No abstract

The expression of the chemokine CC-chemokine ligand 20 (CCL20)/macrophage inflammatory protein (MIP)-3A and its receptor CC-chemokine receptor 6 (CCR6) by multiple myeloma (MM) and microenvironment cells and their potential relationship with osteoclast (OC) formation and osteolytic bone lesions in MM patients was investigated in this study. First, we found that MM cells rarely produce CCL20/ MIP-3A but up-regulate its production by bone marrow (BM) osteoprogenitor cells and osteoblasts in coculture with the involvement of soluble factors as interleukin-1B and tumor necrosis factor A. MM cells also stimulate both CCL20/MIP-3A and CCR6 expression by OCs in coculture. Thereafter, we showed that CCL20/MIP-3A significantly increases both the number of multinucleated tartrate-resistant acid phosphatase-positive OCs and receptor activator of nuclear factor-KB-positive OC progenitor cells similar to CCL3/MIP-1A. Finally, we found that blocking anti-CCL20/MIP-3A and anti-CCR6 antibodies significantly inhibits MM-induced OC formation. In vitro data were further expanded in vivo analyzing a total number of 64 MM patients. Significantly higher CCL20/ MIP-3A levels were detected in MM patients versus monoclonal gammopathy of uncertain significance (MGUS) subjects and in MM osteolytic patients versus nonosteolytic ones. Moreover, a significant increase of CCL20/MIP-3A-positive osteoblasts in osteolytic MM patients compared with nonosteolytic ones was observed. Interestingly, no significant difference in BM CCL20/MIP-3A expression and level was observed between MGUS and nonosteolytic MM patients. Our data indicate that CCL20/MIP-3A and its receptor CCR6 are up-regulated in the bone microenvironment by MM cells and contribute to OC formation and osteolytic bone lesions in MM patients. [Cancer Res 2008;68(16):6840-50]

Predicting mobilization failure before it starts may enable patient-tailored strategies. Although consensus criteria for predicted PM (pPM) are available, their predictive performance has never been measured on real data. We retrospectively collected and analyzed 1318 mobilization procedures performed for MM and lymphoma patients in the plerixafor era. In our sample, 180/1318 (13.7%) were PM. The score resulting from published pPM criteria had sufficient performance for predicting PM, as measured by AUC (0.67, 95%CI: 0.63-0.72). We developed a new prediction model from multivariate analysis whose score (pPM-score) resulted in better AUC (0.80, 95%CI: 0.76-0.84, p < 0001). pPM-score included as risk factors: increasing age, diagnosis of NHL, positive bone marrow biopsy or cytopenias before mobilization, previous mobilization failure, priming strategy with G-CSF alone, or without upfront plerixafor. A simplified version of pPM-score was categorized using a cut-off to maximize positive likelihood ratio (15.7, 95%CI: 9.9-24.8); specificity was 98% (95%CI: 97-98.7%), sensitivity 31.7% (95%CI: 24.9-39%); positive predictive value in our sample was 71.3% (95%CI: 60-80.8%). Simplified pPM-score can "rule in" patients at very high risk for PM before starting mobilization, allowing changes in clinical management, such as choice of alternative priming strategies, to avoid highly likely mobilization failure.

Bone marrow stromal cells (MSCs) and osteoblasts are the two main non-haematopoietic cellular components of human bone tissue. To identify novel osteoblast-related molecules, we performed a gene expression profiling analysis comparing MSCs and osteoblasts isolated from the same donors. Genes differentially overexpressed in osteoblasts were mainly related to the negative control of cell proliferation, pro-apoptotic processes, protein metabolism and bone remodelling. Notably, we also identified the collagen XV (COL15A1) gene as the most up-regulated gene in osteoblasts compared with MSCs, previously described as being expressed in the basement membrane in other cell types. The expression of collagen type XV was confirmed at the protein level on isolated osteoblasts and we demonstrated that it significantly increases during the osteogenic differentiation of MSCs in vitro and that free ionised extracellular calcium significantly down-modulates its expression. Moreover, light and electron microscopy showed that collagen type XV is expressed in bone tissue biopsies mainly by working osteoblasts forming new bone tissue or lining bone trabeculae. To our knowledge, these data represent the first evidence of the expression of collagen type XV in human osteoblasts, a calcium-regulated protein which correlates to a specific functional state of these cells.