Deciphering the Biology of Circulating Tumor Cells through Single-Cell RNA Sequencing: Implications for Precision Medicine in Cancer

Abstract

Circulating tumor cells (CTCs) hold unique biological characteristics that directly involve them in hematogenous dissemination. Studying CTCs systematically is technically challenging due to their extreme rarity and heterogeneity and the lack of specific markers to specify metastasis-initiating CTCs. With cutting-edge technology, single-cell RNA sequencing (scRNA-seq) provides insights into the biology of metastatic processes driven by CTCs. Transcriptomics analysis of single CTCs can decipher tumor heterogeneity and phenotypic plasticity for exploring promising novel therapeutic targets. The integrated approach provides a perspective on the mechanisms underlying tumor development and interrogates CTCs interactions with other blood cell types, particularly those of the immune system. This review aims to comprehensively describe the current study on CTC transcriptomic analysis through scRNA-seq technology. We emphasize the workflow for scRNA-seq analysis of CTCs, including enrichment, single cell isolation, and bioinformatic tools applied for this purpose. Furthermore, we elucidated the translational knowledge from the transcriptomic profile of individual CTCs and the biology of cancer metastasis for developing effective therapeutics through targeting key pathways in CTCs.

Prognostic evaluation of a multi-target magnetic bead-enriched circulating tumor cell-enriched identification system for colorectal cancer

“…Studies have shown that the 5-year survival rate of CRC patients is only 65%, and about half of CRC patients will eventually relapse and metastasize ( 24 , 25 ). CellSearch ® enables clinical surveillance of patients with CRC ( 26 - 29 ), in addition there is a high association between the number of CTCs and clinical outcome in tumor patients ( 30 ). Since some of the CTCs lack EpCAM expression, they could not be analyzed using CellSearch ® , which limited the Clinical practice of CTCs.…”

Integrated Microfluidics for Single‐Cell Separation and On‐Chip Analysis: Novel Applications and Recent Advances

“…[ 114,183,184 ] Furthermore, CTCs may exist as clusters rather than single cells, complicating their handling in microfluidic devices. [ 185,186 ] Lastly, the expectation for direct isolation and analysis of CTCs from blood samples without prior off‐chip processing adds a layer of complexity to the design of integrated microfluidic platforms. Despite such challenges, systems capable of executing complete workflows from whole blood samples have been emerging.…”

Circulating Nucleic Acids in Colorectal Cancer: Diagnostic and Prognostic Value

“…Viability is the paramount consideration, particularly in the context of drug efficacy evaluations at the level of a single CTC and culture experiments. Accordingly, the separation procedure must ensure cell viability and purity of CTCs for genome and protein profiling, allowing for adequate materials for characterizing heterogeneity through large-scale single-cell data [ 23 ]. Insufficient enrichment purity can introduce enigmas, making single-cell data analysis more challenging [ 14 ].…”