Athina Xekalou

In multiple myeloma, there are many factors influencing the growth of the malignant clone in direct and indirect manners. BAFF is a growth factor for myeloma cells. The aim of the study was to measure its circulating levels in 54 pretreatment patients, along with serum levels of other proliferation markers, such as interleukins-6, -10, and -15, CRP, and beta-2 microglobulin, as well as bone marrow plasma cell infiltration and expression of Ki-67 PI, in various stages of the disease and after effective treatment in 28 of them. Serum levels of the previously mentioned factors were measured by ELISA, whereas bone marrow plasma cell infiltration and Ki-67 expression were estimated immunohistochemically. All measured parameters were higher in pretreated myeloma patients compared to healthy population and were also increasing with the progression of the disease. They all also decreased after effective therapy. Furthermore, all pretreatment values correlated to each other. BAFF seems to be an important growth factor for myeloma plasma cells. Measuring its serum levels, along with the previously mentioned cytokines, may provide important information regarding the degree of myeloma cells’ proliferation. Therefore, they all could be used as markers of proliferation and disease activity.

Soluble interleukin-6 receptor (sIL-6R) is part of IL-6 receptor that may stimulate cells that do not express the whole molecule. It may enhance myeloma cell proliferation and furthermore angiogenesis. The aim of the study was to evaluate the clinical significance and the relationship between serum levels of sIL-6R, with various stimulators of angiogenesis, such as hepatocyte growth factor (HGF) and interleukin-18 (IL-18) and with markers of proliferation, such as beta-2 microglobulin (B2M) levels and plasma cell Ki-67 proliferation index in the bone marrow, in patients with multiple myeloma (MM). We studied 45 newly diagnosed MM patients. Serum levels of sIL-6R, HGF, IL-18, and B2M and Ki-67 proliferation index (Ki-67 PI) in bone marrow’s plasma cells were determined. The mean concentrations of sIL-6R, HGF, IL-18, and B2M and the value of Ki-67 were significantly higher in the patients compared to controls and with increasing disease stage. sIL-6R was strongly positively correlated with HGF, IL-18, B2M, and Ki-67 PI. There is a positive correlation between plasma cell growth, as determined by Ki-67 PI, and different angiogenic cytokines, such as HGF and IL-18, with sIL-6R. This relationship suggests the significant role of these cytokines in the proliferation and disease activity in MM patients.

Angiogenesis is a complex process essential for the growth, invasion, and metastasis of various malignant tumours, including multiple myeloma (MM). Various angiogenic cytokines have been implicated in the angiogenic process. Among them, platelet‐derived growth factor‐AB (PDGF‐AB) has been reported to be a potent stimulator of angiogenesis in many solid tumours and haematological malignancies, including MM. The aim of the study was to investigate the relationship between PDGF‐AB, microvascular density (MVD), and various angiogenic cytokines, such as basic fibroblast growth factor (b‐FGF), angiogenin (ANG), and interleukin‐6 (IL‐6), in MM patients. Forty‐seven MM patients before treatment, 22 of whom were in plateau phase, were studied. We determined the serum levels of the aforementioned cytokines and MVD in bone marrow biopsies before and after treatment. Mean serum values of PDGF‐AB, b‐FGF, ANG, and MVD were significantly higher in patients compared with controls and with increasing disease stage. Significant positive correlations were observed between serum PDGF‐AB, ANG, and IL‐6 levels and MVD. Furthermore, we found significant positive correlations between PDGF‐AB and b‐FGF, IL‐6, ANG, and β2 microglobulin. We also found that patients with high MVD had statistically significantly higher serum levels of PDGF‐AB when a median MVD value of 7.7 was used as the cutoff point. Furthermore, a significant difference was found in serum levels of PDGF‐AB between pre‐ and post‐treatment patients. Finally, survival time was significantly higher in the low MVD group versus the high MVD group (76 vs 51 months). Our results showed that there is a strong positive correlation between PDGF‐AB and the studied angiogenic cytokines and MVD. It seems that PDGF‐AB plays a role in the complex network of cytokines inducing bone marrow neovascularization in patients with MM. Copyright © 2011 John Wiley & Sons, Ltd.

Multiple myeloma (MM) is a malignant plasma cell disease. Several proinflammatory cytokines produced by malignant plasma cells and bone marrow (BM) stromal cells are involved in the pathogenesis of the disease. We evaluated serum levels of the proinflammatory cytokines Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), macrophage inflammatory protein-1α (MIP-1α), in MM patients before treatment, and determined its significance in tumor progression. We also analyzed the correlation between measured parameters with proliferating cell nuclear antigen (PCNA). Forty-four MM patients and 20 healthy controls were studied. Serum levels of the proinflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA), whereas PCNA value in the BM was determined by immunohistochemistry staining. The mean concentrations of the measured cytokines were significantly different among the three stages of disease, with higher values in advanced disease stage. Furthermore, patients with MM had significantly higher serum levels of the measured cytokines than in controls. A positive correlation was found between IL-6 with IL-1β, IL-8 and MIP-1α. Similarly, IL-8 and MIP-1α were positively correlated with markers of disease activity such as beta 2 microglobulin and LDH. The proliferation index, determined by PCNA immunostaining, was higher in advanced disease stage. Furthermore PCNA value correlated significantly with beta 2 microglobulin, LDH and the levels of the measured cytokines. Our results showed that the proliferative activity, as measured with PCNA, increases in parallel with disease stage. The positive correlation between PCNA and other measured mediators supports the involvement of these factors in the biology of myeloma cell growth and can be used as markers of disease activity and as possible therapeutic targets.