OBJECTIVETo establish an animal model visualizing orthotopic growth and metastasis of colorectal cancer.

METHODSpEGFP-N1 plasmid was transfected into human colorectal carcinoma cell line SW480 so that the resultant SW480/EGFP cells emitted fluorescence that could be detected externally by fluorescence stereo microscope. SW480/EGFP cells were inoculated subcutaneously in nude mice, and the orthotopic tumor growth was evaluated in real time. Whole-body visualization models of orthotopically implanted colorectal carcinoma was established surgically, and the tumor growth and metastasis are evaluated by conventional pathological methods.

RESULTSSW480/EGFP cells stably expressed high-levels of enhanced green fluorescent protein. Subcutaneous injection of SW480/EGFP cells resulted in tumor growth in nude mice, and the emitted fluorescence could be quantitatively detected and imaged with fluorescence stereo microscope to visualize real-time tumor growth. Visualization animal model was established successfully with surgical orthotopic implantation (SOI) of the tumor, and all mice survived. After two weeks, all the mice developed colorectal carcinoma without metastasis, but 4 weeks later, 75%percnt; of the mice developed peritoneal tumor metastasis and 50% had liver metastasis. The whole-body visualization animal model was successfully validated by pathological detection.

CONCLUSIONWhole-body visualization model of orthotopic and metastatic tumor growths provides a reliable means for observing the behavior of human colorectal carcinoma and can be helpful to study the growth and metastasis patterns of the cancer.