Non-invasive and real-time monitoring of molecular targeting therapy for lymph node and peritoneal metastasis in nude mice bearing xenografts of human colorectal cancer cells tagged with GFP and DsRed

摘要

We have developed an in vivo imaging system consisting of GFP- and DsRed-tagged human colonic cancer cell line, which has peritoneal and lymph node metastatic potential and show high sensitivity to EGFR targeting drugs, and convenient detection devices for GFP and DsRed. The latter includes a small handy fluorescence detection device for external monitoring of the therapeutic effect of the drug and a convenient stereo fluorescent microscope for internal visualization of micrometastases. We applied this imaging system to investigate anti-metastatic effects of EGFR targeting drugs such as gefitinib (Iressa). This system allowed sensitive detection of the development of peritoneal and lymph node metastases from the micrometastasis stage at the cellular level and also permited noninvasive, non-anesthetic monitoring of anti-metastatic effect of the drug in an animal facility without any pretreatment. Significant decreases in the intraabdominal metastatic tumor growth and prevention of inguinal lymph node metastasis by gefitinib treatment could be clearly monitored. These results suggest that convenient, low-cost, true real-time monitoring of therapeutic effect using such a fluorescence-mediated whole body imaging system seems to enhance the speed of preclinical study for novel anti-cancer agents and will allow us to understand the action mechanism of molecular targeting drugs.