Cell Lines of Circulating Tumor Cells: What Is Known and What Needs to Be Resolved

Abstract

The importance of circulating tumor cells (CTC) is well recognized. However, the biological characteristics of CTC in the bloodstream have not yet been examined in detail, due to the limited number of CTC cell lines currently available. Thirty-nine CTC cell lines were reported by 2021. For successful cell culturing, these CTC cell lines were reviewed. Previous studies on short-term cultures of CTC also analyzed approaches for establishing the long-term culture of CTC. Negative selection, hypoxic conditions, three-dimensional conditions, and careful management are preferable for the long-term culture of CTC. However, the establishment of CTC cell lines is dependent on the specific characteristics of each cell type. Therefore, a method to establish CTC cell lines has not yet been developed. Further efforts are needed to resolve this issue.

Circulating Tumor Cells in Cancer Diagnostics and Prognostics by Single-Molecule and Single-Cell Characterization

“…94 The generation of CTC-derived cell lines can be achieved in both 2D or 3D cell culture environments. 95 Conventional (2D) cell culture has been used for both short-(48 h up to 6 months) and long-term (>6 months) CTC culture. 95 Zhang et al monitored survival and proliferation of mBRCA patientderived CTCs in culture over 28 days.…”

“…95 Conventional (2D) cell culture has been used for both short-(48 h up to 6 months) and long-term (>6 months) CTC culture. 95 Zhang et al monitored survival and proliferation of mBRCA patientderived CTCs in culture over 28 days. Sequential FACS sorting allowed the identification of an expanded cell subpopulation with a brain metastasis signature (HER2+/ EGFR+/HPSE+/Notch1+).…”

“…The seminal study generating the very first permanent CTC line from a mCRC patient led to the establishment of eight more permanent CTC lines corresponding to different time points throughout the patient’s follow-up . The reader is referred to the recent review of Shimada et al for a more detailed summary of the protocols used for the establishment of CTC lines . As mentioned above, 3D models are more appropriate biomimetic substrates, as they present higher relevance to human physiology compared to 2D or commercialized 2.5D approaches (e.g., Matrigel) .…”

“…101 The reader is referred to the recent review of Shimada et al for a more detailed summary of the protocols used for the establishment of CTC lines. 95 As mentioned above, 3D models are more appropriate biomimetic substrates, as they present higher relevance to human physiology compared to 2D or commercialized 2.5D approaches (e.g., Matrigel). 102 Both in vivo and in vitro CTC-derived preclinical 3D tumor models have been developed.…”

Systematic optimization of culture conditions and evaluation of in vitro Circulating tumor cell clusters

“…CTC permanent cell lines are difficult to culture and have a low success rate, resulting in the small number available. In addition, the final molecular characteristics of CTC cells after long-term culture no longer represent the original tumor phenotype, so the availability of CTC cell lines is often questioned [8].…”