How can we monitor the course of tumor growth and metastasis in living animals and what can it tell us about cancer?

We are working to optimize fluorescent molecular detection of tumor cells in living mice. We use a near-infrared fluorophore (i.e.; LI-COR IRDye 800CW) coupled to a targeting molecule such as EGF, which binds EGF receptor that is elevated on tumor cells, or 2-deoxyglucose, which binds the glucose transporter GLUT1 that is elevated in hypoxic tissue. This coupled targeting fluorophore accumulates where there is tumor tissue and can be detected in near-infrared wavelengths when activated by a laser. One advantage of a method like this is that we can locate tumors within the mouse, approximate their size, and track changes in size and location over time. Another advantage is that the targeting molecule allows us to probe changes in receptor density within the tumors. This allows us to examine the effects of various treatments on receptor expression and correlate with tumor progression or regression.

Two-color imaging of bone turnover and tumor metabolic activity. Nuce mice were injected with bone label (LI-COR IRDye 680 conjugated to a bone-specific targeting agent) at 3 and 4 weeks of age. Tumor cells were injected subcutaneously at 6 weeks. Animals bearing 22Rv1 or A431 tumors were injected via the tail vein with IRDye 800CW 2-DG (2-deoxyglucose, targeting GLUT1) and imaged in two wavelengths on the Pearl Small Animal Imager 24 h post-injection. Excised tumors were fixed, paraffin-embedded, sectioned and scanned on the Odyssey Imaging System. Specific fluorescence in the 800 nm channel is in green and autofluorescence in the 700 nm channel is in red.