Angiogenic Cytokines Are Increased in the Serum of Patients with Waldenstrom's Macroglobulinemia: Correlations with Clinical Data.

Abstract

Angiogenesis represents an essential step of disease progression in several hematologic malignancies including multiple myeloma (MM). Bone marrow angiogenesis, assessed by microvessel density (MVD), is increased in 30% of patients with Waldenstrom's macroglobulinemia (WM) and showed only weak correlation with bone marrow infiltration. The orchestration of two major classes of angiogenic factors, namely the vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2), has been shown to play a pivotal role in tumor angiogenesis. Angiogenin is a member of the ribonuclease superfamily, which participates in angiogenesis by influencing the migration and proliferation of endothelial cells, while basic fibroblast growth factor (bFGF) is another cytokine with angiogenic properties which is produced by stromal cells and plays a significant role in the pathogenesis of MM. The aim of this study was the evaluation of angiogenesis, as assessed by the measurement of the above mentioned angiogenic cytokines, in patients with WM and its correlation with clinical data of the patients. We studied 53 serum samples of 38 patients with WM (26M/12F; median age: 74 years, range: 39–85 years) in different phases of their disease. Thirteen patients were evaluated prior any kind of treatment, while 24 patients were studied during an active phase of their disease and 12 patients during remission. Furthermore, 4 patients with IgM MGUS were also studied. VEGF, angiogenin, Ang-2 and bFGF were measured using an ELISA method (R&D Systems, Minneapolis, MN, USA). In all patients, we also evaluated hemoglobin, platelet count, β2-microglobulin, and albumin levels as well as the presence of splenomegaly, hepatomegaly and lymphadenopathy at the time of sample collection. The angiogenic cytokines were also measured in 20 gender- and age-matched controls. WM patients had increased serum levels of all angiogenic cytokines compared with controls: mean ± SD for VEGF was 231 ± 168 vs. 59.2 ± 37.2 pg/ml in patients and controls, respectively (p<0.0001); for angiogenin 412.2 ± 191.3 ng/ml vs. 230.9 ± 18.9 ng/ml (p<0.0001); for Ang-2 2766 ± 917 vs. 1372 ± 541 pg/ml (p<0.0001) and for bFGF 10.6 ± 10.6 vs. 0 pg/ml (p<0.0001). Patients with IgM MGUS had also elevated values of VEGF, Ang-2, and bFGF (p<0.001), but not of angiogenin compared with controls. Untreated WM patients had increased levels of angiogenin compared with patients at remission (mean ± SD: 547.6 ± 49.4 vs. 333 ±126.8 ng/ml; p=0.01). At the time of samples collection, 9 patients had anemia (Hb<10 g/dl), while 11 patients had increased levels of β2-microglobulina (>3.5 mg/l), and 7 patients had reduced albumin levels (<3.5 g/dl). VEGF serum levels correlated with β2-microglobulin (r=0.4, p=0.012), while angiogenin levels correlated with serum albumin (r=−0.307, p=0.031). This ongoing study suggests that angiogenic cytokines are increased in patients with WM supporting a possible paracrine role of these molecules. Our results, if confirmed, may provide the basis for clinical trials in WM, which involve anti-angiogenic agents.