ABSTRACT
BACKGROUND & OBJECTIVE: The aim of this study was to investigate the influence of low dosage (131)I-labeled anti-carcinoembryonic antigen (CEA) monoclonal antibody C50 ((131)I-C50) on tumor growth and the therapeutic efficacy of combination of low dosage (131)I-C50 with chemotherapy using 5-fluorouracil (5-FU) on human colorectal cancer xenografts in nude mice. METHODS: Human colorectal cancer xenografts with positive CEA expression were established in nude mice with LoVo cell line. 5-FU, 2,775 kBq (131)I-C50, and 5-FU combined with (131)I-C50 were given to nude mice through tail vein to treat xenografts at 9(th) day after implantation of tumor cells. Two of the mice of each group were sacrificed randomly at 7(th) day after the treatment; and cellular ultrastructure of tumor tissues was examined under electron microscope. Pathological changes of tumor tissues were examined under light microscope. Tumor volume, tumor doubling time, and inhibition rate of each group were calculated. Tumor volumes of all groups at 30(th) day after implantation were compared with each other. RESULTS: There was significant difference of tumor volumes at 30(th) day after implantation between each other among control group, chemotherapy group, radioimmunotherapy (RAIT) group, and RAIT+chemotherapy group (P< 0.001). Tumor doubling time of these groups was prolonged and tumor inhibition rates increased successively. CONCLUSION: Low dosage (131)I-C50 can inhibit tumor growth of human colorectal cancer xenografts in nude mice. Efficacy of tumor growth inhibition can be enhanced by combination of low dosage (131)I-C50 with chemotherapy.
