Clinical significance of sCD105 in angiogenesis and disease activity in multiple myeloma.

Background: Τhe importance of angiogenesis in malignancies' growth is well recognized. CD105 (Endoglin), a proliferation-associated glycoprotein, is a powerful marker of neovascularization. Elevated amounts of soluble CD105 (sCD105) have been identified in selected solid tumors. The aim of the study was to estimate circulating levels of sCD105 and soluble transforming growth factor-β(1) (sTGF-β(1)), in multiple myeloma (MM) patients, to determine their significance in tumor progression and to investigate the correlation between sCD105 and markers of disease activity.

Methods: We studied 50 newly diagnosed MM patients. Twenty-five of them were also investigated in plateauphase. Twenty patients with monoclonal gammopathy of undetermined significance (MGUS) were enrolled in this study. As control group 28 healthy persons were studied. We determined sCD105, sTGF-β(1) and interleukin-6 (IL-6) in the serum, Ki-67 proliferation index (Ki-67 PI) expression and microvascular density(MVD) in bone marrow with immunohistochemistry.

Results: The mean concentrations of sCD105 and IL-6 were higher in MM and MGUS patients compared to controls, whereas serum levels of sTGF-β(1) were lower in MM patients compared to MGUS patients and controls. sCD105 levels, were significantly different among disease stages, with higher values in advanced stages. It was found that sCD105 correlated with Ki-67 PI, MVD and IL-6.

Conclusions: CD105 seems to play an important role in angiogenesis and tumor progression. Circulating levels of sCD105 could detect patients with more advanced disease and might help in evaluating the response to treatment.