We previously reported the genetic engineering of dual-color fluorescent cancer cells with one color in the nucleus and the other in the cytoplasm that enables real-time nuclear-cytoplasmic dynamics to be visualized in living cells in vivo. To obtain the dual-color cells, red fluorescent protein (RFP) was expressed in the cytoplasm of 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. Thus, total cellular dynamics can be visualized in the living dual-color cells in real time. In order to visualize the trafficking of single cancer cells in the bone, dual-color Lewis lung carcinoma cells were injected into the right common carotid artery. The frontal bone and parietal bone of the skull were exposed after an arc-shaped scalp incision. The animals were observed with the Olympus OV100 Small Animal Imaging System under high magnification. The double labeling enabled cellular and nuclear dynamics to be imaged as cancer cells trafficked intra- and extra-vascularly within the bone. Many of the cancer cells rapidly lost their cytoplasm and thereby their viability. A small number of the extravascular cells survived after 24 hours and were able to form colonies in the bone. The mechanism of bone trafficking, seeding and bone colonization by cancer cells can now be visualized in real time.

98th AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA