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To evaluate nuclear factor-kappaB (NF-kappaB) activity in primary myeloma cells from myeloma patients, we confirmed that the expression levels of CD54 showed a good correlation with the levels of DNA binding activity for NF-kappaB in human myeloma cell lines, and thus analyzed the expression levels of CD54 on CD38(++) plasma cell fractions as one of NF-kappaB activity. Primary myeloma cells unexpectedly showed constitutively lower expressions of CD54 than normal bone marrow (BM) plasma cells. Furthermore, the expression levels of CD54 on these plasma cells showed a significant correlation with the plasma levels of CXCL12 stromal cell-derived factor-1alpha (SDF-1alpha) in their BM aspirates, and the expressions of CXCR4, the receptor for CXCL12, decreased on primary myeloma cells compared with normal BM plasma cells. It was also confirmed that the addition of CXCL12 to the in vitro culture significantly induced the up-regulation of CD54 expression in primary myeloma cells. In addition, myeloma cells with lower expressions of CD54 were more unstable in the in vitro culture, resulting in a marked reduction of the viable cell number. In the immunohistochemical analysis of BM aspirates, myeloma cells with lower CD54 expression resided in the perivascular regions. Therefore, these data suggest that primary myeloma cells exhibit constitutively lower CD54 that might be partially regulated by CXCL12, and their localizations in the BM may be associated with the expression levels of CD54.

Bone disease (BD) in multiple myeloma (MM) is because of the activation of osteoclasts and impairment of osteoblast differentiation. Connective tissue growth factor (CTGF) is known to participate in the differentiation of mesenchymal stem cells to committed osteoprogenitor cells. We analysed the concentration of circulating CTGF in 35 MM patients and 22 malignant lymphoma (ML) patients and 14 normal individuals. CTGF is protease-sensitive and thus is found as both an N-terminal half fragment (N-half CTGF) and whole (W-CTGF). Serum levels of W-CTGF and N-half CTGF + W-CTGF were determined by separate sandwich enzyme-linked immunosorbent assays. The level of W-CTGF was significantly lower ( P < 0·005) in MM patients compared with ML patients and normal individuals, while N-half + W-CTGF was similar in all groups. Furthermore, W-CTGF was significantly lower in MM patients with BD compared with those without BD ( P < 0·005) and this was independent of previous treatment. Matrix metalloproteinase (MMP)-9 is produced by myeloma cells and is thought to be related to BD in MM. However, MMP-9 does not cleave CTGF and serum MMP-9 level was not related to BD in MM. Thus, CTGF is an indicator of BD in MM; its metabolism and function in MM should be clarified. [ABSTRACT FROM AUTHOR]

In this study, we examined osteopontin (OPN) production in myeloma cells and plasma OPN levels in multiple myeloma (MM) patients. We assessed OPN production in bone marrow cells (BMCs) by immunocytochemistry and enzyme-linked immunosorbent assay (ELISA). We also assessed OPN production in various B-cell malignant cell lines, including three myeloma cell lines by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. In addition, we measured plasma OPN concentrations by ELISA in 30 MM patients, 21 monoclonal gammopathy of undetermined significance (MGUS) patients and 30 healthy volunteers. As a result, in an immunocytochemical study, abundant OPN was detected in BMCs from overt MM patients, whereas no OPN was detected in BMCs from patients with other haematological diseases, including MGUS. Cultured BMCs from overt MM patients produced more OPN than those from patients with either smouldering MM or MGUS. Myeloma cell lines spontaneously produced OPN. Plasma OPN levels of MM patients were significantly higher than those of MGUS patients and healthy volunteers ( P < 0·05). Moreover, they correlated with both progression and bone destruction of the disease ( P < 0·05). These suggest that myeloma cells actively produce OPN, which possibly contributes to osteoclastic bone resorption in MM. Plasma OPN levels may be a useful biomarker for assessing bone destruction in MM and distinguishing MM from MGUS or smouldering MM. [ABSTRACT FROM AUTHOR]