Tumor Cells Genetically Labeled with GFP in the Nucleus and RFP in the Cytoplasm for Imaging Cellular Dynamics

Dual-color fluorescent cells with one color fluorescent protein in the nucleus and another color fluorescent protein in the cytoplasm were genetically engineered. The dual-color cancer cells enable real-time nuclear-cytoplasmic dynamics to be visualized in living cells in vivo as well as in vitro. To obtain the dual-color cells, red fluorescent protein (RFP) was expressed in the cytoplasm of a series of human and rodent cancer cells, and green fluorescent protein (GFP) linked to histone H2B was expressed in the nucleus. Nuclear GFP expression enabled visualization of nuclear dynamics, whereas simultaneous cytoplasmic RFP expression enabled visualization of nuclear-cytoplasmic ratios as well as simultaneous cell and nuclear shape changes. Using the Olympus OV100 Whole-Mouse Imaging System, total sub-cellular dynamics can be visualized in the living dual-color cells in real time in the live mouse after cell injection. Highly elongated cancer cells and nuclei in narrow capillaries were visualized where both the nuclei and cytoplasm deform. Both cytoplasm and nuclei were visualized to undergo extreme deformation during extravasation with cytoplasmic processing exiting vessels first and nuclei following along these processes. The dual-color cells described here thus enable the sub-cellular dynamics of cancer cell trafficking to be imaged in the living animal.