The experimental study on anti-tumor effect of 131I-Tyr-octreotide in nude mice bearing human non-small cell lung cancer

Objective: Radionuclide-labeled low molecular weight polypeptide is recently advocated for the diagnosis and treatment of malignant tumor. The purpose of this study was to evaluate the anti-tumor effect of 131I-Tyr-octreotide in nude mice bearing human non-small cell lung cancer (NSCLC). Methods: 131I-Tyr-octreotide was prepared by Ch-T method. The radiochemical purity was measured and biodistribution was evaluated. The nude mice models bearing human NSCLC were studied and divided into four groups: group A injected 131I-Tyr-octreotide through tail vein, group B injected normal saline, group C injected 131I-Tyr-octreotide through stroma and group D injected 131I through stroma. The radioactivity ratio of tumor to normal tis- sue (T/NT) was calculated over region of interest (ROI). The tumor cell cycle and cell apoptosis were analyzed by flow cytometry (FCM), terminal deoxynucleotidyl transferase mediated dUTP-biotion nick end labeling (TUNEL) and histopathological analysis. Statistical analysis was performed with SPSS 11.0, and the comparison for difference between groups performed with one-way ANOVA analysis. Results: The labeled radiochemical purity was (95.23 ± 1.67)% and specific activity of 3.5 x l06 Bq/μg. The biodistribution showed high uptake in kidney, and low uptake in liver and spleen. The radioactive uptake in group C was higher than the other groups, and the retention time was longer. The T/NT was 52.74 ± 0.13 after 24 h, which was much higher than that of the other groups (group D: 8.90 ± 0.23, group A: 6.42 ± 0.02, q=628.81 and 664.33, all P<0.05). The results of tumor call cycle determined by FCM showed that the G1 phase was blocked most remarkably in group C than the other groups [group C: (83.17 ± 6.86)%, group A: (57.02 ± 18.81)%, group D: (49.29 ± 7.80)%, group B: (45.88 ± 5.13)%, q=5.29, 6.86, 7.55, 1.56, 2.26, 0.69, all P<0.05]. Apoptotic cells were observed by TUNEL, and apoptotic body was detected by immuno-histochemical examination. Conclusions: 131I-Tyr-octreotide was easily labeled by Ch-T. 131I-Tyr-octreotide could induce tumor cell apoptosis and inhibit the tumor cell of NSCLC. It might be a potential target-directed agent in NSCLC. (authors)