| Lung cancer is one of the most common malignant tumors in the worldwide. Now, the morbidity and mortality of lung cancer are the highest in the world. For the past few years, the morbidity is hoicking in China, the five-year survival rate of lung cancer is less than 15 % because of the low diagnosis, most of the patients who are defined as lung cancer are often already in advanced stage or metastasis. Now, the treatment of lung cancer is mainly operation and combination chemotherapy. Many adverse reactions are generated because of the cytotoxic chemotherapy, so it results in bad tolerance, improving the early diagnosis and targeted treatment of lung cancer are the investigation trend in the world. ZS-1 is a peptide derived from a Phage-displayed peptide library, which is specifically bound to human non-small cell lung carcinoma cell, so, to study the targeted identification and pharmacokinetics of ZS-1 in this paper to provide the theory of a new drug targeted to lung cancer.First, the targeting and the speciality of the peptide were identified in this paper . immunofluorescence assay was used to identify the speciality of ZS-1 in two non-small cell lung cancer cells NCI-H1299 and A549, human normal liver cell line LO-2 and human lung embryo fibroblasts cell line WI-38 were control cells. The result showed that the polypeptide [ZS-1]FITC had high affinity with lung squamous carcinoma cell line NCI-H1299 and lung adenocarcinoma cell line A549, but almost no affinity with normal liver cell line and lung cell line. Human ling cancer tissues chip was used to the speciality of ZS-1, positive was defined as the fluorescence intensity of lung cancer tissues was twice than the normal control tissues, the fluorescent scanning result showed that the positive rate of [ZS-1]FITC was 37.3 %, the fluorescence intensity of eight control tissues was twice less than the lung cancer tissues, so the false-positive rate of [ZS-1]FITC was 0 %, the result indicated that ZS-1 had high speciality with lung cancer tissues. [ZS-1]FITC was administrated intravenously to NCI-H1299-bearing nude mouse, tumor, heart, liver, spleen, lung, kidney, cerebrum, and myeloid were made into frozen sections to observe the fluorescence intensity. Result showed that the fluorescence intensity of the tumor was the most, ZS-1 was mainly in the tumor tissue, second, ZS-1 was distributed to the liver and kidney, the fluorescence intensity of heart, spleen, ling, cerebrum and myeloid was very low. The result indicated that ZS-1 had high affinity with lung cancer tissues.On account of good target of ZS-1, the chapter is to study the pharmacokinetics of ZS-1 in rats to learn the stability and the metabolism, the results of methodology showed that no interference from endogenous substances was observed at the retention time of ZS-1 in rat plasma. Overall chromatographic running time was established at 40 min with the retention time of ZS-1 was 13.8 min, The calibration curve was linear over a concentration range of 0.1-50μg.mL-1. The calibration curve was y = 19894 x -196.89, the determination coefficient (R2) was 1. The LOD of the assay defined as the concentration of ZS-1 for which the signal-to-noise ratio was 3:1 was 0.02μg.mL-1. The overall precision, expressed as RSD, was < 10 %. RSD of intra-day was ranged from 1.5 % to 8.9 % and RSD of inter-day was ranged from 0.9 % to 5.4 %. Measurement accuracy ranged between 95.0 % and 102.0 % (intra-day) and between 102.0 % and 119.5 % (inter-day). These results indicated precision and accuracy were acceptable for pharmacokinetic analysis of ZS-1. The mean extraction recovery of ZS-1 was 86.1 %. The stability result of ZS-1 in rat plasma in vitro showed that the concentration of ZS-1 in rat plasma decreased with time increasing, at 5 min, the recovery rate was 91.2 %, and the RSD was 2.4 %. at 35 min, the recovery rate was 12.5 %, and the RSD was 7.8 %, after 35 min, the concentration of ZS-1 in rat plasma was below the limit of the determination, at -20℃three freeze-thaw cycles, the recovery rate was 86.1 %, and the RSD was 2.4 %, the degradation rate of ZS-1 was 13.9 %, at -20℃for a month, the recovery rate was 92.7 %, and the RSD was 8.0 %, the significant degradation was not observed, at -80℃for a month, the recovery rate was 71.3 %, and the RSD was 5.3 %, the degradation rate of ZS-1 was 28.7 %. However, ZS-1 had good stability in the mixture of acetonitrile and water. The results indicated there was no significant degradation of ZS-1 under room temperature (25℃) for 2, 4, 6 h, three freeze-thaw cycles, -20℃for a month, and -80℃for three months. The accuracy of ZS-1 was between 96.8 % and 103.0 %. This demonstrated that ZS-1 had a good stability under the four conditions. ZS-1 was administered at a dose of 20 mg.kg-1, 30 mg.kg-1 and 45 mg.kg-1, respectively. Blood samples were collected at 0.5, 3, 8, 12, 15, 20, 30, 40 and 45 min. ZS-1 in rat plasma was measured by RP-HPLC. Pharmacokinetic data were estimated from measured ZS-1 plasma concentrations using 3P87. The result showed that the concentration-time curves of ZS-1 fitted well to one compartment model. Area under the concentration-time curves (AUC) increased with dose. Clearance rates (CL) and elimination half-lives (T1/2) had no significant difference between different dose groups. After administration 20 mg.kg-1 of ZS-1, AUC0-45, Cmax, T1/2, V, and CL were 155.5±25.7μg.min.mL-1, 17.9±1.0μg.mL-1, 7.2±1.4 min, 1117.1±20.2 mL.kg -1 and 143.5±28.0 mL.min-1.kg-1. After administration of 30 mg.kg-1, the respective values were 307.5±57.5μg.min.mL-1, 31.6±2.5μg.mL-1, 8.3±1.4 min, 1187.2±150.1 mL.kg -1 and 102.6±28.8 mL.min-1.kg-1. After administration of 45 mg.kg-1, the respective values were 573.3±60.2μg.min.mL-1, 47.4±3.1μg.mL-1, 8.8±1.7 min, 652.4±68.0 mL.kg -1 and 75.6±8.2 mL.min-1.kg-1, respectively.In the end, the distribution of ZS-1 in NCI-H1299-bearing nude mouse was studied by RP-HPLC, The calibration curve of tissues was linear over a concentration range of 0.1-50μg.mL-1. The recovery of ZS-1 in tissues was between 60.4 % and 85.1 %, and the RSD was between 2.3 % and 7.7 %. After administration of 30 mg kg-1, the nude mouse was etherized at 5, 10, 15, 20, 25 min then the tumor, heart, spleen, lung, kidney and cerebrum were homogenated, ZS-1 in tissues were measured by RP-HPLC. The result showed that ZS-1 could be determined at 5 min except for cerebrum, ZS-1 was mainly distributed in heart, liver, kidney. At 10 min, ZS-1 could not be determined in lung, the concentration of ZS-1 in tumor was 11.3±0.31μg mL-1, it was highest in tumor. At 15 min, ZS-1 could not be determined in lung, the concentration of ZS-1 in tumor was 11.3±0.31μg.mL-1, it was highest in tumor. ZS-1 could only be determined in tumor, liver, kidney, the corresponding concentration of ZS-1 was 4.2±0.27μg.mL-1, 1.6±0.15μg.mL-1,3.5±0.17μg.mL-1, it was also highest in tumor. At 20 min, ZS-1 could only be determined in tumor and kidney, the corresponding concentration of ZS-1 was 1.3±0.05μg.mL-1, 0.9±0.05μg.mL-1. At 25 min, the concentration of ZS-1 in all tissues was below the limit of determination, therefor, ZS-1 had high affinity with lung squamous carcinoma tissue.The results above indicate that in vitro the peptide ZS-1 has good targeting and tussue affinity, in vivo the peptide ZS-1 has good tussue targeting and stability. Therefor, it can be a basis for developing the targeting drug delivery and diagnosis agent of lung cancer.
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