Background
The purposes of the study were to enumerate and characterise the circulating tumour cell (CTC) and cluster/micro-emboli (CTM) in blood from patients with colorectal carcinoma (CRC) as well as to investigate their clinical relevance.
Conclusion
Our findings provide insights into the biology of the CTC, presence of heterogeneous CTC populations in CRC and differential expression of genes in different pathological stages of CTC which can improve the management of patients with CRC.
Methods
Peripheral blood of six healthy donors (control) and sixty-two patients with CRC were collected to isolate CTCs by an immunomagnetic negative selection approach. EPCAM and cytokeratin 18 (CK18) antibodies were used to identify the CTCs. The size and the phenotypic variations were evaluated to characterise these isolated CTCs. Additionally, mRNA expressions of the CTCs and the corresponding primary carcinoma were assessed using a multi-gene panel to determine the cellular heterogeneities between CTCs and primary carcinoma.
Results
We detected CTCs and CTMs in 72% (41/57) and 32% (18/57) of the patients with CRC, respectively. The total number and length were significantly higher (p<0.0001) in the CTCs than the CTMs. CTCs, especially EPCAMPositiveCK18Posositve subclones, were detected more in the patients with advanced pathological cancer stages when compared to those with early cancer stages (mean: 12.5 vs 4.0, p=0.0068). mRNA profiling of CTCs unveiled three different CTC subtypes expressing epithelial, epithelium-mesenchymal transition (EMT) and stemness signatures, which were different from those of the primary carcinoma. The expressions of EPCAM, HRAS, BRAF, TP53, SLUG, TWIST1, CD44 and MMP9 of CTCs were altered when compared to the primary tumours in patients with CRC.