A preliminary study on the association between epithelial-mesenchymal transition and circulating tumor cells in renal cell carcinoma

BACKGROUND: Circulating tumor cells (CTCs) are considered useful prognostic factors for various cancers, and in 2014, our research group conducted a comparative experiment of CTC detection in patients with renal cell cancer (RCC). However, the reason for the low detection rate of CTCs in cancer patients using the CellSearch(®) system is still unknown, although it has been hypothesized to be attributed to the likelihood that CTCs undergoing epithelial-mesenchymal transition (EMT) do not express the CTC biomarkers cytokeratin (CK)8/18/19 or epithelial cell adhesion molecule (EpCAM). The overall aim of the current study was to investigate the expression levels of CK8/18/19 and EpCAM in relation to the EMT biomarkers vimentin and E-cadherin in patients with RCC. METHODS: Patients with RCC who had undergone radical nephrectomy or partial resection between May 2014 and December 2014 were initially recruited. RESULTS: Among 34 RCC patients, nine co-expressed EpCAM and CK8/18/19 in primary tumor tissues. The CellSearch(®) results showed that CK8/18/19 was expressed in 5 of 6 patients (5/6) and EpCAM was expressed in 6 patients (6/6). However, the isolation by size of tumor cells (ISET) technique showed these were co-expressed in only four of the 10. The expression of CK8/18/19, EpCAM, vimentin, and E-cadherin was distributed unequally in different enumeration groups of CTCs (all P>0.05), and the positive expression of CK8/18/19 was correlated with neutrophil number and tumor size (P<0.05). The positive expression of vimentin was correlated with the Karnofsky Performance Status (KPS) score and clinical stage of renal cancer patients (P<0.05). CONCLUSIONS: Our results indirectly proved the occurrence of EMT in the formation of CTCs by comparing and analyzing the expression of CK8/18/19 and EpCAM in renal cancer tissues and the detection results of CTCs.