To the Editor:
Cruz-Munoz and colleagues (1) state that their findings represent the first report of spontaneous central nervous system metastases generated from primary tumors of any human cancer in mice, which heritably maintain this phenotype. It should be noted, however, that with the use of imaging based on green fluorescent protein (GFP) expression in tumor cells (2), we have observed spontaneous metastasis to the brain in three orthotopic nude mouse model systems of human cancer: the PC-3 human prostate cancer cell line (3); the LOX human melanoma cell line (Fig. 1; ref. 4); and spinal cord glioma model using the U87 human glioma cell line (5).
Brain metastasis of LOX cells visualized by GFP. A to C, micrometastases (arrows) are visualized in the brain of nude mice by GFP expression. Imaging was done with a Nikon microscope equipped with a Xenon lamp power supply with a GFP filter set (Chroma Technology). Bar, 80 μm.
Brain metastasis of LOX cells visualized by GFP. A to C, micrometastases (arrows) are visualized in the brain of nude mice by GFP expression. Imaging was done with a Nikon microscope equipped with a Xenon lamp power supply with a GFP filter set (Chroma Technology). Bar, 80 μm.
Our observations increase the importance of the work of Cruz-Munoz and colleagues (1) because our data suggest that stable cell lines with predilection for metastasis to the brain could be readily identified with the use of GFP.
Disclosure of Potential Conflicts of Interest
No potential conflicts of interest were disclosed.
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