CD44 variant isoforms are involved in plasma cell adhesion to bone marrow stromal cells.

Expression of CD44v9-containing isoforms (CD44v9) on myeloma plasma cells correlates with unfavorable prognosis, suggesting that CD44 variant molecules are involved in the disease process. In this study, the presence of CD44v on B cell lines from different stages of development was analyzed by flow cytometry and a role in adhesion to stromal cells from different tissues was evaluated in in vitro binding assays. CD44v3, v6 and v9 isoforms were exclusively expressed on plasma cell lines and CD44v9 expression correlated with IL-6-dependent plasma cell growth.

CD44 isoforms distinguish between bone marrow plasma cells from normal individuals and patients with multiple myeloma at different stages of disease.

CD44 variant isoforms (CD44v) have been shown to be important factors in adverse prognosis in hematological malignancies. To investigate whether CD44 expression is associated with malignant transformation in multiple myeloma, RNA and protein expression of CD44 standard (CD44s) and CD44v4, v6, v9, v10 containing isoforms was compared on bone marrow plasma cells from normal individuals and myeloma patients at different stages of disease. CD44s protein expression is strongly decreased on myeloma plasma cells and non-malignant B cells in affected bone marrow of myeloma patients, while no differences in CD44s expression were found between blood B cells from normal individuals and myeloma patients.

Immunohistochemical analysis of decalcified paraffin-embedded human bone marrow biopsies with emphasis on MHC class I and CD34 expression.

Aims: To identify the stromal structures and haematopoietic cell lineages in normal bone marrow. The optimal conditions were studied for the reactivity of a panel of antibodies, applicable to paraffin sections of decalcified trephine biopsies using antigen retrieval methods.

Methods And Results: Two methods of antigen retrieval (pepsin and acid citrate buffer) were tested.

The actin binding domain of the epidermal growth factor receptor is required for EGF-stimulated tissue invasion.

NIH-3T3 fibroblasts expressing epidermal growth factor receptors (EGFRs) lacking the actin binding domain (ABD) were analyzed for their EGF-induced capacity to invade a bone marrow stromal cell (BMSC) monolayer. The fibroblasts display a reduction in the percentage of cytoskeleton-associated EGFRs. Furthermore, EGF-induced tyrosine kinase activity is unaffected by the mutation.

Fibronectin distribution in human bone marrow stroma: matrix assembly and tumor cell adhesion via alpha5 beta1 integrin.

Tumor cell interactions with fibronectin (FN) are important for the development of secondary tumors inside the bone marrow stroma. We studied and compared the in situ distribution of FN in paraffin-embedded human bone marrow sections and investigated the in vitro regulation of FN assemblage by bone marrow stromal cells (BMSC). Finally, the role of FN in the interaction of BMSC with tumor cells was studied.