Figure 8
Clinical significance of gene expression signatures in the CTC cluster-originating clone. (a) GSEA comparing breast cancer patient-derived CTC clusters with single CTCs, thereby illustrating cellular components that characterize CTC clusters. Cytoscape and Enrichment Map were used to visualize GSEA results as a network of enriched gene sets (FDR q-value < 0.18). Nodes representing enriched gene sets are grouped and annotated by their similarity according to related gene sets. The node size is proportional to the number of genes in each gene set. Gene sets are shown with enrichment significance (FDR q-value), which is seen as a node color gradient. The proportion of genes shared between gene sets (similarity coefficient) is represented as the thickness of green lines between nodes. Black circles represent summarized gene set clusters based on AutoAnnotate. The annotation names involved in cortical actin-myosin assemblies and cell–cell adhesion are in purple type. Detailed GSEA results can be found in Supplementary Table S6. (b) GSEA enrichment plots showing representative enriched gene sets in up-regulated genes in CTC clusters compared with single CTCs. Normalized enrichment scores (NESs) and FDR q-values are shown for sarcoplasm and actomyosin. (c) GSEA results for genes in the signature EBP-H for various clinicopathological indexes in the TCGA HNSCC cohorts of primary tumor samples. NES, nominal (Nom) p-values, and FDR q-values are shown. Meta., metastasis. (d) GSEA enrichment plots for the LDR group compared with the NR group, which correspond to (c). (e) A proposed model in which relatively rare clones in primary tumors, which highly express a subset of EBP genes, aggressively generate and maintain homotypic CTC clusters through cell–cell adhesion by E-cadherin in blood circulation, which leads to dominant colonization of secondary sites. Homotypic CTC clusters originating from such clones can reorganize the actin cytoskeleton along with regulation of cortical tensions by myosin in response to external FSS, which leads to lower cortical tension along attachment surfaces compared with their free external surfaces and thereby strengthened cell–cell adhesion.
