RESUMEN
Objective To establish the radiolabeling method for peptide K237 with 131I and investigate the biodistribution and therapeutic efficacy of 131I-K237 on nude mice bearing human lung cancer.Methods Iodogen method was used for labeling K237. The bioactivity of 131I-K237 was tested by human umbilical vein endothelial cell ( HUVEC ) proliferation inhibitory assay and the affinity of 131I-K237 was examined by competition binding studies. Twenty-five mice were divided into five groups randomly, including physiologic saline (group 1), K237 (40 μg) (group 2), 131I ( 11. 1 MBq) (group 3), 131I-K237 (K237 40 μg, 11. 1 MBq) intravenously ( group 4), and 131I-K237 ( K237 40 μg, 11.1 MBq) intratumorally (group 5). Injections were repeated at 15 d after the first injection. The tumor growth inhibition rate was calculated. Student's t-test and analysis of variance (ANOVA) were used for testing significant differences of data. Results The inhibition rate of HUVEC proliferation had no significant difference between radiolabeled K237 and unlabeled K237 ( (73.69 ± 5.36) % vs ( 62.68 ± 3.83 ) %, t = 1.67, P ＞ 0.05 ). The growth of transplanted lung cancer was inhibited by 75. 01 % in group 4, 78.99% in group 5, 31.15% in group 2 and 12.61% in group 3, respectively. The average tumor volume of groups 4 and 5 were significantly smaller than that of groups 1,2, and 3 ( F = 15. 233 and 13.611, respectively, P ＜0. 01 ). Conclusion 131I-K237 can be readily radiolabeled and it can effectively inhibit the growth of tumor in nude mice bearing human lung cancer.