Background: Non-small cell lung cancer (NSCLC) is the most common histological type of lung cancer, and one of the malignant tumor with the highest mortality. As the main part of the optical molecular imaging probe, peptide can realize the early screening and diagnosis of tumor and improve the survival rate of patients. The aim of this study was to screen the small-molecule peptide that highly binds to NSCLC NCI-H1299 cells using in vivo phage display technology and to identify their binding specificity by in vitro experiment.
Methods: To prepare a tumor-bearing nude mouse model of NCI-H1299 cells, after 3 rounds of in vivo screening with Ph.D.-C7CTM Peptide Library, phage clones were randomly picked, using immunohistochemistry and enzyme-linked immunosorbent assay (ELISA) to identify the affinity of phage clones to NCI-H1299 cells. The positive monoclonal phages DNA was extracted and sequenced to obtain the amino acid sequence of the peptides. The peptides with the highest repetition rate was chemically synthesized and labeled with fluorescein (FITC) to prepare optical molecular probe. We preliminary identified the specificity of the probe binding to lung cancer cells by in vitro experiment.
Results: After three rounds of in vivo screening, the phages enrichment rate was 341.3 times compared with the first round. Immunohistochemical staining showed that with the increase of screening times, the phages binding to tumor tissues continued to increase, and the binding amount was significantly higher than normal tissues; ELISA results showed that 20 clones among the 30 randomly selected phage clones were positive. After sequencing, the peptide with the highest repetition rate was synthesized and named NSP1; Methyl thiazolyl tetrazolium assay (MTT) and would healing assay showed that NSP1 will not affect cell proliferation and migration. Flow cytometry and immunofluorescence showed specific binding of NSP1 to NCI-H1299 cells.
Conclusions: We successfully obtained the peptide NSP1 that specifically binds to lung cancer NCI-H1299 cells by in vivo phage display, which provide a theoretical basis for NSCLC early diagnosis and targeted therapy.
【中文题目：人非小细胞肺癌NCI-H1299细胞 特异性结合肽的筛选及鉴定】 【中文摘要：背景与目的 非小细胞肺癌（non-small cell lung cancer, NSCLC）是最常见的肺癌组织学类型，也是病死率最高的恶性肿瘤之一。多肽作为光学分子成像探针的主体可以实现肿瘤的早期筛查及诊断，提高患者存活率。本研究旨在利用体内噬菌体展示技术筛选与人NSCLC细胞NCI-H1299高度结合的小分子多肽并通过体外实验鉴定其结合特异性。方法 制备NCI-H1299细胞荷瘤裸鼠模型，用噬菌体展示环七肽库进行3轮体内筛选后随机挑取噬菌体克隆，免疫组织化学法及酶联免疫吸附法（enzyme-linked immunosorbent assay, ELISA）鉴定噬菌体克隆对NCI-H1299细胞的亲和力。提取阳性单克隆噬菌体DNA测序获得外源多肽氨基酸序列，将重复率最高的序列化学合成多肽并进行异硫氰酸荧光素（fluorescein, FITC）标记，制备光学分子探针，初步鉴定其对NCI-H1299细胞的特异性。结果 经3轮体内筛选后噬菌体富集率是首轮的341.3倍；免疫组织化学染色显示随着筛选次数增加，肿瘤组织中结合的噬菌体不断增加，且结合量明显高于正常组织；ELISA结果显示随机挑取的30个噬菌体克隆中20个为阳性克隆，经测序后将重复率最高的序列合成多肽并命名为NSP1；四甲基偶氮唑盐比色法（methyl thiazolyl tetrazolium assay, MTT）、细胞划痕实验表明NSP1不会影响细胞增殖、迁移；流式细胞术、细胞免疫荧光结果表明NSP1可与NCI-H1299细胞特异性结合。结论 利用体内噬菌体展示技术成功得到了与肺癌NCI-H1299细胞特异性结合的多肽NSP1，为NSCLC的早期诊断及靶向治疗奠定了研究基础。】 【中文关键词：噬菌体展示技术；肺肿瘤；NCI-H1299细胞；特异性结合肽】.
Keywords: Lung neoplasms; NCI-H1299 cells; Phage display technology; Specific binding peptide.