Proteomics of REPLICANT perfusate detects changes in the metastatic lymph node microenvironment

• Main Authors: Julia Stevenson, Rachel Barrow-McGee, Lu Yu, Angela Paul, David Mansfield, Julie Owen, Natalie Woodman, Rachael Natrajan, Syed Haider, Cheryl Gillett, Andrew Tutt, Sarah E. Pinder, Jyoti Choudary, Kalnisha Naidoo
• Format: Article
• Language: English
• Published: Nature Publishing Group 2021-03-01
• Series: npj Breast Cancer
• Online Access: https://doi.org/10.1038/s41523-021-00227-7

Abstract In breast cancer (BC), detecting low volumes of axillary lymph node (ALN) metastasis pre-operatively is difficult and novel biomarkers are needed. We recently showed that patient-derived ALNs can be sustained ex-vivo using normothermic perfusion. We now compare reactive (tumour-free; n = 5) and macrometastatic (containing tumour deposits >2 mm; n = 4) ALNs by combining whole section multiplex immunofluorescence with TMT-labelled LC-MS/MS of the circulating perfusate. Macrometastases contained significantly fewer B cells and T cells (CD4+/CD8+/regulatory) than reactive nodes (p = 0.02). Similarly, pathway analysis of the perfusate proteome (119/1453 proteins significantly differentially expressed) showed that immune function was diminished in macrometastases in favour of ‘extracellular matrix degradation’; only ‘neutrophil degranulation’ was preserved. Qualitative comparison of the perfusate proteome to that of node-positive pancreatic and prostatic adenocarcinoma also highlighted ‘neutrophil degranulation’ as a contributing factor to nodal metastasis. Thus, metastasis-induced changes in the REPLICANT perfusate proteome are detectable, and could facilitate biomarker discovery.