TIMP-1 and TIMP-2 Levels Are Directly Correlated with Neoangiogenesis and Are Prognostic Factors in Multiple Myeloma Patients.

Multiple myeloma (MM) is an incurable malignant disease, characterized by increased angiogenesis in the bone marrow (BM) microenvironment and aberrant BM metabolism. Matrix metalloproteinases (MMP) are a family of zinc-dependent endopeptidases implicated in tumour progression, invasion, metastasis and angiogenesis, via proteolytic degradation of extracellular matrix. MMPs are inhibited by tissue inhibitors of metalloproteinase (TIMP). Although recent studies have implicated MMP 9 in MM bone disease, little is known about the role of the TIMPs.

a) to compare levels of sRANKL, OPG, MMP-2, MMP-9, TIMP-1, TIMP-2, VEGF, bFGF, microvessel density (MVD) between newly diagnosed MM patients and healthy controls; b) to determine the association of these molecules with disease progression, bone disease and neoangiogenesis and c) to evaluate the impact of these variables on survival.

As of July 2009 38 newly diagnosed and untreated multiple myeloma patients were enrolled in the study. The median age was 61years-old (range 39-91) with 24 (63%) males. Patients were diagnosed and categorized according The International Myeloma Working Group criteria and ISS, respectively. Bone involvement was graded according to standard X-ray: patients with no lesions, or with one/ two bones involved or diffuse osteoporosis were classified as low score, whereas patients with lesions in more than two bones or presence of bone fracture were classified as high score. MMP-2 and MMP-9 were determined by PAGE gelatin zymography from plasma as previously described. MMP-9, TIMP-1 and TIMP-2, OPG and sRANKL concentrations were measured by ELISA. The levels of VEGF, bFGF were obtained using cytometric bead array. Ten healthy volunteers were used as controls. Bone marrow MVD measured in hotspots was evaluated in 26 out of 38 patients at diagnosis and 15 patients with Hodgkin Lymphoma stage IA and IIA (used as controls) by staining immunohistochemically for CD34. Comparisons among groups were analyzed by ANOVA and the correlation by the Spearman's correlation coefficient. Cox regression were performed for overall survival (OS) analysis.

Patients with MM had elevated TIMP-1, TIMP-2 and OPG values compared with controls. No significant difference was found between plasma sRANKL, pro-MMP2, pro-MMP9 and MMP-9 levels. We found that plasma TIMP-1 levels correlated positively with bFGF, VEGF, MVD, beta-2 microglobulin (B2M) and OPG (r: 0.514, p=0,001, r: 0.350, p=0,031; r: 0.610, p<0.0001; r: 0.760, p<0.0001 and r: 0.701, p<0.0001, respectively) and TIMP-2 levels with bFGF, DMV, B2M and OPG (r: 0.512, p=0.002; r: 0.595, p<0.0001; r: 0.587, p<0.0001 and r: 0.552, p<0.0001, respectively). TIMP-1 and TIMP-2 levels correlated with the ISS stage (p<0.0001, p=0.006, respectively). The only variables that correlated with clinical bone disease staging were hemoglobin, B2M and albumin levels, whereas TIMP-1, TIMP-2, bFGF, VEGF and OPG correlated with DMV. On the univariate analyses, age, gender, proMMP2, TIMP-1, TIMP-2, creatinine, B2M and MVD were significantly associated with overall survival. In Cox regression model, TIMP-1, TIMP-2 and B2M levels remained to be significantly associated with OS. In conclusion, our results suggest that TIMP-1 and TIMP-2 levels are strongly associated with neoangiogenesis and are independent prognostic factors in MM.

No relevant conflicts of interest to declare.