Selective initial in vivo homing pattern of 5T2 multiple myeloma cells in the C57BL/KalwRij mouse

Abstract

Multiple myeloma (MM) is a B-cell neoplasm, mainly characterized by the monoclonal expansion of plasma cells, the presence of monoclonal serum immunoglobulin and the occurrence of osteolysis. The malignant cell corresponds to a long-lived plasma cell located in the bone marrow (BM) carrying somatically rearranged Ig genes with clonally fixed hypervariable regions (Bakkus et al, 1992;Hallek et al, 1998). This implies a post-germinal centre origin of the MM cells (Bakkus et al, 1992) having a specific migration to the extravascular compartment of the BM. This process of migration of MM cells to the extravascular compartment of the BM, and referred to as 'homing', is believed to be highly specific since no elevated quantity of malignant B-cells are observed in the peripheral blood or in other organs. After their specific homing to the BM, these cells proliferate and differentiate into mature plasma cells. It is only at the endstage of the disease of some patients that extramedullar spread is observed.In our previous work we have reported the 5T2MM model in the C57BL/KaLwRij mice (Radl et al, 1979) as a good model to study the homing of human myeloma cells in the BM (Vanderkerken et al, 1996(Vanderkerken et al, , 1997. In this model, MM cells are isolated from diseased animals and are transplanted into young syngeneic recipients by intravenous injection. From 9 weeks on after injection we observe a specific localization of the MM cells in the BM and partly in the spleen of the mice. This study did not, however, reveal whether this selective localization of MM cells in the BM is due to a selective initial entry of the cells through the endothelial barrier of the BM, or whether this homing is more random, and survival and growth factors, only present in BM, determine the unique presence of MM cells.The migration of lymphocytes in general (Butcher and Picker, 1996) is known to include a multistep cascade of processes mainly involving the endothelium. This interaction with the endothelium requires at least four independent steps: initial tethering, arrest, adhesion and transendothelial migration. It is the combination of the selectivity of each independent step which makes the process highly specific. In vivo, BM endothelial cells (BM EC) act as gate-keepers separating the BM compartment from the sinusoidal lumen. These cells may therefore play an important role in the selective entry of the MM cells.We conclude here that MM cells have a selective homing behaviour which is the result of the combination of a selective adhesion to the BM EC followed by the entry in the extravascular compartment and a selective survival and growth, making the BM and spleen microenvironment unique. Summary One of the main characteristics of multiple myeloma cells is their predominant localization in the bone marrow. It is, however, unclear whether this is due to a selective initial entry, or whether this entry is more random and other processes like survival and/or growth stimulation, only present in the medullar microenvironment, are uniqu...

Specific roles for the PI3K and the MEK–ERK pathway in IGF-1-stimulated chemotaxis, VEGF secretion and proliferation of multiple myeloma cells: study in the 5T33MM model

“…Butcher and Picker (1996) have described the homing process as a multistep event. Our group has already demonstrated the selective homing of the MM cells to the BM (Vanderkerken et al, 2000). Once in the BM, the MM cells interact with the stromal cells to receive proliferation and survival signals, unique to the BM.…”

“…The presence of the tumour cells in the BM is associated with enhanced angiogenesis (Van Valckenborgh et al, 2002) and induction of bone lesions. On a more cellular basis, a similar profile of adhesion molecules and chemokine receptors is observed and similar mechanisms are used to induce osteoclastogenesis (Radl et al, 1979;Vanderkerken et al, 1997;Vanderkerken et al, 2000;Asosingh et al, 2000a). …”

Erythropoietin enhances immune responses in mice

“…All experiments were performed on female mice aged 3-5 months. The 5T2 MM cell line [60][61][62], generously provided by K. Vanderkerken (VUB, Brussels), was propagated in C57BL/KaLwRij mice (Harlan, CPB Zeist, The Netherlands). Bone marrow cells from these MM-carrying mice were transferred by i.v.…”

Myeloma isotype-switch variants in the murine 5T myeloma model: evidence that myeloma IgM and IgA expressing subclones can originate from the IgG expressing tumour

“…With this myeloma-specific PCR assay it is possible to detect at least one tumour cell in 100 000 normal cells. 20 Positive PCR samples were cloned into the pCRII vector (Invitrogen, Groningen, The Netherlands), bacterial colonies were screened by hybridisation with the CDR3 probe. Plasmids from positive colonies were sequenced using the autoload solid phase sequencing kit and the ALFexpress (Pharmacia, Roosendaal, The Netherlands).…”