Visualizing collagen proteolysis by peptide hybridization: From 3D cell culture to in vivo imaging.
Degradation of the extracellular matrix (ECM) is one of the fundamental factors contributing to a variety of life-threatening or disabling pathological conditions. However, a thorough understanding of the degradation mechanism and development of new ECM-targeting diagnostics are severely hindered by a lack of technologies for direct interrogation of the ECM structures at the molecular level. Previously we demonstrated that the collagen hybridizing peptide [CHP, sequence: (GPO)9, O: hydroxyproline] can specifically recognize the degraded and unfolded collagen chains through triple helix formation. Here we show that fluorescently labeled CHP robustly visualizes the pericellular matrix turnover caused by proteolytic migration of cancer cells within 3D collagen culture, without the use of synthetic fluorogenic matrices or genetically modified cells. To facilitate in vivo imaging, we modified the CHP sequence by replacing each proline with a (2S,4S)-4-fluoroproline (f) residue which interferes with the peptide's inherent propensity to self-assemble into homo-triple helices. We show that the new CHP, (GfO)9, tagged with a near-infrared fluorophore, enables in vivo imaging and semi-quantitative assessment of osteolytic bone lesions in mouse models of multiple myeloma. Compared to conventional techniques (e.g., micro-CT), CHP-based imaging is simple and versatile in vitro and in vivo. Therefore, we envision CHP's applications in broad biomedical contexts ranging from studies of ECM biology and drug efficiency to development of clinical molecular imaging.
['Bennink|Lucas L|LL|', 'Li|Yang|Y|', 'Kim|Bumjin|B|', 'Shin|Ik Jae|IJ|', 'San|Boi Hoa|BH|', 'Zangari|Maurizio|M|', 'Yoon|Donghoon|D|', 'Yu|S Michael|SM|']
D000818:Animals D001862:Bone Resorption D045744:Cell Line, Tumor D002465:Cell Movement D002478:Cells, Cultured D003094:Collagen D005109:Extracellular Matrix D005260:Female D005456:Fluorescent Dyes D051379:Mice D009101:Multiple Myeloma D009842:Oligopeptides D011392:Proline D000072756:Protein Conformation, alpha-Helical D059748:Proteolysis
Triple helix Bone resorption Cell migration ECM proteolysis Imaging probe