In invasion assays, the breast cancer cell nucleus leads the way

OBJECTIVE: Cancer cell metastasis determines disease prognosis. During cancer cell metastasis, the cancer cell and the cancer cell nucleus have to undergo extreme shape changes. To monitor shape changes of cancer cells and cancer cell nuclei and the positioning of the cancer cell nucleus during cancer cell invasion, a customized invasion assay with 8-μm pores and reconstituted basal membrane was imaged using fluorescence live-cell microscopy. RESULTS: The observed cells changed their shape from a distinct fibroblast-like spindle shape to an amoeboid shape without polarization immediately after the passage through an 8-μm pore of the invasion assay. During the process of invasion, the cancer cell centered the cancer cell nucleus over the 8-μm pore, and cancer cell nucleus and adjacent cytoplasmic areas moved first through such a pore. Seemingly testing if the largest and least deformable organelle may fit, the cancer cell nucleus led the way through the porous membrane of the invasion assay.