title: Imaging tumor-induced sentinel lymph node lymphangiogenesis with LyP-1 peptide.
abstract: Lymphangiogenesis in tumor-draining lymph nodes (LNs) starts before the onset of metastasis and is associated with metastasis to distant LNs and organs. In this study, we aimed to visualize tumor-induced lymphangiogenesis with a tumor lymphatics-specific peptide LyP-1. The LyP-1 peptide was labeled with a near-infrared fluorophore (Cy5.5) for optical imaging. At days 3, 7, 14 and 21 after subcutaneous 4T1 tumor inoculation, Cy5.5-LyP-1 was administered through the middle phalanges of the upper extremities of the tumor-bearing mice. At 45 min and 24 h postinjection, brachial LN fluorescence imaging was performed. Ex vivo fluorescence images were acquired for quantitative analysis of the fluorescence intensity. Tumor-induced lymphangiogenesis was confirmed by LYVE-1 immunostaining and increased size of tumor side brachial LNs. Cy5.5-LyP-1 staining in LNs co-localized with LYVE-1, suggesting lymphatics-specific binding of LyP-1 peptide. The brachial LNs were clearly visualized by optical imaging at both time points. The tumor side LNs showed significantly higher fluorescence intensities than the contralateral brachial LNs at days 7, 14, and 21, but not day 3 after tumor inoculation. At day 21 after tumor inoculation, the average signal of tumor-draining LNs was 78.0±2.44, 24.3±5.43, 25.6±0.25 (×10(3) photon/cm2/s) using Cy5.5-LyP-1, Cy5.5-LyP-1 with blocking, and Cy5.5 only, respectively. Tumor-draining brachial LNs showed extensive growth of lymphatic sinuses throughout the cortex and medulla. Use of LyP-1 based imaging probes with optical imaging offers a useful tool for the study of tumor-induced lymphangiogenesis. LyP-1 may serve as a marker of lymphangiogenesis useful in detecting "high risk" LNs before tumor metastasis and after micro-metastasis, as well as for screening potential anti-lymphatic therapies.
authors.affiliation: Department of Radiology, Nanjing Jinling Hospital, Clinical School of the Medical College of Nanjing University, Nanjing, 210002, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: Gang
authors.initials: G
authors.lastname: Niu
authors.forename: Xin
authors.initials: X
authors.lastname: Lin
authors.forename: Orit
authors.initials: O
authors.lastname: Jacobson
authors.forename: Ying
authors.initials: Y
authors.lastname: Ma
authors.forename: Henry S
authors.initials: HS
authors.lastname: Eden
authors.forename: Yulong
authors.initials: Y
authors.lastname: He
authors.forename: Guangming
authors.initials: G
authors.lastname: Lu
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Chen
mesh_terms: D000818:Animals; D002232:Carbocyanines; D003952:Diagnostic Imaging / Q000379:methods*; D005456:Fluorescent Dyes; D006023:Glycoproteins / Q000032:analysis; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D007279:Injections, Subcutaneous; D008198:Lymph Nodes / Q000473:pathology*; D042583:Lymphangiogenesis; D008207:Lymphatic Metastasis / Q000473:pathology*; D042601:Lymphatic Vessels / Q000473:pathology*; D026901:Membrane Transport Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D010456:Peptides, Cyclic / Q000737:chemistry*; D047368:Tumor Burden
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; D006023:Glycoproteins; D026901:Membrane Transport Proteins; D010456:Peptides, Cyclic; C098793:CY5.5 cyanine dye; C533969:LyP-1 peptide; C492273:LYVE1 protein, mouse