Characterising the epithelial-mesenchymal transition status of circulating tumour cells in head and neck squamous cell carcinoma

BACKGROUND: Circulating tumour cells (CTCs), in particular those undergoing an epithelial-mesenchymal-transition (EMT), are a promising source of biomarkers in head and neck squamous cell carcinoma (HNSCC). Our aim was to validate a protocol using microfluidic enrichment (Parsortix platform) with flow-cytometry CTC characterisation.

METHOD: Blood samples from 20 treatment naïve HNSCC patients underwent Parsortix enrichment and flow-cytometry analysis to quantify CTCs and identify epithelial or EMT sub-groups - correlated to EMT gene-expression in tumour tissue.

RESULTS: CTCs were detected in 65% of patients (mean count 4 CTCs/ml). CTCs correlated with advanced disease (p=0.0121), but not T or N stage. Epithelial or EMT CTCs did not correlate with progression-free or overall-survival. Tumour mesenchymal gene-expression did not correlate with CTC EMT expression (p=0.347).

DISCUSSION: Microfluidic enrichment and flow-cytometry successfully characterises EMT CTCs in HNSCC. The lack of association between tumour and CTC EMT profile suggests may undergo an adaptive EMT in response to stimuli within the circulation.