Increased numbers of rosettes of podosomes were observed in overgrown rat Rous sarcoma RsK4 cells. A possible role of these structures in nutrient uptake in tumour cell survival was investigated by exposure to acute starvation. A single cell suspension of RsK4 cells in Hanks balanced salt solution was allowed to interact with either clean uncoated or serum-coated for bait coverglasses. Confocal microscopy revealed contrasting 3D cell morphologies that were associated with conspicuous patterns of podosomal structures, which on the coated coverglasses resembled the sealing zones of osteoclasts, while on the uncoated coverglasses they resembled the marginal podosomes of migrating monocyte-derived cells. Thus, the arising podosomal structures, the involvement of which in an uptake of nutrients appeared feasible morphologically, were associated with the emerging 3D cell shapes guided by the microenvironment. Such phenotypic plasticity of neoplastic RsK4 cells in response to microenvironmental challenge suggested that uniqueness in cellular attributes within the neoplastic cell population could be crucial for the malignant potential.

Institute of Molecular Genetics AS CR Prague 6 166 37 Czech Republic

Digital holographic microscopy in human sperm imaging