Background:Melphalan is one of the most active chemotherapeutic agents in the treatment of multiple myeloma (MM). However, the mechanism underlying differential patient responses to melphalan therapy is unknown.Methods:Chromatin structure, transcriptional activity and DNA damage response signals were examined following ex vivo treatment with melphalan of both malignant bone marrow plasma cells (BMPCs) and peripheral blood mononuclear cells (PBMCs) of MM patients, responders (n=57) or non-responders (n=28) to melphalan therapy. PBMCs from healthy controls (n=25) were also included in the study.Results:In both BMPCs and PBMCs, the local chromatin looseness, transcriptional activity and repair efficiency of the transcribed strand (TS) were significantly higher in non-responders than in responders and lowest in healthy controls (all P<0.05). Moreover, we found that melphalan-induced apoptosis inversely correlated with the repair efficiency of the TS, with the duration of the inhibition of mRNA synthesis, phosphorylation of p53 at serine 15 and apoptosis rates being higher in responders than in non-responders (all P<0.001).Conclusions:Our findings provide a mechanistic basis for the link between DNA repair efficiency and response to melphalan therapy. Interestingly, the observation of these phenomena in PBMCs provides a novel approach for the prediction of response to anti-myeloma therapy.
Objective. To further investigate the mechanism of action of gold compounds by studying their effects on interleukin-2 (IL-2) and IL-2 receptor (IL3R) biosynthesis.Methods. We cultured phytohemagglutinin-or anti-CD3 antibody-activated normal peripheral blood mononuclear cells (PBMC), as well as the erythroleukemic K562 cell line, in the presence of gold sodium thiomalate or auranofin. Tritiated thymidine incorporation assays, cytotoxicity assays, immunofluorescence analysis, enzyme-linked immunosorbent assay, Northern blot, and RNA dot-blot hybridization were used.Results. Gold compounds, at concentrations attainable in vivo, inhibited the proliferation of normal PBMC, with no evidence of direct cytotoxicity. This inhibitory effect was associated with a dose-dependent suppression of both IL-2 and 1L-2R messenger RNA accumulation. In contrast, the same concentrations of gold compounds failed to inhibit the spontaneous proliferation of the IL-Sindependent K562 cells.Conclusion. Our findings suggest an IL-2AL-2R-mediated mechanism for suppression of lymphocyte proliferation by gold compounds, which might account for the immunomodulatory effects of gold in patients with rheumatoid arthritis.
Aberrant expression of apoptosis-related genes, including the "cell death suppressor gene" bcl-2, may play an important pathogenetic role in cancer and autoimmune diseases, In vivo upregulation of bcl-2 mRNA in synovial lining cells of patients with rheumatoid arthritis but not in patients with osteoarthritis has been recently found. In the present study we investigated whether agents exerting beneficial effects in patients with rheumatoid arthritis, namely the long used Gold Sodium Thiomalate (GST) and the novel immunosuppressive, purine analogue 2-chlorodeoxyadenosine (2-CdA), a lymphocyte apoptosis-inducing agent interfere directly with induction of bcl-2 mRNA expression. The phytohemagglutinin (PHA)-induced in vitro proliferation of normal human peripheral blood lymphocytes was significantly inhibited by non-toxic concentrations of 2-CdA and GST which are within the range of in vivo plasma concentrations in patients receiving the respective treatment. Using mRNA dot-blot analysis and hybridization with an IL-2-specific probe we found that GST, similarly to dexamethasone that served as control, suppressed the PHA-induced IL-2 mRNA accumulation dose-dependently. In contrast, 2-CdA (0.1 microgram/ml) at concentrations that inhibit by 80-90% the PHA-induced proliferative responses of lymphocytes did not affect IL-2 mRNA accumulation. Hybridization with a bcl-2-specific probe showed that the activation-induced accumulation and kinetics of bcl-2 mRNA were not changed in the presence of a wide range of concentrations of either GST or 2-CdA. Similarly, the mRNA accumulation of the "house-keeping" control gene beta-action remained unchanged by both agents. These findings indicate that biosynthesis of bcl-2 is not specifically affected by GST and CdA, suggesting that the immunomodulating effects of these agents, including their efficacy in suppressing chronic arthritis, are not related with a bcl-2-dependent mechanism.
BackgroundSymptomatic multiple myeloma (MM) evolves from an asymptomatic precursor state termed monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma (SMM). Angiogenesis plays a key role in the pathogenesis of MM but there are very limited data for angiogenesis in SMM.Material/MethodsWe measured the circulating levels of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), vascular endothelial growth factor (VEGF), and angiogenin in 54 patients with SMM. The results were compared with those of 27 MGUS patients, 55 MM patients, and 22 healthy controls. The expression of VEGF-A gene was also evaluated in 10 patients with SMM, 10 with symptomatic MM, and 10 with MGUS.ResultsThe ratio of circulating Ang-1/Ang-2 was reduced in MM patients with symptomatic disease due to a dramatic increase of Ang-2 (p<0.001), but not in patients with SMM or MGUS, in whom it did not differ compared to controls. VEGF and angiogenin were increased in all patients compared to controls. However, circulating VEGF was higher in symptomatic MM compared to SMM and MGUS, while angiogenin was reduced. There were no differences in the expression of VEGF-A among the 3 patients categories.ConclusionsSMM has a circulating angiogenic cytokine profile similar to that of MGUS, but has altered profile compared to symptomatic MM. Thus, in the progression of MGUS to SMM, circulating angiogenic cytokines seem to be the same. On the contrary, in symptomatic myeloma, the alterations of angiopoietins along with VEGF contribute to myeloma cell growth, supporting the target of these molecules for the development of novel anti-myeloma agents.
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