Analysis Of Circulating Tumor Cell Subpopulations Based On Epithelial-mesenchymal Transition:A Proof-of-principle Study On The Heterogeneity Of Circulating Tumor Cells

Although the enumeration of circulating tumor cells(CTCs)has been demonstrated to be a prognostic indicator in metastatic breast cancer,the heterogeneous characteristics of CTCs,such as variations in the epithelial-mesenchymal transition(EMT),may limit its broad clinical application.To investigate an uncomplicated and practicable detection approach based on the potential utility of the heterogeneity of CTCs from the standpoint of the EMT phenotype and ER/PR status of CTCs,an analysis was conducted using peripheral blood samples obtained from 28 metastatic breast cancer patients.The CanPatrol CTC enrichment technique was used to identify different CTC subpopulations,including epithelial-dominated CTCs,biophenotypic epithelial/mesenchymal CTCs,and mesenchymal-dominated CTCs,according to epithelial and mesenchymal markers.Furthermore,the hormone receptor(HR)status of each CTC was determined based on the expression levels of three reference genes and was characterized by four levels,which ranged from high-level expression to non-expression.We subsequently concluded that based on EMT phenotypes,the order of different CTC subgroups differed according to the HR expression status of the primary tumor.With respect to the HR status between tissues and CTCs,the variation tendency from high-level expression to non-expression of HR in CTCs was significantly correlated with the HR status of the primary tumor.The findings could provide evidence for the potential application of this uncomplicated and practicable detection approach for prognostic analysis and individualized endocrine therapeutic direction in a real-time manner via confirmation in further large-scale trials.The epithelial-mesenchymal transition(EMT)progression of circulating tumor cells(CTCs)is considered to be related with disease progression in metastatic breast cancer(MBC).However,the possible relationship between CTC subpopulation based on EMT and clinicopathological features associated with prognosis of early breast cancer patients are still to be certificated.Therefore,we performed this prospective observational study enrolled 150 patients with early breast cancer using the CanPatrol CTC enrichment technique to investigate the CTC subpopulations based on EMT in peripheral blood samples.By comparing with clinicopathological features,we found that different categories of the CTC subpopulations based on EMT phenotype were significantly different in variation tendency from epithelial-dominated CTCs to mesenchymal-dominated CTCs with respect to clinical TNM stage(Z= 39.723,P<0.001).Besides that,significant difference was observed in the variation tendency from epithelial-dominated CTCs to mesenchymal-dominated CTCs between different recurrence risk groups(Z=-7.101,P<0.001).Moreover,the variation tendency from epithelial-dominated CTCs to mesenchymal-dominated CTCs also demonstrated statistically significant difference when taking 20%as the cutoff for Ki 67 index of histopathology(Z=-5.687,P<0.001).In conclusion,the variation tendency from epithelial-dominated CTCs to mesenchymal-dominated CTCs has correlation with the clinicopathological features and increased percentage of M+ CTCs may be associated with relatively poor prognosis,which indicates the prognostic significance of CTC phenotypes based on EMT.