Patients with breast cancer (BC) often display elevated levels of circulating neutrophils (Ns). Evidence from mouse models of early breast cancer (EBC) shows that Ns can either have a tumour promoting or inhibitory role. CD62L (L-selectin) is a cell adhesion molecule found on the surface of Ns which helps them bind to the endothelium and migrate into tissues and is also rapidly shed upon N activation. Our laboratory found a lower proportion of Ns expressing CD62L in mouse models of BC, which implies that these Ns have less endothelial- adhesive capacity and may remain in the circulation for longer. There is limited knowledge whether different circulatory N subsets are present in patients with BC and if this is influenced by BC subtype. In order to address these questions, we phenotyped Ns from BC patients.
We investigated changes in CD62L expression via flow cytometry in Ns from patients and healthy volunteers (HVs). Since kinases govern many aspects of intracellular signalling, we assessed the kinase activity (n = 340 kinases) within Ns using a Pamgene kinase assay. We recruited 28 patients with EBC (10 Node +, 18 node -; 10 T1 and 16 T2 and 2 T3) and paired HVs (age matched) to compare the phenotype of Ns isolated from blood. 21 Patients with Oestrogen receptor positive (ER+) and 7 with Oestrogen receptor negative (ER−) EBC were recruited between June 2018 and June 2021. No patient had overt metastatic disease and all were screened for exclusion factors.
ER+ patients had lower level of CD62Llow N subsets compared to HVs (P< 0.0375). There was a significant increase in CD62Llow N subsets (2-fold higher) for ER- patients compared to HVs (P< 0.0316). There was a general upregulation in kinase activity for patients with ER+ BC and a downregulation in kinase activity for ER- BC patients compared to paired HVs. The functional implications of these differences in kinase activity are being actively investigated.
We have detected changes in CD62L expression and kinase activity within circulatory Ns in patients with EBC and the nature of these changes appear to be intrinsically linked to ER subtype. These findings may have important implications for use as part of an early diagnostic multi-omic platform.
Legal entity responsible for the study
Imperial College London.
Medical Research Council.
All authors have declared no conflicts of interest.