Circulating Tumor Cells Investigation in Esophageal Cancer

Background: An increasing number of studies have established that circulating tumor cells (CTCs) are a heterogeneous population in which cells have different degrees of metastatic potential mainly due to epithelial-mesenchymal transition (EMT). This study aimed to assess the feasibility of circulating esophageal cancer cells identification, characterization and to evaluate their prognostic value in esophageal cancer Methods: In order to closely mimic CTC heterogeneity, MC10A and HMEL cell lines differently forced in EMT are used. Single cell analysis was conducted by DEPArray. We assigned a specific phenotypic tag to each potential CTC population: Epithelial-tag, Mesenchymal/stem-tag. We evaluated the basal cell phenotype and after EMT induction. Subsequently, the Grab all assay was performed on peripheral blood samples from patients with esophageal cancer. This feasibility study enrolled 11 patients (4 M1, 7 M0). Analyses were conducted on 3 peripheral blood samples (15/20 ml) per patients. Blood samples from non-metastatic patients were taken before and after primary neo-adjuvant therapy and after secondary treatment (surgery). Samples from metastatic patients were taken before and after first line therapy and after second line therapy. CTCs were identified and sorted singly by DEPArray system. Results: The assay was able to detect the phenotypic changes in cell lines mimicking CTC heterogeneity. Before therapy, CTCs were found in 3/4 metastatic patients. Of the 7 non-metastatic patients, 3 were positive for CTCs before therapy. Examining CTC status at different clinical time points, it was possible to suggest a correlation between the presence of CTCs and disease progression. Conclusions: Data showed that the assay is feasible, capable to analyze the phenotypic tags by DEPArray using a multiple staining without aspecific signals. Experiments carried out from both metastatic/non metastatic cancer patients showed the ability of the Grab-allassay to identify subpopulations of CTCs with different epithelial/stem/mesenchymal or hybrid phenotypes potentially related to disease progression.