关键词: 壳聚糖, 奥曲肽, 肺肿瘤, 分子信标, miR-155, 分子成像

Abstract:

Objective To investigate the identification of octreotide (OCT) modified chitosan (CS) miR-155 molecular beacon nanoparticles (CS-miR-155-MB-OCT) and imaging of lung cancer cells for the early screening of lung cancer. Methods A nude mouse model of lung transplantation tumor was established by injecting A549 lung cancer cells into tail veins to establish lung xenograft models. Cre adenovirus was injected through nasal cavity, and mice were killed at 4, 6, 8 and 12 weeks after adenovirus injection to establish lung cancer models of atypical hyperplasia, adenoma, carcinoma in situ and adenocarcinoma of lung in LSL K-ras G12D transgenic mice at different pathological stages. Lung tissue samples were taken and observed by HE staining. Immunohistochemistry were used to detect the expression of somatostatin receptor 2 (SSTR2). Real-time fluorescence quantitative PCR was used to detect miR-155 expression levels in lung xenograft models and transgenic mice at different stages of lung cancer. Then CS-miR-155-MB and CS-miR-155-MB-OCT were injected via tail vein in lung xenograft models. CS-miR-155-MB-OCT was injected via tail vein in transgenic mice models. The fluorescence signals of lung in nude mice and transgenic mice at different disease stages were imaged by living imaging system. Frozen slices of lung tissue were made. The source of fluorescence signal was detected by laser confocal scanning microscope (CLSM). Results HE staining showed that lung transplantation tumor models and lung cancer models of atypical hyperplasia, adenoma, carcinoma in situ and lung adenocarcinoma at different pathological stages were successfully constructed. Immunohistochemical analysis showed somatostatin receptor 2 (SSTR2) was expressed in transplanted lung tumor and tissue at different pathological stages. In transgenic mouse models，the expression of miR-155 was gradually increased as the disease progressed (P<0.05). In lung xenograft models, the fluorescence signals were significantly higher in the CS-miR-155-MB-OCT group than those of the CS-miR-155-MB group (P<0.05). In transgenic mouse models, the fluorescence signals gradually increased with the gradual progression of lesions (P<0.05). After re-imaging the lung tissue, it was found that the fluorescence signal came from lung, and CLSM showed that the fluorescence signal came from cancer cells and some normal alveolar epithelial cells. Conclusion CS-miR-155-MB-OCT can dynamically reflect the occurrence and development of lung cancer according to changes of different fluorescence intensity, thus providing a new technology for the early diagnosis of lung cancer.

Key words: chitosan, octreotide, lung neoplasm, molecular beacon, miR-155, molecular imaging