncogenic ras in myeloma cells which contribute to stimulation of cytokine-independent growth. They also suggest that therapeutic strategies which target these pathways may be particularly efficacious in patients whose myeloma clones contain ras mutations.


Dendritic cell vaccines in the treatment of multiple myeloma: advances and limitations.
Buchler T, Hajek R.
Department of Internal Medicine-Hematooncology, Masaryk University Hospital, Jihlavska 20, 63900 Brno, Czech Republic.
Med Oncol 2002;19(4):213-8

Dendritic cells (DCs) are antigen-presenting cells that play a key role in the induction of cytotoxic T-lymphocytes. Adjuvant immunotherapy with antigen-loaded DCs represents an attractive anticancer strategy for multiple myeloma (MM). Autologous DCs loaded with idiotypic protein or other myeloma-associated antigen have been used in several clinical trials. Preclinical and first clinical experience have provided valuable insights in the mechanisms of cellular immunity, but few, if any, patients with MM benefited from such vaccination. Taken together, the data suggest that antitumor T-cell responses fail in MM because of a deregulated cytokine network, downregulation of costimulatory surface receptor expression, and changes in T-cell repertoire, enabling tumor cells to escape immune effectors by preventing the antitumor immune response. We discuss current clinical protocols for DC-based immunotherapy in MM and review some strategies that may increase the efficacy of DC vaccines.


Use of melphalan, thalidomide, and dexamethasone in treatment of refractory and relapsed multiple myeloma.
Srkalovic G, Elson P, Trebisky B, Karam MA, Hussein MA.
Multiple Myeloma Research Program, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Med Oncol 2002;19(4):219-26

Twenty-one patients with relapsed and refractory Durie-Salmon stage III multiple myeloma who had either failed at least three previous regimens or presented with poor performance status, neutropenia, or thrombocytopenia were treated with up to four cycles of combination melphalan (50 mg intravenously), thalidomide (titrated to target of 400 mg orally daily), and dexamethasone (40 mg/day orally on d 1 to 4) every 4-6 wk. Maintenance treatment consisting of daily thalidomide and monthly dexamethasone was continued until disease progression. Although generally tolerated, combination melphalan/thalidomide/dexamethasone produced grade 4 neutropenia and thrombocytopenia in 52% and 38% of patients, respectively. Grade 3 nonhematologic toxicities included fatigue (14% of patients), neuropathy/paresthesia (5%), and nausea (5%). Four patients died while on therapy: two from neutropenic complications and two from progressive disease. Melphalan/ thalidomide/dexamethasone was highly active in this poor prognosis population: Serum monoclonal protein reductions > or = 25% occurred in 14 (70%) of 20 evaluable patients, including 1 patient with a complete response and 2 (13%) patients with reductions of 96%. Median progression-free-survival was 270 d (range: 73 to > 787 d) and median overall survival was 382 d. Median progression-free survival (> 420 d) has not been reached among patients responding to melphalan/thalidomide/dexamethasone. These results show that melphalan/thalidomide/dexamethasone therapy is active and generally tolerated in heavily pretreated multiple myeloma patients whose prognosis is otherwise poor.


Serum free light chain immunoassays and their clinical application
Clinical and Applied Immunology Reviews, Vol. 3 (1-2) (2002) pp. 17-33.
A.R. Bradwell FRCP, H.D. Carr-Smith Ph.D., G.P. Mead Ph.D. and M.T. Drayson

Abstract

Measurement of urine free light chains (flc) is important for assessing monoclonal plasma cell diseases. However, since the kidneys metabolize large amounts of flc, urine concentrations may not accurately reflect plasma cell synthesis. From a theoretical viewpoint, serum measurements would be preferable, just as blood glucose measurements are preferable to urine measurements for managing patients with diabetes mellitus. Unfortunately, the development of satisfactory serum flc immunoassays has been hampered by the lack of specific, high-affinity antisera. Recent publications indicate that this situation has now changed. Serum flc have been quantified using routine clinical laboratory instruments and have produced useful diagnostic results in several diseases. Thus, 100% of patients with light-chain multiple myeloma, 75% of patients with nonsecretory myeloma and more than 95% of patients with primary amyloidosis could be diagnosed using serum flc assays. This improvement in disease detection rates and the potential for superior disease monitoring may obviate the need for urine flc tests in most patients with monoclonal plasma cell diseases.

Abbreviations: AL, light chain amyloid disease; CZE, capillary zone electrophoresis; EIA, enzyme immunoassay; flc, free light chains; IFE, immunofixation electrophoresis; IgA, immunoglobulin A; , kappa; , lambda; LCDD, light chain deposition disease; LCMM, light chain multiple myeloma; MGUS, monoclonal gammopathy of undetermined significance; MM, multiple myeloma; NSM, nonsecretory myeloma; PE, protein electrophoresis; RIA, radioimmunoassay; SDS-PAGE, sodium dodecylsulfate-polyacrylamide gel electrophoresis


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