Cancer cells that transit from primary tumours into the circulatory system are known as circulating tumour cells (CTCs). These cancer cells have unique phenotypic and genotypic characteristics which allow them to survive within the circulation, subsequently extravasate and metastasise. CTCs have emerged as a useful diagnostic tool using “liquid biopsies” to report on the metastatic potential of cancers. However, CTCs by their nature interact with components of the blood circulatory system on a constant basis, influencing both their physical and morphological characteristics as well as metastatic capabilities. These properties and the associated molecular profile may provide critical diagnostic and prognostic capabilities in the clinic. Platelets interact with CTCs within minutes of their dissemination and are crucial in the formation of the initial metastatic niche. Platelets and coagulation proteins also alter the fate of a CTC by influencing EMT, promoting pro-survival signalling and aiding in evading immune cell destruction. CTCs have the capacity to directly hijack immune cells and utilise them to aid in CTC metastatic seeding processes. The disruption of CTC clusters may also offer a strategy for the treatment of advance staged cancers. Therapeutic disruption of these heterotypical interactions as well as direct CTC targeting hold great promise, especially with the advent of new immunotherapies and personalised medicines. Understanding the molecular role that platelets, immune cells and the coagulation cascade play in CTC biology will allow us to identify and characterise the most clinically relevant CTCs from patients. This will subsequently advance the clinical utility of CTCs in cancer diagnosis/prognosis.

RationaleMutations in the cystic fibrosis transmembrane regulator (CFTR) gene form the basis of cystic fibrosis (CF). There remains an important knowledge gap in CF as to how diminished CFTR activity leads to the dominant inflammatory response within CF airways.ObjectivesTo investigate if extracellular vesicles (EVs) contribute to inflammatory signalling in CF.MethodsEVs released from CFBE41o-, CuFi-5, 16HBE14o- and NuLi-1 cells were characterised by nanoparticle tracking analysis (NTA). EVs isolated from bronchoalveolar lavage fluid (BALF) from 30 people with CF (PWCF) were analysed by NTA and mass spectrometry and compared with controls. Neutrophils were isolated from the blood of 8 PWCF to examine neutrophil migration in the presence of CFBE41o- EVs.ResultsA significantly higher level of EVs were released from CFBE41o- (p<0.0001) and CuFi-5 (p=0.0209) relative to control cell lines. A significantly higher level of EVs were detected in BALF of PWCF, in three different age groups relative to controls (p=0.01, 0.001, 0.002). A significantly lower level of EVs were released from CFBE41o- (p<0.001) and CuFi-5 (p=0.0002) cell lines treated with CFTR modulators. Significant changes in the protein expression of 126 unique proteins was determined in EVs obtained from the BALF of PWCF of different age groups (p<0.001–0.05). A significant increase in chemotaxis of neutrophils derived from PWCF was observed in the presence of CFBE41o EVs (p=0.0024) compared with controls.ConclusionThis study demonstrates that EVs are produced in CF airway cells, have differential protein expression at different ages and drive neutrophil recruitment in CF.