Functional profiling of circulating tumor cells with an integrated vortex capture and single-cell protease activity assay
Menée à l'aide de lignées cellulaires de cancer du poumon ou de la prostate puis à l'aide d'échantillons sanguins prélevés sur 7 patients atteints d'un cancer de la prostate et sur 4 témoins, cette étude présente un dispositif permettant, à partir d'une faible quantité de sang, d'isoler rapidement des cellules tumorales circulantes et de mesurer à l'échelle d'une seule cellule l'activité des métalloprotéinases matricielles, des enzymes impliquées dans l'envahissement tumoral
Tumor cells are hypothesized to use proteolytic enzymes to facilitate invasion. Whether circulating tumor cells (CTCs) secrete these enzymes to aid metastasis is unknown. A quantitative and high-throughput approach to assay CTC secretion is needed to address this question. We developed an integrated microfluidic system that concentrates rare cancer cells >100,000-fold from 1 mL of whole blood into about 50,000 2-nL drops composed of assay reagents within 15 min. The system isolates CTCs by size, exchanges fluid around CTCs to remove contaminants, introduces a matrix metalloprotease (MMP) substrate, and encapsulates CTCs into microdroplets. We found CTCs from prostate cancer patients possessed above baseline levels of MMP activity (1.7- to 200-fold). Activity of CTCs was generally higher than leukocytes from the same patient (average CTC/leukocyte MMP activity ratio, 2.6 ± 1.5). Higher MMP activity of CTCs suggests active proteolytic processes that may facilitate invasion or immune evasion and be relevant phenotypic biomarkers enabling companion diagnostics for anti-MMP therapies.
Proceedings of the National Academy of Sciences , résumé, 2017