Fig. 1

Intercellular interactions between cancer cells and Bone Marrow Host Cells (BMHC). a Paraffin-embedded immunohistochemistry. Antibody against CD-10 was used. Picture showed a network of BMHC (brown cells) surrounding cancer cell clusters (blue cells). The insert picture showed the metastatic node the tissue micro-array. b Electronic microscopy imaging. MDA-MB-231 and BMHC or MCF7 and BMHC were co-cultured during 48 h and analyzed by electronic microscopy. A pseudopodia of BMHC with two MDA-MB-231 cells were closely interacting with the pseudopodia (left panel, arrows). Very close interaction between the two cellular membranes of MCF7 and BMHC can be observed with formation of tight junction (right panel, arrows). c Co-culture of BMHC and MDA-MB231 in phase microscopy. Cancer cells are growing on BMHC. Scale bar 250 μm. d Confocal imaging of BMHC and eGFP MDA-MB231 co-culture. BMHC were co-cultured with tumor cells for 3 days. Before imaging by confocal microscopy, co-cultures were stained with Alexa Fluor 594 conjugated-wheat germ agglutinin (WGA). Z-X reconstitution shows that cancer cells (green) are growing on BMHC. Scale bar 10 μm. e Adhesion assay testing the specificity of the adhesion between MDA-MB231 cells and BMHC. BMHC were plated up to 60 % confluency, 50,000 eGFP MDA-MB231 were allowed to adhere for 1 h. HBMEC (human bone marrow endothelial cells) or plastic were used as negative control. f Proliferation assay. MDA-MB231 were plated and counted every 2 days in presence or not of BMHC during 6 days. BMHC were able to increase proliferation of MDA-MB231. g Migration in agarose gel assay. MDA-MB231 cells were seeded in the central well. Media only was poured in the left well as negative control and BMHC were seeded in the right well. Cells could be observed during migration through the agarose gel (black part, wall). The picture represents MDA-MB231 cells migration through the agarose wall to the BMHC well at day 4 (bottom picture, arrows) or to the media only (top picture)