Detection of circulating tumor cells and evaluation of epithelial-mesenchymal transition patterns of circulating tumor cells in ovarian cancer

Abstract

Background: Circulating tumor cells (CTCs) have considered to be promising liquid biopsy in cancer due to the intact information of whole cells and the potential to reflect micrometastasis. However, CTCs research are extremely limited in ovarian cancer, probably due to their rarity. The predictive value of CTCs and circulating tumor microemboli (CTM) in metastasis remains to be elucidated in ovarian cancer. This study tried to identify CTCs/CTM in ovarian cancer with considerably positive rate. To preliminarily identify the invasive capacity of CTCs/CTM, the epithelial-mesenchymal transition (EMT) patterns of CTCs/CTM was evaluated. Moreover, for comprehensive understanding of invasiveness of disseminated cells in ovarian cancer, EMT pattern of exfoliated tumor cells in ascites were also confirmed in this study.Methods: Peripheral blood samples and ascites samples were collected from 22 ovarian cancer patients.The Microfiltration combined with morphological analysis was used to detect CTC single cells or cell clusters. Microfiltration combined with morphological analysis was applied in the CTC isolation and identification. EMT was evaluated by immunofluorescence via markers including vimentin and cytokeratin.Results: Microfiltration combined with morphological analysis was introduced to detect CTCs/CTM with a positivity rate of 40.9% in ovarian cancer patients. The number of CTC varied from 1 to 8, with CTM number from 4 to 30. CTCs/CTM of all samples have experienced EMT process. Vimentin was expressed in all CTC samples and all tumor cells in ascites, while cytokeratin was expressed in 44.4% (4/9) of CTC samples. There were no significant differences of the clinical parameters between the CTC-positive and CTC-negative patients.Conclusions: This study showed that both CTCs/CTM and detached tumor cells in ascites might have undergone complete or partial EMT in ovarian cancer. Moreover, microfiltration combined with cytomorphological analysis showed a considerable CTC detection rate.

Liquid biopsy in ovarian cancer in China and the world: current status and future perspectives

“…However, the concentration of CTCs in peripheral blood in early stages of OC is low, necessitating specialized techniques for enrichment and detection ( 42 , 54 – 56 ). These techniques may include immunoaffinity and immunomagnetic techniques ( 54 ), dialectrophoresis and other microfluidic techniques ( 44 , 57 ), as well as others for enrichment and detection.…”

Single-cell analysis technologies for cancer research: from tumor-specific single cell discovery to cancer therapy

“…CTCs are present in peripheral blood in different forms, both as free individual CTCs and as aggregated cell clusters ( Amintas et al, 2020 ), known as circulating tumor microemboli (CTM). Tumor cells undergo epithelial mesenchymal transition (EMT) ( Jie et al, 2022 ) during their entry into peripheral circulation, resulting in different types of CTC, including those with an epithelial phenotype, those with a mesenchymal phenotype, and those with a mixed epithelial and mesenchymal phenotype. During EMT, the expression of epithelial markers such as E-cadherin, EpCAM, and cytokeratins decreases, while the expression of mesenchymal markers such as N-cadherin, vimentin, and fibronectin increases.…”